[multicast] prevent VLAN translation via match key enforcement - #195

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zeeshanlakhani merged 9 commits into
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vlan-translation
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[multicast] prevent VLAN translation via match key enforcement#195
zeeshanlakhani merged 9 commits into
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This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation. Previously, a packet arriving with VLAN 100 destined to a multicast group configured for VLAN 200 would be NAT encapsulated and forwarded, effectively translating the packet to the wrong customer's network.

NAT ingress table matching (mcast_nat.rs, mod.rs):

  • Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address, VLAN header validity, and VLAN ID
  • Each group installs a single NAT entry with an exact VLAN match key. Decapsulated Geneve packets never reach the NatIngress tables (guarded by !hdr.geneve.isValid()), so a separate untagged entry is unnecessary.
  • Packets with the wrong VLAN miss the entry and are not NAT encapsulated

Multicast router VLAN handling (sidecar.p4):

  • forward_vlan(vlan_id) action re-adds the group's configured VLAN on egress
  • Fix MulticastRouter4 using IPv6 ICMP error codes (ICMP6_DST_UNREACH) instead of IPv4 (ICMP_DEST_UNREACH)

Rollback changes:

  • Remove dead NAT rollback branches for internal groups (no NAT entries)
  • Add rollback support for VLAN changes in NAT and route tables

@zeeshanlakhani
[multicast] Narrow underlay scope to ff04::/64 and add ASM source fil…
731a821
…tering
Underlay changes:
- Restrict internal multicast from admin/site/org scoped (ff04, ff05, ff08)
to just Omicron's reserved subnet (ff04::/64). These underlay addresses are
made unique in Omicron.
- Rename `AdminScopedIpv6` to `UnderlayMulticastIpv6`.
- Simplify P4 to only match ff04::/64.
- Use omicron-common multicast constants for validation.
Source filtering changes:
- Replace IpSrc::Subnet with IpSrc::Any for any-source matching.
- Change IPv6 source filter from exact to LPM match.
- Allow source filters on ASM groups (previously SSM-only).
API changes:
- API v5 adds IpSrc::Any for ASM source filtering.
- API v6 enforces strict underlay subnet validation.
@zeeshanlakhani
[multicast] prevent VLAN translation via match key enforcement
e15d9e0
Fixes#107.
Stacked on #189.
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation.
Previously, a packet arriving with VLAN 100 destined to a multicast group
configured for VLAN 200 would be NAT encapsulated and forwarded, effectively
translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
- Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address,
VLAN header validity, and VLAN ID
- For groups with VLAN, install two entries: untagged (for decapsulated Geneve
from underlay) and correctly tagged (for customer packets)
- Packets with the wrong VLAN miss both entries and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
- Strip incoming VLAN tag before routing lookup in MulticastRouter4/6
- forward_vlan action re-adds the group's configured VLAN on egress
- Prevents unintended VLAN translation at the routing stage
Rollback changes:
- Remove dead NAT rollback branches for internal groups (no NAT entries)
- Add rollback support for VLAN changes in NAT and route tables
Counter fix:
- The underlay multicast counter condition was unreachable for packets tagged
MULTICAST_TAG_UNDERLAY_EXTERNAL that were not decapped. The check for
== MULTICAST_TAG_UNDERLAY excluded these packets, causing them to fall
through to the external counter.
Pull Request: #194
@zeeshanlakhanizeeshanlakhani self-assigned this Feb 19, 2026
@zeeshanlakhani
[merge+] merge main, renumber multicast API versions, add proper oper…
a1c8a94
…ation_ids
This includes some cleanup as well.
Base automatically changed from zl/admin-scope-oxnet to mainFebruary 26, 2026 12:07
FelixMcFelix
FelixMcFelix reviewed Feb 27, 2026
View reviewed changes
Comment threaddpd/src/table/mcast/mcast_nat.rs Outdated
@zeeshanlakhani
merge main into vlan-translation (includes#220Tofino observability)
dac47eb
@zeeshanlakhani
[review] simplify NAT entries to single exact-match per group
6669c82
Decapsulated Geneve packets never reach the NatIngress tables due to the
outermost !hdr.geneve.isValid() check, so the dual-entry approach (untagged +
tagged) per VLAN group is unnecessary. Each group now installs a single NAT
entry with an exact VLAN match key.
This also contains a fix for MulticastRouter4 (in P4) using IPv6 ICMP error codes
(ICMP6_DST_UNREACH) instead of IPv4 ones (ICMP_DEST_UNREACH), and removes redundant
entry-count assertions from VLAN lifecycle tests.
@zeeshanlakhani

zeeshanlakhani commented Mar 4, 2026

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@FelixMcFelix updated.

FelixMcFelix
FelixMcFelix approved these changes Mar 9, 2026
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I'm concerned about IPV4_LPM_SIZE, but I think I'm happy that this change is more correct. Thanks for acting on the earlier feedback!

Comment threaddpd-client/tests/integration_tests/mcast.rs Outdated
Comment threaddpd-client/tests/integration_tests/table_tests.rs
@zeeshanlakhani
[review] extract EthHdr::hdr_len() and add TODO for multicast LPM cap…
2d92c0b
…acity drop
- Adds EthHdr::hdr_len() to the packet crate to return the wire size of
the L2 header including any 802.1Q tag, replacing duplicate inline ops.
- Add a TODO noting multicast reduces IPv4 LPM capacity from 8187 to
7164.
@zeeshanlakhani
zeeshanlakhani merged commit 375a0f2 into mainMar 10, 2026
6 checks passed
@zeeshanlakhani
zeeshanlakhani deleted the vlan-translation branch March 10, 2026 01:14
zeeshanlakhani added a commit to oxidecomputer/omicron that referenced this pull request Mar 10, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite
2576c34
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
@zeeshanlakhanizeeshanlakhani mentioned this pull request Mar 10, 2026
Merged
zeeshanlakhani added a commit to oxidecomputer/omicron that referenced this pull request Mar 16, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite (#9951)
2353600
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
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Test flake in integration_tests::mcast::test_multicast_vlan_translation_not_possible

2 participants

@zeeshanlakhani@FelixMcFelix
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
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}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

