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5736 Views 5 Replies Latest reply: May 24, 2009 4:28 AM by Krzysztof Przybylski RSS

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Cisco_c7:c9:82     LOOP     Reply- Clarity

May 23, 2009 4:38 PM

Hello everyone,

 

I am using wireshark to capture OSPF traffic i see the following loop reply:

 

 

9    6.131242    Cisco_c7:c9:82    Cisco_c7:c9:82    LOOP    Reply

 

Can somone please clarify the output above?

 

Thanks

  • Krzysztof Przybylski 64 posts since
    May 8, 2009

    Hi !

     

    You could add  more info

    for example that:

     

    - this traffic is on Ethernet interface

    - it is send every 10 sec.

     

    It is a normal situation, because its a keepalive

    Device is checking / testing itself

     

     

     

    - Krzysztof Przybylski

  • Conwyn 7,914 posts since
    Sep 10, 2008
    Currently Being Moderated
    2. May 24, 2009 1:16 AM (in response to Krzysztof Przybylski)
    Re: Cisco_c7:c9:82 LOOP Reply- Clarity

    Hi Miizarebel and Krzysztof

     

    Here is a ospf packet debug of two routers connect by a serial and the packets are every 10 seconds.

    Do we know what is Cisco_C7:C9:82 in the title? It looks like a LAT name generated when the hostname is > 16 characters

     

    r1#debug ip ospf packet
    OSPF packet debugging is on
    r1#
    *Mar  1 00:01:56.967: OSPF: rcv. v:2 t:1 l:48 rid:10.0.0.1
          aid:0.0.0.0 chk:D79B aut:0 auk: from Serial1/0
    *Mar  1 00:02:06.963: OSPF: rcv. v:2 t:1 l:48 rid:10.0.0.1
          aid:0.0.0.0 chk:D79B aut:0 auk: from Serial1/0
    *Mar  1 00:02:16.955: OSPF: rcv. v:2 t:1 l:48 rid:10.0.0.1
          aid:0.0.0.0 chk:D79B aut:0 auk: from Serial1/0
    *Mar  1 00:02:26.967: OSPF: rcv. v:2 t:1 l:48 rid:10.0.0.1
          aid:0.0.0.0 chk:D79B aut:0 auk: from Serial1/0
    *Mar  1 00:02:36.975: OSPF: rcv. v:2 t:1 l:48 rid:10.0.0.1
          aid:0.0.0.0 chk:D79B aut:0 auk: from Serial1/0
    *Mar  1 00:02:46.963: OSPF: rcv. v:2 t:1 l:48 rid:10.0.0.1
          aid:0.0.0.0 chk:D79B aut:0 auk: from Serial1/0
    *Mar  1 00:02:56.979: OSPF: rcv. v:2 t:1 l:48 rid:10.0.0.1
          aid:0.0.0.0 chk:D79B aut:0 auk: from Serial1/0
    r1#no debug
    *Mar  1 00:03:06.963: OSPF: rcv. v:2 t:1 l:48 rid:10.0.0.1
          aid:0.0.0.0 chk:D79B aut:0 auk: from Serial1/0all
    All possible debugging has been turned off

     

