[c-nsp] MTU Mismatch

[Ryan West]

Mohammad,

> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> bounces at puck.nether.net] On Behalf Of Mohammad Khalil
> Sent: Monday, December 28, 2009 10:11 AM
> 
> hi all
> 
> i have Cisco 3750 connected to 6523 switch
> on the 3750:
> interface GigabitEthernet1/1/2
>  no switchport
>  ip address 10.20.3.18 255.255.255.252
>  no ip redirects
>  no ip unreachables
>  no ip proxy-arp
>  ip ospf network point-to-point
>  speed nonegotiate
> end
> sh int g1/1/2 | inc MTU
>   MTU 1512 bytes, BW 1000000 Kbit, DLY 10 usec,
> 
> on the 6523:
> interface GigabitEthernet1/27
>  ip address 10.20.3.17 255.255.255.252
>  ip ospf network point-to-point
>  load-interval 30
>  speed nonegotiate
>  no mop enabled
> end
> 
> sh int g1/27 | inc MTU
>   MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec
> 
> The problem is that the OSPF is running and functioning well , how does
> the OSPF neighbor relation is up and there is an MTU mismatch ?

The routing MTU may still be set to 1500, post "show system mtu" on your 3750.

show system mtu

System MTU size is 1500 bytes
System Jumbo MTU size is 1500 bytes
Routing MTU size is 1500 bytes

Thanks,

-ryan