Skip to content
[multicast] prevent VLAN translation via match key enforcement - #195
Merged
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Mar 10, 2026
Merged
[multicast] prevent VLAN translation via match key enforcement#195
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Conversation
@zeeshanlakhani
@zeeshanlakhanizeeshanlakhani
commented
Jan 22, 2026•

edited

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Contributor
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation. Previously, a packet arriving with VLAN 100 destined to a multicast group configured for VLAN 200 would be NAT encapsulated and forwarded, effectively translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
  • Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address, VLAN header validity, and VLAN ID
  • Each group installs a single NAT entry with an exact VLAN match key. Decapsulated Geneve packets never reach the NatIngress tables (guarded by !hdr.geneve.isValid()), so a separate untagged entry is unnecessary.
  • Packets with the wrong VLAN miss the entry and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
  • forward_vlan(vlan_id) action re-adds the group's configured VLAN on egress
  • Fix MulticastRouter4 using IPv6 ICMP error codes (ICMP6_DST_UNREACH) instead of IPv4 (ICMP_DEST_UNREACH)
Rollback changes:
  • Remove dead NAT rollback branches for internal groups (no NAT entries)
  • Add rollback support for VLAN changes in NAT and route tables
@zeeshanlakhani
[multicast] Narrow underlay scope to ff04::/64 and add ASM source fil…
731a821
…tering
Underlay changes:
- Restrict internal multicast from admin/site/org scoped (ff04, ff05, ff08)
to just Omicron's reserved subnet (ff04::/64). These underlay addresses are
made unique in Omicron.
- Rename `AdminScopedIpv6` to `UnderlayMulticastIpv6`.
- Simplify P4 to only match ff04::/64.
- Use omicron-common multicast constants for validation.
Source filtering changes:
- Replace IpSrc::Subnet with IpSrc::Any for any-source matching.
- Change IPv6 source filter from exact to LPM match.
- Allow source filters on ASM groups (previously SSM-only).
API changes:
- API v5 adds IpSrc::Any for ASM source filtering.
- API v6 enforces strict underlay subnet validation.
@zeeshanlakhani
[multicast] prevent VLAN translation via match key enforcement
e15d9e0
Fixes#107.
Stacked on #189.
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation.
Previously, a packet arriving with VLAN 100 destined to a multicast group
configured for VLAN 200 would be NAT encapsulated and forwarded, effectively
translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
- Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address,
VLAN header validity, and VLAN ID
- For groups with VLAN, install two entries: untagged (for decapsulated Geneve
from underlay) and correctly tagged (for customer packets)
- Packets with the wrong VLAN miss both entries and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
- Strip incoming VLAN tag before routing lookup in MulticastRouter4/6
- forward_vlan action re-adds the group's configured VLAN on egress
- Prevents unintended VLAN translation at the routing stage
Rollback changes:
- Remove dead NAT rollback branches for internal groups (no NAT entries)
- Add rollback support for VLAN changes in NAT and route tables
Counter fix:
- The underlay multicast counter condition was unreachable for packets tagged
MULTICAST_TAG_UNDERLAY_EXTERNAL that were not decapped. The check for
== MULTICAST_TAG_UNDERLAY excluded these packets, causing them to fall
through to the external counter.
Pull Request: #194
@zeeshanlakhanizeeshanlakhani
self-assigned this
Feb 19, 2026
@zeeshanlakhani
[merge+] merge main, renumber multicast API versions, add proper oper…
a1c8a94
…ation_ids
This includes some cleanup as well.

Base automatically changed from
zl/admin-scope-oxnet to
mainFebruary 26, 2026 12:07
FelixMcFelix
FelixMcFelix
reviewed
Feb 27, 2026
View reviewed changes
Comment threaddpd/src/table/mcast/mcast_nat.rs
Outdated

@zeeshanlakhani
merge main into vlan-translation (includes#220Tofino observability)
dac47eb
@zeeshanlakhani
[review] simplify NAT entries to single exact-match per group
6669c82
Decapsulated Geneve packets never reach the NatIngress tables due to the
outermost !hdr.geneve.isValid() check, so the dual-entry approach (untagged +
tagged) per VLAN group is unnecessary. Each group now installs a single NAT
entry with an exact VLAN match key.
This also contains a fix for MulticastRouter4 (in P4) using IPv6 ICMP error codes
(ICMP6_DST_UNREACH) instead of IPv4 ones (ICMP_DEST_UNREACH), and removes redundant
entry-count assertions from VLAN lifecycle tests.
@zeeshanlakhani
zeeshanlakhani
commented
Mar 4, 2026

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ContributorAuthor
@FelixMcFelix updated.
FelixMcFelix
FelixMcFelix
approved these changes
Mar 9, 2026
View reviewed changes
@FelixMcFelixFelixMcFelix
left a comment


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I'm concerned about IPV4_LPM_SIZE, but I think I'm happy that this change is more correct. Thanks for acting on the earlier feedback!
Comment threaddpd-client/tests/integration_tests/mcast.rs
Outdated

Comment threaddpd-client/tests/integration_tests/table_tests.rs
@zeeshanlakhani
[review] extract EthHdr::hdr_len() and add TODO for multicast LPM cap…
2d92c0b
…acity drop
- Adds EthHdr::hdr_len() to the packet crate to return the wire size of
the L2 header including any 802.1Q tag, replacing duplicate inline ops.
- Add a TODO noting multicast reduces IPv4 LPM capacity from 8187 to
7164.
@zeeshanlakhani
zeeshanlakhani
merged commit 375a0f2
into
mainMar 10, 2026

6 checks passed

@zeeshanlakhani
zeeshanlakhani
deleted the

vlan-translation

branch
March 10, 2026 01:14
zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 10, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite
2576c34
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
@zeeshanlakhanizeeshanlakhani
mentioned this pull request
Mar 10, 2026
 Merged

zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 16, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite (#9951)
2353600
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
Sign up for freeto join this conversation on GitHub.
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@FelixMcFelixFelixMcFelixFelixMcFelix approved these changes
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Test flake in integration_tests::mcast::test_multicast_vlan_translation_not_possible

