From: Vincent Fortunato (Vincent_Fortunato@xxxxxxx)
Date: Wed Jul 28 1999 - 17:11:46 GMT-3
>From a logical standpoint, I can see why it would still not synchronize:
The purpose of the sync rule is to prevent routes FROM any of R2's EBGP
neighbors (none in this case) destined for 10.10.10.0. Why? - because R6,
even with a static route in R3, does not know about 10.10.10.0. Therefore
the BGP protocol would need to see that the route learned dynamically via an
IGP. This is my logic - I cannot find any specific references to this in
Halabi. I believe your only options are to redistribute at R1 or turn off
synchronization.
Vince Fortunato
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Chuah Eng Wee
Sent: Wednesday, July 28, 1999 6:49 AM
To: Joe Soricelli; ccielab@groupstudy.com
Subject: Re: Question on Synchronization
Hi Joe,
>Does r2 know how to get to the next hop (R3 interface) for that route via
an
>IGP?
Yes, R2 does know how to get to the next hop r3. In fact, I use OSPF
as the IGP and include the segment between r3 and r1 inside ospf.
The BGP table at r2 is ok, i.e I saw the > sign indicating that
it doesn't have problem with the next-hop.
Any other thing I miss out ??
Thanks
Eng Wee
>
>-joe
>------------------------------------------------------------------
> Joseph M. Soricelli, CCIE #4803, CCNP
> EMAIL: jsoricelli@ccci.com
>
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>-----Original Message-----
>From: Chuah Eng Wee <chuahew@cyberway.com.sg>
>To: ccielab@groupstudy.com <ccielab@groupstudy.com>
>Date: Wednesday, July 28, 1999 2:56 AM
>Subject: Question on Synchronization
>
>
>>Hi..
>>
>>Some questions on synchronisation. Below is the setup
>>
>> [r6]
>> / \
>>[r1]/ \[r2]
>> |
>> |
>>[r3]
>>
>>
>>r1,r6,r2 in AS 100; r1 and r2 running IBGP
>>r3 in AS 200
>>
>>r3 announced the network 10.10.10.0 to r1 via EBGP.
>>r2 then rx 10.10.10.0 in its BGP table via IBGP from r1.
>>r2 did not put the route 10.10.10.0 into its IP routing
>>table becos it does not know how to reach 10.10.10.0.
>>This is a synchronisation issue.
>>
>>So I put a static route
>>ip route 10.10.10.0 255.255.255.0 next-hop-to-r6
>>
>>with this statement, there is a static entry in the routing
>>table. But debug ip bgp update shows that it is not synchronised.
>>
>>BGP: nettable_walker 10.10.10.0/255.255.255.0 calling revise_route
>>BGP: revise route installing 10.10.10.0/255.255.255.0 -> 128.213.63.2
>>BGP: nettable_walker 10.10.10.0/255.255.255.0 not synchronized
>>
>>
>>WHY ?? I thot syncrhonisation rule states that if IGP knows the route
>>it'll be considered synchronised and the router will advertise
>>the route to external peers.
>>
>>Any advice ??
>>
>>Thanks
>>Eng Wee
>>
>>
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