I remember once seeing an IOS command that, given a mac address, would trace that address through the network to its end point. For example; a PC is connected to port 8 of a 2950 switch. The 2950 uplinks to a 3550 which, in turn, uplinks to a core 6509. From the 6509 i can issue a command which shows me all intermediary devices and shows me the end switch and which port the target device connects to. Does anyone know the syntax for this command?
In article , dexx wrote: :I remember once seeing an IOS command that, given a mac address, would :trace that address through the network to its end point. For example; a :PC is connected to port 8 of a 2950 switch. The 2950 uplinks to a 3550 :which, in turn, uplinks to a core 6509. From the 6509 i can issue a :command which shows me all intermediary devices and shows me the end :switch and which port the target device connects to. Does anyone know :the syntax for this command?
If it can be done at all, it would be via cdp .
In general, it can't be done with much degree of certainty. And 75% of the time, when you go to look for the information, it isn't there anymore.
You are probably thinking of L2trace. But there are severe limitations. We have asked Cisco for such a tool though. They have it for multicasts (mapping out the MC tree) so it would be pretty easy to convert it to unicast traffic.
In the tool, I wanted to see L3 *and* L2 port information, associated error counters, and it *had* to account for redundant paths since every link on our network is redundant. Getting cef exact-route info was considered gravy.
IOS and CatOS switches use different portnames, Gi3/1 (4506) and 1/1 (6509).
The script is based on SNMP read-only and searches the mac-address-table for the specific MAC/VLAN. Some conversions have to be made (hex MAC to decimal notation). The script also provides a conversion for ifindex to readable (Gi1/1 or 6/5) portnumbers. Works like a charm for me.
Also problems like duplicate MAC can be found easily, the script searches all given switches for the MAC/VLAN. Only caveat of the script is the .txt file which must be kept uptodate with the actual topology.
I'm using the script with Activestate PERL v5.6.1 build 635, MS C++ 6.0 (nmake) and NET-SNMP 4.1.2 library on a W2k station.
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