2 participants

@zeeshanlakhani@FelixMcFelix

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
[multicast] prevent VLAN translation via match key enforcement - #195
Merged
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Mar 10, 2026
Merged
[multicast] prevent VLAN translation via match key enforcement#195
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Conversation
@zeeshanlakhani
@zeeshanlakhanizeeshanlakhani
commented
Jan 22, 2026•

edited

Loading

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Contributor
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation. Previously, a packet arriving with VLAN 100 destined to a multicast group configured for VLAN 200 would be NAT encapsulated and forwarded, effectively translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
  • Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address, VLAN header validity, and VLAN ID
  • Each group installs a single NAT entry with an exact VLAN match key. Decapsulated Geneve packets never reach the NatIngress tables (guarded by !hdr.geneve.isValid()), so a separate untagged entry is unnecessary.
  • Packets with the wrong VLAN miss the entry and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
  • forward_vlan(vlan_id) action re-adds the group's configured VLAN on egress
  • Fix MulticastRouter4 using IPv6 ICMP error codes (ICMP6_DST_UNREACH) instead of IPv4 (ICMP_DEST_UNREACH)
Rollback changes:
  • Remove dead NAT rollback branches for internal groups (no NAT entries)
  • Add rollback support for VLAN changes in NAT and route tables
@zeeshanlakhani
[multicast] Narrow underlay scope to ff04::/64 and add ASM source fil…
731a821
…tering
Underlay changes:
- Restrict internal multicast from admin/site/org scoped (ff04, ff05, ff08)
to just Omicron's reserved subnet (ff04::/64). These underlay addresses are
made unique in Omicron.
- Rename `AdminScopedIpv6` to `UnderlayMulticastIpv6`.
- Simplify P4 to only match ff04::/64.
- Use omicron-common multicast constants for validation.
Source filtering changes:
- Replace IpSrc::Subnet with IpSrc::Any for any-source matching.
- Change IPv6 source filter from exact to LPM match.
- Allow source filters on ASM groups (previously SSM-only).
API changes:
- API v5 adds IpSrc::Any for ASM source filtering.
- API v6 enforces strict underlay subnet validation.
@zeeshanlakhani
[multicast] prevent VLAN translation via match key enforcement
e15d9e0
Fixes#107.
Stacked on #189.
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation.
Previously, a packet arriving with VLAN 100 destined to a multicast group
configured for VLAN 200 would be NAT encapsulated and forwarded, effectively
translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
- Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address,
VLAN header validity, and VLAN ID
- For groups with VLAN, install two entries: untagged (for decapsulated Geneve
from underlay) and correctly tagged (for customer packets)
- Packets with the wrong VLAN miss both entries and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
- Strip incoming VLAN tag before routing lookup in MulticastRouter4/6
- forward_vlan action re-adds the group's configured VLAN on egress
- Prevents unintended VLAN translation at the routing stage
Rollback changes:
- Remove dead NAT rollback branches for internal groups (no NAT entries)
- Add rollback support for VLAN changes in NAT and route tables
Counter fix:
- The underlay multicast counter condition was unreachable for packets tagged
MULTICAST_TAG_UNDERLAY_EXTERNAL that were not decapped. The check for
== MULTICAST_TAG_UNDERLAY excluded these packets, causing them to fall
through to the external counter.
Pull Request: #194
@zeeshanlakhanizeeshanlakhani
self-assigned this
Feb 19, 2026
@zeeshanlakhani
[merge+] merge main, renumber multicast API versions, add proper oper…
a1c8a94
…ation_ids
This includes some cleanup as well.

Base automatically changed from
zl/admin-scope-oxnet to
mainFebruary 26, 2026 12:07
FelixMcFelix
FelixMcFelix
reviewed
Feb 27, 2026
View reviewed changes
Comment threaddpd/src/table/mcast/mcast_nat.rs
Outdated

@zeeshanlakhani
merge main into vlan-translation (includes#220Tofino observability)
dac47eb
@zeeshanlakhani
[review] simplify NAT entries to single exact-match per group
6669c82
Decapsulated Geneve packets never reach the NatIngress tables due to the
outermost !hdr.geneve.isValid() check, so the dual-entry approach (untagged +
tagged) per VLAN group is unnecessary. Each group now installs a single NAT
entry with an exact VLAN match key.
This also contains a fix for MulticastRouter4 (in P4) using IPv6 ICMP error codes
(ICMP6_DST_UNREACH) instead of IPv4 ones (ICMP_DEST_UNREACH), and removes redundant
entry-count assertions from VLAN lifecycle tests.
@zeeshanlakhani
zeeshanlakhani
commented
Mar 4, 2026

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@FelixMcFelix updated.
FelixMcFelix
FelixMcFelix
approved these changes
Mar 9, 2026
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I'm concerned about IPV4_LPM_SIZE, but I think I'm happy that this change is more correct. Thanks for acting on the earlier feedback!
Comment threaddpd-client/tests/integration_tests/mcast.rs
Outdated

Comment threaddpd-client/tests/integration_tests/table_tests.rs
@zeeshanlakhani
[review] extract EthHdr::hdr_len() and add TODO for multicast LPM cap…
2d92c0b
…acity drop
- Adds EthHdr::hdr_len() to the packet crate to return the wire size of
the L2 header including any 802.1Q tag, replacing duplicate inline ops.
- Add a TODO noting multicast reduces IPv4 LPM capacity from 8187 to
7164.
@zeeshanlakhani
zeeshanlakhani
merged commit 375a0f2
into
mainMar 10, 2026

6 checks passed

@zeeshanlakhani
zeeshanlakhani
deleted the

vlan-translation

branch
March 10, 2026 01:14
zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 10, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite
2576c34
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
@zeeshanlakhanizeeshanlakhani
mentioned this pull request
Mar 10, 2026
 Merged

zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 16, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite (#9951)
2353600
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
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@FelixMcFelixFelixMcFelixFelixMcFelix approved these changes
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Successfully merging this pull request may close these issues.

