Follow on to changing MTU value on 7609 gig port

Unanswered Question

Hi Again

I am looking to set the value on a gig port on a 7609 to 1000 bytes to troubleshoot an issue and it seems that the only value that I can use is 9216?

IEBHCATE1(config-if)#mtu ?
  <9216-9216>  MTU size in bytes

IEBHCATE1(config-if)#mtu 1000
% Invalid input detected at '^' marker.

Is it not possibel to set the MTU value down to 1000 bytes?

Best Regards,


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Jon Marshall Thu, 08/05/2010 - 04:53
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What is the module you are trying to set it on ?


u1kumar2002 Thu, 08/05/2010 - 05:27
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Perform show interface and see what is default MTU on interface and clear interface and clear counters.

if then also not resolving , then u can reset the interface by default command and then try to configure again.

default interface ( global config mode)


Hi Jon

The Module I am trying to change the MTU on is a WS-X6724-SFP 24 port Gigabit Ethernet SFP and I was trying to change the MTU value to 1000 on a number of interfaces on this blade.

The default MTU value on each interface is 1500.

GigabitEthernet1/16 is up, line protocol is up (connected)
  Hardware is C6k 1000Mb 802.3, address is 0011.5cdd.ac63 (bia 0011.5cdd.ac63)
  Description: AXD-20-03 lmijtn
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

When I go into interface configuration mode and run the command "mtu ?" this is the output shown

IEBHCATE1(config)#int g1/16
IEBHCATE1(config-if)#mtu ?
  <9216-9216>  MTU size in bytes


Which leads me to believe that I can only change the MTU value to 9216 bytes.

Uttam: As this is a live port I cannot simply set it back to defaults. I would need to get a downtime window first. I was hoping that the MTU value was something that could be set on the fly.

What I have managed to do is set theMTU value on the VLANs that these ports are associated with to 1000 bytes, and I am waiting to hear back from the troubleshooters whether this is sufficient for their requirements.

Best Regards & Thanks for the responses.


Sinan Bayraktar Sun, 10/10/2010 - 04:57
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When the port  is L2 it only support  9216 I think.If you wanna make it lets say 1600 you have to use routed interface  i  mean L3 interface .

The port default came with 1500 mtu size in L2 mode whenever you wanna change the only optinon is 9216.


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