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IOS simulator

This is a generic issue, although I'll use a specific example to illustrate my question:

When booting an IOS box into a new config, the console will display error messages for lines it doesn't like.  But it doesn't give a lot of clues as to *which* lines it didn't like.


no mop enabled
% Invalid input detected at '^' marker.

OK, that time, the IOS gave lots of clues -- I can search through my config, find 'no mop enabled' and delete it.  [I'm upgrading from SXF17 to SXI4a on a Cat6K containing IPSec SPA modules.]

But sometimes, the parser doesn't give much guidance ... clearly the errors below relate to three of the 'crypto' stanzas ... but which ones?

This will remove previously installed VPN routes and SAs
This will remove previously installed VPN routes and SAs
This will remove previously installed VPN routes and SAs

Here's another example ... the 'router eigrp xxx' stanzas don't mention any of these VLANs ...

%EIGRP: Interface Vlan410 not a member of this routing table
%EIGRP: Interface Vlan414 not a member of this routing table
%EIGRP: Interface Vlan416 not a member of this routing table

So, I can wipe the box's configuration.  Create a simple configuration, one which loads SXI4a and does hardly anything else.  Reboot it.  Gradually type/paste small chunks of my new configuration into 'confg t' at the console ... and then I can see which lines induce the parser to whine, figure out what mistake I'm making, and so forth. [Yes, this box is in production, and no, I don't have a test C6K (with or without IPSec SPA modules) available.]

My question:  is there an easier way?

In some sense, I think I'm wanting an 'IOS simulator', kind of like the ONTAP simulator which NetApp offers ... an IOS simulation which would run under Linux and allow me to play around with syntax, without, of course, actually doing anything (the box wouldn't forward packets, for example).



Stuart Kendrick

Fred Hutchinson Cancer Research Center

Seattle, WA USA

Everyone's tags (5)

Re: IOS simulator

You may find dynamips helpful:


Re: IOS simulator


yes, it's a good one!

Here also with a user-friendly GUI:



Hall of Fame Guru

Re: IOS simulator

As Christopher and Milan have said dynamips is an excellent simulator for routers/IOS however be aware that it won't help with things like the 6500 simply because it can't emulate a 6500 switch. There are no really good switch simulators because most of the switches operation are done in hardware on dedicated ASICs.


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