Recent posts

Fast GNS3 Router Bootup

October 08, 2011 | 1 minute read

As all Cisco IOS users/Cisco engineers will have seen when booting up a switch or a router, the device will decompress the image file which is represented by a series of # signs that flood across the screen. While it does not take an extremely long time to decompress the image, it can seem like it is taking an eternity if your wanting to get a l...

Emulating a Multi Layer Switch in GNS3

September 28, 2011 | 2 minute read

As most of you know, you can get switch-like capabilities in GNS3 by inserting a NM-16ESW in to a compatible router. This is necessary because at present, dynamips is unable to emulate a real switch. This is because Cisco switches use hardware ASICs to perform their duties and unfortunately it is difficult/impossible for this to be emulated in s...

GNS3 Duplex Mismatch Messages

September 24, 2011 | 1 minute read

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...

GNS3 IOS Memory Errors

September 23, 2011 | 4 minute read

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 : ...

Connecting Your PC to Your Virtual GNS3 Routers

September 18, 2011 | 3 minute read

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...