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RE: BGP Aggregate Summary only posted 04/13/2003
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If you use the summary-only on the aggregate command, more specific routes
are suppressed whether they are redistributed or the network command is
used.

-----Original Message-----
From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx]On Behalf Of
Denis Theodossiou
Sent: Sunday, April 13, 2003 12:39 PM
To: ccielab@xxxxxxxxxxxxxx
Subject: BGP Aggregate Summary only


Hi,
I've been doing Fatkid's Lab #505 and I've seen a strange behaviour on the
aggregate address, based on what Cisco says. The topology is very simple :
R1 [AS300] connected to R2 [AS200] and R5 [AS200], R2 and R5 are in confed
with local AS 10060. R1 has four loopbacks (206.11.4.0, 206.11.5.0,
206.11.6.0, 206.11.7.0) injected in BGP via network commands. The
requirement is to just send the aggregate 206.11.0.0/16. And I'm using the
"aggregate 206.11.0.0 255.255.0.0 summary-only".
In case #4 in
http://www.cisco.com/en/US/customer/tech/tk826/tk365/technologies_tech_note0
9186a00800c95bb.shtml, it says :
"Please note that if we are aggregating a network that is injected into our
BGP via the network statement (ex: network 160.10.0.0 on RTB) then the
network entry is always injected into BGP updates even though we are using
"the aggregate summary-only" command. The upcoming CIDR example discusses
this situation.", where it basically talks about redistributing statics
instead of using "network".

So according to Cisco, this should NOT work ! BUT it does !!! : R2 & R5
don't have the subnets and only have the summary. And "sh ip bgp" on R1
shows the 4 subnets as "s>", ie. suppressed.

Is the doc wrong ?

Thanks,
Denis