Frame-Relay Inverse ARP problem

Discussion in 'Cisco' started by jmarkotic, Jan 7, 2004.

  1. jmarkotic

    jmarkotic Guest

    Hi,
    I have 2 spoke locations connected to a hub, but these two locations also
    have a pvc between them which I dont want to use. I want all traffic to go
    trhu central hub router.
    I statically mapped all pvc-to-ip addresses and they all point to central
    location.
    For example, location1 have pvc 101 to hub, and location2 has pvc 102 to
    hub. PVC between spokes is 112 and I dont want to use it.
    I disabled arp and inverse arp on both spokes so they dont use pvc which I
    didn't manually set.
    But for some reason, despite all that, 2 spokes create adjacency over that
    phantom pvc.
    FR ip addresses:
    hub: 10.10.1.9
    spoke1: 10.10.1.10
    spoke2: 10.10.1.11
    PVCs
    spoke1-hub: 101
    spoke2-hub: 102
    spoke1-spoke2: 112

    Here is the config for spoke1 (spoke2 is similar)
    interface Serial0/0
    ip address 10.10.1.10 255.255.255.248
    encapsulation frame-relay IETF
    no arp frame-relay
    ! mapping for central hub
    frame-relay map ip 10.10.1.9 101 broadcast
    ! mapping for another spoke so that two spokes can ping each other
    ! mapping to another spoke is made via hub's pvc
    frame-relay map ip 10.10.1.11 101 broadcast
    no frame-relay inverse-arp
    frame-relay lmi-type ansi

    # sh frame map
    ! there is no mapping for this one, everything looks fine
    Serial0/0 (up): ip 0.0.0.0 dlci 112(0x70,0x1C00)
    Serial0/0 (up): ip 10.10.1.9 dlci 101(0x65,0x1850), static,
    Serial0/0 (up): ip 10.10.1.11 dlci 101(0x65,0x1850), static,

    Spokes should create eigrp adjacency only with hub, and all traffic should
    go thru hub.
    But spokes somehow still manage to create adjacency with each other and
    route traffic among them directly over that pvc. When I remove spoke-2-spoke
    pvc from FR switch, then it works fine and all traffic goes thru hub.

    But when I debug eigrp hello packets I see that they manage to go trhu pvc
    112.
    01:30:37: Serial0/0(i): dlci 112(0x1C01), pkt type 0x800, datagramsize 64
    01:30:37: EIGRP: Received HELLO on Serial0/0 nbr 10.10.1.10

    How can I forbid two spokes to use direct PVC between them ?

    thanks,
    jura
     
    jmarkotic, Jan 7, 2004
    #1
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  2. jmarkotic

    Ivan Ostres Guest

    Another thing. It seems that using 'passive interface' would not do much
    good since you have just one interface for both connections. You can
    always make path between spokes undesirable by using route filtering.
     
    Ivan Ostres, Jan 8, 2004
    #2
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  3. Jura,

    Maybe a neater way of connecting these three sites (which are in a full FR
    mesh) would be to create 3 point-to-point connections and increase the
    metric so that the connection between the two remote sites wont get used
    unless one remote site loses its connection to the hub site?

    Regards,

    Scott.
    \|/
    (o o)
    ---------------------oOOO--(_)--OOOo----------------------
    Out the 100Base-T, off the firewall, through the router, down
    the T1, over the leased line, off the bridge, nothing but Net.
    (Use ROT13 to see my email address)
    .oooO Oooo.
    ----------------------( )---( )-----------------------
    \ ( ) /
    \_) (_/
     
    scott enwright, Jan 8, 2004
    #3
  4. jmarkotic

    jmarkotic Guest

    Huh,
    I was not clear enough. There are so many good ways to work around this
    situation, but this is a leb scenario from "CCIE practical studies" and
    there it says that disabling FR inverse-arp/arp you effectively disable
    unwanted PVC.
    Well, for some reason that doesn't work for me and I wonder why.
    thanks,
    j
     
    jmarkotic, Jan 8, 2004
    #4
  5. jmarkotic

    Hansang Bae Guest

    Did you pop the interface *after* disabling inverse arp?


    --

    hsb

    "Somehow I imagined this experience would be more rewarding" Calvin
    *************** USE ROT13 TO SEE MY EMAIL ADDRESS ****************
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    Hansang Bae, Jan 8, 2004
    #5
  6. jmarkotic

    jmarkotic Guest

    You mean shut/no shut ? Yes, many times with same results.
     
    jmarkotic, Jan 9, 2004
    #6
  7. jmarkotic

    Ivan Ostres Guest

    Did you check bugs for your IOS version?
     
    Ivan Ostres, Jan 9, 2004
    #7
  8. Try

    [no] frame-relay inverse-arp protocol dlci


    Regards,

    Scott.
    \|/
    (o o)
    ---------------------oOOO--(_)--OOOo----------------------
    Out the 100Base-T, off the firewall, through the router, down
    the T1, over the leased line, off the bridge, nothing but Net.
    (Use ROT13 to see my email address)
    .oooO Oooo.
    ----------------------( )---( )-----------------------
    \ ( ) /
    \_) (_/
     
    scott enwright, Jan 9, 2004
    #8
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