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The IS-IS Neighbor Relationship Fails to Be Set Up on an NE40E-X3 V600R001C00SPC800

Publication Date:  2019-04-24 Views:  52 Downloads:  0

Issue Description

The IS-IS neighbor relationship fails to be set up between an NE40E-X3 and an NE40E-X16.
<NE40E-X3>display isis peer

                          Peer information for ISIS(1)

  System Id     Interface          Circuit Id       State HoldTime Type     PRI
BJ-BJHXW-AR04-N Eth-Trunk0         BJ-BJHXW-AR04-NE4 Up   299s     L2       64
E40E-X3                            0E-X3.01                                   
BJ-BJDDS-CR01-N GE1/0/0            ---               Init 58s      L2       64
Total Peer(s): 2

Handling Process

Check the error information of IS-IS process 1.

Check the interface information.
<NE40E-X3>display cu interface GigabitEthernet1/0/0
interface GigabitEthernet1/0/0
mtu 1512
ip address x.x.x.42
isis enable 1
isis circuit-level level-2
isis cost 200 level-2
< NE40EX-16>display cu interface GigabitEthernet2/3/0
interface GigabitEthernet2/3/0
ip address x.x.x.41
isis enable 1
isis circuit-level level-2
isis cost 200 level-2

Root Cause

In IS-IS, Hello packets are sent based on the MTU setting on the interface. If the MTU values on both ends are inconsistent, an IS-IS neighbore relationship fails to be set up.


Change the MTU value of GigabitEthernet 1/0/0 on an NE40E-X3 to 1500.
[NE40E-X3- GigabitEthernet1/0/0]MTU 1500
[NE40E-X3- GigabitEthernet1/0/0]undo MTU  //The default MTU of the interface is 1500.
[NE40E-X3- GigabitEthernet1/0/0]restart   //After the MTU value is changed, restart the interface to make the change take effect.