Supported

RFC 7705 - Autonomous System Migration Mechanisms and Their Effects on the BGP AS_PATH Attribute

Every requirement this repository extracted from RFC 7705, 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 ways100.0%9 of 9 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 9 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 9 gated MUSTs

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

Partial proof; remaining gap0.0%0 of 9 gated MUSTs

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

No test at all0.0%0 of 9 gated MUSTs

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

Proven by a recorded break100.0%20 of 20 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

Audit verdicts9of 9 gated MUSTs judged

0 weak, wrong or unimplemented, 0 no longer current. Each is named below under its own requirement id

Neutral

measures that are neither good news nor bad

Gated MUSTs9of 17 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 scope0of 9 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 applicable0.0%0 of 9 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 9 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 9 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 9 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	ok	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	Supported
Enrolment	Enrolled
Requirements	17
Gated MUST-level	9
Not applicable, so out of scope	0
Declared gaps	0
Declared gaps a test demonstrates	0
Gated with no test	0
Nightly-only evidence	0
Test tags	20
Tagged units	20
Recorded audit verdicts	9
Discrimination records	20
Summary	`rfc/short/rfc7705.md`
Requirement shard	`rfc/requirements/rfc7705.md`
RFC text	`rfc/full/rfc7705.txt`

Enrolment

Enrolled: Autonomous System migration: the four de facto mechanisms a renumbering speaker runs, all four implemented, and all nine of this document's MUST-level requirements proven by a tagged test in both polarities. Section 3.3 "Local AS", "No Prepend Inbound" and "Replace Old AS" reach the AS_PATH through `secondaryPrependAS` and `localASPrependFor` (internal/component/bgp/reactor/peer_forward_facts.go). Section 4.2 "Internal BGP AS Migration" is `setMigrationAS`, `isIBGPWith`, `peerASAccepted`, `openLocalAS` and `noteASMigrationRejection` (internal/component/bgp/reactor/session_as_migration.go). The extraction sign-off is rfc/extraction/rfc7705.json: eight derived sites, all mapped, none excluded.

What the public ledger says

Status: Supported

What the ledger says is covered

All four mechanisms. Configuration is one session > asn container read by parsePeerSettings (internal/component/bgp/reactor/config.go) out of the peer-fields grouping that a group and a peer both use, so local, local-options and migration are each settable per neighbor and per neighbor group (RFC7705-3.3-1, RFC7705-4.2-1). Section 3.3: local-options no-prepend keeps the Local AS value out of the AS_PATH of a route received from that peer, and leaves the globally configured AS number on the path every other external neighbor receives (RFC7705-3.3-2, RFC7705-3.3-3)
local-options replace-as sends the Local AS value alone toward that peer, with the globally configured AS number absent from AS_PATH and from AS4_PATH (RFC7705-3.3-4, RFC7705-3.3-5). Section 4.2: session > asn > migration widens one iBGP session to exactly two of this speaker's AS numbers. An OPEN carrying either is accepted and any third AS is answered with OPEN Message Error / Bad Peer AS, which ze originates for the first time (validateOpenPeerAS, internal/component/bgp/reactor/session_open_as.go, RFC7705-4.2-2). The OPEN ze sends carries the globally configured AS number first and the locally configured one after a peer answers Bad Peer AS, in My Autonomous System and in the Four-octet AS capability alike (openLocalAS, RFC7705-4.2-3, and the Section 4.2 SHOULD RFC7705-4.2-5 through noteASMigrationRejection). The session is internal under either AS number, from one rule every AS-scoped decision reads (isIBGPWith, RFC7705-4.2-4), so no external AS_PATH prepend runs and the RFC 4456 reflection rules apply. Requirements bound per line below.

What the ledger says remains

Two advisory items, neither of them a MUST. RFC7705-3.3-9, the Section 3.3 SHOULD that the Local AS value be appended inbound before a route is installed or advertised to an internal neighbor, is not performed by the engine: an operator writes it as policy, and plan/spec-bgp-local-as-inbound-append.md holds the ruling. RFC7705-3.3-11, the MAY letting an EXTERNAL speaker attempt the session under either AS number, is not offered: the two-AS session is iBGP only, because setMigrationAS refuses a remote AS that is neither of the pair. RFC7705-3.3-8, the SHOULD NOT that follows from that MAY, is therefore met by the scope decision rather than by a branch: no external session of ze establishes on the globally configured AS number while a Local AS is set for it.

