The MPLS WG Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] What to do when label has error?
Sherry,
Refer to rfc 3031 section 3.18 and 3.22. If the LSR can determine
through some external means that forwarding the packet is not going to
result in a loop (or any other harm) than it can forward the packet.
Otherwise it MUST drop the packet. The rfc is silent about generating ICMP
messages in such a situation. If the LSR prefers to generate an ICMP message
than it should be able to route the ICMP Message to the source. (The LSR
might not have the routing information to the source. Also, if you are using
a shim header than you might not be able to identify the network layer
encapsulation correctly (in case of an invalid label)).
In the second case, i.e. if the LSR can identify somehow that forwarding
the packet unlabeled is not going to cause any harm and resorts to IP
Forwarding after stripping the label stack than it should not(IMHO) send an
ICMP error message to the source.
Akshat
----- Original Message -----
From: "Sherry Wei" <sherry_wei@hotmail.com>
To: <mpls@UU.NET>
Sent: Wednesday, May 23, 2001 10:08 AM
Subject: What to do when label has error?
> Hello,
>
> I have a doubt about the real operation in the case that the LSR can't
find
> the according ILM or NHLFE. What will it do then? Drop the packet and send
> the ICMP message to the source, or strip off the label stack and deal with
> the packet with IP forwarding meanwhile send the ICMP message?
>
> Sherry
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>
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