Experimental

RFC 5305 - IS-IS Extensions for Traffic Engineering

Every requirement this repository extracted from RFC 5305, the tests bound to it, and what a reader has verified about them. This summary is enrolled and gated by ./le rfc check.

Overview

Positive

what Ze has

Tested both ways64.3%9 of 14 gated MUSTs

a positive test proves Ze does what the requirement demands and a negative one proves it refuses what the requirement forbids

One polarity plus reason0.0%0 of 14 gated MUSTs

the requirement admits no counter-case, so one polarity plus a recorded reason is the whole proof available for it

One polarity, unexcused0.0%0 of 14 gated MUSTs

one direction is tested, the other is neither tested nor excused, and nothing states which

Partial proof; remaining gap0.0%0 of 14 gated MUSTs

scoped tests exist; the remaining obligation is unmet or unproven, with zero whole-requirement credit

No test at all0.0%0 of 14 gated MUSTs

no test carries the requirement id, whether or not a gap states why

Proven by a recorded break83.3%20 of 24 tagged units

a red was observed once under a recorded procedure, and the unit, the claim and the producer it rested on still hash to what was recorded. The break is not re-run. A test pair is not a proof until one has been observed

Neutral

measures that are neither good news nor bad

Gated MUSTs14of 22 this summary declares

MUST-level requirements the gate HOLDS. A population, not a result: the shares beside it are what says how Ze stands

Out of scope5of 14 gated MUSTs

an obligation that does not bind Ze. A {not-applicable} annotation says it never bound; a {feature-declined} annotation says its condition is an optional feature Ze does not offer, and quotes the RFC sentence that makes it optional. Scope, not coverage: it stays in the denominator every share on this page is taken over

Not applicable35.7%5 of 14 gated MUSTs

a {not-applicable} annotation says the obligation does not bind Ze, so no test is owed for it. It stays in the denominator every share here is taken over

Met below Ze0.0%0 of 14 gated MUSTs

a {lower-layer} annotation says a layer under Ze performs the behavior, on state Ze installs into that layer, and names the producer that installs it. The obligation binds Ze and is met; Ze proves none of it, because its own boundary carries no value the behavior reads

Optional feature declined0.0%0 of 14 gated MUSTs

a {feature-declined} annotation says the obligation is conditional on a feature the RFC makes optional and Ze does not offer, and it quotes the sentence that makes it optional. The condition is false, so nothing is owed and nothing is missing. It stays in the denominator every share here is taken over

The 8 shares marked as a part above are the whole of the 14 gated MUSTs: they add to 100%. Proven by a recorded break is a share of TAGGED UNITS, a different population, so it is not one of them.

How to read the colors

A color names what the measure MEANS, not how well Ze scores on it. Green is a good outcome at any value, red is a bad one, and neither a population nor a scope count is an outcome, so both take no color. The number under the label is what says how far Ze has got.

Card	Tone here	Why that color
Gated MUSTs	neutral	no color: a population is a scale, and a larger one is neither good news nor bad. It is the accounting total
Out of scope	neutral	no color: an obligation that never bound Ze is neither an achievement nor a failure, and counting it either way would be a claim
Tested both ways	ok	green at every value: a test pair is the outcome this gate exists to produce, and the share under the label is what says how far Ze has got
One polarity plus reason	ok	green at every value: where no counter-case exists, one polarity IS the complete answer, and a recorded reason is what the gate demands beside it
One polarity, unexcused	ok	green at zero, RED above it: half a proof with no reason for the other half
Partial proof; remaining gap	ok	green at zero, RED above it: a tested clause cannot prove the whole requirement
No test at all	ok	green at zero, RED above it: a binding obligation nothing exercises is a claim with nothing behind it, whether or not a reason is stated
Not applicable	neutral	no color: an obligation that never bound Ze is neither an achievement nor a failure, and counting it either way would be a claim
Met below Ze	neutral	no color: an obligation met below Ze is neither a test Ze wrote nor work Ze owes, and the two green shares above are what says how much Ze proves itself
Optional feature declined	neutral	no color: an obligation whose condition Ze never meets is neither an achievement nor a failure. The absent FEATURE is disclosed on the RFC's own status row, as an implementation gap a later scope decision can revisit
Proven by a recorded break	ok	green at every value: an observed break is the outcome the discrimination gate exists to produce. The denominator is TAGGED UNITS, not obligations, so this share is not one of the parts above
Audit verdicts	warn	RED on the first weak, wrong or unimplemented verdict, amber while a verdict is no longer current or a gated MUST is unjudged, green when every one is judged sound and current

