suehares
commented
4 months ago G3-31: Section 7.1.2 (Clarity of English Text) - 07 text review
08-status: resolved, closed after discussion with DJ.
07-status: Partially Resolved. This issue contains the following three sub-issues: 31a, 31b, 31c. Resolved: 31a, 31b, Not resolved: 31c
31-c Issue:
-07 text:/ BGP CAR distribution of (E, C) underlay route:
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The intent-aware path to the egress PE within the egress domain is provided by an SR-TE or similar policy (E, C) [RFC9256]. This (E, C) policy is distributed into the multi-domain network from egress BRs using a BGP CAR Type-1 route, towards ingress PEs in other domains. This signaling is the same as for SR-MPLS, as described in earlier sections.
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The (E, C) BGP CAR Type-1 route is advertised from a BR with an SRv6 transport SID allocated from an SRv6 locator assigned for the intent C. An SR-PCE or local configuration may ensure multiple BRs in the egress domain that originate the (E, C) route advertise the same SRv6 transport SID./
New text:/ BGP CAR distribution of (E, C) underlay route is done by:
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The intent-aware path to the egress PE within the egress domain being provided by an SR-TE or similar policy (E, C) [RFC9256]. This
(E, C) policy is distributed into the multi-domain network from an egress BR using a BGP CAR Type-1 route to ingress PEs in other domains.
This signaling is the same as for SR-MPLS, as described in section 2 (see sections 2.3, 2.4, 2.5, and 2.8). -
This (E, C) BGP CAR Type-1 route is advertised from a BR with an SRv6 transport SID allocated from an SRv6 locator assigned for the intent C.
note for -08: Split here missing
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An SR-PCE or local configuration may ensure multiple BRs in the egress domain that originate this (E, C) route is advertise the same SRv6 transport SID./
Note: If the above sections within the draft are incorrect, please provide specific sections.
G3-31: Section 7.1.2 - English Text clarity
G3-31a Old text:/ The SRv6 Service SID allocated by an egress PE is not routed. The service route is advertised by the egress PE with a Color Extended- Community C ([RFC9252] section 5). /
New text:/ The SRv6 Service SID allocated by an egress PE is not routed. The service route is advertised by the egress PE with a Color Extended- Community C (definition [RFC9012], usage [RFC9252] section 5). /
G3-31b: Old Text:/ An ingress PE in a remote domain steers a received service route with Color C via this (E, C) BGP CAR route, as described in Section 3. /
New text:/ An ingress PE in a remote domain steers traffic associated with the received service route with Color C via this (E, C) BGP CAR route, as described in Section 3. /
G3-31c: Old text: Clarity of procedures BGP-CAR may also provide the underlay intent-aware inter-domain reachability to this SRv6 transport SID:
An egress domain BR advertises an IP Prefix Type-2 CAR route for the locator prefix that covers the SRv6 transport SID allocated by the egress BR for this (E, C) route. This IP Prefix CAR route is distributed across BGP hops in the underlay towards ingress PEs similar to previous case and may be summarized.
Thus, the colored service route resolves via the Type-1 CAR route, which in turn carries a SRv6 transport SID that resolves via the Type-2 CAR route. Multiple Type-1 routes may resolve via a single Type-2 route. / New text:/ BGP-CAR may also provide the underlay intent-aware inter-domain reachability to this SRv6 transport SID by:
An egress domain BR advertises an IP Prefix Type-2 CAR route for the locator prefix that covers the SRv6 transport SID allocated by the egress BR for this (E, C) route.
This IP Prefix CAR route is distributed across BGP hops in the underlay towards ingress PEs similar to previous case and may be summarized.
the colored service route resolves via the Type-1 CAR route, which in turn carries a SRv6 transport SID that resolves via the Type-2 CAR route. Multiple Type-1 routes may resolve via a single Type-2 route. /
G3-32: Section 7.2, Editorial
Old text:/ A few options to forward packets for BGP Rv6 prefixes described in ([I-D.agrawal-spring-srv6-mpls-interworking] also apply to BGP CAR as follows: / New text:/ A few options to forward packets for BGP SRv6 prefixes described in ([I-D.agrawal-spring-srv6-mpls-interworking] also apply to BGP CAR for Hop by Hop IPv6 forwarding (section 7.2.1) and Encapsulation between Border routes (BR) for BGP SRv6 Prefixes (section 7.2.2). /
Why: English Grammar. Sentences do not linger over sections.
