EDIT: My general question is if different versions of ios, spanning from 12 and 15, can work well in direct connection.

I am in way over my head because I went ahead and ordered a full CCIE lab without even taking my CCENT, I just really wanted something to practice on.

Here's the problem, I ordered six 2811 Routers (running on ios15), and then got three more routers to function as my backbone routers. These backbones are 2821XM, which run on ios12. That won't be a problem right? I just want them for OSPF and BGP labs.

I'm dying here because I actually paid more for the 2621XMs than I did for the 2821s: they were all refurbished, and I am learning that the refurbished market is highly illogical price-wise.

Should I bite the bullet and just buy three more 2821s to keep the ios15 uniform? I might be able to salvage the 2621XMs* for random home projects. I'm ordering from Hawaii, so returning and reshipping some heavy cheap refurbished routers isn't going to be an option.

Thanks to anyone who can help a noob out!

  • As far as I know ios 12 is fine. But you have 6 that can run 15 which is more than you'll need for CCENT anyways. Sep 4 '14 at 23:40
  • Thank you (I don't know if it's because this section is still in Beta or because I'm a new user but I see no way to rate up your comment.) Anyway it occurred to me that I will probably just be getting random samples of ios 12 on all my refurbished routers; they are still being shipped. I just get nervous about whether different ios can communicate well. These were $100 each refurbished and I wouldn't be surprised if Cisco wanted something 4-figures for an upgrade license so I can probably forget about that. Sep 5 '14 at 0:12
  • The first and last thing to know about IOS: www.cisco.com/go/fn (fn = feature navigator)
    – Ricky
    Sep 5 '14 at 6:19
  • 1
    I'm currently administrator of a mixed 12.x and 15.x environment. You might as well learn what commands don't work on 12.x because you will see non-updated devices out in the world and some people are deliberately not using 15.x on Catalyst switches because of CPU utilization of certain processes. And they will absolutely talk to each other just fine. Sep 5 '14 at 17:17
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Aug 9 '17 at 2:39

You will be fine. In fact, you have yourself quite a lab for whatever exam you attempt. Remember that routing protocols like BGP and OSPF are standards, so all routers will run them compatibly, even (gasp!) other manufacturers.

The newer IOS versions may have some extra "knobs" you can tweak, but you are unlikely to run into that on any of your tests. IIRC, the IOS in the labs isn't always the latest and greatest.

  • I don't have enough reputation points to rate you up yet but thank you! I'm glad to hear that it's the standard that we can severely dumb down labs financially! I also went cheap only getting one 3560 switch with EMI and the other three with just SMI hoping that they will simply inherit the more expensive software option so long as my primary one doesn't break. Sep 5 '14 at 0:31
  • 1
    @EricAllione, even if you can't upvote, you can still accept the answer, which awards Ron 15 points, and you 2 points.
    – This
    Sep 5 '14 at 1:25
  • Some old bugs fixed, new bugs created, an old bug or two unfixed... Features added, removed, and/or augmented. But, yes, in areas where there are "standards", they're mostly followed. (there's "the standard" and then there's "what Cisco does" -- other vendors do it too)
    – Ricky
    Sep 5 '14 at 6:24

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