Subject: [mpls] mpls-ldp-ipv6 : Issue needs WG input

From: "Rajiv Asati (rajiva)" <[email-masked]>
Date: Thu, 22 Sep 2011 15:52:48 -0500

While this document passed the WGLC without any comments, we wanted to
bring up an issue to seek your feedback.
	
The issue is that the current LDP spec rfc5036 allows an LDP peer to
advertise IPv6 bindings to an LDP IPv4 peer, even though the peer may
not have any IPv6 enabled (or IPv6 LDP), and vice versa*. See figure 3
in section 1.1.1 of ldp-ipv6 document. 

While mpls-ldp-ipv6 section 7** addresses this issue (by checking for v6
hello adj, in line with existing 'targeted adj check for PW binding
advertisement'), we want to pose the following questions:

(1) is this a reasonable issue to be fixed? 
(2) is ldp-ipv6 document the right place to fix it?
(3) is the solution highlighted in section 7 a reasonable solution, if
you answered yes to both 1 and 2?

You may answer simple yes/no to each Q, if you like.

Cheers,
Rajiv

*	Consequently, an LDP peer advertising IPv4 bindings to
	an LDP IPv6 only peer, which doesn't have IPv4 any more
	(out in the future, of course).

**
7. Label Distribution

   This document specifies that an LSR should advertise and receive
   both IPv4 and IPv6 label bindings from and to the peer, only if it
   has valid IPv4 and IPv6 Hello Adjacencies for that peer, as
   specified in section 6.2.	

   This means that the LSR must not advertise any IPv6 label bindings
   to a peer over an IPv4 LDP session, if no IPv6 Hello Adjacency
   existed for that peer (and vice versa).

---

From: "Mallette, Edwin" <[email-masked]>
Date: Sat, 24 Sep 2011 10:28:48 -0400

Rajiv, my response is in-line.

>(1) is this a reasonable issue to be fixed?
[EJM] Yes!
>(2) is ldp-ipv6 document the right place to fix it?
[EJM] It's certainly the most expedient.  It strikes me that the plan
would be to "fix" this issue within LDP-IPv6 and then when RFC5036 is
incremented, create a new ID which includes the LDP-IPV6 additions, along
with the fix, within the updated LDP Specification.
My 2c yes.
>you answered yes to both 1 and 2?
[EJM] Yes.
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