At a glance

Field	Value
Public status	Experimental
Enrolment	Enrolled
Requirements	22
Gated MUST-level	14
Not applicable, so out of scope	5
Declared gaps	0
Declared gaps a test demonstrates	0
Gated with no test	0
Nightly-only evidence	0
Test tags	24
Tagged units	24
Recorded audit verdicts	9
Discrimination records	20
Summary	`rfc/short/rfc5305.md`
Requirement shard	`rfc/requirements/rfc5305.md`
RFC text	`rfc/full/rfc5305.txt`

Enrolment

Enrolled: IS-IS Extensions for Traffic Engineering (TLV 22 extended IS reachability, TLV 135 extended IP reachability): eight MUST-level requirements. Five are met with positive+negative tags in internal/plugins/isis: 3-1 (a maximum-metric link is not considered in normal SPF), 4-1 (do not install a route at or above MaxPathMetric), 4.1-1 (set the up/down bit correctly on a down-leak), 2-1 (retain unknown sub-TLVs without rejecting). 3.2-2, 4.3-1 are {not-applicable}: ze originates no IS-IS TE sub-TLVs (6/8) or TLV 134. On 2026-09-30 the {not-applicable} markers came off 3.2-1, 3.3-1 and 4.3-4: those rows ban injecting a /32 for an address received in sub-TLV 6, sub-TLV 8 or TLV 134, Ze fills that receiving role (the BGP-LS export decodes all three), and TestRFC5305TEAddressesLeaveOnlyReachabilityRoutes and TestRFC5305TEAddressesInjectNoHostRoute prove from a received LSP that only the reachability prefix is installed and no /32 for any of the three addresses reaches the Loc-RIB or a BGP-LS Prefix NLRI.

What the public ledger says

Status: Experimental

What the ledger says is covered:

Extended IS reachability (TLV 22) and extended IPv4 reachability (TLV 135) with wide metrics and the up/down bit
unknown sub-TLVs retained
tests bound per requirement in rfc/requirements/rfc5305.md.

What the ledger says remains:

TE sub-TLVs (6/8) and TLV 134 (TE Router ID) are not implemented (no IS-IS TE).

Coverage

Bucket	Count	What it counts
Positive and negative tests	9	one part of the gated population
Annotated (including scoped evidence)	5	one part of the gated population
One polarity only	0	one part of the gated population
No test and no annotation	0	one part of the gated population
Partial proof; remaining gap (subset of annotated; zero whole-requirement credit)	0	an overlay: each of these is also counted by the part it falls in
Evidence that runs nightly only	0	an overlay: each of these is also counted by the part it falls in
Derived from other rows	0	outside the gated population: each asserts nothing and derives its state from the rows it names, which the parts above already count
Gated MUST-level requirements	14	every gated MUST falls in exactly one bucket above

Positive and negative tests (9): RFC5305-3-1, RFC5305-4-1, RFC5305-4.1-1, RFC5305-4.1-2, RFC5305-4.2-1, RFC5305-3.2-1, RFC5305-3.3-1, RFC5305-4.3-4, RFC5305-2-1

Annotated (including scoped evidence) (5): RFC5305-4.1-3, RFC5305-3.7-1, RFC5305-3.2-2, RFC5305-3.3-2, RFC5305-4.3-1

