From: Darek Kuzma (darekk@xxxxxxxxxxxxx)
Date: Fri Jul 19 2002 - 12:32:16 GMT-3
Timothy,
As far as tag for redistributed routes into OSPF it is normal!
OSPF (and EIGRP (checked) and possibly RIP v2 (didn't check) ) automatically
uses tag to convey path info through IGP domain.
In other direction it is not automatic (you need to use route-map with set
as-path tag)
I don't know why 0/0 got tag=1. But as far as this is OSPF originated route
I don't think it is related to the issue described above.
For more on BGP->OSPF redistribution and use of tags check Doyle volume II
Thanks,
Darek
Timothy Ouellette wrote:
> Having another wonderfull night listening to the hum of 10 routers.
> Here's the deal.
>
> router5 ----ebgp--- router3 ----- ospf area 0 ----- r1
>
> Router 5 is generating a couple of external networks via the loopback.
> Namely 172.16.0.0/24, 10.0.0.0/24, 192.168.1.0/24, 69.69.0.0/16, and is
> also sending in a 0.0.0.0/0 default.
>
> On r3, i'm also using a "default-information originate" in order for the
> ospf speaks behind r1 to get the default. Everything was running fine
> and I started filtering with OSPF tags.
>
> The one thing that I noticed on r1 (see below) is that the 0.0.0.0/0 had
> already had a tag of "1" so when I started filtering things broke
> because I assumed that it would have a tag of 0 (like all the other ospf
> routes prior to modification/redistro)
>
> The next odd thing was that the routes that r3 was receving from BGP
> were getting redistributed into OSPF (i know, i know, bad design) but
> the weird part is that on r1 they were showing with a tag as 11 (which
> is the as that r5 is in)
>
> Below is a "sh ip ospf d" on r1. Does this look normal? All of the ebgp
> learned routes sent to r3 from r5 have an ospf tag of 11?
>
> r1#sh ip ospf d
>
> OSPF Router with ID (141.108.255.5) (Process ID 1)
>
> Router Link States (Area 0)
>
> Link ID ADV Router Age Seq# Checksum Link
> count
> 141.108.3.1 141.108.3.1 1247 0x80000003 0x747B 2
> 141.108.4.1 141.108.4.1 607 0x80000005 0xF601 1
> 141.108.255.5 141.108.255.5 1284 0x80000003 0x9888 3
>
> Net Link States (Area 0)
>
> Link ID ADV Router Age Seq# Checksum
> 141.108.255.1 141.108.255.5 1284 0x80000002 0xA1A2
> 141.108.255.5 141.108.255.5 1284 0x80000002 0x6CD4
>
> Summary Net Link States (Area 0)
>
> Link ID ADV Router Age Seq# Checksum
> 141.108.4.0 141.108.4.1 1435 0x80000002 0x4607
>
> Type-5 AS External Link States
>
> Link ID ADV Router Age Seq# Checksum Tag
> 0.0.0.0 141.108.4.1 425 0x80000001 0xBBF7 1
> 10.10.10.0 141.108.4.1 581 0x80000001 0x784 11
> 16.16.16.0 141.108.255.5 1532 0x80000002 0xB1CB 0
> 69.69.0.0 141.108.4.1 582 0x80000001 0xAC72 11
> 141.108.1.0 141.108.255.5 1532 0x80000002 0x1A8B 0
> 141.108.2.0 141.108.255.5 1532 0x80000002 0xAA04 0
> 141.108.3.0 141.108.255.5 1285 0x80000002 0x9F0E 0
> 141.108.4.0 141.108.255.5 1285 0x80000002 0x9418 0
> 141.108.255.0 141.108.255.5 1532 0x80000002 0xC0EF 0
> 150.150.0.0 141.108.255.5 1532 0x80000002 0xB5BD 0
> 172.16.1.0 141.108.4.1 582 0x80000001 0xDF0C 11
> 192.168.1.0 141.108.4.1 582 0x80000001 0xB38B 11
> r1#
This archive was generated by hypermail 2.1.4 : Sat Sep 07 2002 - 19:36:36 GMT-3