Confusion with slot/port/adapter nomenclature . Please help

Unanswered Question
Mar 8th, 2008

Although I've been working with couple of Service Providers for 3 years, but since

I didn't do lots of field work, I always had confusions about slot/port/adapter

nomenclatures. Can somebody explain me below given output of "sh ip int brief" and "sh diag" on or give me some resources to read. I want to know how does the "sh diag" command

tells us if Fastethernet is going to be F0/0 and F0/1. Similarly with S0/0, ATM 0/1, ATM 0/2 etc

The outputs are given in attached file.

I have this problem too.
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Danilo Dy Sat, 03/08/2008 - 22:48


Cisco Router Interfaces use the following naming slot# / port#

'media-type' are ethernet, serial, atm, etc..take note that Ethernet is 10Mbps, FastEthernet is 100Mbps, and GigabitEthernet is 1000Mbps.

'slot# / port#' old model routers don't have slot#. For example 2500 routers, if 2500 router have two Ethernet Interface, they were named Ethernet0 and Ethernet1...take note that slot# and port# always start with zero '0' then one '1'. Most new model routers have slots, and if they have, the built-in interface is considered to be in 'slot 0'. For WIC, sometimes the naming convention can be confusing, this is because any WIC installed in the router is in 'slot 0'. For example you have two WIC slot in a router (called W0 and W1) and you install WIC-2T in W0 and another WIC-2T in W1, they will be named Serial0/0, Serial0/1, Serial0/2, and Serial0/3

Your "show ip interface brief" command is a very useful command to see the interfaces and their names.

Here's a link for further reading




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