Coverage

Bucket	Count	What it counts
Positive and negative tests	9	one part of the gated population
Annotated (including scoped evidence)	0	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	9	every gated MUST falls in exactly one bucket above

Positive and negative tests (9): RFC7705-3.3-1, RFC7705-3.3-2, RFC7705-3.3-3, RFC7705-3.3-4, RFC7705-3.3-5, RFC7705-4.2-1, RFC7705-4.2-2, RFC7705-4.2-3, RFC7705-4.2-4

Requirements

Requirement	Level	Section	Tests
`RFC7705-3.3-1`	The mechanisms introduced in this section MUST be configurable on a per-neighbor or per-neighbor-group basis to allow for maximum flexibility. (§3.3)
	MUST	3.3	positive`unit/verifyTestPeersFromConfigTree_LocalASOptionsPerNeighborGroup` negative`unit/verifyTestPeersFromConfigTree_LocalASOptionsPerNeighborGroup`
`RFC7705-3.3-2`	"No Prepend Inbound": When the BGP router receives inbound BGP UPDATEs from its eBGP neighbor configured with this option, it MUST NOT append the "Local AS" ASN value in the AS_PATH attribute when installing the route or advertising that UPDATE to iBGP neighbors (§3.3)
	MUST NOT	3.3	positive`unit/verifyTestRFC7705NoPrependInstalledAndAdvertised` negative`unit/verifyTestRFC7705NoPrependInstalledAndAdvertised`
`RFC7705-3.3-3`	it MUST still append the globally configured ASN as normal when advertising the UPDATE to other local eBGP neighbors (§3.3)
	MUST	3.3	positive`unit/verifyTestLocalASNoPrependLeavesEveryOutboundPathAlone` negative`unit/verifyTestLocalASNoPrependLeavesEveryOutboundPathAlone`
`RFC7705-3.3-4`	"Replace Old AS" (outbound): When the BGP router generates outbound BGP UPDATEs toward an eBGP neighbor configured with this option, the BGP speaker MUST NOT append the globally configured ASN from the AS_PATH attribute. (§3.3)
	MUST NOT	3.3	positive`unit/verifyTestLocalASReplaceASSendsOnlyTheLocalAS` negative`unit/verifyTestLocalASReplaceASSendsOnlyTheLocalAS`
`RFC7705-3.3-5`	The BGP router MUST append only the configured "Local AS" ASN value to the AS_PATH attribute before sending the BGP UPDATEs outbound to the eBGP neighbor. (§3.3)
	MUST	3.3	positive`unit/verifyTestLocalASReplaceASSendsOnlyTheLocalAS` negative`unit/verifyTestLocalASReplaceASSendsOnlyTheLocalAS`
`RFC7705-4.2-1`	The mechanism introduced in this section MUST be configurable on a per-neighbor or per-neighbor-group basis to allow for maximum flexibility. (§4.2)
	MUST	4.2	positive`unit/verifyTestPeersFromConfigTree_ASMigrationPerNeighborGroup` negative`unit/verifyTestPeersFromConfigTree_ASMigrationPerNeighborGroup`
`RFC7705-4.2-2`	When configured with this mechanism, a BGP speaker MUST accept BGP OPEN and establish an iBGP session from configured iBGP peers if the ASN value in "My Autonomous System" is either the globally configured ASN or a locally configured ASN provided when this capability is utilized. (§4.2)
	MUST	4.2	positive`unit/verifyTestMigrationAcceptsEitherASN` positive`unit/verifyTestRFC7705MigratingPeerEstablishesAsIBGP` negative`unit/verifyTestMigrationAcceptsEitherASN` negative`unit/verifyTestRFC7705MigratingPeerEstablishesAsIBGP`
