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[Syslog Message] KERN_ARP_DUPLICATE_ADDR or KERN_ARP_ADDR_CHANGE

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Article ID: KB33414 KB Last Updated: 30 May 2019Version: 2.0
Summary:

The syslog message KERN_ARP_DUPLICATE_ADDR or KERN_ARP_ADDR_CHANGE is generated continuously for the em1 interface.

Symptoms:

When SRX5K uses RE1 for dual control link redundancy, KERN_ARP_DUPLICATE_ADDR messages are generated under certain conditions.

When SPC3 is used in a SRX5k cluster, SPC3 fails to bootup with this error:

Nov 20 08:17:38   kernel: KERN_ARP_DUPLICATE_ADDR: duplicate IP address 129.16.0.1! sent from address: 02:01:00:01:00:05 (error count = 1985)
Nov 20 08:18:49   kernel: KERN_ARP_DUPLICATE_ADDR: duplicate IP address 129.16.0.1! sent from address: 02:01:00:01:00:05 (error count = 1994) 
Nov 20 08:19:50   kernel: KERN_ARP_DUPLICATE_ADDR: duplicate IP address 129.16.0.1! sent from address: 02:01:00:01:00:05 (error count = 2002)
Nov 20 08:20:51   kernel: KERN_ARP_DUPLICATE_ADDR: duplicate IP address 129.16.0.1! sent from address: 02:01:00:01:00:05 (error count = 2010)

The following log messages may be generated at the same time in a chassis cluster:

kernel: KERN_ARP_ADDR_CHANGE: arp info overwritten for 129.16.0.1 from 02:01:00:01:00:05 to 02:00:00:02:00:04
kernel: KERN_ARP_ADDR_CHANGE: arp info overwritten for 129.16.0.1 from 02:00:00:02:00:04 to 02:01:00:01:00:05
kernel: KERN_ARP_ADDR_CHANGE: arp info overwritten for 129.16.0.1 from 02:01:00:01:00:05 to 02:00:00:02:00:04
kernel: KERN_ARP_ADDR_CHANGE: arp info overwritten for 129.16.0.1 from 02:00:00:02:00:04 to 02:01:00:01:00:05

Hardware condition:

root> show chassis hardware
node0:
--------------------------------------------------------------------------
Hardware inventory:
Item             Version  Part number  Serial number     Description
<-snip->
CB 0             REV 03   750-066337   xxxxxxxx          SRX5k SCB3
CB 1             REV 06   750-062257   xxxxxxxx          SRX5k SCB3   <-- RE1 is installed.
Cause:

This issue happens because chassis cluster is enabled in SCB slot 1. Refer to the details about SCB in Switch Control Board SRX5K-SCB3 Overview.

When configuring SRX to enable chassis cluster, the following command is used:

set chassis cluster cluster-id <cluster id> node <node number>

This configuration is saved in SCB slot 0 (not in RE). If this SCB slot 0 replaces SCB slot 1 without disabling chassis cluster, this issue will happen. From the IP address and MAC address in the message, we can determine that this message is related to SCB slot 1. IP address 129.16.0.1 is used for em0 and em1 interface.

root> show interfaces terse
Interface      Admin Link Proto    Local                Remote
em0            up    up
em0.0          up    up   inet     129.16.0.1/2
                                            143.16.0.1/2
                          tnp      0x1100004
em1            up    up
em1.0          up    up   inet     129.16.0.1/2
                                            143.16.0.1/2
                          tnp      0x1100004


The MAC address 02:01:00:01:00:05 is used by re1 em1.

root@:~ # tnpdump
   Name                TNPaddr   MAC address    IF     MTU E H R
backup                   0x6 02:01:00:01:00:05 em1    1500 2 0 3
cluster1.node0     0x1100001 02:00:00:01:00:04 em0    1500 0 0 3
cluster1.node0     0x1100001 02:00:01:01:00:04 em1    1500 0 1 3
node0.re0          0x1100004 02:00:00:01:00:04 em0    1500 0 0 3
node0.re0          0x1100004 02:00:01:01:00:04 em1    1500 0 1 3
node0.re1          0x1100005 02:01:00:01:00:05 em1    1500 2 0 3
node0.fpc4         0x1100014 02:00:00:01:00:14 em0    1500 4 0 3
cluster1.master    0xf100001 02:00:00:01:00:04 em0    1500 0 0 3
cluster1.master    0xf100001 02:00:01:01:00:04 em1    1500 0 1 3
bcast             0xffffffff ff:ff:ff:ff:ff:ff em0    1500 0 0 3
bcast             0xffffffff ff:ff:ff:ff:ff:ff em1    1500 0 1 
Solution:

1. Remove SCB from slot 1 and insert it to SCB slot 0.

2. Then disable the chassis cluster configuration using the command, 'set chassis cluster disable'.

Modification History:
2019-05-30: Added KERN_ARP_ADDR_CHANGE error to the article.
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