intervlan offical BCMSN question/issues

livenliven Member Posts: 918
Has anyone completed the offical lab book for the BCMSN from cisco?

I am going the first intervlan routing lab from chapter 4.

It is two access layer switches with one switch trunked to a router and that router is connected to an "ISP" router

like this:

ISP (router) <----> GATEWAY (router)
access layer switch1
access layer switch2

I have a host pc connected to access layer switch two.

So ISP router has a loopback with on it. I can ping that IP from the gateway router. But when I ping to that IP from my access layer switches the first packet goes through but the next 4 time out. So it makes sense to me that my config should be partially correct. I am seeing really high times on the pings so maybe they are timing out, but it just seems odd because this is a lab with no load on it. The access layer switches are connected with port channels and switch port trunks. Then they are connected to the Gateway router with a 801tq encapsulated trunk. The gateway router has sub interfaces setup and sees the VLANS/switches correctly.

Does any one have any suggestions on the top of their heads? I don't see any errors on my interfaces...
encrypt the encryption, never mind my brain hurts.


  • Mrock4Mrock4 Banned Posts: 2,359 ■■■■■■■■□□
    Could you post your configs if possible? I didn't use the official book, but it would probably help everyone see what's going on.
  • kryollakryolla Member Posts: 785
    I am assuming you are doing router on a stick due to sub interfaces on your ethernet link for the router. Because of this you are using layer 2 switches such as 2950. So when you try to ping the ISP router from 2950 pings fail but not to the directly connected router. On the 2950 I assume you have an ip address for you management vlan to talk to the directly connected router and also a default gateway set up pointing to the directly connected router for off subnet traffic such as ISP router. This will take care of the traffic from switch to router to ISP but ISP might not have a route back to switch or PC so check that out. That is all I can think of right now.
    Studying for CCIE and drinking Home Brew
  • Sanis4lifeSanis4life Banned Posts: 60 ■■□□□□□□□□
    Config or it didnt happen ;)

    Seriously, it could be a few things. Kryolla explained them all pretty well, but the only way for sure is by looking at your config.
  • livenliven Member Posts: 918
    I understand the need for the config. I am sure I made a mistake in there some where. Yes this is a router on a stick. It is the first lab in the intervlan routing section for this test.

    I will post configs later if I don't figure it out myself. I did the lab late last night so I was tired and probably fat fingered something.
    encrypt the encryption, never mind my brain hurts.
  • livenliven Member Posts: 918
    figured it out...

    The issue was my test pc. It is a SUSE box that has 2 nics. One NIC is connected to the server subnet hanging off my firewall. The other NIC is connected to my Lab setup as a test PC.

    So I am sshing into the test box on an IP on my server subnet. This box has a gateway in the server subnet NOT in the lab subnet....

    So I had to change the default gateway (to the IP of sub int on router) and then ssh into the test PC from my firewall (because I could no longer ssh into it from my wifi subnet, untill I configure some static routes) and PRESTO.

    I was trying to test using:

    ping -I


    traceroute -I

    And they worked perfectly on any thing on their subnet. But when I tried to send packets to a different subnet those command still used the regular default gateway... DUH!!!!

    so anyway I got it fixed and it was a noobish mistake on my behalf. I guess if I wasn't so lazy and would just study in the room that my lab is in I would have seen this sooner. None the less I can move on now without feeling like a loser because I didn't figure out what was causing things to not work correctly.
    encrypt the encryption, never mind my brain hurts.
Sign In or Register to comment.