`RFC7705-4.2-3`	Additionally, a BGP router configured with this mechanism MUST send its own BGP OPEN [RFC4271] (see Section 4.2) using either the globally configured or the locally configured ASN in "My Autonomous System" as follows. (§4.2)
	MUST	4.2	positive`unit/verifyTestMigrationOpenCarriesResolvedASN` negative`unit/verifyTestMigrationOpenCarriesResolvedASN`
`RFC7705-4.2-4`	In each case, the BGP speaker MUST treat UPDATEs sent and received to this peer as if this was a natively configured iBGP session, as defined by [RFC4271] and [RFC4456]. (§4.2)
	MUST	4.2	positive`unit/verifyTestRFC7705MigrationWireSemantics` negative`unit/verifyTestRFC7705MigrationWireSemantics`
`RFC7705-3.3-6`	To implement this mechanism, a BGP speaker SHOULD send BGP OPEN [RFC4271] (see Section 4.2) messages to the configured eBGP peer(s) using the local ASN configured for this session as the value sent in "My Autonomous System". (§3.3)
	SHOULD	3.3	positive`no test`no positive test negative`no test`no negative test
`RFC7705-3.3-7`	The BGP router SHOULD NOT use the ASN configured globally within the BGP process as the value sent in "My Autonomous System" in the OPEN message. (§3.3)
	SHOULD NOT	3.3	positive`no test`no positive test negative`no test`no negative test
`RFC7705-3.3-8`	If the session is successfully established to the globally configured ASN, then the modifications to AS_PATH described in this document SHOULD NOT be performed, as they are unnecessary. (§3.3)
	SHOULD NOT	3.3	positive`no test`no positive test negative`no test`no negative test
`RFC7705-3.3-9`	The router SHOULD append the configured "Local AS" ASN in the AS_PATH attribute before installing the route or advertising the UPDATE to an iBGP neighbor. (§3.3)
	SHOULD	3.3	positive`no test`no positive test negative`no test`no negative test
`RFC7705-3.3-10`	The BGP router SHOULD first append the globally configured ASN to the AS_PATH immediately followed by the "Local AS" value before advertising the UPDATE to an eBGP neighbor. (§3.3)
	SHOULD	3.3	positive`no test`no positive test negative`no test`no negative test
`RFC7705-4.2-5`	To avoid potential deadlocks when two BGP speakers are attempting to establish a BGP peering session and are both configured with this mechanism, the speaker SHOULD send BGP OPEN using the globally configured ASN first, and only send a BGP OPEN using the locally configured ASN as a fallback if the remote neighbor responds with the BGP error "Bad Peer AS". (§4.2)
	SHOULD	4.2	positive`no test`no positive test negative`no test`no negative test
`RFC7705-6-1`	Additionally, BGP sessions SHOULD be protected using TCP Authentication Option [RFC5925] and the Generalized TTL Security Mechanism [RFC5082] (§6)
	SHOULD	6	positive`no test`no positive test negative`no test`no negative test
`RFC7705-3.3-11`	Implementations MAY support a more flexible model where the eBGP speaker attempts to open the BGP session using either the ASN configured as "Local AS" or the globally configured AS as discussed in BGP Alias (Section 4.2). (§3.3)
	MAY	3.3	positive`no test`no positive test negative`no test`no negative test

