[Idr] Regarding ICMP "Packet Too Big" message in 6PE RFC 4798

"Sriram K" <ksriram29@gmail.com> Tue, 25 November 2008 13:27 UTC

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Date: Tue, 25 Nov 2008 18:57:09 +0530
From: "Sriram K" <ksriram29@gmail.com>
To: idr@ietf.org
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Subject: [Idr] Regarding ICMP "Packet Too Big" message in 6PE RFC 4798
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Dear All,

The penultimate para in Section 3, Page 6 of 6PE RFC 4798 states the
following:

 "Otherwise, routers in the IPv4 MPLS network have the option to generate an
ICMP "Packet Too Big" message using mechanisms as described in Section 2.3.2
.... of [RFC3032]"

As per RFC3032, the routers in the IPv4 MPLS network can generate ICMP "Time
Exceeded" message or "Destination Unreachable because fragmentation needed
and DF set" message.

Can someone please explain, how a IPv4 MPLS router will generate an ICMP
"Packet Too Big"? This requires that the router in IPv4 MPLS network be a
dual stack router to understand the IPv6 header under the label stack. Is my
understanding correct?

If the router is an intermediate LSR, how will it know the path to the IPv6
destination even if it is dual stack router?

Thanks in advance.

Cheers,
Sriram
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