Test flake in integration_tests::mcast::test_multicast_vlan_translation_not_possible

2 participants

@zeeshanlakhani@FelixMcFelix

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
[multicast] prevent VLAN translation via match key enforcement - #195
Merged
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Mar 10, 2026
Merged
[multicast] prevent VLAN translation via match key enforcement#195
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Conversation
@zeeshanlakhani
@zeeshanlakhanizeeshanlakhani
commented
Jan 22, 2026•

edited

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This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation. Previously, a packet arriving with VLAN 100 destined to a multicast group configured for VLAN 200 would be NAT encapsulated and forwarded, effectively translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
  • Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address, VLAN header validity, and VLAN ID
  • Each group installs a single NAT entry with an exact VLAN match key. Decapsulated Geneve packets never reach the NatIngress tables (guarded by !hdr.geneve.isValid()), so a separate untagged entry is unnecessary.
  • Packets with the wrong VLAN miss the entry and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
  • forward_vlan(vlan_id) action re-adds the group's configured VLAN on egress
  • Fix MulticastRouter4 using IPv6 ICMP error codes (ICMP6_DST_UNREACH) instead of IPv4 (ICMP_DEST_UNREACH)
Rollback changes:
  • Remove dead NAT rollback branches for internal groups (no NAT entries)
  • Add rollback support for VLAN changes in NAT and route tables
@zeeshanlakhani
[multicast] Narrow underlay scope to ff04::/64 and add ASM source fil…
731a821
…tering
Underlay changes:
- Restrict internal multicast from admin/site/org scoped (ff04, ff05, ff08)
to just Omicron's reserved subnet (ff04::/64). These underlay addresses are
made unique in Omicron.
- Rename `AdminScopedIpv6` to `UnderlayMulticastIpv6`.
- Simplify P4 to only match ff04::/64.
- Use omicron-common multicast constants for validation.
Source filtering changes:
- Replace IpSrc::Subnet with IpSrc::Any for any-source matching.
- Change IPv6 source filter from exact to LPM match.
- Allow source filters on ASM groups (previously SSM-only).
API changes:
- API v5 adds IpSrc::Any for ASM source filtering.
- API v6 enforces strict underlay subnet validation.
@zeeshanlakhani
[multicast] prevent VLAN translation via match key enforcement
e15d9e0
Fixes#107.
Stacked on #189.
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation.
Previously, a packet arriving with VLAN 100 destined to a multicast group
configured for VLAN 200 would be NAT encapsulated and forwarded, effectively
translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
- Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address,
VLAN header validity, and VLAN ID
- For groups with VLAN, install two entries: untagged (for decapsulated Geneve
from underlay) and correctly tagged (for customer packets)
- Packets with the wrong VLAN miss both entries and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
- Strip incoming VLAN tag before routing lookup in MulticastRouter4/6
- forward_vlan action re-adds the group's configured VLAN on egress
- Prevents unintended VLAN translation at the routing stage
Rollback changes:
- Remove dead NAT rollback branches for internal groups (no NAT entries)
- Add rollback support for VLAN changes in NAT and route tables
Counter fix:
- The underlay multicast counter condition was unreachable for packets tagged
MULTICAST_TAG_UNDERLAY_EXTERNAL that were not decapped. The check for
== MULTICAST_TAG_UNDERLAY excluded these packets, causing them to fall
through to the external counter.
Pull Request: #194
@zeeshanlakhanizeeshanlakhani
self-assigned this
Feb 19, 2026
@zeeshanlakhani
[merge+] merge main, renumber multicast API versions, add proper oper…
a1c8a94
…ation_ids
This includes some cleanup as well.

Base automatically changed from
zl/admin-scope-oxnet to
mainFebruary 26, 2026 12:07
FelixMcFelix
FelixMcFelix
reviewed
Feb 27, 2026
View reviewed changes
Comment threaddpd/src/table/mcast/mcast_nat.rs
Outdated

@zeeshanlakhani
merge main into vlan-translation (includes#220Tofino observability)
dac47eb
@zeeshanlakhani
[review] simplify NAT entries to single exact-match per group
6669c82
Decapsulated Geneve packets never reach the NatIngress tables due to the
outermost !hdr.geneve.isValid() check, so the dual-entry approach (untagged +
tagged) per VLAN group is unnecessary. Each group now installs a single NAT
entry with an exact VLAN match key.
This also contains a fix for MulticastRouter4 (in P4) using IPv6 ICMP error codes
(ICMP6_DST_UNREACH) instead of IPv4 ones (ICMP_DEST_UNREACH), and removes redundant
entry-count assertions from VLAN lifecycle tests.
@zeeshanlakhani
zeeshanlakhani
commented
Mar 4, 2026

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@FelixMcFelix updated.
FelixMcFelix
FelixMcFelix
approved these changes
Mar 9, 2026
View reviewed changes
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I'm concerned about IPV4_LPM_SIZE, but I think I'm happy that this change is more correct. Thanks for acting on the earlier feedback!
Comment threaddpd-client/tests/integration_tests/mcast.rs
Outdated

Comment threaddpd-client/tests/integration_tests/table_tests.rs
@zeeshanlakhani
[review] extract EthHdr::hdr_len() and add TODO for multicast LPM cap…
2d92c0b
…acity drop
- Adds EthHdr::hdr_len() to the packet crate to return the wire size of
the L2 header including any 802.1Q tag, replacing duplicate inline ops.
- Add a TODO noting multicast reduces IPv4 LPM capacity from 8187 to
7164.
@zeeshanlakhani
zeeshanlakhani
merged commit 375a0f2
into
mainMar 10, 2026

6 checks passed

@zeeshanlakhani
zeeshanlakhani
deleted the

vlan-translation

branch
March 10, 2026 01:14
zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 10, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite
2576c34
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
@zeeshanlakhanizeeshanlakhani
mentioned this pull request
Mar 10, 2026
 Merged

zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 16, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite (#9951)
2353600
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
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@FelixMcFelixFelixMcFelixFelixMcFelix approved these changes
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Test flake in integration_tests::mcast::test_multicast_vlan_translation_not_possible

