Command Reference Guide

3Com Router 5000 Family and Router 6000 Family is-level ● 181
Command Reference
As described in ISIS protocol, there is only one type of PDU Hello message on a
point-to-point link, while there are two types of PDU Hello messages on a LAN
interface, namely, Level-1 and Level-2. If you have configured different Level-1 and
Level-2 authentication passwords on a point-to-point link, the system will have to
choose one type of password, since only one type of Hello message exists on a
point-to-point link. Hence the system will choose one password from Level-1 and
Level-2 and put it into the Hello message.
As for sender:
■ If the sender is of Level-1 or Level-1-2 interface, it encapsulates the
Level-1authenticator into Hello message.
■ If the sender is of Level-2 interface, it encapsulates the Level-2 authenticator into
Hello message.
■ As for receiver:
■ Supposing that the receiver is of Level-1 interface, it uses the Level-1 authenticator.
■ Supposing that the receiver is of Level-2 interface, it uses the Level-1 authenticator
if its neighbors are of Level-1-2; otherwise, it uses the Level-2 authenticator.
■ Supposing that the receiver is of Level-1-2 interface, it uses the Level-1
authenticator if its neighbors are of Level-1-2 or Level-1; otherwise, it uses the
Level-2 authenticator.
Related Command isis circuit-level