Re: [Lsr] OSPF Routing with Cross-Address Family Traffic Engineering Tunnels - draft-ietf-ospf-xaf-te-04.txt

Anton Smirnov <asmirnov@cisco.com> Thu, 25 October 2018 16:57 UTC

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To: "Ketan Talaulikar (ketant)" <ketant@cisco.com>, "Acee Lindem (acee)" <acee@cisco.com>, "lsr@ietf.org" <lsr@ietf.org>
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From: Anton Smirnov <asmirnov@cisco.com>
Organization: Cisco Systems
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Date: Thu, 25 Oct 2018 18:57:11 +0200
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Subject: Re: [Lsr] OSPF Routing with Cross-Address Family Traffic Engineering Tunnels - draft-ietf-ospf-xaf-te-04.txt
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    Hi Ketan,

1. I am not sure I understood the question. Your example says "using the 
TE topology from OSPFv2 to compute a tunnel". In that case TE router ID 
is an IPv4 address. So no, advertising IPv6 address won't help to 
identify the tunnel.

2. my opinion (not discussed with other authors): RFC 3906 is 
Informational RFC, so it is not mandatory for implementation to follow. 
I think we can insert mention to that RFC somewhere in the Introduction 
but wording should be sufficiently weak (like "one possible example of 
route computation algorithm...").

---
Anton

On 10/24/18 12:06, Ketan Talaulikar (ketant) wrote:
>
> Hello All,
>
> I support this simple but important extension.
>
> A couple of minor comments on the draft:
>
> 1)Sec 3 says
>
>    A node that implements X-AF routing SHOULD advertise, in the
>    corresponding Node Local Address sub-TLV, all X-AF IPv4 and IPv6
>    addresses local to the router that can be used by Constrained SPF
>    (CSPF) to calculate MPLS TE LSPs.  In general, OSPF SHOULD advertise
>    the IP address listed in the Router Address TLV [RFC3630 
> <https://tools.ietf.org/html/rfc3630>] [RFC5329 
> <https://tools.ietf.org/html/rfc5329>]
>    of the X-AF instance maintaining the MPLS TE database, plus any
>    additional local addresses advertised by the X-AF OSPF instance in
>    its Node Local Address sub-TLVs.  An implementation MAY advertise
>    other local X-AF addresses.
>
> Generally speaking, should the IP address (TE router ID in common 
> terms) which is candidate for inclusion in the Router Address TLV not 
> be a MUST candidate for X-AF advertisement?
>
> I also have a question about the first statement with the SHOULD in 
> it. Consider we are using the TE topology from OSPFv2 to compute a 
> tunnel for use with OSPFv3. Any IPv6 addresses associated with the 
> OSPFv3 instance on a router would be advertised as a Node attribute 
> and would not help identify a specific link. So practically, if any 
> IPv6 addresses (if at all) were to be used for CSPF then it would just 
> identify the node – in this case, isn’t advertising the IPv6 address 
> (TE router ID used in Router Address TLV) sufficient?
>
> For practical deployment, it think it would help if this was clarified 
> that we really need only the TE Router ID Address to go X-AF in 
> most/general cases and not the others?
>
> 2)Isn’t the mapping algorithm in Sec 3 actually going to be used for 
> IGP short-cut use-case with its reference to the IGP cost of the 
> tunnel? If so, would a reference to rfc3906 be helpful in this document.
>
> Thanks,
>
> Ketan
>
> *From:*Lsr <lsr-bounces@ietf.org>; *On Behalf Of *Acee Lindem (acee)
> *Sent:* 23 October 2018 03:55
> *To:* lsr@ietf.org
> *Subject:* [Lsr] OSPF Routing with Cross-Address Family Traffic 
> Engineering Tunnels - draft-ietf-ospf-xaf-te-04.txt
>
> This begins an LSR WG last call for the subject draft. Please send 
> your comments to this list prior to 12:00 AM GMT, November 13^th , 
> 2018. While its only an 8 page document, I added an extra week due to 
> the IETF. Please let me know if anyone needs any more time.
>
> https://datatracker.ietf.org/doc/draft-ietf-ospf-xaf-te/
>
> Thanks,
> Acee
>
>
>
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