2 participants

@zeeshanlakhani@FelixMcFelix

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
[multicast] prevent VLAN translation via match key enforcement - #195
Merged
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Mar 10, 2026
Merged
[multicast] prevent VLAN translation via match key enforcement#195
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Conversation
@zeeshanlakhani
@zeeshanlakhanizeeshanlakhani
commented
Jan 22, 2026•

edited

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Contributor
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation. Previously, a packet arriving with VLAN 100 destined to a multicast group configured for VLAN 200 would be NAT encapsulated and forwarded, effectively translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
  • Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address, VLAN header validity, and VLAN ID
  • Each group installs a single NAT entry with an exact VLAN match key. Decapsulated Geneve packets never reach the NatIngress tables (guarded by !hdr.geneve.isValid()), so a separate untagged entry is unnecessary.
  • Packets with the wrong VLAN miss the entry and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
  • forward_vlan(vlan_id) action re-adds the group's configured VLAN on egress
  • Fix MulticastRouter4 using IPv6 ICMP error codes (ICMP6_DST_UNREACH) instead of IPv4 (ICMP_DEST_UNREACH)
Rollback changes:
  • Remove dead NAT rollback branches for internal groups (no NAT entries)
  • Add rollback support for VLAN changes in NAT and route tables
@zeeshanlakhani
[multicast] Narrow underlay scope to ff04::/64 and add ASM source fil…
731a821
…tering
Underlay changes:
- Restrict internal multicast from admin/site/org scoped (ff04, ff05, ff08)
to just Omicron's reserved subnet (ff04::/64). These underlay addresses are
made unique in Omicron.
- Rename `AdminScopedIpv6` to `UnderlayMulticastIpv6`.
- Simplify P4 to only match ff04::/64.
- Use omicron-common multicast constants for validation.
Source filtering changes:
- Replace IpSrc::Subnet with IpSrc::Any for any-source matching.
- Change IPv6 source filter from exact to LPM match.
- Allow source filters on ASM groups (previously SSM-only).
API changes:
- API v5 adds IpSrc::Any for ASM source filtering.
- API v6 enforces strict underlay subnet validation.
@zeeshanlakhani
[multicast] prevent VLAN translation via match key enforcement
e15d9e0
Fixes#107.
Stacked on #189.
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation.
Previously, a packet arriving with VLAN 100 destined to a multicast group
configured for VLAN 200 would be NAT encapsulated and forwarded, effectively
translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
- Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address,
VLAN header validity, and VLAN ID
- For groups with VLAN, install two entries: untagged (for decapsulated Geneve
from underlay) and correctly tagged (for customer packets)
- Packets with the wrong VLAN miss both entries and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
- Strip incoming VLAN tag before routing lookup in MulticastRouter4/6
- forward_vlan action re-adds the group's configured VLAN on egress
- Prevents unintended VLAN translation at the routing stage
Rollback changes:
- Remove dead NAT rollback branches for internal groups (no NAT entries)
- Add rollback support for VLAN changes in NAT and route tables
Counter fix:
- The underlay multicast counter condition was unreachable for packets tagged
MULTICAST_TAG_UNDERLAY_EXTERNAL that were not decapped. The check for
== MULTICAST_TAG_UNDERLAY excluded these packets, causing them to fall
through to the external counter.
Pull Request: #194
@zeeshanlakhanizeeshanlakhani
self-assigned this
Feb 19, 2026
@zeeshanlakhani
[merge+] merge main, renumber multicast API versions, add proper oper…
a1c8a94
…ation_ids
This includes some cleanup as well.

Base automatically changed from
zl/admin-scope-oxnet to
mainFebruary 26, 2026 12:07
FelixMcFelix
FelixMcFelix
reviewed
Feb 27, 2026
View reviewed changes
Comment threaddpd/src/table/mcast/mcast_nat.rs
Outdated

@zeeshanlakhani
merge main into vlan-translation (includes#220Tofino observability)
dac47eb
@zeeshanlakhani
[review] simplify NAT entries to single exact-match per group
6669c82
Decapsulated Geneve packets never reach the NatIngress tables due to the
outermost !hdr.geneve.isValid() check, so the dual-entry approach (untagged +
tagged) per VLAN group is unnecessary. Each group now installs a single NAT
entry with an exact VLAN match key.
This also contains a fix for MulticastRouter4 (in P4) using IPv6 ICMP error codes
(ICMP6_DST_UNREACH) instead of IPv4 ones (ICMP_DEST_UNREACH), and removes redundant
entry-count assertions from VLAN lifecycle tests.
@zeeshanlakhani
zeeshanlakhani
commented
Mar 4, 2026

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ContributorAuthor
@FelixMcFelix updated.
FelixMcFelix
FelixMcFelix
approved these changes
Mar 9, 2026
View reviewed changes
@FelixMcFelixFelixMcFelix
left a comment


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I'm concerned about IPV4_LPM_SIZE, but I think I'm happy that this change is more correct. Thanks for acting on the earlier feedback!
Comment threaddpd-client/tests/integration_tests/mcast.rs
Outdated

Comment threaddpd-client/tests/integration_tests/table_tests.rs
@zeeshanlakhani
[review] extract EthHdr::hdr_len() and add TODO for multicast LPM cap…
2d92c0b
…acity drop
- Adds EthHdr::hdr_len() to the packet crate to return the wire size of
the L2 header including any 802.1Q tag, replacing duplicate inline ops.
- Add a TODO noting multicast reduces IPv4 LPM capacity from 8187 to
7164.
@zeeshanlakhani
zeeshanlakhani
merged commit 375a0f2
into
mainMar 10, 2026

6 checks passed

@zeeshanlakhani
zeeshanlakhani
deleted the

vlan-translation

branch
March 10, 2026 01:14
zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 10, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite
2576c34
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
@zeeshanlakhanizeeshanlakhani
mentioned this pull request
Mar 10, 2026
 Merged

zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 16, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite (#9951)
2353600
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers

@FelixMcFelixFelixMcFelixFelixMcFelix approved these changes
@NieuwejaarNieuwejaarAwaiting requested review from Nieuwejaar

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Successfully merging this pull request may close these issues.