    A later debug of ip

    r1#debug ip packet detail
    IP packet debugging is on (detailed)
    r1#
    *Mar  1 00:17:06.983: IP: s=10.0.0.1 (Serial1/0), d=224.0.0.5, len 80, rcvd 0, p
    roto=89
    *Mar  1 00:17:10.707: IP: s=10.0.0.2 (local), d=224.0.0.5 (Serial1/0), len 80, s
    ending broad/multicast, proto=89
    *Mar  1 00:17:16.959: IP: s=10.0.0.1 (Serial1/0), d=224.0.0.5, len 80, rcvd 0, p
    roto=89
    r1#no de
    *Mar  1 00:17:20.707: IP: s=10.0.0.2 (local), d=224.0.0.5 (Serial1/0), len 80, s
    ending broad/multicast, proto=89bug all
    All possible debugging has been turned off
    r1#debug ip packet dump
    IP packet debugging is on (dump)
    r1#
    *Mar  1 00:17:36.967: IP: s=10.0.0.1 (Serial1/0), d=224.0.0.5, len 80, rcvd 0
    0F401750:          0F000800 45C00050 006C0000      ....E@.P.l..
    0F401760: 0159CE23 0A000001 E0000005 02010030  .YN#....`......0
    0F401770: 0A000001 00000000 D79B0000 00000000  ........W.......
    0F401780: 00000000 FFFFFFFC 000A1201 00000028  .......|.......(
    0F401790: 00000000 00000000 0A000002 FFF60003  .............v..
    0F4017A0: 00010004 00000001                    ........
    *Mar  1 00:17:40.707: IP: s=10.0.0.2 (local), d=224.0.0.5 (Serial1/0), len 80, s
    ending broad/multicast
    0F401890:                   45C00050 00680000          E@.P.h..
    0F4018A0: 0159CE26 0A000002 E0000005 02010030  .YN&....`......0
    0F4018B0: 0A000002 00000000 D8970000 00000000  ........X.......
    0F4018C0: 00000000 FFFFFF00 000A1201 00000028  ...............(
    0F4018D0: 00000000 00000000 0A000001 FFF60003  .............v..
    0F4018E0: 00010004 00000001                    ........
    *Mar  1 00:17:46.967: IP: s=10.0.0.1 (Serial1/0), d=224.0.0.5, len 80, rcvd 0
    0F401C50:          0F000800 45C00050 006D0000      ....E@.P.m..
    0F401C60: 0159CE22 0A000001 E0000005 02010030  .YN"....`......0
    0F401C70: 0A000001 00000000 D79B0000 00000000  ........W.......
    0F401C80: 00000000 FFFFFFFC 000A1201 00000028  .......|.......(
    0F401C90: 00000000 00000000 0A000002 FFF60003  .............v..
    0F401CA0: 00010004 00000001                    ........        no debug al
    *Mar  1 00:17:50.707: IP: s=10.0.0.2 (local), d=224.0.0.5 (Serial1/0), len 80, s
    ending broad/multicast
    0F401D90:                   45C00050 00690000          E@.P.i..
    0F401DA0: 0159CE25 0A000002 E0000005 02010030  .YN%....`......0
    0F401DB0: 0A000002 00000000 D8970000 00000000  ........X.......
    0F401DC0: 00000000 FFFFFF00 000A1201 00000028  ...............(
    0F401DD0: 00000000 00000000 0A000001 FFF60003  .............v..
    0F401DE0: 00010004 00000001                    ........        l
    All possible debugging has been turned off
    r1#

  • Krzysztof Przybylski 64 posts since
    May 8, 2009
    Currently Being Moderated
    3. May 24, 2009 2:56 AM (in response to Conwyn)
    Re: Cisco_c7:c9:82 LOOP Reply- Clarity

    Hello Conwyn,

     

    I hope I understand you right,

    In my opinion "Cisco_C7:C9:82" (precisely C7:C9:82 part) is a MAC address of the Ethernet interface.

    And like I said before, this message is simply Ethernet Cisco keepalive.

    On serial interface there is no such thing like above loop reply 'keepalive' example.

     

     

    - Krzysztof

  • Conwyn 7,914 posts since
    Sep 10, 2008
    Currently Being Moderated
    4. May 24, 2009 3:11 AM (in response to Krzysztof Przybylski)
    Re: Cisco_c7:c9:82 LOOP Reply- Clarity

    Hi Krzysztof

     

    My apolgies since the question referred to OSPF I assumed the wireshark reference also concerned OSPF packets. As you can see OSPF is also transmitting those packets every 10 seconds. I was thinking about the convention before I saw your post and I wondered if Wireshark had identified the manufacturer identification within the Ethernet and displayed CISCO and then the specific element of the Ethernet frame. When the thread lacks specific detail it is always a dilema whether to guess and try to answer or whether to request more information and given the different timezones of the CLN the answering of a question can take days.

     

    Regards Conwyn

  • Krzysztof Przybylski 64 posts since
    May 8, 2009
    Currently Being Moderated
    5. May 24, 2009 4:28 AM (in response to Conwyn)
    Re: Cisco_c7:c9:82 LOOP Reply- Clarity

    You are absolutely right

    Sometimes when problem seems very complicated, the solution is very simple

     

    pozdrawiam

    greetings

     

    Krzysztof

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