GNS3-ER Switching Setup?
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Author:  aaron123 [ Wed Oct 01, 2014 10:00 pm ]
Post subject:  GNS3-ER Switching Setup?

It's been a while since I've been messing around on GNS3 and was wondering how you go about setting up the switching features in the early release version. Do I need a specific image? Is this much different than adding a router's image? Are there any guides available for this?

Also, I assume only L2 switching is being added at this point, what about L3 switching? L3 switching would be really nice when you're trying to recreate a topology from work!

Author:  rlouarn [ Wed Oct 01, 2014 10:39 pm ]
Post subject:  Re: GNS3-ER Switching Setup?


Switching isn't integrated in GNS3 because Cisco use specific ASIC for the switching ( In that way, it is difficult to emulate. Knowing that the ASIC is there for strong calculation process, and programmed specifically for switching functions, I can understand that it is very had to emulate and would need a lot of CPU/GPU power to do the same.

Therefore, only switches are implemented because they are using CPU for their operations. So, the solution to use switching commands inside GNS3 is to configure slots of Ethernet ports inside your router, and only using the switching configuration.
Frankly, it is not as powerful as a real switch (RSTP/MSTP aren't operational, some advanced VLAN options neither,...) but it is usable, and allow you to do most of the simple configurations to test the behavior of your network.
In that way, you do a sort of simple CPU emulation... I agree that it is not the proper way networks are working, but it is so nice to be able to emulate a complex network, I think this is a good "simple" solution for most cases :) At least for my "small" needs :)

For the images, I think that every ipbase have the L2 implementation, so it should be ok, no need of specific images. Not sure, but I think that most advanced switching functions not implemented in the ipbase version, are not integrated in GNS3 anyway.
They're only few differences in commands, you should have no problems. If a command doesn't exist/work, probably it is not compatible with GNS3 (look at the link above for the list of switching functions, at the EtherSwitch Cards section)

I hope this will answer your expectations :)

Author:  aaron123 [ Wed Oct 01, 2014 10:52 pm ]
Post subject:  Re: GNS3-ER Switching Setup?

I'm referring to the early release build of GNS3 which is supposed to support switching simulation.

Author:  rednectar [ Sat Oct 04, 2014 9:15 pm ]
Post subject:  Re: GNS3-ER Switching Setup?

See The answer to Q1 on the new GNS3 FAQ

New GNS3 | FAQ
Q. Will you support Cisco switching?

A. Switching is going be supported in GNS3 using L2IOU images, which are special IOS images made to work on PC/Linux. These are more like generic Cisco switches with most of the same features as in real switches. So in the end you can have 90% of the same features, just a bit slower.

In other words, to get the promised switching support you need an L2 IOU image, such as i86bi-linux-l2-adventerprisek9-15.1a.bin

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