Test flake in integration_tests::mcast::test_multicast_vlan_translation_not_possible

2 participants

@zeeshanlakhani@FelixMcFelix

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
[multicast] prevent VLAN translation via match key enforcement - #195
Merged
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Mar 10, 2026
Merged
[multicast] prevent VLAN translation via match key enforcement#195
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Conversation
@zeeshanlakhani
@zeeshanlakhanizeeshanlakhani
commented
Jan 22, 2026•

edited

Loading

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Contributor
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation. Previously, a packet arriving with VLAN 100 destined to a multicast group configured for VLAN 200 would be NAT encapsulated and forwarded, effectively translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
  • Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address, VLAN header validity, and VLAN ID
  • Each group installs a single NAT entry with an exact VLAN match key. Decapsulated Geneve packets never reach the NatIngress tables (guarded by !hdr.geneve.isValid()), so a separate untagged entry is unnecessary.
  • Packets with the wrong VLAN miss the entry and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
  • forward_vlan(vlan_id) action re-adds the group's configured VLAN on egress
  • Fix MulticastRouter4 using IPv6 ICMP error codes (ICMP6_DST_UNREACH) instead of IPv4 (ICMP_DEST_UNREACH)
Rollback changes:
  • Remove dead NAT rollback branches for internal groups (no NAT entries)
  • Add rollback support for VLAN changes in NAT and route tables
@zeeshanlakhani
[multicast] Narrow underlay scope to ff04::/64 and add ASM source fil…
731a821
…tering
Underlay changes:
- Restrict internal multicast from admin/site/org scoped (ff04, ff05, ff08)
to just Omicron's reserved subnet (ff04::/64). These underlay addresses are
made unique in Omicron.
- Rename `AdminScopedIpv6` to `UnderlayMulticastIpv6`.
- Simplify P4 to only match ff04::/64.
- Use omicron-common multicast constants for validation.
Source filtering changes:
- Replace IpSrc::Subnet with IpSrc::Any for any-source matching.
- Change IPv6 source filter from exact to LPM match.
- Allow source filters on ASM groups (previously SSM-only).
API changes:
- API v5 adds IpSrc::Any for ASM source filtering.
- API v6 enforces strict underlay subnet validation.
@zeeshanlakhani
[multicast] prevent VLAN translation via match key enforcement
e15d9e0
Fixes#107.
Stacked on #189.
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation.
Previously, a packet arriving with VLAN 100 destined to a multicast group
configured for VLAN 200 would be NAT encapsulated and forwarded, effectively
translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
- Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address,
VLAN header validity, and VLAN ID
- For groups with VLAN, install two entries: untagged (for decapsulated Geneve
from underlay) and correctly tagged (for customer packets)
- Packets with the wrong VLAN miss both entries and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
- Strip incoming VLAN tag before routing lookup in MulticastRouter4/6
- forward_vlan action re-adds the group's configured VLAN on egress
- Prevents unintended VLAN translation at the routing stage
Rollback changes:
- Remove dead NAT rollback branches for internal groups (no NAT entries)
- Add rollback support for VLAN changes in NAT and route tables
Counter fix:
- The underlay multicast counter condition was unreachable for packets tagged
MULTICAST_TAG_UNDERLAY_EXTERNAL that were not decapped. The check for
== MULTICAST_TAG_UNDERLAY excluded these packets, causing them to fall
through to the external counter.
Pull Request: #194
@zeeshanlakhanizeeshanlakhani
self-assigned this
Feb 19, 2026
@zeeshanlakhani
[merge+] merge main, renumber multicast API versions, add proper oper…
a1c8a94
…ation_ids
This includes some cleanup as well.

Base automatically changed from
zl/admin-scope-oxnet to
mainFebruary 26, 2026 12:07
FelixMcFelix
FelixMcFelix
reviewed
Feb 27, 2026
View reviewed changes
Comment threaddpd/src/table/mcast/mcast_nat.rs
Outdated

@zeeshanlakhani
merge main into vlan-translation (includes#220Tofino observability)
dac47eb
@zeeshanlakhani
[review] simplify NAT entries to single exact-match per group
6669c82
Decapsulated Geneve packets never reach the NatIngress tables due to the
outermost !hdr.geneve.isValid() check, so the dual-entry approach (untagged +
tagged) per VLAN group is unnecessary. Each group now installs a single NAT
entry with an exact VLAN match key.
This also contains a fix for MulticastRouter4 (in P4) using IPv6 ICMP error codes
(ICMP6_DST_UNREACH) instead of IPv4 ones (ICMP_DEST_UNREACH), and removes redundant
entry-count assertions from VLAN lifecycle tests.
@zeeshanlakhani
zeeshanlakhani
commented
Mar 4, 2026

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ContributorAuthor
@FelixMcFelix updated.
FelixMcFelix
FelixMcFelix
approved these changes
Mar 9, 2026
View reviewed changes
@FelixMcFelixFelixMcFelix
left a comment


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I'm concerned about IPV4_LPM_SIZE, but I think I'm happy that this change is more correct. Thanks for acting on the earlier feedback!
Comment threaddpd-client/tests/integration_tests/mcast.rs
Outdated

Comment threaddpd-client/tests/integration_tests/table_tests.rs
@zeeshanlakhani
[review] extract EthHdr::hdr_len() and add TODO for multicast LPM cap…
2d92c0b
…acity drop
- Adds EthHdr::hdr_len() to the packet crate to return the wire size of
the L2 header including any 802.1Q tag, replacing duplicate inline ops.
- Add a TODO noting multicast reduces IPv4 LPM capacity from 8187 to
7164.
@zeeshanlakhani
zeeshanlakhani
merged commit 375a0f2
into
mainMar 10, 2026

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to oxidecomputer/omicron
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Mar 10, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite
2576c34
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
@zeeshanlakhanizeeshanlakhani
mentioned this pull request
Mar 10, 2026
 Merged

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Mar 16, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite (#9951)
2353600
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
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Test flake in integration_tests::mcast::test_multicast_vlan_translation_not_possible

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@zeeshanlakhani@FelixMcFelix

