Hi all,
I have a question that has boggled my mind and hopefully someone has come across this issue.
I am running a Cisco 3560 with Version 12.2(50)SE1, and using GRE tunnels to from field sites to the core....I have one of the sites showing the interface MTU to be 9108 bytes, irregardless that I try to change the MTU to 1500 it still shows on the interface as as 9108 bytes:
1#sh int tu1
Tunnel1 is up, line protocol is up
Hardware is Tunnel
Description: Tunnel 1
Internet address is 10.1.1.246/30
MTU 9108 bytes, BW 1500 Kbit, DLY 500000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation TUNNEL, loopback not set
Keepalive set (5 sec), retries 3
Tunnel source 10.1.1.9, destination 10.1.4.54
Tunnel protocol/transport GRE/IP
Key disabled, sequencing disabled
Checksumming of packets disabled
Tunnel TTL 255, Fast tunneling enabled
Tunnel transport MTU 1476 bytes
On my configuration for the interface:
interface Tunnel1
description Tunnel 1
bandwidth 1500
ip address
ip ospf authentication message-digest
ip ospf message-digest-key
ip ospf mtu-ignore
delay 50000
keepalive 5
tunnel source
tunnel destination
end
Configuration on the system:
system mtu routing 1500
I have also tried to just have the system mtu 1500, but this does not change on the Tunnel interface.
Any help will be appreciated....
