ARP-cache Vs CAM-table

[rhamdaoui1]

Im asking for the behavior of a layer 3 switch when receiving a packet with A destination ip address  that have a resolution in the arp-cache but no entry is found for the mac-add in the cam-table

same question if there is an entry in the cam-table.and no entry in the arp-cache.

[Madhukrishnan Gopinathan Nair]

Hi,

Did not get  the exact situation you are talking  about, however if no arp, it will send an ARP request if needed.(remember if it is within the same vlan (L2), to forward the packet the switch does not need to have an ARP entry, all it needs a mac address.)

Again if no mac , it will flood it, it is called unicast flooding. 

Hope this helps

Madhu

[rhamdaoui1]

im talking about the situation where a layer 3 switch has an arp entry for a given ip address.

exemple : IP-@-1===> MAC-@-1, but when it comes to the Cam-table there is no entry for the MAC-@-1

[pwwiddicombe]

The CAM table will only be populated if the MAC-@-1 is in a port on this switch or one of the same VLAN.  If it is inbound from another VLAN on another switch, then there is no CAM entry for the device as it isn't present on the switch.