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
[multicast] prevent VLAN translation via match key enforcement - #195
Merged
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Mar 10, 2026
Merged
[multicast] prevent VLAN translation via match key enforcement#195
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Conversation
@zeeshanlakhani
@zeeshanlakhanizeeshanlakhani
commented
Jan 22, 2026•

edited

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This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation. Previously, a packet arriving with VLAN 100 destined to a multicast group configured for VLAN 200 would be NAT encapsulated and forwarded, effectively translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
  • Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address, VLAN header validity, and VLAN ID
  • Each group installs a single NAT entry with an exact VLAN match key. Decapsulated Geneve packets never reach the NatIngress tables (guarded by !hdr.geneve.isValid()), so a separate untagged entry is unnecessary.
  • Packets with the wrong VLAN miss the entry and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
  • forward_vlan(vlan_id) action re-adds the group's configured VLAN on egress
  • Fix MulticastRouter4 using IPv6 ICMP error codes (ICMP6_DST_UNREACH) instead of IPv4 (ICMP_DEST_UNREACH)
Rollback changes:
  • Remove dead NAT rollback branches for internal groups (no NAT entries)
  • Add rollback support for VLAN changes in NAT and route tables
@zeeshanlakhani
[multicast] Narrow underlay scope to ff04::/64 and add ASM source fil…
731a821
…tering
Underlay changes:
- Restrict internal multicast from admin/site/org scoped (ff04, ff05, ff08)
to just Omicron's reserved subnet (ff04::/64). These underlay addresses are
made unique in Omicron.
- Rename `AdminScopedIpv6` to `UnderlayMulticastIpv6`.
- Simplify P4 to only match ff04::/64.
- Use omicron-common multicast constants for validation.
Source filtering changes:
- Replace IpSrc::Subnet with IpSrc::Any for any-source matching.
- Change IPv6 source filter from exact to LPM match.
- Allow source filters on ASM groups (previously SSM-only).
API changes:
- API v5 adds IpSrc::Any for ASM source filtering.
- API v6 enforces strict underlay subnet validation.
@zeeshanlakhani
[multicast] prevent VLAN translation via match key enforcement
e15d9e0
Fixes#107.
Stacked on #189.
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation.
Previously, a packet arriving with VLAN 100 destined to a multicast group
configured for VLAN 200 would be NAT encapsulated and forwarded, effectively
translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
- Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address,
VLAN header validity, and VLAN ID
- For groups with VLAN, install two entries: untagged (for decapsulated Geneve
from underlay) and correctly tagged (for customer packets)
- Packets with the wrong VLAN miss both entries and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
- Strip incoming VLAN tag before routing lookup in MulticastRouter4/6
- forward_vlan action re-adds the group's configured VLAN on egress
- Prevents unintended VLAN translation at the routing stage
Rollback changes:
- Remove dead NAT rollback branches for internal groups (no NAT entries)
- Add rollback support for VLAN changes in NAT and route tables
Counter fix:
- The underlay multicast counter condition was unreachable for packets tagged
MULTICAST_TAG_UNDERLAY_EXTERNAL that were not decapped. The check for
== MULTICAST_TAG_UNDERLAY excluded these packets, causing them to fall
through to the external counter.
Pull Request: #194
@zeeshanlakhanizeeshanlakhani
self-assigned this
Feb 19, 2026
@zeeshanlakhani
[merge+] merge main, renumber multicast API versions, add proper oper…
a1c8a94
…ation_ids
This includes some cleanup as well.

Base automatically changed from
zl/admin-scope-oxnet to
mainFebruary 26, 2026 12:07
FelixMcFelix
FelixMcFelix
reviewed
Feb 27, 2026
View reviewed changes
Comment threaddpd/src/table/mcast/mcast_nat.rs
Outdated

@zeeshanlakhani
merge main into vlan-translation (includes#220Tofino observability)
dac47eb
@zeeshanlakhani
[review] simplify NAT entries to single exact-match per group
6669c82
Decapsulated Geneve packets never reach the NatIngress tables due to the
outermost !hdr.geneve.isValid() check, so the dual-entry approach (untagged +
tagged) per VLAN group is unnecessary. Each group now installs a single NAT
entry with an exact VLAN match key.
This also contains a fix for MulticastRouter4 (in P4) using IPv6 ICMP error codes
(ICMP6_DST_UNREACH) instead of IPv4 ones (ICMP_DEST_UNREACH), and removes redundant
entry-count assertions from VLAN lifecycle tests.
@zeeshanlakhani
zeeshanlakhani
commented
Mar 4, 2026

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@FelixMcFelix updated.
FelixMcFelix
FelixMcFelix
approved these changes
Mar 9, 2026
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I'm concerned about IPV4_LPM_SIZE, but I think I'm happy that this change is more correct. Thanks for acting on the earlier feedback!
Comment threaddpd-client/tests/integration_tests/mcast.rs
Outdated

Comment threaddpd-client/tests/integration_tests/table_tests.rs
@zeeshanlakhani
[review] extract EthHdr::hdr_len() and add TODO for multicast LPM cap…
2d92c0b
…acity drop
- Adds EthHdr::hdr_len() to the packet crate to return the wire size of
the L2 header including any 802.1Q tag, replacing duplicate inline ops.
- Add a TODO noting multicast reduces IPv4 LPM capacity from 8187 to
7164.
@zeeshanlakhani
zeeshanlakhani
merged commit 375a0f2
into
mainMar 10, 2026

6 checks passed

@zeeshanlakhani
zeeshanlakhani
deleted the

vlan-translation

branch
March 10, 2026 01:14
zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 10, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite
2576c34
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
@zeeshanlakhanizeeshanlakhani
mentioned this pull request
Mar 10, 2026
 Merged

zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 16, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite (#9951)
2353600
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers

@FelixMcFelixFelixMcFelixFelixMcFelix approved these changes
@NieuwejaarNieuwejaarAwaiting requested review from Nieuwejaar

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Successfully merging this pull request may close these issues.

Test flake in integration_tests::mcast::test_multicast_vlan_translation_not_possible

