Hi Bala,
no-cspf, Signalling of Path hop-by-hop
If you have no-cspf then the LSP is built hop-by-hop by RSVP, following the
restrictions in the explicit path if you have configured one and using the
IGP routing table to resolve next hops along the path.
cspf, Calculation of path at Ingress LER:
If you have CSPF enabled then the path is calculated on the Ingress LER
before RSVP signals the path. If an Explicit Path is configured, it is taken
into account when CSPF carries out its calculation of the LSP path. (if your
explicit path is the a full strict path then the CSPF won't be calculating
much).
Hops this clarifies it for you
The is a diagram an step by step calculation process in MPLS applications
JunOS 4.4 page 23 of the PDF format Title: How CSPF Selects a Path, which
should help.
Gary
>-----Original Message-----
>From: Bala Subrahmanyam Venkata [mailto:bsubrahm@doradosoftware.com]
>Sent: 17 August 2001 16:58
>To: MPuras@solunet.com
>Cc: juniper-nsp@puck.nether.net
>Subject: RE: LSP config: CSPF and named path
>
>
>Mario-
>
>Thanx for the reply. Yes, I have read the doc and I was wondering what
>happens if
>I enable CSPF and specify an expliti path for my LSP..is there
>a precedence
>check
>between CSPF computed path and my explicitly defined named path ?
>
>
>/bala
>
>
>> -----Original Message-----
>> From: MPuras@solunet.com [mailto:MPuras@solunet.com]
>> Sent: Friday, August 17, 2001 8:44 AM
>> To: bsubrahm@doradosoftware.com
>> Subject: RE: LSP config: CSPF and named path
>>
>>
>> Hi Bala,
>>
>>
>> Here is the link for your answer:
>> http://arachne3.juniper.net/techpubs/software/junos44/swconfig44-m
>> pls-apps/d
>> ownload/mpls-overview.pdf
>>
>>
>> CSPF is used when you are not depending on the IGP-TE extensions,
>> therefore
>> not having any knowledge of bandwidth resv, hop-limits
>etc.... When you
>> enable cspf you essentially know your topology but in
>addition you also
>> learn groups, priorities, bandwidth resv, hop-limits from the
>> extensions to
>> the IGP. There is an additiona database build called the
>TED that stores
>> all these attributes. Check out the link for further review.
>>
>>
>>
>> Mario Puras
>> SoluNet Technical Support
>> Network Support Engineer
>> We don't make network products,
>> we make them Work!
>> Mailto:mpuras@solunet.com
>> 888.SOLUNET (Canada) / 888.449.5766 (USA)
>>
>>
>> -----Original Message-----
>> From: Bala Subrahmanyam Venkata [mailto:bsubrahm@doradosoftware.com]
>> Sent: Friday, August 17, 2001 11:32 AM
>> To: juniper-nsp@puck.nether.net
>> Subject: LSP config: CSPF and named path
>>
>>
>> When do we need the "no-cspf" command in an LSP ? Suppose if I
>> have a named
>> path for the primary and say couple of secondary named
>paths, then not
>> having "no-cspf" does what ? (i.e. what does CSPF do when there is an
>> explicitly configured path for an LSP ?)
>>
>> Similary when we dont have "no-cspf" in an LSP's configuration do
>> we need a
>> named path for that LSP ?
>>
>>
>> /bala
>>
>>
>
>
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