Home / server / Questions / 536247
Accepted
Arun
Asked: 2013-09-05 04:54:54 +0800 CST

Router Behavior for MAC Address Change for same IP

  • 772
 +-----------+           +------------+           +---------+
 | LAN       |eth0   lan0| Router     |wan    eth0|         |
 | PC        |===========|            |===========| WAN-PC  |
 |           |           |            |       eth1|         |
 +-----------+           +------------+           +---------+
     192.168.0.4      192.168.0.123  1.2.3.123   1.2.3.4

I think above diagram will be helpful for understanding my setup.

Step 1 . pinging from LAN-PC to WAN PC ( from 192.168.0.4 to 1.2.3.4) ping will work fine..

Step 2. While ping is going on cable switching from eth0 to eth1 in WAN-PC [IMPORTANT: eth0 and eth1 is having same IP ( ie 1.2.3.4)]

In this case ping will resume (few packets will lose).

My Question is : What is the mechanism behind identifying MAC Address change ?

networking

1 Answers

  1. Best Answer

    Unless WAN-PC has some kind of gratuitous ARP process going, which is unlikely, there is no such mechanism.

    ARP cache entries have timestamps, and the entries time out after a certain period of time; often it's 20s, but it can vary. Once an entry times out of cache, a new ARP request will be made by Router, and the new MAC address on WAN-PC will be picked up by its response.

    • 1