Requirements

Requirement	Level	Section	Tests
`RFC5305-3-1`	If a link is advertised with the maximum link metric (2^24 - 1), this link MUST NOT be considered during the normal SPF computation. (§3)
	MUST NOT	3	positive`unit/verifyTestISISSPFMaxLinkMetricExcluded` negative`unit/verifyTestISISSPFMaxLinkMetricExcluded`
`RFC5305-4-1`	If a prefix is advertised with a metric larger then MAX_PATH_METRIC (0xFE000000, see paragraph 3.0), this prefix MUST NOT be considered during the normal SPF computation. (§4)
	MUST NOT	4	positive`unit/verifyTestISISMetricWidth` positive`unit/verifyTestRFC5305PrefixAboveMaxPathMetricNotConsidered` negative`unit/verifyTestISISMetricWidth` negative`unit/verifyTestRFC5305PrefixAboveMaxPathMetricNotConsidered`
`RFC5305-4.1-1`	If a prefix is advertised from a higher level to a lower level (e.g., level 2 to level 1), the bit MUST be set to 1, indicating that the prefix has traveled down the hierarchy. Prefixes that have the up/down bit set to 1 may only be advertised down the hierarchy, i.e., to lower levels. These semantics apply even if IS-IS is extended in the future to have additional levels. By ensuring that prefixes follow only the IS-IS hierarchy, we have ensured that the information does not loop, thereby ensuring that there are no persistent forwarding loops. (§4.1)
	MUST	4.1	positive`unit/verifyTestISISEngineLeakOrigination` positive`unit/verifyTestISISLeakOriginationL1L2` negative`unit/verifyTestISISEngineLeakOrigination` negative`unit/verifyTestISISLeakOriginationL1L2` negative`unit/verifyTestISISRedistConsumerConnected`
`RFC5305-4.1-3`	If a prefix is advertised from one area to another at the same level, then the up/down bit SHALL be set to 1. (§4.1)
	SHALL	4.1	positive`no test`no positive test negative`no test`no negative test {not-applicable}: the condition never holds in Ze. A Ze IS-IS instance belongs to one Level 1 area, and internal/plugins/isis/spf/leak.go LeakPrefixes moves prefixes only between levels (IntoL1 from Level 2, IntoL2 from Level 1); no producer advertises a prefix from one area to another at the same level
`RFC5305-3.7-1`	If a link is advertised without this sub-TLV, traffic engineering SPF calculations MUST use the normal default metric of this link, which is advertised in the fixed part of the extended IS reachability TLV. (§3.7)
	MUST	3.7	positive`no test`no positive test negative`no test`no negative test {not-applicable}: Owner decision 2026-09-21: "Keep configured routes" for TE path computation. The conditional subject is "traffic engineering SPF calculations"; internal/plugins/rsvpte/register.go parseERO, routing.go resolveExplicitPath and frr.go selectBypass consume configured routes, native next-hop lookups and configured bypasses. internal/plugins/isis/spf/spf.go computes normal SPF. There is no CSPF/TE shortest-path consumer to apply this fallback. This exclusion does not cover native TE advertisement or wire duties, and BGP-LS export is not TE-SPF
`RFC5305-4.1-2`	The up/down bit SHALL be set to 0 when a prefix is first injected into IS-IS (Section 4.1)
	SHALL	4.1	positive`unit/verifyTestRFC5305FirstInjectionClearsUpDown` negative`unit/verifyTestRFC5305ConnectedInjectionClearsUpDown`
`RFC5305-4.2-1`	If there are no sub-TLVs associated with a prefix, the bit indicating the presence of sub-TLVs SHALL be set to 0 (Section 4.2)
	SHALL	4.2	positive`unit/verifyTestRFC5305NoSubTLVsClearsPresenceBit` negative`unit/verifyTestRFC5305SubTLVsSetPresenceBit`
`RFC5305-3.2-1`	Implementations MUST NOT inject a /32 prefix for the interface address into their routing or forwarding table because this can lead to forwarding loops when interacting with systems that do not support this sub-TLV. (§3.2)
	MUST NOT	3.2	positive`unit/verifyTestRFC5305TEAddressesLeaveOnlyReachabilityRoutes` negative`unit/verifyTestRFC5305TEAddressesInjectNoHostRoute`
`RFC5305-3.2-2`	If a router implements traffic engineering, it MUST include this sub- TLV. (§3.2)
	MUST	3.2	positive`no test`no positive test negative`no test`no negative test {not-applicable}: this obligation is conditional on implementing IS-IS TE; ze originates no TLV 22 TE sub-TLVs (internal/plugins/isis/lsdb/encode.go:101-107 writes a zero sub-TLV length), so it does not implement the TE metric it would govern
`RFC5305-3.3-1`	Implementations MUST NOT inject a /32 prefix for the neighbor address into their routing or forwarding table because this can lead to forwarding loops when interacting with systems that do not support this sub-TLV. (§3.3)
	MUST NOT	3.3	positive`unit/verifyTestRFC5305TEAddressesLeaveOnlyReachabilityRoutes` negative`unit/verifyTestRFC5305TEAddressesInjectNoHostRoute`
`RFC5305-3.3-2`	If a router implements traffic engineering, it MUST include this sub- TLV on point-to-point adjacencies. (§3.3)
	MUST	3.3	positive`no test`no positive test negative`no test`no negative test {not-applicable}: this obligation is conditional on implementing IS-IS TE; ze originates no TLV 22 TE sub-TLVs (internal/plugins/isis/lsdb/encode.go:101-107 writes a zero sub-TLV length), so it does not implement the TE metric it would govern
`RFC5305-4.3-4`	Implementations MUST NOT inject a /32 prefix for the router ID into their forwarding table because this can lead to forwarding loops when interacting with systems that do not support this TLV. (§4.3)
	MUST NOT	4.3	positive`unit/verifyTestRFC5305TEAddressesLeaveOnlyReachabilityRoutes` negative`unit/verifyTestRFC5305TEAddressesInjectNoHostRoute`
`RFC5305-3.4-1`	This sub-TLV is optional. This sub-TLV SHOULD appear once at most in each extended IS reachability TLV. (§3.4)
	SHOULD	3.4	positive`no test`no positive test negative`no test`no negative test
`RFC5305-3.5-1`	This sub-TLV is optional. This sub-TLV SHOULD appear once at most in each extended IS reachability TLV. (§3.5)
	SHOULD	3.5	positive`no test`no positive test negative`no test`no negative test
`RFC5305-3.6-2`	This sub-TLV is optional. This sub-TLV SHOULD appear once at most in each extended IS reachability TLV. (§3.6)
	SHOULD	3.6	positive`no test`no positive test negative`no test`no negative test
`RFC5305-3.7-2`	This sub-TLV is optional. This sub-TLV SHOULD appear once at most in each extended IS reachability TLV. (§3.7)
	SHOULD	3.7	positive`no test`no positive test negative`no test`no negative test
`RFC5305-4.3-1`	If a router implements traffic engineering, it MUST include this TLV in its LSP. (§4.3)
	MUST	4.3	positive`no test`no positive test negative`no test`no negative test {not-applicable}: this obligation is conditional on implementing IS-IS TE; TLV 134 (TE Router ID) is absent from ze's IS-IS codec type set (internal/plugins/isis/packet/tlv.go:17-32), so ze originates and consumes no TLV 134
`RFC5305-2-1`	Unknown sub-TLVs are to be ignored and skipped upon receipt. (§2)
	MUST	2	positive`unit/verifyTestISISTLV22RoundTrip` positive`unit/verifyTestISISTLVIPv4RoundTrip` negative`unit/verifyTestISISTLV22Truncated`
`RFC5305-3.1-1`	This sub-TLV is OPTIONAL. This sub-TLV SHOULD appear once at most in each extended IS reachability TLV. (§3.1)
	SHOULD	3.1	positive`no test`no positive test negative`no test`no negative test
`RFC5305-4.3-2`	This TLV SHOULD not be included more than once in an LSP. (§4.3)
	SHOULD NOT	4.3	positive`no test`no positive test negative`no test`no negative test
`RFC5305-3.6-1`	For stability reasons, rapid changes in the values in this sub-TLV SHOULD NOT cause rapid generation of LSPs. (§3.6)
	SHOULD NOT	3.6	positive`no test`no positive test negative`no test`no negative test
`RFC5305-4.3-3`	If a router advertises the Traffic Engineering router ID TLV in its LSP, and if it advertises prefixes via the Border Gateway Protocol (BGP) with the BGP next hop attribute set to the BGP router ID, the Traffic Engineering router ID SHOULD be the same as the BGP router ID. (§4.3)
	SHOULD	4.3	positive`no test`no positive test negative`no test`no negative test

