Showing posts from January, 2012

Cisco Configuration Tip - Command Macro To Change IP Address

Remotely changing an IP address on a Cisco router or switch, or moving an IP from one interface to another can be a challenge.

Cisco allows you to use macros although I have not really worked with them. rekrowteN has a great blog post about using macros to move an IP address from one VLAN interface to another.

In a previous Configuration Tip I discussed using the reload in/at commands to prevent getting locked out of a router or switch.

In this scenario we need to move the IP Address assigned to interface VLAN 1 to VLAN 10.
For this tip start by entering reload in 15.

Next we create the macro
conf t
macro name mgmtchange
interface vlan 1
no ip address
interface vlan 10
ip address
no shutdown
The "@" signifys  at the end of the macro. To apply the macro enter:
conf t
macro global apply mgmtchange
Once the change is made and you can reconnect don't forget reload cancel.

Configuring Command Macros

Have you used macro's? What Macro scrip…

Cisco Configuration Tip - Protect Your Tail

I have long been a fan of the Cisco "reload in/at" commands. These have saved my tail a number of times. This enables a brave network engineer to schedule a device reload for either a specific amount of time from now, 15 minutes, or just a specific time such as 11:00pm.
Protect Your Tail
This has saved my tail a few times when working on a remote device. When changing ACLs or firewall rules there is always the potential of getting locked out. It has also saved me when debug messages flooded a device and I could not get the telnet/ssh session to respond.

Bonus Tip: When I have to debug a router or a switch I open a second telnet/ssh window. The primary window is set to terminal monitor so I can see the messages. In the second window I type in "undebug all" but don't press enter. If the debug messages get out of hand in the primary window, I switch to the second window and hit enter. Before making configuration changes, do the following:
copy run start
terminal monit…

Configuration Tricks - Catalyst 4900M with CVR-X2-SFP and 1Gb SFP

The Cisco Catalyst 4900M is a high performance, low latency, layer-3 switch suitable for Top of Rack 10Gb link aggregation or small data centers server connectivity. eWeek testing validated 320 Gbps throughput, or 16 10G ports running at full line speed with latency of ~2.6 microseconds.

The 4900M chassis includes 8 fixed wire-speed X2 ports. Two half-card module slots can be added for additional ports. Supported modules available are:
WS-X4920-GB-RJ45 - 20 port 10/100/1000 RJ45WS-X4904-10GE - 4 port wire speed 10GE (X2)WS-X4908-10GE - 8 PORT 2:1 over subscription 10GE (X2)WS-X4908-10G-RJ45 -  8 PORT 2:1 over subscription 10GbaseTI recently had a situation were we deployed a Catalyst 4900M with the WS-X4920-GB-RJ45 and WS-X4908-10GE modules. The switch needed to connect a 1GB metro Ethernet circuit. No problem, with the 20 port 10/100/1000 module we had it covered...So I thought.

The service provider handed off 1GB multi-mode fiber.

How Do I Connect 1GB Multi-Mode Fiber To This Thing?