When Cisco devices are connected to one another and CDP is enabled (which it is by default), if one port is configured as full duplex but the other is configured as half duplex, the two devices will log “duplex mismatch” messages. This can be very helpful in the real world. However, when using GNS3 these messages can appear for no reason at all...
Update: Please see this page for a fix to this issue. The other day I decided to upgrade my GNS3 IOS to c3725-adventerprisek9-mz.124-15.T14.bin. All seemed to be going well until I tried to issued the “ip nat inside” command on one of the interfaces… R1(config)#int fa0/0 R1(config-if)#ip nat inside % NBAR ERROR: parsing stopped % NBAR Error : ...
Update: Please also see my Virtual Equipment + Physical Equipment = Big Lab post for more information. As you already know, GNS3 allows you to create virtual routers on your PC. What some people struggle with is connecting their physical PC to their virtual GNS3 network. In this blog entry, I’ll explain how this can be done using GNS3’s cloud o...
In my previous post, Router URL Filtering using NBAR, I explained how it was possible to block users from accessing websites simply by using NBAR, a class-map and a policy-map. In this post I’ll describe how you can redirect your users’ web requests instead of simply blocking them. This time we’ll use NAT instead of NBAR. For this example, let...
I covered subnetting in my earlier posts, Subnetting Made Easy, Part 1 and Subnetting Made Easy, Part 2. In the latter mentioned post, I explained how you can use simple additions or subtractions to work out the First Usable Address, the Last Usable Address and the Broadcast Address of a subnet. As the post was quite long, I thought I should r...