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luis.rueda
Beginner

MTU Change C7200-I/O-2FE/E

Anybody knows if the MTU for the FastEthernet interface on the C7200-I/O-2FE/E can be changed ?

I'm planning on implementing MPLS/VPNs using the FA Port as a MPLS Trunk and I need to change de MTU.

6 REPLIES 6
maher
Beginner

Hi,

Not so sure about this on FastEthernet on any cisco routers, I've tried to change the MTU size but couldn't, perhaps required to specific IOS?

regards,

maher

jayjorda
Cisco Employee

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:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/ipras_r/ip1_i2g.htm#wp1078699

MPLS MTU Command Reference:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/swtch_r/swi_m2.htm#wp1150889

Hope this helps.

g.grof
Beginner

Hi

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.

luis.rueda
Beginner

7204_ZOFR_I#sh ver

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"

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to

export@cisco.com.

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

Building configuration...

Current configuration : 121 bytes

!

interface FastEthernet0/1

ip address 10.85.237.10 255.255.255.240

duplex auto

speed auto

no clns route-cache

end

7204_ZOFR_I#conf t

Enter configuration commands, one per line. End with CNTL/Z.

7204_ZOFR_I(config)#int fa0/1

7204_ZOFR_I(config-if)#mtu 2000

% Interface FastEthernet0/1 does not support user settable mtu.

hope this helps!!!!!!!!!!

shows same error

% Interface FastEthernet0/1 does not support user settable mtu.

filopeter
Beginner

Hello,

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

!

interface FastEthernet0/1
mpls label protocol ldp
tag-switching mtu 1512
tag-switching ip

!

After configuration, you can check the mpls mtu using "show mpls interfaces FastEthernet0/1 detail" command.