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Re: beginner's query

  • From: "Eric Osborne" <eosborne@cisco.com>
  • Date: Thu, 20 May 2004 09:51:20 -0400
  • Organization: Cisco Systems, Inc.
  • Resent-Date: Thu, 20 May 2004 10:25:29 -0400
  • To: "Sundeep Singh" <singh0de@ee.iitb.ac.in>, mpls-ops@mplsrc.com
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On Thu, 20 May 2004 10:15:29 +0530 (IST), Sundeep Singh  
<singh0de@ee.iitb.ac.in> wrote:

> Hi,
> I fail to understand the format of the "Path message" as specified in RFC
> 3209. what does the different types of brackets signify?

That stuff is written in Backus-Naur Form (BNF):

http://cui.unige.ch/db-research/Enseignement/analyseinfo/AboutBNF.html


> And say i wish to reserve 10kbps of bandwidth for a particular FEC, how  
> is
> this conveyed using a Path message?

This is signalled in the SENDER_TSPEC.  On a cisco box:

*Dec 23 17:57:17.029:  SENDER_TSPEC         type 2 length 36:
*Dec 23 17:57:17.029:   version=0, length in words=7
*Dec 23 17:57:17.029:   Token bucket fragment (service_id=1, length=6 words
*Dec 23 17:57:17.029:     parameter id=127, flags=0, parameter length=5
*Dec 23 17:57:17.029:     average rate=1250 bytes/sec, burst depth=1000  
bytes
*Dec 23 17:57:17.029:     peak rate   =1250 bytes/sec
*Dec 23 17:57:17.029:     min unit=0 bytes, max pkt size=4294967295 bytes

average rate==peak rate==1250 Bytes/sec==10,000 bits/sec==10Kbps

Exactly where to put the BW isn't well specified, so it was a source of  
confusion during the early days of TE, but seems to have all settled down  
now.

> Also is there some good reference other than the RFC, where i can look  
> for
> a better understanding of RSVP-TE.

I can wholeheartedly recommend "Traffic Engineering with MPLS" by Osborne  
& Simha, but I'm perhaps a little biased in that area. :)



eric

> Thanks,
> Sundeep.


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