Gaps and untested MUSTs

RFC 7705 declares no gap, and every gated MUST it carries has a test bound to it.

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.

`RFC7705-3.3-1`

The mechanisms introduced in this section MUST be configurable on a per-neighbor or per-neighbor-group basis to allow for maximum flexibility. (§3.3)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Forbidden: a Section 3.3 mechanism settable on neither a neighbor nor a neighbor group. TestPeersFromConfigTree_LocalASOptionsPerNeighborGroup drives PeersFromConfigTree: the group's local (65010) and replace-as reach the inheriting peer (assert.Equal LocalAS, assert.True LocalASReplaceAS), and no-prepend set on a peer reaches that peer (assert.True LocalASNoPrepend); each of the three mechanisms goes red if it cannot be configured on the basis the test uses. Negative: the group options do not reach the peer outside the group or override the peer's own leaf-list.

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

`RFC7705-3.3-2`

"No Prepend Inbound": When the BGP router receives inbound BGP UPDATEs from its eBGP neighbor configured with this option, it MUST NOT append the "Local AS" ASN value in the AS_PATH attribute when installing the route or advertising that UPDATE to iBGP neighbors (§3.3)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Rejudged against RFC 7705 section 3.3: the No Prepend Inbound sentence forbids adding Local AS both on installation and on advertisement to iBGP; the sentence's native-eBGP global-AS obligation is separately RFC7705-3.3-3, not renewed here. TestRFC7705NoPrependInstalledAndAdvertised now sends real inbound UPDATEs, reads the running bgp-rib snapshot and captures the internal neighbor's wire; both exact AS_PATH comparisons reject any added legacy ASN. Its second input already contains the legacy ASN and rejects duplicate insertion or stripping, independently of the first input. This remedies the old verdict's missing installed-route assertion. Absence of the advisory default inbound prepend is not a violation of this conditional MUST NOT and is not credited as implemented here. The startup commit changes only spacing in the tagged body and waits for plugin startup in lowLiveRouter; neither alters inputs or assertions. Read handleReceivedStructured and publishBase: installed and published attributes are real production results, not values injected by the test. Existing producer-changed discrimination records still require renewal; this semantic judgment does not claim that renewal has run. Post-lint rejudgment 2026-10-04: lowLiveRouter no longer returns the discarded Reactor; the same running router and peers remain owned by cleanup. lowInstalledAttributes now embeds the identical source address 192.0.2.1 formerly passed by every caller, and still requires peer index, AFI/SAFI, prefix length and prefix bytes. Exact installed and transmitted attribute assertions and independent countercases are unchanged. Full governing sentence, RFC 7705 section 3.3: ""No Prepend Inbound": When the BGP router receives inbound BGP UPDATEs from its eBGP neighbor configured with this option, it MUST NOT append the "Local AS" ASN value in the AS_PATH attribute when installing the route or advertising that UPDATE to iBGP neighbors, but it MUST still append the globally configured ASN as normal when advertising the UPDATE to other local eBGP neighbors (i.e., those natively peering with the globally configured ASN)."

Polarity	Test	Kind and tier	Proof state
negative	`TestRFC7705NoPrependInstalledAndAdvertised`	unit/verify	revert, verified
positive	`TestRFC7705NoPrependInstalledAndAdvertised`	unit/verify	revert, verified

`RFC7705-3.3-3`

it MUST still append the globally configured ASN as normal when advertising the UPDATE to other local eBGP neighbors (§3.3)

Audit verdict: enforced (the tests do what the requirement demands), fresh. RFC 7705 Section 3.3: ""No Prepend Inbound": When the BGP router receives inbound BGP UPDATEs from its eBGP neighbor configured with this option, it MUST NOT append the "Local AS" ASN value in the AS_PATH attribute when installing the route or advertising that UPDATE to iBGP neighbors, but it MUST still append the globally configured ASN as normal when advertising the UPDATE to other local eBGP neighbors (i.e., those natively peering with the globally configured ASN)." The row owns the latter MUST, while 3.3-2 owns the inbound clause. TestLocalASNoPrependLeavesEveryOutboundPathAlone calls forwardLocalAS with noPrepend on the source, forwards actual NLRI, and compares decoded AS_PATH exactly: native eBGP [65000,65002], iBGP [65002], local-AS/no-prepend destination [legacy,global,source]. The first two independently pin append and its boundary. Producers peer_forward_facts.go secondaryPrependAS and session_as_migration.go isIBGPWith select the destination facts, not an outbound interpretation of the source's no-prepend option. A missing global ASN or blanket prepend fails. Independent source rejudgment only; no test, mutation, build or gate was executed by this auditor. Native observed-red renewal is a separate parent step.

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

`RFC7705-3.3-4`

"Replace Old AS" (outbound): When the BGP router generates outbound BGP UPDATEs toward an eBGP neighbor configured with this option, the BGP speaker MUST NOT append the globally configured ASN from the AS_PATH attribute. (§3.3)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Forbidden: appending the globally configured ASN toward a Replace Old AS eBGP neighbor. TestLocalASReplaceASSendsOnlyTheLocalAS asserts the replace-as destinations receive exactly [65010 65002] (assert.Equal), red if 65000 appears; TestLocalASOptionsProduceDifferentASPaths adds assert.NotContains 65000. Negative: the no-option destination receives [65010 65000 65002].

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

`RFC7705-3.3-5`

The BGP router MUST append only the configured "Local AS" ASN value to the AS_PATH attribute before sending the BGP UPDATEs outbound to the eBGP neighbor. (§3.3)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Forbidden: toward a Replace Old AS eBGP neighbor, appending anything other than the Local AS value, or omitting it. TestLocalASReplaceASSendsOnlyTheLocalAS asserts exact equality with [65010 65002], red on a missing 65010 or any extra ASN. Negative: the no-option destination's [65010 65000 65002].

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

`RFC7705-4.2-1`

The mechanism introduced in this section MUST be configurable on a per-neighbor or per-neighbor-group basis to allow for maximum flexibility. (§4.2)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Forbidden: the Internal BGP AS Migration mechanism settable on neither a neighbor nor a neighbor group. TestPeersFromConfigTree_ASMigrationPerNeighborGroup drives PeersFromConfigTree: the group's migration 64510 reaches the inheriting peer and the peer's own migration 64520 reaches that peer (assert.Equal MigrationAS), red if either basis is not read. Negative: the peer outside the group keeps MigrationAS zero and stays eBGP.

