Cisco 3500 XL - Dot1q trunk - mtu is at 1496 for tagged vlan, MTU issue
Posted on 2008-10-14
I have two csico 3500 xl switches that are connected via a 10Mbit point to point radio. The interfaces are configured for dot1q tag and trunk with vlan 1 being native.
I can ping at 1500 on vlan 1, but only 1496 on vlan 10.
It appears that there is an MTU issue with the 4 extra bytes that are added to vlan 10 for the dot1q tags.
I have adjusted the interface and vlan MTU to 1536, rebooted, and still can't transfer traffic at 1500, which is affecting traffic flows that are on vlan 10. vlan 1 is not affected.
Any ideas on what could be causing this?