Gaps and untested MUSTs

Requirement	State	Reason
`RFC5305-4.1-3` If a prefix is advertised from one area to another at the same level, then the up/down bit SHALL be set to 1. (§4.1)	no test	no test carries this requirement id; annotated {not-applicable}: the condition never holds in Ze. A Ze IS-IS instance belongs to one Level 1 area, and internal/plugins/isis/spf/leak.go LeakPrefixes moves prefixes only between levels (IntoL1 from Level 2, IntoL2 from Level 1); no producer advertises a prefix from one area to another at the same level
`RFC5305-3.7-1` If a link is advertised without this sub-TLV, traffic engineering SPF calculations MUST use the normal default metric of this link, which is advertised in the fixed part of the extended IS reachability TLV. (§3.7)	no test	no test carries this requirement id; annotated {not-applicable}: Owner decision 2026-09-21: "Keep configured routes" for TE path computation. The conditional subject is "traffic engineering SPF calculations"; internal/plugins/rsvpte/register.go parseERO, routing.go resolveExplicitPath and frr.go selectBypass consume configured routes, native next-hop lookups and configured bypasses. internal/plugins/isis/spf/spf.go computes normal SPF. There is no CSPF/TE shortest-path consumer to apply this fallback. This exclusion does not cover native TE advertisement or wire duties, and BGP-LS export is not TE-SPF
`RFC5305-3.2-2` If a router implements traffic engineering, it MUST include this sub- TLV. (§3.2)	no test	no test carries this requirement id; annotated {not-applicable}: this obligation is conditional on implementing IS-IS TE; ze originates no TLV 22 TE sub-TLVs (internal/plugins/isis/lsdb/encode.go:101-107 writes a zero sub-TLV length), so it does not implement the TE metric it would govern
`RFC5305-3.3-2` If a router implements traffic engineering, it MUST include this sub- TLV on point-to-point adjacencies. (§3.3)	no test	no test carries this requirement id; annotated {not-applicable}: this obligation is conditional on implementing IS-IS TE; ze originates no TLV 22 TE sub-TLVs (internal/plugins/isis/lsdb/encode.go:101-107 writes a zero sub-TLV length), so it does not implement the TE metric it would govern
`RFC5305-4.3-1` If a router implements traffic engineering, it MUST include this TLV in its LSP. (§4.3)	no test	no test carries this requirement id; annotated {not-applicable}: this obligation is conditional on implementing IS-IS TE; TLV 134 (TE Router ID) is absent from ze's IS-IS codec type set (internal/plugins/isis/packet/tlv.go:17-32), so ze originates and consumes no TLV 134

