[c-nsp] TTL not decrementing (MPLS, SXI, Sup720)

[Peter Rathlev]

On Wed, 2011-01-26 at 20:01 +0000, Phil Mayers wrote:
> There are some funny behaviours w.r.t traceroute under PFC-3B and 
> earlier versions. Do you have a mix of PFC/DFC versions?

Thanks for the tip. I looked more carefully at other devices and found
out that at least one other device behaves like this. And it's also
PFC3B with traffic exiting a CFC-equipped 6724-SFP, like this device.

Other devices with PFC3C (i.e. VS-S720-10G) but similar CFC-equipped
cards haven't got the problem. And PFC3B-equipped cards where the
traffic arrives on DFC3C-equipped cards (WS-X6708-10GE) also haven't.

> We see oddities routinely with penultimate hop popping and vrf aggregate 
> labels, including the same behaviour you're seeing. I believe it's a 
> hardware limitation.

I guess we have to live with it then. At least the PFC3B based sups are
getting close to a well earned pension.

If anyone would happen to know a work-around, even at the cost of
performance, I'd really like to hear about it. It's more than enough
trouble to explain traceroutes without this... :-)

-- 
Peter