08-28-2008 12:23 AM - edited 03-03-2019 11:18 PM
I have a problem whereby the dialer interface is configured to be of MTU 1600 but changes to 1524 when a call is made.
This is causing the OSPF adjacencies not to form in between. I could use the ip ospf mtu-ignore command, but I would like to know why the above problem is happening
The device is a Cisco2811
flash:c2800nm-advsecurityk9-mz.124-7g.bin
Thanks
Mayamba
08-28-2008 12:46 AM
Hello Mayamba,
post the output of
sh int bri0/1/0
sh ip int bri0/1/0
sh int dialer1
sh ip int dialer1
you set the MTU to 1600 to dialer interface and what do you do on the BRI port ?
Hope to help
Giuseppe
08-28-2008 01:20 AM
08-28-2008 02:01 AM
Hello Mayamba,
the BRI has MTU 1500 B
now the dialer has MTU 1500 B too.
To be able to send a 1600 byte IP packet with DF set (like OSPF database packets) you would need to increase both MTU values
If this is not possible I would suggest to stay with the default values of MTU on both interfaces and OSPF will be fine too.
Hope to help
Giuseppe
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