Proof state

A tagged unit reads unproven where no discrimination record exists for it: nothing in this tree has been observed to break it, so the claim its tag makes is unproven.

`RFC5305-3-1`

If a link is advertised with the maximum link metric (2^24 - 1), this link MUST NOT be considered during the normal SPF computation. (§3)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Forbidden behaviour: a link advertised at 2^24-1 being walked by normal SPF. TestISISSPFMaxLinkMetricExcluded builds A-B at 16777215 and t.Errorf fires if B or C appears in the SPF result; the positive half proves 16777214 is still relaxed (B at 16777214, C at 16777224).

Polarity	Test	Kind and tier	Proof state
negative	`TestISISSPFMaxLinkMetricExcluded`	unit/verify	mutant, verified
positive	`TestISISSPFMaxLinkMetricExcluded`	unit/verify	unproven

`RFC5305-4-1`

If a prefix is advertised with a metric larger then MAX_PATH_METRIC (0xFE000000, see paragraph 3.0), this prefix MUST NOT be considered during the normal SPF computation. (§4)

Audit verdict: enforced (the tests do what the requirement demands), fresh. §4 excludes a prefix 'advertised with a metric larger then MAX_PATH_METRIC'. spf TestRFC5305PrefixAboveMaxPathMetricNotConsidered drives BuildRoutes: node 3 (distance 10) advertises 10.9.0.0/24 at 50 (positive, installed at 60 via node 3 alone); node 2 (distance 10) advertises the same prefix at 0xFE000001 and 10.8.0.0/24 only at 0xFFFFFFFF (negative, strictly larger than MAX_PATH_METRIC): one next hop at 60 and the lone prefix absent. The path ceiling in route.go (total >= MaxPathMetric after clampMetric) is the guard; recorded +/- on BuildRoutes. Closure rejudge 2026-10-02: TestISISMetricWidth's positive claim was narrowed to what its body asserts (node B at edge 10 stays in the Compute result while its over-ceiling prefix drops; 'installable' dropped) and re-recorded on spf.go::Compute; its negative (prefix at exactly MAX_PATH_METRIC absent from BuildRoutes) keeps its record on BuildRoutes.

Polarity	Test	Kind and tier	Proof state
negative	`TestRFC5305PrefixAboveMaxPathMetricNotConsidered`	unit/verify	revert, verified
negative	`TestISISMetricWidth`	unit/verify	revert, verified
positive	`TestRFC5305PrefixAboveMaxPathMetricNotConsidered`	unit/verify	revert, verified
positive	`TestISISMetricWidth`	unit/verify	revert, verified

`RFC5305-4.1-1`

If a prefix is advertised from a higher level to a lower level (e.g., level 2 to level 1), the bit MUST be set to 1, indicating that the prefix has traveled down the hierarchy. Prefixes that have the up/down bit set to 1 may only be advertised down the hierarchy, i.e., to lower levels. These semantics apply even if IS-IS is extended in the future to have additional levels. By ensuring that prefixes follow only the IS-IS hierarchy, we have ensured that the information does not loop, thereby ensuring that there are no persistent forwarding loops. (§4.1)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Re-judged 2026-09-30: TestISISEngineLeakOrigination and spf TestISISLeakOriginationL1L2 gained only RFC2966-2-4 tag comments; bodies byte-identical. Clause 1: l2Derived enters L2 with UpDown false and hasLeak(IntoL1, l2Derived, true) is required; the engine L1 LSP decodes it with the bit set. Clause 2: alreadyDown (UpDown true in L1) must be absent from IntoL2, isolated by l1Only from the same node leaking up. Recorded red on spf/leak.go leakInto.

