[j-nsp] Filtering OSPF routes

[Wayne (juniper nsp)]

RE: [j-nsp] Filtering OSPF routesOk,

On the off chance that it wasn't clear in my original post when I said "contrary to the design of OSPF (or any link state

protocol)", I am NOT advocating anyone doing this. I am simply pointing out that Cisco IOS provides a knob to do what he described.

- Wayne



  ----- Original Message ----- 
  From: Elliott, Andrew 
  To: 'Wayne (juniper nsp)' ; 'Ben Buxton' ; 'Ajay Bhardwaj' ; 'juniper-nsp at puck.nether.net' 
  Sent: Tuesday, February 18, 2003 10:26 AM
  Subject: RE: [j-nsp] Filtering OSPF routes


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  Wayne, 
    
  I have seen this in action, and it is ugly. 
    
  I recently had to work on a Cisco network where all routers were in 
  one of two areas, and they were using the distribute-lists to only 
  use the 0/0 LSA.  This created many routing loops, and I asked the 
  "designer" what they were thinking, and basically got the cold 
  shoulder.  I couldn't understand why someone would want to use OSPF 
  and then deliberately break it in that manner. 
    
  Has anyone on this list ever seen a good reason to filter LSAs? 
    
  - -andrew 

  - -----Original Message----- 
  From: Wayne (juniper nsp) [mailto:wg-jnpr-nsp at wgustavus.com] 
  Sent: Saturday, February 15, 2003 11:43 PM 
  To: Ben Buxton; Ajay Bhardwaj; juniper-nsp at puck.nether.net 
  Subject: Re: [j-nsp] Filtering OSPF routes 




  Actually, if you are running a sufficiently high enough version of 
  IOS (e.g. 12.0S), the 7200 can filter some LSAs.  It depends on your 
  exact scenario if this will accomplish what you are trying to do.  It 
  does tend to go contrary to the design of OSPF (or any link state 
  protocol), but I suppose enough people wanted the knob, so they got 
  it. 
    
  Not sure if JUNOS has a similar knob. 
    
  - - Wayne 

  - ----- Original Message ----- 
  From: Ben Buxton 
  To: Ajay Bhardwaj ; juniper-nsp at puck.nether.net 
  Sent: Monday, February 10, 2003 4:18 AM 
  Subject: RE: [j-nsp] Filtering OSPF routes 

   
  You cannot filter OSPF. This would break the requirement that all 
  routers have 
  the same link state view. 
  This is true for both Junos and IOS. 
    
  BB 

  - -----Original Message----- 
  From: Ajay Bhardwaj [mailto:ajay.bhardwaj at in.spectranet.com] 
  Sent: Monday, 10 February 2003 08:39 
  To: juniper-nsp at puck.nether.net 
  Subject: [j-nsp] Filtering OSPF routes 



  Hi all, 
    
  We have cisco 7200 router and M-5 router both running ospf and part 
  of area 10. 
    
  I want to deny few routes which are flowing trough ospf from 7200 to 
  m5 either at 7200 side or m5 side. Pls if anyone have any solution to 
  this would be gr8 help for me. 
    
  Ajay Bhardwaj 




    _____  





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