Cisco 6500 ARP entry issue.

[martin.wang]

Hi guys,

I got some information when I "show arp x.x.x.x detail" and I can't find any explanation about that.

6500#show arp detail
...omitted...
* ARP HA
ARP entry has not been synchronized to standby RP.

Does anyone know why ARP entry is not sync to standby RP?

After "clear ip arp" for this ip address or wait for few minutes maybe few hours, it will be normal.

The normal situation should be like this.

ARP entry for 150.117.119.72, link type IP.
...omitted...

* ARP HA
ARP entry has been synchronized to standby RP.

[Mark Malone]

was it a static arp entry they don't sync ?

ARP High Availability

The ARP subsystem supports ARP high availability (HA) on Cisco networking devices that support dual Route Processors (RPs) for redundant processing capability. However, ARP HA is limited to the synchronization of dynamically learned ARP entries from the active RP to the standby RP. Statically configured ARP entries are not synchronized to the standby RP.

[martin.wang]

Hi Mark,

It's dynamic ARP.

[Tausif Gaddi]

Networking devices that support dual RPs, ARP uses the SSO feature in the Cisco IOS software. SSO provides redundancy and synchronization for many Cisco IOS applications and features. SSO takes advantage of RP redundancy by establishing one of the RPs as the active processor while the other RP is designated as the standby processor, and then synchronizing critical state information between them.
Here is a for more information http://www.cisco.com/c/en/us/td/docs/ios/12_4t/ip_addr/configuration/guide/htarpmon.html#wp1196166