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List:       quagga-users
Subject:    [quagga-users 12271] Re: IPv6 BGP to Cisco - Capabilities Problems
From:       Chris Caputo <ccaputo () alt ! net>
Date:       2011-05-14 1:08:08
Message-ID: Pine.LNX.4.64.1105140106260.26256 () nacho ! alt ! net
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On Wed, 20 Apr 2011, Michael K. Smith - Adhost wrote:
> I'm going to open a bug with tcpdump info.  Perhaps that will help.

I resolved Mike's bug #644 as below:

I dug into Mike's issue.  The culprit was:

 neighbor 2001:4970:ffff::1 dont-capability-negotiate

Resulting in:

 1) Quagga box did not send capabilities.
 2) GSR sent capabilities, including 4-byte AS Path capability.
 3) Quagga box noted 4-byte AS Path capability and recorded peer as such 
    (PEER_CAP_AS4_RCV).
 4) GSR sent UPDATEs with 2-byte AS Path entries.
 5) Quagga box AS_PATH length check code balked, since it was expecting 
    4-byte AS Path entries.

I don't know why the Cisco "override-capability-neg" config didn't cause 
the Cisco to use 4-byte ASNs regardless of what Quagga sent in the open 
dialog, but that is irrelevant.

A possible problem is that Quagga, even with "dont-capability-negotiate", 
honored the GSR's capabilities advertisement of 4-byte AS Path's and 
attempted to decode AS Path attributes as such.  Should 
"dont-capability-negotiate" not cause Quagga to entirely ignore received 
capabilities in bgp_capability_parse()?

Chris
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