From: Edward Taggart (etaggart@xxxxxxxxx)
Date: Mon Sep 06 1999 - 15:55:45 GMT-3
I think I have the answers to both of my questions. Here's what I found...
Question 1: I have 3 routers in the same AS. They are connected as
follows:
R3 <---> R2 <---> R5
They all can reach each other fine through OSPF routes. R5 also has a
loopback that is being redistributed via OSPF. I configured 2 peer
statments on all routers providing a full mesh for the IBGP AS (all sessions
show active). The network that the loopback's address resides in is being
advertised to BGP by R5. When doing a "show ip bgp" it shows up in all 3
routers bgp table. However, R3 does not advertise the route to an external
AS. When doing a "debug ip bgp update" on R3 I see that it is complaining
that the loopbacks network is not synchronized. However, the loopbacks
network is in the IGP routing table..
Now, if I remove the peer statements between R3 & R5 and setup R2 with
router-reflector-client statements, R3 advertises the route to the loopback
to the external AS.
How I understood it was that routers in the same AS do not need to be
directly connected to their peers, they just need IP reachability to them
and a full mesh peer configuration (or route a reflector). What am I
missing?
ANSWER: The loopback address that I was redistributing was on a router (R5)
that was in an NSSA area. That route showed up on R2 as a N2 route and BGP
was in synch. However, when that route got to R3 it was a E2 route and BGP
did not consider it synched. Therefore it looks as if the E2 route was not
considered and BGP complained it was out of synch. I'm a little shaky on
this answer as I would think that any route in the IGP reguardless of how it
got there would be considered. Anyway, clearly turning off synchronization
solved this particular problem, which is OK for the requirements of was I
was trying to do.
---------------------------------------------------------------------------
--------------------------------
Question 2:
If I have an OSPF route and BGP route on a router for the same network, what
would keep the BGP route from injecting itself into the routing table given
that BGP has a lower administrative distance than OSPF?
The following is from a "show ip bgp" command
*> 192.192.2.0 132.4.7.5 0 100 0 (1034 1099) i
The following is from a show ip route from the same router as above:
O E2 192.192.2.0/24 [110/20] via 132.4.8.2, 00:37:01, Serial1
This particular router is in it's own AS so the 192.192.2.0 route is coming
in from AS1034 then AS1099..
ANSWER: I had my three Autonomous systems in a confederation. This caused
the distance to remain the same between sub AS's within the confederation.
When I removed the confederation the route showed up with a distance of 20.
Therefore, since I removed the redistribution of that route from Question#1,
I could re-apply my confederation and the route would show up with a metric
of 200 since it was no longer known through IGP..
B 192.192.2.0/24 [200/0] via 132.4.7.5, 2d03h
Thanks for all the help folks have given me on these two problems!
- Ed
----- Original Message -----
From: Blankenship Mr Gary C <BlankenshipGC@nocfwd.usmc.mil>
To: GRIZZUTI Javier <jgrizzut@softnet.com.ar>; <ccielab@groupstudy.com>
Sent: Monday, September 06, 1999 5:44 PM
Subject: RE: 2 - BGP problems
> Javier:
>
> I know, I caught myself. I posted right after that to use the "ip ospf
> network point-to-point" command instead. Thanks for the correction
though.
> At least someone besides me reads my posts.
>
> Gary
>
> > -----Original Message-----
> > From: GRIZZUTI Javier [mailto:jgrizzut@softnet.com.ar]
> > Sent: Monday, September 06, 1999 10:31 PM
> > To: ccielab@groupstudy.com
> > Subject: RE: 2 - BGP problems
> > Importance: High
> >
> >
> > You cannot do that in a Loopback interface
> >
> > -----Original Message-----
> > From: Blankenship Mr Gary C [mailto:BlankenshipGC@nocfwd.usmc.mil]
> > Sent: Sábado, 04 de Septiembre de 1999 08:20 a.m.
> > To: grcitynet; Edward Taggart; ccielab@groupstudy.com
> > Subject: RE: 2 - BGP problems
> >
> >
> > Question 1: If you put the "no synchronise" command into the
> > BGP config
> > does it advertise? Additionally, OSPF advertises loopbacks
> > as host routes.
> > Try putting the "ip ospf network broadcast" on the loopback
> > interface so
> > that it accepts your entire mask. BGP should synch fine
> > after that and
> > advertise your route.
> >
> > -----Original Message-----
> > From: grcitynet [mailto:gr@citynet.net]
> > Sent: Saturday, September 04, 1999 8:06 AM
> > To: Edward Taggart; ccielab@groupstudy.com
> > Subject: Re: 2 - BGP problems
> >
> >
> > Question 2
> >
> > EBGP has distance of 20 but IBGP has a distance of 200. If
> > you are talking
> > about IBGP in your question then OSPF with a distance of 110 would be
> > prefered.
> >
> > ----- Original Message -----
> > From: Edward <mailto:etaggart@pivot.net> Taggart
> > To: ccielab@groupstudy.com <mailto:ccielab@groupstudy.com>
> > Sent: Friday, September 03, 1999 5:58 PM
> > Subject: 2 - BGP problems
> >
> > I have 2 bgp problems that are driving me crazy.
> >
> > Question 1: I have 3 routers in the same AS. They are connected as
> > follows:
> >
> > R3 <---> R2 <---> R5
> >
> > They all can reach each other fine through OSPF routes. R5 also has a
> > loopback that is being redistributed via OSPF. I configured 2 peer
> > statments on all routers providing a full mesh for the IBGP
> > AS (all sessions
> > show active). The network that the loopback's address
> > resides in is being
> > advertised to BGP by R5. When doing a "show ip bgp" it shows
> > up in all 3
> > routers bgp table. However, R3 does not advertise the route
> > to an external
> > AS. When doing a "debug ip bgp update" on R3 I see that it
> > is complaining
> > that the loopbacks network is not synchronized. However, the
> > loopbacks
> > network is in the IGP routing table..
> >
> > Now, if I remove the peer statements between R3 & R5 and setup R2 with
> > router-reflector-client statements, R3 advertises the route
> > to the loopback
> > to the external AS.
> >
> > How I understood it was that routers in the same AS do not need to be
> > directly connected to their peers, they just need IP
> > reachability to them
> > and a full mesh peer configuration (or route a reflector). What am I
> > missing?
> >
> >
> > Qustion 2:
> > If I have an OSPF route and BGP route on a router for the
> > same network, what
> > would keep the BGP route from injecting itself into the
> > routing table given
> > that BGP has a lower administrative distance than OSPF?
> >
> > The following is from a "show ip bgp" command
> > *> 192.192.2.0 132.4.7.5 0 100 0
> > (1034 1099) i
> >
> > The following is from a show ip route from the same router as above:
> > O E2 192.192.2.0/24 [110/20] via 132.4.8.2, 00:37:01, Serial1
> >
> > This particular router is in it's own AS so the 192.192.2.0
> > route is coming
> > in from AS1034 then AS1099..
> >
> > Any help would be greatly appreciated. I'm looking through
> > both Caslow's
> > and Halabi's books and can't seem to find the answer to these
> > problems.
> >
> >
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 08:21:50 GMT-3