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

`RFC7705-4.2-2`

When configured with this mechanism, a BGP speaker MUST accept BGP OPEN and establish an iBGP session from configured iBGP peers if the ASN value in "My Autonomous System" is either the globally configured ASN or a locally configured ASN provided when this capability is utilized. (§4.2)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Forbidden: refusing the OPEN of a configured iBGP peer presenting the global or the locally configured ASN, or not establishing an iBGP session from it. TestRFC7705MigratingPeerEstablishesAsIBGP drives handleOpen then handleKeepalive for both ASNs and asserts Established, no NOTIFICATION and isIBGPWith(advertised) true; negative: a third ASN draws OPEN Message Error / Bad Peer AS and never reaches Established even after a KEEPALIVE. TestMigrationAcceptsEitherASN remains as OpenConfirm-level support.

Polarity	Test	Kind and tier	Proof state
negative	`TestRFC7705MigratingPeerEstablishesAsIBGP`	unit/verify	revert, verified
negative	`TestMigrationAcceptsEitherASN`	unit/verify	revert, verified
positive	`TestRFC7705MigratingPeerEstablishesAsIBGP`	unit/verify	revert, verified
positive	`TestMigrationAcceptsEitherASN`	unit/verify	revert, verified

`RFC7705-4.2-3`

Additionally, a BGP router configured with this mechanism MUST send its own BGP OPEN [RFC4271] (see Section 4.2) using either the globally configured or the locally configured ASN in "My Autonomous System" as follows. (§4.2)

Audit verdict: enforced (the tests do what the requirement demands), fresh. Forbidden: sending an OPEN whose My Autonomous System is neither the global nor the locally configured ASN. TestMigrationOpenCarriesResolvedASN reads the OPEN buildOpen produces and asserts My AS and the Four-octet AS capability equal the global ASN before a Bad Peer AS and the locally configured ASN after it (assert.Equal MyAS, ASN4, capability ASN), red on any other AS. Negative: without migration configured the local AS is sent whatever the fallback flag holds.

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

`RFC7705-4.2-4`

In each case, the BGP speaker MUST treat UPDATEs sent and received to this peer as if this was a natively configured iBGP session, as defined by [RFC4271] and [RFC4456]. (§4.2)

Audit verdict: enforced (the tests do what the requirement demands), fresh. RFC 7705 section 4.2 says: In each case, the BGP speaker MUST treat UPDATEs sent and received to this peer as if this was a natively configured iBGP session, as defined by RFC4271 and RFC4456. TestRFC7705MigrationWireSemantics compares native, retained-AS migration and legacy-AS migration sessions. Real ingress must install a third-party AS_PATH and LOCAL_PREF 231 unchanged; actual reflection must retain them without eBGP prepend and add exact ORIGINATOR_ID and CLUSTER_LIST. The distinct non-client/non-client forwarding case must return an error and emit no wire bytes. That negative case supplies resolved internal source facts, so it proves the forwarding boundary rather than independently proving source classification; the live positive case exercises source classification through isIBGPWith. Reading forwardUpdateSection confirms the destination classification and non-client suppression gate, reflection attributes and production forwarding path. These observations replace the old classification-only proof and address its named missing UPDATE behaviors. The startup commit changes formatting and fixture startup ordering without weakening assertions. Existing unit-changed discrimination records require renewal; no new mutant execution is claimed. Post-lint rejudgment 2026-10-04: lowLiveRouter no longer returns the discarded Reactor; the same running router and peers remain owned by cleanup. lowInstalledAttributes now embeds the identical source address 192.0.2.1 formerly passed by every caller, and still requires peer index, AFI/SAFI, prefix length and prefix bytes. Exact installed and transmitted attribute assertions and independent countercases are unchanged.

