Thanks Pamela for the detailed reply,
I just got back from a mini vacation so I have not tried your tips yet.
However, I feel that number three is likely the answer. I'll let you know.
Henry Guzman
"Pamela Forsyth" <[EMAIL PROTECTED]> wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Henry,
>
> I don't think it is IOS incompatibilities per se causing your problem for
> simple BGP configurations such as the one you describe, although there are
> some inconsistencies in how BGP handles your network statements according
> to IOS version. It is difficult to tell what's going on without configs
> and a little more explanation, but here are some things to check in order
> to troubleshoot your BGP connectivity:
>
> 1. Is your next-hop address reachable? In the router you're trying to
> ping from, do "show ip bgp" and locate the destination network entry for
> the address you're trying to ping. Find the next-hop IP address listed
for
> this entry. Now, do "show ip route <next-hop>" using the next-hop for
your
> destination that you just found. This will tell you if this router knows
> how to get to that address. If it doesn't, you won't find the entry in
> your IP routing table even if your router is learning of it from BGP, and
> you won't be able to ping it. Your router MUST know how to get to that
next
> hop FROM SOME OTHER MEANS THAN BGP.
>
> 2. Synchronization may be keeping the routes from being advertised to an
> external BGP neighbor if the router has learned about them from an
internal
> BGP neighbor. If all the routers in your AS are running BGP, then you can
> turn synchronization off on all your routers. That might make those
routes
> that are in your BGP table pop into your IP routing table.
>
> 3. If your routes are not even getting into the BGP table on the router
> where your network statements are configured, you need to check those
> statements. One thing that may cause you trouble with IOS versions older
> than 12.0 is the BGP auto-summarization feature. By default,
> auto-summarization is enabled for those versions.
>
> The way auto-summarization will affect you is that if you enter a BGP
> network statement with a classful network number and no mask (e.g.,
> "network 10.0.0.0"), the BGP router will pick up and advertise a BGP
prefix
> entry for the classful network number (10.0.0.0/8) if it finds any subnets
> of it in your IP routing table, but will not advertise the individual
> subnets. This is the opposite of the way your 12.0 IOS versions will
> behave--newer IOS versions (at least the 12.0 IOS images I've had
> experience with over the last 2 years) will pick up the subnets of any
> classful network statement put them in the BGP table, but will not create
> the summary. This despite that the 12.0 documentation still asserts that
> BGP auto-summary is on by default.
>
> To make the 11.x routers advertise your subnets for you, you will need to
> configure a separate network statement for each subnet you want
advertised,
> with the exact mask that corresponds to its prefix length as it appears in
> the IP routing table. As an alternative, you might want to try, "no
> auto-summary" in your configurations, but I have had inconsistent results
> with it. Just to make it more complicated, I have seen routers with IOS
> versions earlier than 11.2 refuse even to advertise the summary if one of
> the subnets exists, with BGP auto-summarization enabled. Can't say
whether
> that was a bug or not.
>
> With respect to pinging, remember that you not only have to see a route in
> your routing table for the destination, but all the routers along the path
> have to have a way to get back to the router you're pinging from in THEIR
> routing tables as well.
>
> Pamela
>
> At 12:59 AM 12/31/00 -0700, henryguzman wrote:
> >Hello All,
> > I just started doing CCNP labs at home and am having some problems
> >getting BGP to work correctly. My home lab consists of 2 Cisco 3000
series
> >routers with v12.0 IOS, two 2501's (borrowed) with version 11.0, and one
> >Cisco Access Pro router card with version 11.3. My question is could the
mix
> >and match nature of the different IOS's in my home lab cause problems
with
> >BGP syncing up correctly? For instance, in one lab I did with 3 routers,
all
> >the routers "found" each others routes via BGP but I could not ping end
to
> >end thru the middle router. In other words if the routes are seen in the
> >routing table, why can't I ping? Yes I checked clocking and the ports are
> >all up & up. Or what's going on if routes don't show up and I've
correctly
> >followed the instructions for entering the neighbor and network
statements?
> >I can ping from point to point. BTW, the labs I'm doing are from The
Cisco
> >Networking Academy Level 5 Chapter 8.
> > Is it just me messing up somewhere, or should I get all the routers
> >talking the same IOS? Problem is, I don't have a login at Cisco's web
site
> >that will enable me to download an IOS image. Suggestions anyone?
> >
> >Thanks for your time and input.
> > Happy New Year!
> >
> >Henry Guzman
>
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