RE: question regarding draft-ietf-6man-rfc3484-revise-02 section 2.3

"Hemant Singh (shemant)" <shemant@cisco.com> Mon, 28 March 2011 14:27 UTC

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Subject: RE: question regarding draft-ietf-6man-rfc3484-revise-02 section 2.3
Date: Mon, 28 Mar 2011 09:28:55 -0500
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From: "Hemant Singh (shemant)" <shemant@cisco.com>
To: "Mikael Abrahamsson" <swmike@swm.pp.se>
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-----Original Message-----
From: Mikael Abrahamsson [mailto:swmike@swm.pp.se] 
Sent: Monday, March 28, 2011 3:04 PM
To: Hemant Singh (shemant)
Cc: ipv6@ietf.org
Subject: RE: question regarding draft-ietf-6man-rfc3484-revise-02
section 2.3

Mikael,

>Right now I couldn't help reading the text in section 2.3 and wondering

>how it was supposed to achieve what was described.

[If SA is assigned by the selected next-hop that will be used to send to
D and SB is assigned by a different next-hop, then prefer SA.
Similarly, if SB is assigned by the next-hop that will be used to send
to D and SA is assigned by a different next-hop, then prefer SB.]

Here is an attempt to explain the text above from section 2.3 of the
document that I have included between squared brackets above.  SA was
acquired using DHCPv6 where the DHCPv6 response did arrive to the client
on the IPv6 link-local address of the first-hop.  The client already
knows this link-local address matches a mac-address of, say,
mac-address1 obtained from the RA from the same first-hop router.  Thus
SA is associated with Router 1 (from Figure 1 of section 2.1.1 of RFC
5220).  Likewise SB is associated with Router 2 with mac-addr of say,
mac-address2.  Thus far we established that SA is used when sending to
the default router of Router 1 and likewise for SB with Router 2.  An
orthogonal question is how does the host know for a destination D which
default router to go to - should such a question be addressed by this
document?  If yes, then an out of band mechanism is needed to let the
host know what default router to use for a destination D.  One out of
band mechanism is use an MSR to signal a specific route to the host.

Did I miss anything?

Thanks,

Hemant