The MPLS-OPS Archive

Cell Relay Retreat>MPLS-OPS Archive>month:2003-Jul> msg00142



[Date Prev][Date Next][Thread Prev][Thread Next]  
  [Date Index][Thread Index][Author Index][Subject Index]

RE: Reg:RSVP LSP without CSPF

  • From: "Lars Higham" <lhigham@yahoo.com>
  • Date: Tue, 29 Jul 2003 19:28:34 +0530
  • Cc: <richard.james@rogers.com>, <carlos@carlos.net>, <bldavis@hyperchip.com>, <eosborne@cisco.com>, <terrylee@huawei.com>, <stephen.mullaney@parc-technologies.com>
  • Importance: Normal
  • Resent-Date: Tue, 29 Jul 2003 10:26:39 -0400
  • To: "'Kavitha.R'" <kar@srasys.co.in>, <mpls-ops@mplsrc.com>

Title: Message
See below:
 
Regards,
Lars Higham
-----Original Message-----
From: Kavitha.R [mailto:kar@srasys.co.in]
Sent: Tuesday, July 29, 2003 6:57 PM
To: mpls-ops@mplsrc.com
Cc: richard.james@rogers.com; carlos@carlos.net; bldavis@hyperchip.com; eosborne@cisco.com; lhigham@yahoo.com; terrylee@huawei.com; stephen.mullaney@parc-technologies.com; kar@srasys.co.in
Subject: [MPLS-OPS]: Reg:RSVP LSP without CSPF

 
Hello All,
        That was a good discussion on RSVP LSP without CSPF.But am sorry am getting confused.
        I am trying to summarise below whatever I have grasped. Pls correct me if I am wrong.
     
 
                                                   
                                                                TEDB FLOW  
 
                              _________________
                             |                              |
                             |       IGP TE             |
                             |_________________|
                                            |
                                            |
                                            |   
                                           \ /
                             ________________                   ________________                         __________________ 
                            |                            |                  |                             |                        |                                |
                            |            TEDB        |--------------->|         CSPF            |<--------------------- |  user constraints      |
                            |________________|                  |_________________|                        |__________________|
                                                                                        |
                                                                                        |
                                                                                        |
                                                                                        |
                                                                                       \ /
                                                                         ___________________
                                                                        |                                  |
                                                                        |        Explicit route      |
                                                                        |           (ERO)              |
                                                                        |___________________ |
                                                                                        |
                                                                                        |
                                                                                        |
                                                                                       \ /
                                                                        ____________________
                                                                        |                                  |
                                                                        |          Signaling           |
                                                                        |                                  |
                                                                        |___________________|

Steps:
 
   1. First IGP TE populates the TEDB.
  
   2. If CSPF option is set CSPF uses the TEDB to calculate the best path with constraints online.
      (Note:CSPF calculation is possible only if u have TEDB.) 
Correct 
   
   3. If verbatim option is set in Cisco or "no cspf" is set in Juniper or other networks it means that
      IGP TE is not necessary and hence cspf will not be used to find the explicit path. 
TE can be accomplished with or without CSPF; CSPF is a method of accomplishing constrained paths locally from the router, but you still have TE if you manually determine the path, or if you use an offline tool to determine the path.  TE is essentially just directing a given LSP along a path that may not be the IGP path.
   
   4. Instead strict/loose path option(manual configuration of static path by user)
      is used to set up the explicit LSP and RSVP signalling takes place along that path.This is without TE.  
 See above comment 
 
    I want to know clearly when TEDB (IGP TE) is required and when it is not.
    Is it true that
   
         if CSPF path - TEDB required 
True 
        if strict/loose path- TEDB not required.Here TE does not come into picture at all. 
First part is true, second part false 
 
 
Thanx in advance
Kavitha