Posted on in Networking
If you're using policy-maps on your Cisco Catalyst switches to handle rate-limiting, you may have noticed that on some models, the show policy-map interface command does not seem to work. The CLI accepts the command and returns properly formatted output, but the output is all zeroes. There is no information …
Posted on in Networking
If you've used Cisco switch clustering in a basic network (for example, when all switches are connected together and <acronym title="Cisco Discovery Protocol">CDP</acronym> is enabled), you've likely never considered how this switches communicate with each other. You might assume that the switches are using IP addresses from …
Posted on in Networking
This week I tried upgrading a Cisco Catalyst 2960 to the newest software release — 12.2(46)SE. The upgrade went just fine, but I noticed that the monitoring software was throwing SNMP errors.
In case you don't know much about SNMP, an ifIndex identifies a specific interface on a …
Posted on in Networking
Error: The image in the archive which would be used to upgrade
Error: system number 1 does not support the same feature set.
I just got this error message while upgrading a Cisco Catalyst 3560 from 12.2(35)SE5 to 12.2(44)SE. The older version was IP …
Posted on in Networking
This is a bit of random oddness I stumbled upon this morning.
I was working on a Cisco Catalyst 2960 switch and
needed to know which MAC addresses the device had learned on a particular
interface. The usual way to do this is with the
show mac-address-table interface command. While …
Posted on in Networking
You'll find that some network problems can only be solved by sticking a packet sniffer on the network and seeing what the packets are doing. In a switched environment, this will not work properly since each port is configured to only broadcast traffic destined for the MAC addresses it has …
Posted on in Networking
If you work on a fairly spread out network (or have remote clients), you might be managing Cisco Catalyst switches that are far, far away. For a long time, I thought the only option was to have someone on site to pre-configure the switch just enough to get it on …
Posted on in Networking
<acronym title="UniDirectional Link Detection">UDLD</acronym> is a Cisco protocol designed to detect and disable unidirectional links in Ethernet (fiber or twisted-pair). In the case of a radio-based Metro Ethernet ring, UDLD goes the extra mile in preventing Spanning-Tree loops and user service interruption.
In this simple network of …