G3-33: Section 7.2.1 - English Grammar
Old text:/
Hop by hop IPv6 lookup and forwarding on both BRs and P nodes in a domain.
P nodes need to learn BGP SRv6 routes. With summarization, route scale requirements can be minimized.
BGP routing is enabled on all internal nodes (iBGP).
BRs distribute external SRv6 routes to internal peers.
Similar to Internet / BGP IP routing well-known model.
Illustration in Appendix C.1. / New text:/ The following characteristics are possible for IPv6 forwarding of BGP SRv6 Prefixes:
Hop by hop IPv6 lookup and forwarding on both BRs and P nodes in a domain.
P nodes need to learn BGP SRv6 routes. With summarization, route scale requirements can be minimized.
BGP routing is enabled on all internal nodes (iBGP).
BRs distribute external SRv6 routes to internal peers.
The scaling of the solution is similar to Internet where BGP IP routing has well-known scaling and can support large scale route distribution. An example illustrating these qualities is in the Appendix in section C.1. / Why: (English Grammar) English Sentences rather than bullet points.
G3-34: Section 7.2.2. - English Edits
Old text:/ 7.2.2. Encapsulation between BRs for BGP SRv6 Prefixes
IPv6 lookup and forwarding for BGP SRv6 prefixes only on BGP BRs.
SRv6 (or other) encapsulation to reach the BGP SRv6 next hop.
SRv6 outer encapsulation may be H.Encaps.Red or H.Insert.Red.
BGP route distribution between BRs (via RRs, or directly if single-hop eBGP).
An egress BR sets itself as BGP next hop, selects and advertises an appropriate SID for SRv6 based encapsulation towards itself.
An ingress BR encapsulates SRv6 egress PE destined packets with encapsulation to BGP next hop, ie. Egress BR.
If SRv6 encapsulation, then SID from egress BR is common SID, shared by multiple BGP SRv6 prefixes.
If MPLS/SR-MPLS transport, route will carry label/prefix-SID allocated by next hop, may be shared.
Illustration in Appendix C.2. /
New text:/ 7.2.2. Encapsulation between BRs for BGP SRv6 Prefixes
Another possible solution is the encapsulation of IPv6 traffic between Border Routers for IPv6 Prefixes. This solution includes the following steps:
IPv6 lookup and forwarding for BGP SRv6 prefixes only on BGP BRs.
SRv6 (or other) encapsulation to reach the BGP SRv6 next hop.
SRv6 outer encapsulation may be H.Encaps.Red or H.Insert.Red.
BGP route distribution between BRs (via RRs, or directly if single-hop eBGP).
An egress BR sets itself as BGP next hop, selects and advertises an appropriate SID for SRv6 based encapsulation towards itself.
An ingress BR encapsulates SRv6 egress PE destined packets with encapsulation to BGP next hop (probably the Egress Border router),
If SRv6 encapsulation, then SID from egress BR is common SID, shared by multiple BGP SRv6 prefixes.
If MPLS/SR-MPLS transport, route will carry label/prefix-SID allocated by next hop, may be shared.
An example illustrating this solution is in Appendix C.2. /
Why: (English Grammar) Sentences rather than bullet points.
G3-35: Section 7.2.3
Old text:/ Using the BGP CAR SAFI provides significant operational advantages: / New text:/ Using the BGP CAR SAFI provides the following operational advantages: /
Why: Unless you can prove "significant" stay with the adjective "following".
G3-36: Section 8
Old text:/ For specific intents, color may be signaled with the CAR Type-2 route for purposes such as intent-aware SRv6 SID or BGP next-hop selection at each transit BR, color based routing policies and filtering, and intent-aware next-hop resolution (Section 2.5), same as with Type-1 routes. For such purposes, color associated with the CAR IP Prefix route is signaled using LCM-EC. / New text:/ For specific intents, color may be signaled with the CAR Type-2 route for purposes such as intent-aware SRv6 SID or BGP next-hop selection at each transit BR, color based routing policies and filtering, and intent-aware next-hop resolution (Section 2.5). These purposes are the same as with Type-1 routes. For such purposes, color associated with the CAR IP Prefix route is signaled using LCM-EC. /
G3-37: Section 9.1.1
Old text:/
G3-38: Section 9.1.2
Old text:/