Cisco 2651xm/cable modem problem
Page 1 of 2 12 LastLast
Results 1 to 10 of 19

Thread: Cisco 2651xm/cable modem problem

  1. #1
    Junior Member
    Join Date
    Oct 2005
    Posts
    16

    Cisco 2651xm/cable modem problem

    I have cox high speed internet and want to start using a Cisco 2651xm router instead of my small appliance router. Here is my basic config:
    cable modem -f0/1 port of 2651xm - f0/0 port into small netgear swtich - pc into netgear switch. (the 2651xm has two fastethernet ports)

    I have set the f0/1 port to dhcp. It grabs an IP address from ISP from cable modem. I set the f0/0 port to static IP of 192.168.1.254. Pc is set to IP of 192.168.1.2.

    I set up RIP routing in the router for network 70.0.0.0 and network 192.168.1.0. (The IP I get from my ISP is in the 70.0.0.0 range.

    I can ping both interfaces of the router from my pc, but I cannot ping any address beyond the f0/1 port (any internet addresses). While I am consoled into my router I am able to ping any internet address, so the router is able to communicate w/ the outside world, it is just not passing any requests from my pc to the outside world.


    I do not have any acl's setup. I have talked to a friend of mine that works w/ cisco routers alot and he said that he had tried the exact same setup and ran into the same problem. He mentioned that it might be an encapsulation problem. any ideas?

  2. #2
    Right turn Clyde Nokia's Avatar
    Join Date
    Aug 2003
    Location
    Button Moon
    Posts
    1,696
    Did you use the correct sub-net masks when setting the IP's for the ports?

    Remember RIP [v.1] is a classfull routing protocol and will only use default masks.

    Sounds like you are passing traffic to the router with IP addys that are not in its routing table and therfore the router will drop it by default.

    What are the exact commands you have used from start to finish?

    Can you configure your switch or is it not an intelligent one?
    Drugs have taught an entire generation of kids the metric system.

    http://tazforum.**********.com/

  3. #3
    Junior Member
    Join Date
    Oct 2005
    Posts
    16
    here is my config in the router. I did know that RIP was classfull, so when I put in the commands as follows:
    router rip
    network 70.0.0.0
    network 192.168.1.0
    It would have defaulted 70.0.0.0 to a subnet of 255.0.0.0 because it is class A
    It would have defaulted 192.168.1.0 to a subnet of 255.255.255.0 because it is class C
    So do you think it is unable to pass class C to class A? If so, would the fix be to put my internal network to a class A subnet such as 10.0.0.0?
    Here is the config:

    version 12.3
    service timestamps debug datetime msec
    service timestamps log datetime msec
    no service password-encryption
    !
    hostname BCSRTR03
    !
    boot-start-marker
    boot system flash:c2600-a3js-mz.123-11.T.bin
    boot-end-marker
    !
    !
    no network-clock-participate slot 1
    no network-clock-participate wic 0
    no aaa new-model
    ip subnet-zero
    !
    !
    ip cef
    !
    !
    interface FastEthernet0/0
    ip address 192.168.1.254 255.255.255.0
    duplex auto
    speed auto
    !
    interface Serial0/0
    no ip address
    shutdown
    !
    interface FastEthernet0/1
    ip address dhcp
    duplex auto
    speed auto
    !
    !
    router rip
    network 70.0.0.0
    network 192.168.1.0
    !
    ip classless
    !
    ip http server
    !
    !
    !
    !
    !
    control-plane
    !
    !
    gateway
    timer receive-rtp 1200
    !
    !
    line con 0
    line aux 0
    line vty 0 4
    login
    !
    !
    end

  4. #4
    Right turn Clyde Nokia's Avatar
    Join Date
    Aug 2003
    Location
    Button Moon
    Posts
    1,696
    Can you post your routing table?

    Have you tried adding a default route for your gateway?

    Code:
    ip route 0.0.0.0 0.0.0.0 f0/1
    this basically tells it that if it does not have an entry for a network in its routing table, forward it out of f0/1.

    The problem you could be having is that when you want to browse the net and open up a web page with an ip of say 66.21.21.45, when your router gets this packet it doesnt know what to do with it as it has no idea where the ip address 66.21.21.45 is, so it will just drop the packet.
    Drugs have taught an entire generation of kids the metric system.

    http://tazforum.**********.com/

  5. #5
    Junior Member
    Join Date
    Oct 2005
    Posts
    16
    Ok, I have changed some of the #'s for my peace of mind, but it is close enough that I think you will get the idea:

    Gateway of last resort is 70.11.11.1 to network 0.0.0.0

    70.0.0.0/24 is subnetted, 1 subnets
    C 70.11.11.0 is directly connected, FastEthernet0/1
    172.11.0.0/32 is subnetted, 1 subnets
    S 172.11.0.11 [254/0] via 70.11.11.1, FastEthernet0/1
    C 192.168.1.0/24 is directly connected, FastEthernet0/0
    S* 0.0.0.0/0 [254/0] via 70.11.11.1

    By the way the entries for 172.11.0.11 and that subnet is for the dhcp server on my ISP's side.

  6. #6
    Junior Member
    Join Date
    Oct 2005
    Posts
    16
    Yes I did put that exact command in (ip route 0.0.0.0 0.0.0.0 f0/1) as well as a few others such as:
    ip route 0.0.0.0 0.0.0.0 dhcp
    which tells it to route all traffic to the default gateway provided to it by the DHCP server. (the closest gateway beyond my router)

  7. #7
    Right turn Clyde Nokia's Avatar
    Join Date
    Aug 2003
    Location
    Button Moon
    Posts
    1,696
    You have two static routes in there which have an AD of 1, RIP had an AD of 120. So aslong as you have those static routes in the RT, RIP is pretty much null and void.

    You dont really need rip on a network such as this.
    Drugs have taught an entire generation of kids the metric system.

    http://tazforum.**********.com/

  8. #8
    Junior Member
    Join Date
    Oct 2005
    Posts
    16
    so do you have any ideas on how I can get around that? Can I use a different routing protocol such as eigrp to get around it?

  9. #9
    Junior Member
    Join Date
    Oct 2005
    Posts
    16
    also I am new to configing Cisco routers, what is AD of 1 and AD of 120?

  10. #10
    Right turn Clyde Nokia's Avatar
    Join Date
    Aug 2003
    Location
    Button Moon
    Posts
    1,696
    are you sure that 172.11.11.0/32 is correct? there cant be a /32 the best you can have is a /30.

    AD - Administrative Distance. It is what cisco routers use to chose which route to take, the lower the AD the better.

    A directly connecteed route has an AD of 0 and is therfore the best route, a static route has an AD of 1 and is the next best route, RIP has an EIGRP (intenal) has an AD of 90, IGRP 100, OSPF 110, RIP 120, the worst you can have is 255 which is an unkown route and will never be used!

    So if you want RIP to work you have to remove the static routes (hence RIP will have the lowest AD after directly connected routes) or put a static route with a higher AD than RIP.
    Drugs have taught an entire generation of kids the metric system.

    http://tazforum.**********.com/

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •