Part 4: Found an IOS bug on R5, and found why IPv6 doesn’t work over my NBMA, so I won’t be able to lab it :(


I’m thinking it has to be something on that frame switch so we’ll dig into the guts of that, but I start off with R5 (not in this Topology in which you will see why), just to get SOMETHING going for R1. As you may not know from previous labs, R5 is attached to R1 via Ethernet, and usually hangs in topology above R2.

So I R5 loaded first so I immediately got into configuring and OSPFv3 Area 15, and not hardly into the configuration at all, I hit a bug in the IOS:

R5#sh ip int bri
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            unassigned      YES NVRAM  administratively down down
FastEthernet0/1       YES NVRAM  administratively down down
Serial0/0/0                unassigned      YES NVRAM  administratively down down
Serial0/0/1                unassigned      YES NVRAM  administratively down down
Loopback5                 YES NVRAM  up                    up
R5#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R5(config)#int lo5
R5(config-if)#no ip add
R5(config)#ipv6 unicast-routing
R5(config)#ipv6 router ospf 1
% Failed to create routing protocol ospf  <-What????
R5(config)#ipv6 router ?
  eigrp  Enhanced Interior Gateway Routing Protocol (EIGRP)
  nemo   Network Mobility (NEMO)
  ospf   Open Shortest Path First (OSPF)
  rip    IPv6 Routing Information Protocol (RIPv6)

R5(config)#ipv6 router ospf ?
  <1-65535>  Process ID

R5(config)#ipv6 router ospf 1
% Failed to create routing protocol ospf

That’s an excellent way to start off a lab 🙂 Yeah, so I am seriously giving this one last attempt, and then I will just have to take the point hits on the exam because this is the kind of material that is a study killer.

However, I’d like to turn this into a learning lesson, so far we have learned that R5 has IPv6 IOS bug issues so I will be keeping the 1800 series router completely out of IPv6 studies if possible.

So what we know, is that when I did add the frame map statements from the last lab, we got Active PVC’s to both peers, so Layer 2 is working. However, for some reason Layer 3 does not want to work, and I am thinking it had to do with something on the NBMA switch that perhaps was configured off camera before the lesson cause Chris Bryant enters about 4 commands and it just works like it should.

So my first thought, is the 2600 router serving as the NBMA switch which works perfectly for IPv4 routing needs some tweaks for IPv6 routing. Now I want to make as little change as possible, preferably just global (ipv6 unicast-routing) to kick it in the butt and get it routing, but I will also enable the interfaces if that doesn’t work.

So then I found the issue, on a 2620XM router (one of the higher end models (unfortunately) in my lab that is the frame switch for R1 / R2 / R3:

FRSW#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
FRSW(config)#ipv6 unicast-routing
% Invalid input detected at ‘^’ marker.

FRSW(config)#ipv6 ?
% Unrecognized command

It has no idea what in the world we are talking about IPv6, so when a packet of Hex jibberish shows up at the Frame-Switch it just goes HUH? So at least that solves the mystery of what was going on there.

So that will conclude IPv6 over NBMA, it’s been my Achilles heel that I was going to squash tonight to start progressing again through the week, and that really sucks it won’t work but I’ll just take in the theory on this one and keep moving forward to exam day.

Not sure what the next topic is on deck, but given I’m a bit under the weather it may be a slow start, but time to start pounding these topics out.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s