Re: System MTU question

Is it IOS version specific then? I'm reviewing the final configs for
the lab and I don't see either command being issued.

Justin G. Mitchell
http://www.google.com/profiles/jgmitchell

On Sun, Oct 18, 2009 at 6:45 AM, Nadeem Rafi <nrafia_at_gmail.com> wrote:
> yes Ryan... its correct. Its under interface.
>
> On Sun, Oct 18, 2009 at 2:38 PM, Ryan West <rwest_at_zyedge.com> wrote:
>>
>> Justin,
>>
>> That's normal, probably a left over system mtu from QinQ configuration.
>> You do have the option of setting of system mtu routing 1500 as a
>> workaround for the 3560 and above series. You can also tell the OSPF
>> process to ignore the MTU on a per-interface basis. Ip ospf mtu-ignore (I
>> think).
>>
>> -ryan
>>
>> -----Original Message-----
>> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
>> Justin Mitchell
>> Sent: Sunday, October 18, 2009 7:35 AM
>> To: Cisco certification
>> Subject: System MTU question
>>
>> I am working on an OSPF configuration and watching the console
>> messages long enough I get to see one neighbor go up and down with the
>> message:
>>
>> R3#
>> *Nov 7 21:13:10.955: %OSPF-5-ADJCHG: Process 1, Nbr 112.12.108.1 on
>> FastEthernet0/0 from EXSTART to DOWN, Neighbor Down: Too many
>> retransmissions
>> R3#
>> *Nov 7 21:14:10.955: %OSPF-5-ADJCHG: Process 1, Nbr 112.12.108.1 on
>> FastEthernet0/0 from DOWN to DOWN, Neighbor Down: Ignore timer expired
>>
>> So I issue "debug ip ospf ev" and get the notice the following:
>>
>> *Nov 7 21:11:12.815: OSPF: Rcv DBD from 112.12.108.1 on
>> FastEthernet0/0 seq 0x12A6 opt 0x52 flag 0x7 len 32 mtu 1504 state
>> EXSTART
>> *Nov 7 21:11:12.815: OSPF: Nbr 112.12.108.1 has larger interface MTU
>>
>> I changed to the switch causing the problem and set "system mtu 1500"
>> reloaded and then the adjacency forms without any problems.
>>
>> Is this normal? I usually don't set the MTU unless required for
>> overhead reasons.
>>
>> Justin G. Mitchell
>> http://www.google.com/profiles/jgmitchell
>>
>>
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Received on Sun Oct 18 2009 - 06:48:33 ART