Polarity	Test	Kind and tier	Proof state
negative	`TestISISEngineLeakOrigination`	unit/verify	revert, verified
negative	`TestISISRedistConsumerConnected`	unit/verify	revert, verified
negative	`TestISISLeakOriginationL1L2`	unit/verify	revert, verified
positive	`TestISISEngineLeakOrigination`	unit/verify	revert, verified
positive	`TestISISLeakOriginationL1L2`	unit/verify	revert, verified

`RFC5305-4.1-3`

If a prefix is advertised from one area to another at the same level, then the up/down bit SHALL be set to 1. (§4.1)

Audit verdict: not-applicable (the requirement has no reachable code path in Ze), fresh. The condition, a prefix advertised from one area to another at the same level, never arises in Ze.

No test carries RFC5305-4.1-3, so no unit is bound to it.

`RFC5305-3.7-1`

If a link is advertised without this sub-TLV, traffic engineering SPF calculations MUST use the normal default metric of this link, which is advertised in the fixed part of the extended IS reachability TLV. (§3.7)

Audit verdict: not audited: no reader has judged these tests

No test carries RFC5305-3.7-1, so no unit is bound to it.

`RFC5305-4.1-2`

The up/down bit SHALL be set to 0 when a prefix is first injected into IS-IS (Section 4.1)

Audit verdict: not audited: no reader has judged these tests

Polarity	Test	Kind and tier	Proof state
negative	`TestRFC5305ConnectedInjectionClearsUpDown`	unit/verify	revert, verified
positive	`TestRFC5305FirstInjectionClearsUpDown`	unit/verify	revert, verified

`RFC5305-4.2-1`

If there are no sub-TLVs associated with a prefix, the bit indicating the presence of sub-TLVs SHALL be set to 0 (Section 4.2)

Audit verdict: not audited: no reader has judged these tests

Polarity	Test	Kind and tier	Proof state
negative	`TestRFC5305SubTLVsSetPresenceBit`	unit/verify	revert, verified
positive	`TestRFC5305NoSubTLVsClearsPresenceBit`	unit/verify	revert, verified

`RFC5305-3.2-1`

Implementations MUST NOT inject a /32 prefix for the interface address into their routing or forwarding table because this can lead to forwarding loops when interacting with systems that do not support this sub-TLV. (§3.2)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Judged 2026-09-30 under OWNER RULING 2 (a receive-side ban: the positive is Ze processing the LSP that carries the address, the negative is Ze's handling of the address it knows: no /32). Setup: a peer L1 LSP with TLV 22 to the root carrying sub-TLV 6 (203.0.113.1), sub-TLV 8, TLV 134 and a TLV 128 prefix goes through packet.DecodePDU and lsdb.Receive, SPF runs into a real Loc-RIB. Positive TestRFC5305TEAddressesLeaveOnlyReachabilityRoutes: 198.51.100.0/24 installed via the neighbor and Loc-RIB Len == 1 (a /32 for the interface address would make it 2). Negative TestRFC5305TEAddressesInjectNoHostRoute: the BGP-LS builder decodes 203.0.113.1 as a link local address (so Ze holds the address the ban names), yet no 203.0.113.1/32 is in the Loc-RIB and no BGP-LS Prefix NLRI contains it. LIMIT, stated honestly: no Ze code path injects a /32 from sub-TLV 6 (spf/graph.go drops sub-TLVs), so no break of existing code can make the ban assertions red; the negative's observed red (linkAttribute disabled) comes from its decode precondition, and the positive's (BuildRoutes disabled) from the missing reachability route. The ban assertions are load-bearing only against future code that adds an injection. Accepted as enforced under R1(b): the input is forced to the exact trigger of the ban and the output complies.

Polarity	Test	Kind and tier	Proof state
negative	`TestRFC5305TEAddressesInjectNoHostRoute`	unit/verify	revert, verified
positive	`TestRFC5305TEAddressesLeaveOnlyReachabilityRoutes`	unit/verify	revert, verified

`RFC5305-3.2-2`

If a router implements traffic engineering, it MUST include this sub- TLV. (§3.2)

Audit verdict: not audited: no reader has judged these tests

No test carries RFC5305-3.2-2, so no unit is bound to it.

