Help with CME in a high latency (SATCOM) environment

Discussion in 'Cisco' started by JohnInRochester, Jan 10, 2008.

  1. I'm having trouble getting a Cisco 7911 or 7941 phone to stay
    registered in a CME environment where the link latency is on the order
    of 250 mS each direction. The phones will appear to have registered as
    indicated by messages at the router console, but within 2 seconds, an
    unregistered abnormally message is seen. The message flow as seen by
    Wireshark looks the same as a normal registration up until the router
    closes the control connection on port 2000. This sequence repeats over
    and over again as long as the phone is powered.

    Can anyone provide some insight on what might be going on and what I
    can try to sort this out? I could swear I was told that CME would work
    over SATCOM links. What have I gotten wrong?

    Thanks in advance for clues, insights, and solutions.

    John in Rochester
     
    JohnInRochester, Jan 10, 2008
    #1
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  2. JohnInRochester

    Merv Guest

    I think there is a Cisco DDTS that indicates that for any latency over
    240 ms that you need to have a local TFTP server
    to download the phone firmware
     
    Merv, Jan 10, 2008
    #2
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  3. On Jan 10, 4:52 pm, Merv <> wrote:
    > I think there is a Cisco DDTS that indicates that for any latency over
    > 240 ms that you need to have a local TFTP server
    > to download the phone firmware


    Here's the Wireshark trace:

    No. Time Source Destination
    Protocol Info
    41 43.851564 192.168.135.151 192.168.130.1
    TFTP Read Request, File: CTLSEP001E7A25B6C8.tlv, Transfer type:
    octet
    42 43.853648 192.168.130.1 192.168.135.151
    TFTP Error Code, Code: File not found, Message: No such file
    44 44.391688 192.168.135.151 192.168.130.1
    TFTP Read Request, File: SEP001E7A25B6C8.cnf.xml, Transfer type:
    octet
    45 44.393693 192.168.130.1 192.168.135.151
    TFTP Error Code, Code: File not found, Message: No such file
    46 44.796587 192.168.135.151 192.168.130.1
    TFTP Read Request, File: XMLDefault.cnf.xml, Transfer type: octet
    47 44.799582 192.168.130.1 192.168.135.151
    TFTP Data Packet, Block: 1
    48 45.201354 192.168.135.151 192.168.130.1
    TFTP Acknowledgement, Block: 1
    49 45.202976 192.168.130.1 192.168.135.151
    TFTP Data Packet, Block: 2
    50 45.606495 192.168.135.151 192.168.130.1
    TFTP Acknowledgement, Block: 2
    51 45.607616 192.168.130.1 192.168.135.151
    TFTP Data Packet, Block: 3 (last)
    52 46.011445 192.168.135.151 192.168.130.1
    TFTP Acknowledgement, Block: 3
    56 46.701342 192.168.135.151 192.168.130.1
    TCP 52053 > tdbm [SYN] Seq=0 Len=0 MSS=1400
    57 46.702777 192.168.130.1 192.168.135.151
    TCP tdbm > 52053 [SYN, ACK] Seq=0 Ack=1 Win=4128 Len=0 MSS=536
    59 47.095500 192.168.135.151 192.168.130.1
    TCP 52053 > tdbm [ACK] Seq=1 Ack=1 Win=8192 Len=0
    60 47.095506 192.168.135.151 192.168.130.1
    SKINNY AlarmMessage
    61 47.095807 192.168.135.151 192.168.130.1
    SKINNY AlarmMessage
    63 47.230405 192.168.135.151 192.168.130.1
    SKINNY RegisterMessage
    64 47.293941 192.168.130.1 192.168.135.151
    TCP tdbm > 52053 [ACK] Seq=1 Ack=273 Win=3856 Len=0
    65 47.372566 192.168.130.1 192.168.135.151
    SKINNY RegisterAckMessage
    66 47.372780 192.168.130.1 192.168.135.151
    SKINNY CapabilitiesReqMessage
    67 47.771395 192.168.135.151 192.168.130.1
    SKINNY IpPortMessage
    68 47.771586 192.168.135.151 192.168.130.1
    SKINNY ButtonTemplateReqMessage
    69 47.771588 192.168.135.151 192.168.130.1
    SKINNY SoftKeyTemplateReqMessage
    70 47.771793 192.168.135.151 192.168.130.1
    SKINNY SoftKeySetReqMessage
    71 47.771795 192.168.135.151 192.168.130.1
    SKINNY ConfigStatReqMessage
    72 47.772209 192.168.135.151 192.168.130.1
    SKINNY CapabilitiesResMessage
    73 47.772211 192.168.135.151 192.168.130.1
    SKINNY HeadsetStatusMessage
    76 47.875883 192.168.130.1 192.168.135.151
    TCP [TCP segment of a reassembled PDU]
    82 48.310389 192.168.135.151 192.168.130.1
    TCP 52053 > tdbm [ACK] Seq=513 Ack=538 Win=8192 Len=0
    83 48.378127 192.168.130.1 192.168.135.151
    SKINNY SoftKeyTemplateResMessage
    84 48.379981 192.168.130.1 192.168.135.151
    TCP [TCP segment of a reassembled PDU]
    85 48.380194 192.168.130.1 192.168.135.151
    SKINNY SoftKeySetResMessage
    87 48.630168 192.168.130.1 192.168.135.151
    TCP tdbm > 52053 [FIN, PSH, ACK] Seq=1501 Ack=513 Win=3616 Len=0
    88 48.850357 192.168.135.151 192.168.130.1
    TCP 52053 > tdbm [ACK] Seq=513 Ack=1501 Win=8192 Len=0
    89 49.120218 192.168.135.151 192.168.130.1
    TCP 52053 > tdbm [FIN, ACK] Seq=513 Ack=1502 Win=8192 Len=0
    90 49.120926 192.168.130.1 192.168.135.151
    TCP tdbm > 52053 [ACK] Seq=1502 Ack=514 Win=3616 Len=0



