ADTRAN AOS Version R10.1.0 Command Reference Manual page 1746

Command Reference Guide FDL Interface Command Set
Functional Notes
Open shortest path first (OSPF) will not become adjacent on links where the MTU sizes do not match. If
router A and router B are exchanging hello packets but their MTU sizes do not match, they will never reach
adjacency. This is by design and required by the RFC.
Usage Examples
The following example specifies an IPv4 MTU of 1200 on the interface:
(config)#interface fdl 1/1
(config-fdl 1/1)#ip mtu 1200
60000CRG0-35E Copyright © 2012 ADTRAN, Inc. 1746