`RFC5305-3.3-1`

Implementations MUST NOT inject a /32 prefix for the neighbor address into their routing or forwarding table because this can lead to forwarding loops when interacting with systems that do not support this sub-TLV. (§3.3)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Judged 2026-09-30 under OWNER RULING 2, same setup as RFC5305-3.2-1. Positive TestRFC5305TEAddressesLeaveOnlyReachabilityRoutes: with sub-TLV 8 (IPv4 neighbor address 203.0.113.2) on the received adjacency the Loc-RIB holds exactly 198.51.100.0/24 via the neighbor (Len == 1). Negative TestRFC5305TEAddressesInjectNoHostRoute: the BGP-LS builder decodes 203.0.113.2 as a link remote address, yet no 203.0.113.2/32 is in the Loc-RIB and no BGP-LS Prefix NLRI contains it. LIMIT: no Ze code path injects a /32 from sub-TLV 8, so no break of existing code reddens the ban assertions; the negative's observed red (linkAttribute disabled) comes from the decode precondition. Enforced under R1(b): input forced to the ban's trigger, output complies.

Polarity	Test	Kind and tier	Proof state
negative	`TestRFC5305TEAddressesInjectNoHostRoute`	unit/verify	revert, verified
positive	`TestRFC5305TEAddressesLeaveOnlyReachabilityRoutes`	unit/verify	revert, verified

`RFC5305-3.3-2`

If a router implements traffic engineering, it MUST include this sub- TLV on point-to-point adjacencies. (§3.3)

Audit verdict: not-applicable (the requirement has no reachable code path in Ze), fresh. Judged 2026-09-30. Accepted as mirroring the HEAD siblings; under ruling R23 the stricter form for all three TE-conditional rows is an extraction exclusion feature-out-of-scope quoting the 'If a router implements traffic engineering' condition.

No test carries RFC5305-3.3-2, so no unit is bound to it.

`RFC5305-4.3-4`

Implementations MUST NOT inject a /32 prefix for the router ID into their forwarding table because this can lead to forwarding loops when interacting with systems that do not support this TLV. (§4.3)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Judged 2026-09-30 under OWNER RULING 2, same setup as RFC5305-3.2-1. Positive TestRFC5305TEAddressesLeaveOnlyReachabilityRoutes: with a TLV 134 router ID (203.0.113.9) in the received LSP the Loc-RIB holds exactly 198.51.100.0/24 (Len == 1). Negative TestRFC5305TEAddressesInjectNoHostRoute: bgplsBuilder.lsp exports 203.0.113.9 as node attribute 1028, yet no 203.0.113.9/32 is in the Loc-RIB (Ze's forwarding feed) and no BGP-LS Prefix NLRI contains it. LIMIT: no Ze code path injects a /32 from TLV 134, so no break of existing code reddens the ban assertions; the negative's observed red (bgplsBuilder.lsp disabled) comes from the export precondition. Enforced under R1(b): input forced to the ban's trigger, output complies.

Polarity	Test	Kind and tier	Proof state
negative	`TestRFC5305TEAddressesInjectNoHostRoute`	unit/verify	revert, verified
positive	`TestRFC5305TEAddressesLeaveOnlyReachabilityRoutes`	unit/verify	revert, verified

`RFC5305-4.3-1`

If a router implements traffic engineering, it MUST include this TLV in its LSP. (§4.3)

Audit verdict: not audited: no reader has judged these tests

No test carries RFC5305-4.3-1, so no unit is bound to it.

`RFC5305-2-1`

Unknown sub-TLVs are to be ignored and skipped upon receipt. (§2)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Unchanged on re-read: TestISISTLVIPv4RoundTrip lost only its RFC1195-5.2-4 comment tag. Forbidden behaviour: rejecting a TLV that carries unknown sub-TLVs, or not skipping them so the next entry misparses. TestISISTLV22RoundTrip (tlv_core_test.go) keeps entry0's three uninterpreted sub-TLVs opaque and then asserts entry1's metric equals types.MaxMetric, which goes red on a wrong skip; TestISISTLVIPv4RoundTrip (with-subtlv) goes red if a type-1 sub-TLV is rejected. Negative TestISISTLV22Truncated proves an overrunning length is not skipped as absent.

