[c-nsp] Recommended 7206 12.2(x)SB for MPLS?

[Vinny Abello]

Mark Tinka wrote:
> On Wednesday 19 September 2007 02:06, Vinny Abello wrote:
> 
>> I know we're up to SB9 last I
>> checked, but I haven't tested that yet. On SB6, when I
>> started configuring "mpls ip" and "mpls traffic-eng
>> tunnels" on interfaces with other routers and the LDP
>> adjacency comes up, I notice a slight level of packet
>> loss both to and through the router using that interface.
>> I recall finding a bug on Cisco's web site (sorry, I
>> don't have the ID handy) where having netflow enabled on
>> an interface with MPLS IP enabled may prevent packets
>> from being forwarded via CEF and I think SB6 is affected
>> by that bug.
> 
> You also want to make sure the switch that router port is 
> attached to supports a larger Ethernet MTU. Also, setting 
> your MPLS MTU to at least 1526 (depending on whether you 
> are doing vanilla MPLS or AToM as well, e.t.c.) would help.

Thanks, but I already have the MTU maxed to 1526 and most of these routers are direct attached so there is no switch involved to adjust MTU on. Other transport may go through another carrier and fiber transceivers may be involved, but I test the maximum MTU ahead of time to make sure what I set the interfaces to will actually work.

> I faced the same issue with a box connected to a 2950 
> Catalyst switch (supports only 1500 bytes MTU) with MPLS 
> enabled. Granted, I was running 12.3(20) at the time.

Coincidentally, 12.3(x) on one of my 7206VXR's doesn't display this issue with the packet loss. We actually "upgraded" it to 12.2(28)SB6 and started experiencing the problem then.

-- 

Vinny Abello
Network Engineer
Server Management
vinny at tellurian.com
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