Re: OSPF distance manipulation

From: Bob Sinclair (bobsinclair@frontiernet.net)
Date: Mon Jun 26 2006 - 11:32:14 ART


Drayton,

As I understand your scenario, the SOURCE in the OSPF distance command would
need to be the RID of the preferred ABR. The following sequence works for me,
where 172.16.102.1 is the RID of my preferred ABR, and 172.16.101.0/24 is the
route in question.

router ospf 1
 log-adjacency-changes
 network 172.16.0.0 0.0.255.255 area 10
 distance 109 172.16.102.1 0.0.0.0 OSPF

ip access-list standard OSPF
 permit 172.16.101.0

R6#sh ip route 172.16.101.0
Routing entry for 172.16.101.0/24
  Known via "ospf 1", distance 109, metric 139, type inter area
  Last update from 172.16.45.4 on Ethernet0, 00:03:47 ago
  Routing Descriptor Blocks:
  * 172.16.45.4, from 172.16.102.1, 00:03:47 ago, via Ethernet0
      Route metric is 139, traffic share count is 1

HTH,

Bob Sinclair
CCIE #10427, CCSI 30427
www.netmasterclass.net

  ----- Original Message -----
  From: Drayton Williams
  To: ccielab@groupstudy.com
  Sent: Monday, June 26, 2006 8:45 AM
  Subject: OSPF distance manipulation

  Hey guys,

  Quick question on an issue I had last night doing a lab, here is the setup;
  hub router (r1) with two spokes (r2)(r3); the spoke routers both have hdlc
  connections to r4; running ospf area 10 between r1, r2, and r3 using ip
  ospf point-to-point between hub and spokes (obviously r2 and r3 going to
  hub are in different subnets). The hdlc connection between r2, r3, and r4
  are in ospf area 0;

  from r1, I'm getting two routes to get 4.4.4.4 on r4 (just a loopback
  interface i'm advertising into area 0 there); one from r2 and one from r3;
  i'm trying to manipulate the administrative distance on r1 (since it should
  only be locally significant) to prefer going to r2 as apposed to r3 to get
  to this route; here is what i entered on r1;

  router ospf 1
   distance 109 2.2.2.2 0.0.0.0 OSPF

  ip access-list standard OSPF
   permit 2.2.2.2 0.0.0.0

  Oddly enough, I could never get the distance to change, even after clearing
  the ospf process and actually rebooting all 4 routers. My question, when
  doing the distance command for ospf, is the "source ip" in the distance
  command the router-id of the advertising router in ospf? I thought it was,
  I also tried the following

  distance 109 10.1.1.2 0.0.0.0 OSPF

  where 10.1.1.2 is the serial ip; again, the distance never changed; Any
  comments on this would be appreciated. Sorry I can't include the show ip
  route ospf, and show ip ospf data, commands, as I'm sending this from a
  location where I don't have access to my rack.

  Thanks for your help in advance!

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