On Tue, 7 May 2002, Duane de Witt wrote:
> I have been dabbling with MPLS on 3660 and 7200 platforms. Seems that every
> time I enable tag-switching everything slows down to a virtual halt.
> Contacted Cisco and they gave me "mpls mtu 1508" for all my interfaces and
> "mtu 1530" for my switches to allow jumbo frames over Ethernet. Has anyone
> else come across this problem and how was it resolved? I find it strange
> that none of this is mentioned on the CCO.
What are you doing with MPLS? I setup MPLS for MPLS-VPN a while back and
am running MTU 1500 with tag-switching mtu 1520. Our low end catalyst
2900 series switches are apparently incapable of handling these larger
frames, so we're only able to do MPLS traffic on WAN links or router to
router crossover ethernet connections. The only real problem I've had is
the random breakage of traceroute which seems to work or not work
randomly by destination. i.e.
traceroute to jon.lewis.org (209.208.48.114), 30 hops max, 38 byte packets
1 orldflwcom-br-1-fe0-0 (209.208.42.129) 0.626 ms 0.520 ms 0.433 ms
2 gsvlflma-br-1-s4-0 (209.208.90.30) 9.365 ms 9.383 ms 9.216 ms
3 gsvlfl-br-2-e0 (209.208.90.70) 9.493 ms 9.721 ms 9.334 ms
4 sloth.lewis.org (209.208.48.121) 32.585 ms 25.112 ms 27.815 ms
5 jon.lewis.org (209.208.48.114) 29.237 ms 25.214 ms 26.865 ms
traceroute to gtri.ws (209.208.23.133), 30 hops max, 38 byte packets
1 orldflwcom-br-1-fe0-0 (209.208.42.129) 0.575 ms 0.496 ms 0.433 ms
2 * * *
3 * * *
4 209.208.23.129 (209.208.23.129) 18.495 ms 20.990 ms 18.569 ms
5 209.208.23.133 (209.208.23.133) 19.695 ms 18.844 ms 17.989 ms
In these two traces, hops 1-3 are the same. 1-2 are a 7513 connected via
point to point T3 to a 7206. 2 connects to 3 (a 3640 doing ATM for DSL
agg) via a crossover ethernet. Hop 4 in each is a DSL customer.
Why don't I get responses from 2 and 3 in the second trace?
-- ---------------------------------------------------------------------- Jon Lewis *jlewis@lewis.org*| I route System Administrator | therefore you are Atlantic Net | _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________
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