Polarity	Test	Kind and tier	Proof state
negative	`TestRFC7705MigrationWireSemantics`	unit/verify	revert, verified
positive	`TestRFC7705MigrationWireSemantics`	unit/verify	revert, verified

Extraction sign-off

Field	Value
Reviewer	ze-implement agent, plan/immediate/spec-bgp-as-migration.md phase 8, rfc7705 enrolment walk
Signed off	2026-09-14
Register	prose
Source	rfc/full/rfc7705.txt
Source fingerprint	f7503ea9d187b305
Record	rfc/extraction/rfc7705.json
Mapped sentences	8
Declined as scope	4
Relocated to a spec, which Ze OWES	0
Unclassified	0

Sections

Section	Name	Sites	Disposition	Reason
`front`	not stated	1	skipped (front-matter)	Title block, Abstract, Status of This Memo, Copyright Notice and the Table of Contents. It states what the document discusses and under which IETF process it was published, and it binds no implementation.
`1`	not stated	2	walked	not stated
`1.1`	not stated	0	walked	not stated
`1.2`	not stated	0	walked	not stated
`2`	not stated	0	walked	not stated
`3`	not stated	0	walked	not stated
`3.1`	not stated	0	walked	not stated
`3.2`	not stated	0	walked	not stated
`3.3`	not stated	4	walked	not stated
`4`	not stated	0	walked	not stated
`4.1`	not stated	1	walked	not stated
`4.2`	not stated	4	walked	not stated
`5`	not stated	0	walked	not stated
`6`	not stated	0	walked	not stated
`7`	References	0	skipped (references)	References. The heading over the two reference lists below it.
`7.1`	Normative References	0	skipped (references)	Normative References. Citation entries for RFC 2119, RFC 4271, RFC 4456, RFC 5082, RFC 5925 and RFC 6793. Each says where a cited document lives and binds nothing.
`7.2`	Informative References	0	skipped (references)	Informative References. Citation entries for RFC 5065, RFC 5398 and the AS migration drafts. Each says where a cited document lives and binds nothing.
`A`	Appendix A, Implementation Report	0	skipped (appendix-non-normative)	Appendix A, Implementation Report. Names the vendors whose shipping implementations the document describes (Cisco, Juniper, Alcatel-Lucent) and says the list is not exhaustive. It records what other implementations do and imposes nothing.

Excluded sentences

Site	Excluded kind	Reason	Quote
`front:1`	`not-a-requirement` never bound Ze the sentence states a fact or describes another document, and directs no implementation	IETF Trust Legal Provisions boilerplate the splitter did not strip: "Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions". It binds whoever copies code out of the document into another work, and this document contains no code component. It states nothing a BGP speaker does.	Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
`1:1`	`not-a-requirement` never bound Ze the sentence states a fact or describes another document, and directs no implementation	Introduction, describing the base protocol this document then relaxes: "By default, the BGP protocol requires an operator to configure a router to use a single remote ASN for the BGP neighbor, and the ASN must match on both ends of the peering in order to successfully negotiate and establish a BGP session." Indicative, and about BGP-4 rather than about this document. The obligation it describes is RFC 4271 Section 6.2 Bad Peer AS, which rfc/short/rfc4271.md owns; this document's own normative sentence about it is site 4.2:2, which carves the migration exception out of that check and is mapped to RFC7705-4.2-2.	By default, the BGP protocol requires an operator to configure a router to use a single remote ASN for the BGP neighbor, and the ASN must match on both ends of the peering in order to successfully negotiate and establish a BGP session.
`1:2`	`not-a-requirement` never bound Ze the sentence states a fact or describes another document, and directs no implementation	Introduction, a counterfactual about the world before these mechanisms existed: "Prior to the existence of these migration mechanisms, it would have required an ISP to coordinate an ASN change with, in some cases, tens of thousands of customers." The word 'required' sits inside 'it would have required', a past conditional describing what an ISP would have had to do, and it states no obligation on anybody now.	Prior to the existence of these migration mechanisms, it would have required an ISP to coordinate an ASN change with, in some cases, tens of thousands of customers.
`4.1:1`	`not-a-requirement` never bound Ze the sentence states a fact or describes another document, and directs no implementation	Step 2 of the section 4.1 migration recipe: "The 'Internal BGP AS Migration' mechanism is still required on all RRs for all RR Client iBGP sessions." It tells the operator carrying out the five-step renumbering which sessions must keep the mechanism configured while the walk is in progress, immediately after saying it 'is no longer needed' on the Non-Client sessions. It is a deployment instruction to the person running the migration, not a rule an implementation enforces: section 4.1 states outright that the mechanism 'can be enabled independent of the use of Route Reflectors'. The obligation this document places on the implementation is that the mechanism be configurable per neighbor or per neighbor group, which is site 4.2:1, mapped to RFC7705-4.2-1.	The "Internal BGP AS Migration" mechanism is still required on all RRs for all RR Client iBGP sessions.

Superseded

No document obsoletes RFC 7705, so its obligations are stated where they were written.