Polarity	Test	Kind and tier	Proof state
negative	`TestISISTLV22Truncated`	unit/verify	unproven
positive	`TestISISTLV22RoundTrip`	unit/verify	unproven
positive	`TestISISTLVIPv4RoundTrip`	unit/verify	unproven

Extraction sign-off

Field	Value
Reviewer	claude
Signed off	2026-09-30
Register	rfc2119
Source	rfc/full/rfc5305.txt
Source fingerprint	1bb1a875678e75b2
Record	rfc/extraction/rfc5305.json
Mapped sentences	13
Declined as scope	2
Relocated to a spec, which Ze OWES	0
Unclassified	0

Sections

Section	Name	Sites	Disposition	Reason
`front`	not stated	0	walked	not stated
`1`	not stated	0	walked	not stated
`1.1`	not stated	0	walked	not stated
`2`	not stated	0	walked	not stated
`3`	not stated	2	walked	not stated
`3.1`	not stated	0	walked	not stated
`3.2`	not stated	2	walked	not stated
`3.3`	not stated	2	walked	not stated
`3.4`	not stated	0	walked	not stated
`3.5`	not stated	0	walked	not stated
`3.6`	not stated	0	walked	not stated
`3.7`	not stated	2	walked	not stated
`4`	not stated	1	walked	not stated
`4.1`	not stated	3	walked	not stated
`4.2`	not stated	1	walked	not stated
`4.3`	not stated	2	walked	not stated
`5`	not stated	0	walked	not stated
`5.1`	not stated	0	walked	not stated
`5.2`	not stated	0	walked	not stated
`5.2.1`	not stated	0	walked	not stated
`5.2.2`	not stated	0	walked	not stated
`6`	not stated	0	walked	not stated
`7`	not stated	0	walked	not stated
`8`	not stated	0	walked	not stated
`8.1`	not stated	0	walked	not stated
`8.2`	not stated	0	walked	not stated

Excluded sentences

Site	Excluded kind	Reason	Quote
`3:1`	`feature-out-of-scope` never bound Ze the RFC makes a feature OPTIONAL, Ze decided not to offer it, and this obligation is conditional on offering it	Conditional on a traffic engineering SPF implementation, a feature Ze does not provide. RFC 5305 Section 3: 'To preclude overflow within a traffic engineering Shortest Path First (SPF) implementation, all metrics greater than or equal to MAX_PATH_METRIC SHALL be considered to have a metric of MAX_PATH_METRIC.' Section 3.7 repeats it for the TE Default metric sub-TLV. Ze runs no TE SPF: owner decision 2026-09-21 'Keep configured routes' for TE path computation (the same scope decision RFC5305-3.7-1 records), so RSVP-TE paths come from configured EROs, native next-hop lookups and configured bypasses (internal/plugins/rsvpte parseERO, resolveExplicitPath, selectBypass), and Ze decodes no TE metric sub-TLV. Ze's normal SPF saturates path sums at MAX_PATH_METRIC anyway (spf.go clampMetric), which RFC 5308 Section 5 obliges and RFC5308-5-2 carries. This is a SCOPE DECISION: TE SPF is an implementation gap, not a conformance gap.	To preclude overflow within a traffic engineering Shortest Path First (SPF) implementation, all metrics greater than or equal to MAX_PATH_METRIC SHALL be considered to have a metric of MAX_PATH_METRIC.
`3.7:1`	`feature-out-of-scope` never bound Ze the RFC makes a feature OPTIONAL, Ze decided not to offer it, and this obligation is conditional on offering it	Conditional on a traffic engineering SPF implementation, a feature Ze does not provide. RFC 5305 Section 3: 'To preclude overflow within a traffic engineering Shortest Path First (SPF) implementation, all metrics greater than or equal to MAX_PATH_METRIC SHALL be considered to have a metric of MAX_PATH_METRIC.' Section 3.7 repeats it for the TE Default metric sub-TLV. Ze runs no TE SPF: owner decision 2026-09-21 'Keep configured routes' for TE path computation (the same scope decision RFC5305-3.7-1 records), so RSVP-TE paths come from configured EROs, native next-hop lookups and configured bypasses (internal/plugins/rsvpte parseERO, resolveExplicitPath, selectBypass), and Ze decodes no TE metric sub-TLV. Ze's normal SPF saturates path sums at MAX_PATH_METRIC anyway (spf.go clampMetric), which RFC 5308 Section 5 obliges and RFC5308-5-2 carries. This is a SCOPE DECISION: TE SPF is an implementation gap, not a conformance gap.	To preclude overflow within a traffic engineering SPF implementation, all metrics greater than or equal to MAX_PATH_METRIC SHALL be considered to have a metric of MAX_PATH_METRIC.

Superseded

No document obsoletes RFC 5305, so its obligations are stated where they were written.