Command Reference Guide

3Com Router 3000 Ethernet Family
Command Reference Guide
Chapter 4 Integrated IS-IS Configuration Commands
3Com Corporation
4-27
level-1-2: Configures the router to operate at Level-1-2, calculate both the L1 and L2
routes and maintain the LSDB of Level-1 and Level-2.
level-2: Configures the router to operate at Level-2, only switch Level-2 LSP and
calculate the Level-2 routes and maintain the LSDB of Level-2.
Description
Use the is-level command to configure the IS-IS level.
Use the undo is-level command to restore the default setting.
By default, the value is level-1-2.
You are recommended to set the system level when configuring IS-IS.
If there is only one area, you are recommended to set the level of all the routers as
Level-1 or Level-2, because it is not necessary for all the routers to maintain two
identical databases. You are recommended to set all the routers to Level-2 for
convenient future extension, when applying them to IP network.
 Note:
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:
z If the sender is of Level-1 or Level-1-2 interface, it encapsulates the
Level-1authenticator into Hello message.
z If the sender is of Level-2 interface, it encapsulates the Level-2 authenticator into
Hello message.
z As for receiver:
z Supposing that the receiver is of Level-1 interface, it uses the Level-1 authenticator.
z 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.
z 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.