RE: Opsdir early review of draft-ietf-idr-bgp-ls-segment-routing-ext-06

["Ketan Talaulikar (ketant)" <[e-mail]>]

Hi Joel,

Many thanks for your review and please find responses inline below. I will update the draft with the same based on your feedback.

Thanks,
Ketan

-----Original Message-----
From: Joel Jaeggli <[e-mail]> 
Sent: 09 May 2018 12:16
To: [e-mail]
Cc: [e-mail]; [e-mail]; [e-mail]
Subject: Opsdir early review of draft-ietf-idr-bgp-ls-segment-routing-ext-06

Reviewer: Joel Jaeggli
Review result: Has Nits

I have performed a requested early review on the behalf of the operations directorate of the current draft-ietf-idr-bgp-ls-segment-routing-ext-06.
Generally I think this document is good, I won't say ready, as this review is intended as an early review not a final one.

Some nits

1-
introduction

   This way, all BGP speakers (specifically the route-reflectors) obtain
   Link-State information from all IGP areas (and from other ASes from
   EBGP peers).

* BGP speakers are agnostic about the source of the information beyond that it was exported with certain properties from the rib of it’s neighbor.
[KT] I agree this is generally true in case of BGP. However, in this specific case of BGP-LS, the Node, Link and Prefix NLRIs actually contain the identifiers/descriptors which include the source of the information - as in the specific IGP node originating it. So would you agree that in this specific BGP-LS case the statement is valid?

2 -
   An external component (e.g., a controller) then can
   collect SR information in the "northbound" direction across IGP areas
   or ASes and construct the end-to-end path (with its associated SIDs)
   that need to be applied to an incoming packet to achieve the desired
   end-to-end forwarding.

* Unqualified use of the term northbound I find generally problematic, particularly in the case of a route reflector. Previously RFC 7752 manged to use the term in the title and then never again within the text.
[KT] Sure. I would remove the "northbound" term.

3-

2.3.3.  Source Router Identifier (Source Router-ID) TLV

   The Source Router-ID TLV contains the IPv4 or IPv6 Router-ID of the
   originator of the Prefix.  For IS-IS protocol this is as defined in
   [RFC7794].  The Source Router-ID TLV may be used to carry the OSPF
   Router-ID of the prefix originator.

   The Source Router-ID TLV has the following format:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Type               |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   //                  IPv4/IPv6 Address (Router-ID)              //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

      Type: TBD, see Section 4.

      Length: 4 or 16.

      IPv4/IPv6 Address: 4 octet IPv4 address or 16 octet IPv6 address.

   The semantic of the Source Router-ID TLV is defined in [RFC7794].

* While RFC7794 Router-IDs are in fact IP addresses. OSPF Router-IDs are not even if they happen to look like them, this is particularly germain with ospfv3 but it’s worth making the distinction.
[KT] Agree. I would say "The semantic of the Source Router-ID TLV for ISIS is defined in [RFC7794]. For OSPF, the TLV carries the OSPF Router-ID of the originator of the prefix."

4 -
5.1.1.  Operations

   Existing BGP and BGP-LS operational procedures apply.  No additional
   operation procedures are defined in this document.

* An informative or normative reference (probably to 7752 especially fault
mangement) is probably required.
[KT] Agree and I would specifically put the normative reference to RFC7752.