arp entries

[carl_townshend]

Hi all

is it possible 2 arp entries can exist for the same addresses on a router? or as soon as it sees the same IP will it get overwritten ?

cheers

[cadet alain]

Hi,

You can only have one mapping for 1 IP and as soon as it receives an ARP reply it will update its arp cache entries except static ones.

But you can have multiple IPs having same MAC if proxy-arp is used on the other side.

Regards.

Alain.

[ameya_oke · Accepted solution]

Hey Carl,

When you send an ARP request to an IP say x.y.w.z only one MAC address is resolved.

But there are concepts like HSRP, VRRP, GLBP which allow at virtual level to resolve multiple mac-address for a single IP address.(Insuch cases a virtual mac address is resolved and not the physical mac address of the gateway interfaces)

Even on desktop class machines when you use concepts like  teaming /bridging/bundling /LPAR the same concept of virtualization is applicable.

Please rate if helpful

Ameya