BCMSN - Difficulty emulating a switching lab in GNS3 [CCNP]

A lot of people I know are of the opinion that GNS3 is 'absolutely useless' when it comes to BCMSN and to go buy 'real' 3550 switches as GN3/Dynamips cannot emulate a L3 Switch. The core of a L3 switch is it’s ASIC’s (Application Specific Integrated Circuits), these provide the functionality that make a L3 switch’s performance at L3 so much better that those of a Router. Although a L3 switch runs an IOS image, it is the meeting of both the software (IOS) and the Hardware (ASIC’s) that provide the capabilities that the switch brings to the table. GN3 thus can’t emulate the ASIC’s found within a L3 switch. GN3 with dynamips at its core “simply” emulates a Mips CPU. An IOS image can then be run on this CPU and a Router instance is created"

or so is their argument...

but if you're like me and running low on cash then well let's just say we have no choice but to 'make do'... really though it's not that bad. As I said earlier, the trick here is to add an 'NM-ESW' module to the router slots in GNS3. This effectively emulates a 'real' NM-ESW module that pretty much gives you a layer two switch inside a layer 3 router, which is 'apparently' exactly what a L3 switch is (My understanding of L3 switches was a router inside a switch) but hey... effectively one and the same thing.

I've noticed that this does restrict us from doing quite a few things however. For instance, you cannot use switchport security, also it only supports one instance of spanning tree and you have to use the 'vlan database' command rather than the 'vlan (no)' command in global-config mode to create vlan's.

I don't know whether the CCNP v5 covers 6500 fail-over modes or VSS anymore but given our options at hand, it's best to use the NM-ESW module before going out and buying 'real' switches like the 3550 and spending a heap on it.

GNS3 definitely won't support a few things like rstp, etc but you can always try and find a workaround for that (for e.g. use PT for rstp).