cisco port question

Hi ill.

Of course you cant do the "show mac-address-table" in the 2600 because the 2600 is only a router, not a switch, and the "show mac-address-table" command is only a switch command.

Now I look at the posts above and there you can do both commands ins the same device because it is a multilayer device. so both commands work.

Another idea is that you can install fluke network inspector, and do a disocvery of the network, there shows you wich device with is ip address and associated mac address is learned from which switch and from wich switchport of the selected switch.

i'm still young in my practice with cisco gear.

so, there is no-way that a 2611 router will learn the ports from the LAN's switches (2900 series)?


was my above statement true?

sh arp - resolves ip to mac ?

sh mac - resolves mac to port ?

Wild Post! sorry...

For all your questions thats correct.

From the router you can resolve the mac-address to port, but the router has only one ethernet port fro the switched inside lan, and of course it will learn by the only inside port.

Hi ill.

Of course you cant do the "show mac-address-table" in the 2600 because the 2600 is only a router, not a switch, and the "show mac-address-table" command is only a switch command.

Now I look at the posts above and there you can do both commands ins the same device because it is a multilayer device. so both commands work.

Another idea is that you can install fluke network inspector, and do a disocvery of the network, there shows you wich device with is ip address and associated mac address is learned from which switch and from wich switchport of the selected switch.

i'm still young in my practice with cisco gear.

so, there is no-way that a 2611 router will learn the ports from the LAN's switches (2900 series)?


was my above statement true?

sh arp - resolves ip to mac ?

sh mac - resolves mac to port ?

There is a slight difference between arp and mac-address-table (the elongated Cisco switch command). This is my understanding of that difference

ARP is Address Resolution Protocol and is the local cache of any IP to MAC queries. ARP is used by layer 2 devices (or any device that uses layer 2 ie routers are layer 3, but use layer 2 as well) because the frame header requires updated source and destination MAC addresses to send on to the next physical layer 2+ device.

mac-address-table is a mac address filter listing done by the switch that shows addresses that it has learned of and what ports that it must send frames in order to get to the final destination. This table is used for all forwarding decisions to minimize lan traffic through the network. The closest layer 3 equivelant would be the routing table.

There is a slight difference between arp and mac-address-table (the elongated Cisco switch command). This is my understanding of that difference

ARP is Address Resolution Protocol and is the local cache of any IP to MAC queries. ARP is used by layer 2 devices (or any device that uses layer 2 ie routers are layer 3, but use layer 2 as well) because the frame header requires updated source and destination MAC addresses to send on to the next physical layer 2+ device.

mac-address-table is a mac address filter listing done by the switch that shows addresses that it has learned of and what ports that it must send frames in order to get to the final destination. This table is used for all forwarding decisions to minimize lan traffic through the network. The closest layer 3 equivelant would be the routing table.

I would agree with this assessment.

Also let's not forget routers have their own ARP table. If I'm looking for an IP-to-MAC conversion, I usually look to our local gateway router first, and issue a "show arp" command. Obviously this is limited to certain scenario's, but another option none the less.