The MPLS-OPS Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] Re: Can Protocol packet be distinguished?
Let me give you the following excerpt from RFC 3032 which reserves
a special label value for "Router Alert Label", which should be forwarded
to a local software module for processing.
--- RFC 3032 ---
A value of 1 represents the "Router Alert Label". This label value is legal anywhere
in the label stack except at the bottom. When a received packet contains this label
value at the top of the label stack, it is delivered to a local software module for processing.
The actual forwarding of the packet is determined by the label beneath it in the stack.
However, if the packet is forwarded further, the Router Alert Label should be pushed
back onto the label stack before forwarding. The use of this label is analogous to the use
of the "Router Alert Option" in IP packets [5]. Since this label cannot occur
at the bottom of the stack, it is not associated with a particular network layer protocol.
---
----- Original Message -----
From: "Eric Gray" <eric.gray@sandburst.com>
To: "njzhy" <njzhy@etang.com>
Cc: "MPLSRC" <mpls-ops@mplsrc.com>
Sent: Monday, October 22, 2001 9:56 AM
Subject: Re: Can Protocol packet be distinguished?
Jine,
Protocol (control) packets can be distinguished in the same way that
all other packets can be distinguished in MPLS encapsulated packets -
i.e. - by using the header that follows the last label in the MPLS stack.
You wrote:
> Dear all,
> I have a silly question. In a MPLS domain, can protocal packets be distinguished from the user's data packets? In other words,
are the protocal packets encapsulated with MPLS labels,too?
>
> Thanks in advance!
>
> Jine
>
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--
Eric Gray (mailto:eric.gray@sandburst.com)
http://www.mindspring.com/~ewgray
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