We are always adding to, and updating the technical “how to’s” contained here. When it comes to configuring a new Cisco router, much of the configuration depends on what type of router it is as well as the purpose it will serve. However, there are certain things you should configure on every new Cisco router. […]
Top 10 Cisco IOS Classic Commands Read More »
Many of our MPLS students and colleagues ask us about VRF Lite. The common question is “Can I use VRF Lite to simplify MPLS configuration?” The answer is, that VRF Lite actually has nothing to do with MPLS nor MPLS L3VPN per se. Let’s define what VRF Lite is. A VRF is a Virtual Routing
VRF Lite Configuration in Cisco IOS Read More »
As most of us know, a key to managing the Internet is knowledge of TCP and UDP port numbers. Cisco IOS uses Access Control Lists for many purposes, but in this tip, we will focus on TCP and UDP port numbers. Port numbers are unique, well-known, registered or ephemeral numbers used by TCP (Transmission Control
UDP and TCP Port Number Usage in ACL’s in Cisco IOS Read More »
Welcome to our Cisco IOS Classic Interface Commands Cheat Sheet. You can see our other IOS cheat sheet here. You can view all our Cisco IOS How To’s here. Here are the most frequently used Interface commands as a quick reference/cheat sheet. This will help you remember the key interface configurations: Important show commands show
Cisco IOS Classic Interface Commands Cheat Sheet Read More »
The Show Environment command can be very helpful to alert you of potential hardware issues. You will need to access this command in global Exec mode. Here are the options available for the Show Environment command: show environment [alarms | all | fans | hardware | last | leds | power-supply | table | temperature
Show Environment Command in Cisco IOS Read More »
What happens if there is a system or user on a VLAN that is infected by malware or is deliberately running a scanning program? What if you have some public ports on your switches that you only want to have access to the Internet and not each other? This problem can be easily solved with
Protected Ports on Cisco Switches in Cisco IOS Read More »
Point-to-Point (PPP) Protocol is an excelent Layer 2 protocol used to establish a direct connection between two nodes. It can provide connection authentication, transmission encryption (using ECP, RFC 1968), and compression. PPP was designed somewhat after the original HDLC specifications. The designers of PPP included many additional features that had been seen only in proprietary
PPP Configuration in Cisco IOS Read More »
What is Policy-based Routing? With policy-based routing (which we will call PBR from here on out), you get the option to implement policies that selectively cause packets to take different paths. Additionally, PBR can mark packets so that certain types of traffic get prioritized. One example of PBR is, say that your OSPF routing protocol
Policy Based Routing feature Usage in Cisco IOS Read More »
OSPF (Open Shortest Path First) is an IGP (internal gateway protocol), and OSPF is an open standard protocol originally defined in RFC 2328. Since then OSPF has been updated numerous times including functionality to support IPv6 and Address Families. OSPF is supported on every major routing platform as well as Windows Server 2003 and Linux
OSPF Basics in Cisco IOS Read More »
This How To explains Passwords on Cisco platforms. The question you might ask is: Doesn’t the router already have default passwords? The answer is NO, it doesn’t. There is no automatic password defense that comes with your router. As a Cisco admin, this should be taken very seriously. It is so important and so easy
Passwords in Cisco IOS Read More »
If you want to partition flash memory of routers with flash, you can. On most class B Flash file systems, you can partition banks of Flash memory into separate, logical devices so that the router can hold and maintain two or more different software images. This partitioning allows you to write software into Flash memory
Partitioning Internal FLASH in Cisco IOS Read More »
Routine maintenance is the underpinning of any well run network. Through routine maintenance, consistency, predictability and standardization all result allowing the network to operate as expected and in times of fault, makes a better troubleshooting environment. As part of any routine maintenance activity, Cisco provides several commands to help. One less known command is the
Maintenance with the ‘show diag’ command in Cisco IOS Read More »
You can use the service timestamps command to create timestamps on the router’s log files. Since version 11.3, the Cisco IOS has enabled certain timestamps by default, so most of us have this on. However, there are additional timestamps options that you can enable as well as places where timestamps are probably off by default.
Service Timestamps in Logging in Cisco IOS Read More »
Whenever we teach our Hands-On courses, we always have a section of the course that discusses troubleshooting the network or technology the class is learning. A key part of troubleshooting any network is knowing the technology, no argument. But even the masters of technologies like Multicasting, or IP Networking, or MPLS, still can benefit from
Leveraging Logging for Troubleshooting Using Cisco IOS Read More »
One of the most annoying things in Cisco IOS is its old roots in the 23 line terminals. Every 23 lines, you get a –More– pause, to which you have to hit the space bar to continue the output. Now maybe this does not bother you. Fine, move on to our next Cisco tip. But
Stopping and Changing the –More– Console Output Interrupt Read More »
