Am I going Nuts or what?????
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Thread: Am I going Nuts or what?????

  1. #1
    AO Ancient: Team Leader
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    Am I going Nuts or what?????

    I have a router with a default gateway at 192.168.3.4. It contains routes to all my private subnets. One of those private subnets also has a gateway to the world via T1. I have built a server that will handle DNS and mail relay in case my primary T! here goes down. It's all rather simple really.

    In order to have the secondary mail/dns server function properly I need to be able to route to it's public address from the master router that is 2 hops away. So I merrily palce the following route in the master router:-

    ip route aa.bbb.ccc.0 255.255.255.0 192.168.2.10 (an internal router that several other routes point to and function perfectly well).

    I write it to memory and ping the box... Bingo. So, I'm happily playing when I get a call from one of my other agencies telling me that they cannot get to a web site that they use frequently. I run an nslookup on it and find it is at aa.ee.ff.gg. The letters that are in this address match the letters in the route I put in so if aa = 10 in the route above then aa = 10 in the nslookup. As you can see the aa network is the only common factor. So I run a tracert on the aa.ee.ff.gg address and my master router tell me that the "destination host is unreachable"....

    So I remove the route and everything is peachy except that I, (obviously), can't reach my aa.bbb.ccc.ddd host through the internal network which I need to do. I re-added the route same thing, I checked it for typos - none, I checked to see if there was any possibility of a conflict - none!!!!! But the host is unreachable... In fact _every_ host in the aa network is unreachable.... I have reloaded and done a hard restart and it is still messed up!!!!

    Now correct me if I'm wrong but a network aa.bbb.ccc.0 and a subnet mask of 255.255.255.0 is a collection of hosts from aa.bbb.ccc.0 to aa.bbb.ccc.255 and has no relation whatsoever to the network aa.ee.ff.0.

    So why the hell will my Cisco not get this right
    Don\'t SYN us.... We\'ll SYN you.....
    \"A nation that draws too broad a difference between its scholars and its warriors will have its thinking done by cowards, and its fighting done by fools.\" - Thucydides

  2. #2
    Senior Member RoadClosed's Avatar
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    stupid question. Did you clear the routing tables?

    //EDIT sometimes when you introduce a new route you have to fluch the table cache. I think it is cisco>clear arp

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  3. #3
    AO Ancient: Team Leader
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    OK... Stupid answer....

    Doesn't a reload, and especially a hard restart, clear the table on a Cisco and start from scratch? I really don't know.... I'm not hugely good at routers... Even so, when I add a route for a Class network with the appropriate subnet mask how in the hell does it kill a whole A class? Inquiring minds need to know.....
    Don\'t SYN us.... We\'ll SYN you.....
    \"A nation that draws too broad a difference between its scholars and its warriors will have its thinking done by cowards, and its fighting done by fools.\" - Thucydides

  4. #4
    Senior Member RoadClosed's Avatar
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    Yes powering it off should flush it but I always do that as a habit.

    cisco> clear arp

    I have rarely ever powered off a router or firewall.

    I am cranking up my squeaky brain on routing problems. I am not expert either. ACL perhaps?

    //EDIT TTL on the secondary route?
    West of House
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  5. #5
    Senior Member RoadClosed's Avatar
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    Router pointed to correct DNS server

    boobs# ip ip-nameserver 12.34.56.78
    West of House
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  6. #6
    AO Ancient: Team Leader
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    No ACL's on the router... It's internal and unreachable from the public network....

    Powering off is the last resort.... I did it... I couldn't see any other reason other than it wasn't properly parsing the ip route statement and that a restart may "assist" it to understand.... Clearly it didn't help it.... Stupid router... Never had a poblem like this before.... I have a spare router and may try a replacement tomorrow.... the current one is old... very old.... It might just be failing... I have a newer one that I'll copy the config to and slide in there tomorrow.... That's my best guess at the moment... I _know_ the route statement is good.... I have no idea why it messes up the whole A class other then router failure at this point.....

    [Edit]

    nameservers are irrelevant, all routes are literal....

    [/Edit]
    Don\'t SYN us.... We\'ll SYN you.....
    \"A nation that draws too broad a difference between its scholars and its warriors will have its thinking done by cowards, and its fighting done by fools.\" - Thucydides

  7. #7
    Senior Member RoadClosed's Avatar
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    Try routing the entire network as a trouble shooting measure. Never did it on a router but the pix let's you route 0.0.0.0 as a catch all.

    //EDIT

    well you are going to have to get on the router and use trace on all interfaces to make sure they are set up properly. Perhaps an interface failed during the restart.

    yo# trace 192.1.10.20

    yo# show arp (just make sure they are there)
    yo# show interfaces


    I am going that way because the route seems ok.
    West of House
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  8. #8
    AO Ancient: Team Leader
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    I actually tried the following route:-

    ip route aa.0.0.0 255.0.0.0 192.168.2.10

    all the while there is the default route of:-

    ip route 0.0.0.0 0.0.0.0 192.168.3.4

    It worked perfectly for my aa.bbb.ccc.ddd host but the whole A class was still "destination host unreachable"....

    I dunno.... I'm beginning to think I don't know s**t about this stuff any more... Alzheimers? Maybe...

    [Edit]

    I have to leave the satellite office right now..... I'll look after I have dinner and made my sweetie happy.... Other than that, the router is getting replaced tomorrow and we'll see if it works.... if it stays the same i will be appropriately "miffed"

    [/Edit]
    Don\'t SYN us.... We\'ll SYN you.....
    \"A nation that draws too broad a difference between its scholars and its warriors will have its thinking done by cowards, and its fighting done by fools.\" - Thucydides

  9. #9
    Senior Member RoadClosed's Avatar
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    LOL that is hilarious, I was just going to ask about the Sat. Office. Have fun um... "working"
    I pasted an edit after you gave the latest update.
    West of House
    You are standing in an open field west of a white house, with a boarded front door.
    There is a small mailbox here.

  10. #10
    AO Ancient: Team Leader
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    I'm still at router replacement at this point..... There is nothing wrong with my route statement.... Thus, logically, there is something else throwing itself into this mix.... The router itself has to be a suspect.... We'll see in the morning.....
    Don\'t SYN us.... We\'ll SYN you.....
    \"A nation that draws too broad a difference between its scholars and its warriors will have its thinking done by cowards, and its fighting done by fools.\" - Thucydides

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