Loopback 9 on a layer 2 switch

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I know it works but I cant get my head around how.

A DL switch has a static route to say to get to the loopback address of 192.168.1.1 you have to go to the address on the layer 2 switch which is 172.10.10.10.

The thing I cant get to grips with is, the Layer 2 switch recieves the packet on the 172 network. How does it direct it to the loopback 9 address of 192.168 when there is no routing table to direct it ? I know that loopback 9 is an always on interface, but it is on a different network. The more I think about it, the more confused I get ??

Please enlighten my mind, or it will ruin my xmas !!!!

I have this problem too.
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Giuseppe Larosa Thu, 12/18/2008 - 05:13

Hello Martin,

a Layer2 only switch doesn't examine the ipv4 header and the destination.

It works on frames using MAC addresses it will move the frame to the port where the destination mac address has been heard.

That's all.

The routing decision is performed by somebody else a router for example that sends a packet to the MAC address associated with the IP address of the nexthop to reach 192.168.x.y destination.

This is the layered approach of the OSI model.

Hope to help

Giuseppe

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