Have you tried using the IP MTU and MPLS MTU commands?
These two commands should allow you to adjust the MTU for unlabeled IP packets (IP MTU) and labeled packets (MPLS MTU).
IP MTU Command Reference:
MPLS MTU Command Reference:
Hope this helps.
As I know you can't change the MTU on I/O card. You should use PAs to increase MTU.
After you change MTU (layer2) you are allowed to give more tag-switching MTU.
I hope this help.
Cisco IOS Software, 7200 Software (C7200-K91P-M), Version 12.2(25)S3, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2005 by Cisco Systems, Inc.
Compiled Thu 03-Mar-05 17:21 by ccai
ROM: System Bootstrap, Version 12.2(4r)B2, RELEASE SOFTWARE (fc2)
BOOTLDR: Cisco IOS Software, 7200 Software (C7200-KBOOT-M), Version 12.2(25)S3, RELEASE SOFTWARE (fc1)
7204_ZOFR_I uptime is 2 weeks, 5 days, 13 hours, 25 minutes
System returned to ROM by power-on
System restarted at 11:06:20 COL Wed Mar 30 2005
System image file is "disk0:c7200-k91p-mz.122-25.S3.bin"
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Cisco 7204VXR (NPE400) processor (revision B) with 114688K/16384K bytes of memory.
Processor board ID 32824457
R7000 CPU at 350Mhz, Implementation 39, Rev 3.3, 256KB L2 Cache
4 slot VXR midplane, Version 2.9
Last reset from power-on
2 FastEthernet interfaces
125K bytes of NVRAM.
62976K bytes of ATA PCMCIA card at slot 0 (Sector size 512 bytes).
8192K bytes of Flash internal SIMM (Sector size 256K).
Configuration register is 0x2102
7204_ZOFR_I#sh run int fa0/0
Current configuration : 121 bytes
ip address 10.85.237.10 255.255.255.240
no clns route-cache
Enter configuration commands, one per line. End with CNTL/Z.
% Interface FastEthernet0/1 does not support user settable mtu.
hope this helps!!!!!!!!!!
FastEthernet interfaces on C7200 do not support user settable mtu.
In MPLS environment you can overcome this issue by configuring "mpls mtu" under interface configuration mode. The mpls mtu can be higher than the physical mtu. On C7200 with your IOS version you can use either "mpls mtu", or "tag-switching mtu" command
mpls label protocol ldp
tag-switching mtu 1512
After configuration, you can check the mpls mtu using "show mpls interfaces FastEthernet0/1 detail" command.