The MPLS-OPS Archive

["M. ELK" <elkou141061@hotmail.com>]

Pls find the reply inline .

Brgds


>From: Dave Stewart <dave_stewart1576@yahoo.co.uk>
>To: "M. ELK" <elkou141061@hotmail.com>, mpls-ops@mplsrc.com
>Subject: Re: [MPLS-OPS]: Cisco, Traffic Engineering for RSVP
>Date: Wed, 23 Jul 2003 19:12:56 +0100 (BST)
>
>
>Some nits I would like to clarify, thank you for the response:
>
>"M. ELK" <elkou141061@hotmail.com> wrote:
>
>
>Dave
>
>AFAIK ,
>
>Qa. How do cisco routers learn the information on link utilisation?
>Aa. IGP (any link state , IS-IS or OSPF both supported by cisco) flood the
>link utiilization
>as an attribute for link state .
>
>Q. Is this attribute propogated using Opaque LSA?
>
For OSPF : Yes .

>
>RSVP do the accounting , ie: start with certain B.W anmount per
>interface ( % of link speed)
>and decrease the amount of each LSP set up through this interface .
>Of course RSVP and IGP process at the router need to commuicate .
>U could set the frequency of IGP fllooding due to link utilization
>change (normally as % of
>change ) .
>
>Qb. The 12.3 IOS set does not have anything on support for Katz-Yeung or
>Smit-Li drafts.
>Ab. Ufamiliar with those draft .
>
>
>
>Q. What is the method used to propogate the TE information? These are the 2 
>drafts I am aware of which come from the OSPF and ISIS WG. Does cisco 
>support the same? Can someone please tell me the IOS version this is 
>supported from? We need to get the same for our network here.I have been 
>following new IOS releases closely to get the same.
>

For IS-IS : draft-ietf-isis-traffic-02.txt
For OSPF : draft-katz-yeung-ospf-traffic-01.tx , as U indicated previously .

Guess TE OSPF/IS_IS is supported long ago by csco , saw 12.0(22)S used for 
IS-IS .

>
>Qc. Does this mean all LSP setups are independentof IGP? How does it tell
>RSVP how to setup LSP?
>Ac. IGP populate a TE D.B ,RSVP could use the TE D.B to calculate the path
>of the LSP ie: CSPF ,
>in other word this is an EDUCATED-GUESS .
>RSVP could totally ignore the TE D.B and set LSP with strict or loose
>path , this is when U config
>static path . seting LSP this way is a blind trial which could succeed
>if their is avail B.W on the path
>specified .
>
>Qd. Assuming it is not CSPF either, can RSVP-TE be simply used to set up
>label with constraints? How do routers get information on these 
>constraints?
>Ad. LSP should always have a constrain even if constrain is none ie:LSP B.W
>requirement = 0 .
>CSPF help to calculate best path which statisfy the constraint before
>setting the LSP .
>The RSVP could take a completely blind trial simply setting the path as
>{loose Egress} ,now
>every node along the path find the best path to the egress , this
>appropriate if U set the
>LSP contarin as zero .
>U could set the full path still set the constarin as zero ,this is
>mainly if U calculate the TE by
>offline-tool and U need to totally disable the online CSPF of the
>HEAD-END node and any
>RSVP accounting on transit node .
>
>What is the present method to be doing it? Is it the TE tool?
>
>
Guess , the on-line ie: CSPF is simple and ready available .
>
>
>-Dave Stewart
>
>
>
>
>---------------------------------
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