[c-nsp] BGP "keep alives throttled do to tcp", MTU mismatch?

[David Prall]

BGP Hellos are not sent with pak-priority, while they are marked IP Precedence 6. Thus they need to be prioritized if you have a congested link. That GE Port on the NPE-400 is subrate to begin with, so you could be dropping them before they even make it out or can be processed inbound.

David

--
http://dcp.dcptech.com


> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> bounces at puck.nether.net] On Behalf Of Scott Granados
> Sent: Thursday, July 21, 2011 4:01 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] BGP "keep alives throttled do to tcp", MTU mismatch?
> 
> Hi, I have a puzzler.
> 
> I have two Cisco 7206VXr routers one with a G1 and the other with a 400
> processor.
> Between them terminated on a gig interface on each side is an ILEC
> provided metro E connection that’s pretty vanilla using VLANs to
> address different connections.
> 
> I have a /30 set up on a common VLAN between the two with the BGP peer
> set up on that /30.
>     After 3 minutes, my session will reset I’m assuming do to lack of
> keepalives / problems with MTU.  Lots of googling as pointed me at
> various MTU mismatch situations but I’m not sure what I’m doing wrong
> possibly assuming something is set “in an interesting way” between the
> sites on the ILEC network.
> 
> On each interface I have the following
> 
> int gig x/x
> mtu 1522
> 
> Assuming 1500 for standard Ethernet and 22 for the VLAN tags.
> I also have the following set in global mode
> ip tcp path-mtu-discovery
> 
> On both VXR devices code 12.4-25C is being run.
> 
>     I would appreciate any pointers to investigate.  What have I
> missed?
> 
> 
> Thanks
> Scott
> 
> 
> 
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