First off, fear not. I’ve already recorded videos from DMVPN part 2, I didn’t give up lol. I just need to get some time to toss everything into text format. I just thought I’d do a really short post about DMVPN on the new blueprint. I haven’t tested yet, however from Cisco 360 workbooks, I’m starting to get a good idea of what kind of curve balls to expect on the lab. It’s gets me SUPER excited to see how deep just the workbooks have been getting on the subject matter, Cisco is treating it as a frame-relay replacement more than just a subtle new topic.
So far I seen scenarios where you can’t allow broadcast/multicast in the DMVPN cloud, so OSPF behavior is similar to FR networks without broadcast. I’ve also seen some per-tunnel QoS, where you have to leverage NHRP to apply policy-maps per-dynamic tunnel via NHRP groups (IOS help nhrp, you’ll be fine. Not “ip nhrp”, just nhrp ?). Cisco also loves to trip you up with phrasing like “Map broadcast traffic between spoke routers R1 and R2”, but they’ll make no mention of the hub. This sounds like you’re digging into additional nhrp maps, but that’s not the case. Since so long as you’re mapping multicast to the hub, nhrp will dynamically map broadcast/multicast traffic between spokes, just as it does with unicast traffic.
So I know I’m just rambling in this post, but this new content should get you excited, not scared. Honestly, one of the best study sessions I’ve had on the subject matter was sitting down with a follow CCIEer, building a DMVPN network… and looking for ways to break it. Then doubling back and seeing how manipulate behavior, and of course lots of DOC CD and IOS help along the way.
Study hard! I’ll have my next DMVPN post out soon.