2 participants

@zeeshanlakhani@FelixMcFelix

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

Skip to content
[multicast] prevent VLAN translation via match key enforcement - #195
Merged
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Mar 10, 2026
Merged
[multicast] prevent VLAN translation via match key enforcement#195
zeeshanlakhani merged 9 commits into
mainfrom 
vlan-translation
Conversation
@zeeshanlakhani
@zeeshanlakhanizeeshanlakhani
commented
Jan 22, 2026•

edited

Loading

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Contributor
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation. Previously, a packet arriving with VLAN 100 destined to a multicast group configured for VLAN 200 would be NAT encapsulated and forwarded, effectively translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
  • Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address, VLAN header validity, and VLAN ID
  • Each group installs a single NAT entry with an exact VLAN match key. Decapsulated Geneve packets never reach the NatIngress tables (guarded by !hdr.geneve.isValid()), so a separate untagged entry is unnecessary.
  • Packets with the wrong VLAN miss the entry and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
  • forward_vlan(vlan_id) action re-adds the group's configured VLAN on egress
  • Fix MulticastRouter4 using IPv6 ICMP error codes (ICMP6_DST_UNREACH) instead of IPv4 (ICMP_DEST_UNREACH)
Rollback changes:
  • Remove dead NAT rollback branches for internal groups (no NAT entries)
  • Add rollback support for VLAN changes in NAT and route tables
@zeeshanlakhani
[multicast] Narrow underlay scope to ff04::/64 and add ASM source fil…
731a821
…tering
Underlay changes:
- Restrict internal multicast from admin/site/org scoped (ff04, ff05, ff08)
to just Omicron's reserved subnet (ff04::/64). These underlay addresses are
made unique in Omicron.
- Rename `AdminScopedIpv6` to `UnderlayMulticastIpv6`.
- Simplify P4 to only match ff04::/64.
- Use omicron-common multicast constants for validation.
Source filtering changes:
- Replace IpSrc::Subnet with IpSrc::Any for any-source matching.
- Change IPv6 source filter from exact to LPM match.
- Allow source filters on ASM groups (previously SSM-only).
API changes:
- API v5 adds IpSrc::Any for ASM source filtering.
- API v6 enforces strict underlay subnet validation.
@zeeshanlakhani
[multicast] prevent VLAN translation via match key enforcement
e15d9e0
Fixes#107.
Stacked on #189.
This adds VLAN-aware NAT ingress matching to prevent cross-VLAN translation.
Previously, a packet arriving with VLAN 100 destined to a multicast group
configured for VLAN 200 would be NAT encapsulated and forwarded, effectively
translating the packet to the wrong customer's network.
NAT ingress table matching (mcast_nat.rs, mod.rs):
- Add Ipv4VlanMatchKey and Ipv6VlanMatchKey that match on destination address,
VLAN header validity, and VLAN ID
- For groups with VLAN, install two entries: untagged (for decapsulated Geneve
from underlay) and correctly tagged (for customer packets)
- Packets with the wrong VLAN miss both entries and are not NAT encapsulated
Multicast router VLAN handling (sidecar.p4):
- Strip incoming VLAN tag before routing lookup in MulticastRouter4/6
- forward_vlan action re-adds the group's configured VLAN on egress
- Prevents unintended VLAN translation at the routing stage
Rollback changes:
- Remove dead NAT rollback branches for internal groups (no NAT entries)
- Add rollback support for VLAN changes in NAT and route tables
Counter fix:
- The underlay multicast counter condition was unreachable for packets tagged
MULTICAST_TAG_UNDERLAY_EXTERNAL that were not decapped. The check for
== MULTICAST_TAG_UNDERLAY excluded these packets, causing them to fall
through to the external counter.
Pull Request: #194
@zeeshanlakhanizeeshanlakhani
self-assigned this
Feb 19, 2026
@zeeshanlakhani
[merge+] merge main, renumber multicast API versions, add proper oper…
a1c8a94
…ation_ids
This includes some cleanup as well.

Base automatically changed from
zl/admin-scope-oxnet to
mainFebruary 26, 2026 12:07
FelixMcFelix
FelixMcFelix
reviewed
Feb 27, 2026
View reviewed changes
Comment threaddpd/src/table/mcast/mcast_nat.rs
Outdated

@zeeshanlakhani
merge main into vlan-translation (includes#220Tofino observability)
dac47eb
@zeeshanlakhani
[review] simplify NAT entries to single exact-match per group
6669c82
Decapsulated Geneve packets never reach the NatIngress tables due to the
outermost !hdr.geneve.isValid() check, so the dual-entry approach (untagged +
tagged) per VLAN group is unnecessary. Each group now installs a single NAT
entry with an exact VLAN match key.
This also contains a fix for MulticastRouter4 (in P4) using IPv6 ICMP error codes
(ICMP6_DST_UNREACH) instead of IPv4 ones (ICMP_DEST_UNREACH), and removes redundant
entry-count assertions from VLAN lifecycle tests.
@zeeshanlakhani
zeeshanlakhani
commented
Mar 4, 2026

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ContributorAuthor
@FelixMcFelix updated.
FelixMcFelix
FelixMcFelix
approved these changes
Mar 9, 2026
View reviewed changes
@FelixMcFelixFelixMcFelix
left a comment


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I'm concerned about IPV4_LPM_SIZE, but I think I'm happy that this change is more correct. Thanks for acting on the earlier feedback!
Comment threaddpd-client/tests/integration_tests/mcast.rs
Outdated

Comment threaddpd-client/tests/integration_tests/table_tests.rs
@zeeshanlakhani
[review] extract EthHdr::hdr_len() and add TODO for multicast LPM cap…
2d92c0b
…acity drop
- Adds EthHdr::hdr_len() to the packet crate to return the wire size of
the L2 header including any 802.1Q tag, replacing duplicate inline ops.
- Add a TODO noting multicast reduces IPv4 LPM capacity from 8187 to
7164.
@zeeshanlakhani
zeeshanlakhani
merged commit 375a0f2
into
mainMar 10, 2026

6 checks passed

@zeeshanlakhani
zeeshanlakhani
deleted the

vlan-translation

branch
March 10, 2026 01:14
zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 10, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite
2576c34
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
@zeeshanlakhanizeeshanlakhani
mentioned this pull request
Mar 10, 2026
 Merged

zeeshanlakhani added a commit
to oxidecomputer/omicron
that referenced
this pull request
Mar 16, 2026
@zeeshanlakhani
[multicast] Remove recovery path and update to latest dendrite (#9951)
2353600
This incorporates oxidecomputer/dendrite#232 and oxidecomputer/dendrite#195.
Note: No API changes here.
Sign up for freeto join this conversation on GitHub.
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Sign in to comment

Reviewers

@FelixMcFelixFelixMcFelixFelixMcFelix approved these changes
@NieuwejaarNieuwejaarAwaiting requested review from Nieuwejaar

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Successfully merging this pull request may close these issues.

Test flake in integration_tests::mcast::test_multicast_vlan_translation_not_possible

2 participants

@zeeshanlakhani@FelixMcFelix