Nuts and Bolts
Neighbor Establishment
- IS-IS requires padding of Hello packets to full MTU size under some conditions (to detect media with MTUs smaller than 1497 bytes)--this is effectively useless and causes needless support calls (deprecated in practice)
- OSPF requires routers to have matching MTUs in order to become adjacent (or LSA flooding may fail, since LSUpdates are built at each hop and may be MTU-sized)