[c-nsp] MPLS packets over 3745 - MTU problem

[gladston at br.ibm.com]

Do you ever face this problem? 3745 ethernet module considers packets with 
1546 bytes giants and discard them.

VPN MPLS is configured between the two 7609. Everything is working, but 
packets over 1500bytes. 3745 routers are P routers.

7609-A(giga4/2)------(fast1/3)3745(fast1/5)-------3745--------7609-B

Test
Generated pings from 7609-A to 7609-B (vlan 16 to vlan 17) with size from 
1450 to 1550.

Monitoring
R2 is dropping packets bigger than 1518 bytes.
R2#sh int fa 1/3 | i giants
     Received 1 broadcasts, 0 runts, 0 giants, 0 throttles

R2#sh int fa 1/3 | i giants
     Received 1 broadcasts, 0 runts, 10 giants, 0 throttles

Action
Increased Vlan MTU
R2#sh vlan-switch id 601

VLAN Name                             Status    Ports
---- -------------------------------- --------- 
-------------------------------
601  R-2_OSR-3_VLAN                   active    Fa1/2, Po2

VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  BrdgMode Trans1 
Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ 
------
601  enet  100601     2000  -      -      -        -    -        0      0

Tried to increase the MPLS MTU
When trying to improve the size of mpls mtu, 3745 crashes;
R2(config-if)#tag-switching mtu 1546
Crashes

R2(config-if)#mpls mtu 1546
Crashes

Note:
The Fastethernet module does not accept changing MTU under the interface

Version is c3745-adventerprisek9-mz.123-2.T9.bin
Module is FastEthernet Port adapter, 17 ports

Any Feedback appreciated.

Cordially,
------------------------------------------------------------------
Alaerte Gladston Vidali
IBM Global Services - SO
Tel.55+11+2121-2879   Fax:55+11+2121-2449