    Look at packet number 87. This is the first place an unsuccessful
    registration differs. Note that the router (192.168.130.1) is dropping
    the control connection ~240 mS after sending a SoftKeySetResMessage.
    Also note that the ACK does come, but after 470 mS.

    Is there a way to make the router more tolerant of high latency
    links???
     
    JohnInRochester, Jan 11, 2008
    #3
  4. JohnInRochester

    Thrill5 Guest

    No there isn't. This isn't a router issue, but a VoIP issue. VoIP does not
    like high latency links and anything greater than 250ms will affect voice
    quality so SEVERELY that it isn't usable. You really want latency less than
    150ms as even at that level it is noticeable to callers.

    "JohnInRochester" <> wrote in message
    news:...
    On Jan 10, 4:52 pm, Merv <> wrote:
    > I think there is a Cisco DDTS that indicates that for any latency over
    > 240 ms that you need to have a local TFTP server
    > to download the phone firmware


    Here's the Wireshark trace:

    No. Time Source Destination
    Protocol Info
    41 43.851564 192.168.135.151 192.168.130.1
    TFTP Read Request, File: CTLSEP001E7A25B6C8.tlv, Transfer type:
    octet
    42 43.853648 192.168.130.1 192.168.135.151
    TFTP Error Code, Code: File not found, Message: No such file
    44 44.391688 192.168.135.151 192.168.130.1
    TFTP Read Request, File: SEP001E7A25B6C8.cnf.xml, Transfer type:
    octet
    45 44.393693 192.168.130.1 192.168.135.151
    TFTP Error Code, Code: File not found, Message: No such file
    46 44.796587 192.168.135.151 192.168.130.1
    TFTP Read Request, File: XMLDefault.cnf.xml, Transfer type: octet
    47 44.799582 192.168.130.1 192.168.135.151
    TFTP Data Packet, Block: 1
    48 45.201354 192.168.135.151 192.168.130.1
    TFTP Acknowledgement, Block: 1
    49 45.202976 192.168.130.1 192.168.135.151
    TFTP Data Packet, Block: 2
    50 45.606495 192.168.135.151 192.168.130.1
    TFTP Acknowledgement, Block: 2
    51 45.607616 192.168.130.1 192.168.135.151
    TFTP Data Packet, Block: 3 (last)
    52 46.011445 192.168.135.151 192.168.130.1
    TFTP Acknowledgement, Block: 3
    56 46.701342 192.168.135.151 192.168.130.1
    TCP 52053 > tdbm [SYN] Seq=0 Len=0 MSS=1400
    57 46.702777 192.168.130.1 192.168.135.151
    TCP tdbm > 52053 [SYN, ACK] Seq=0 Ack=1 Win=4128 Len=0 MSS=536
    59 47.095500 192.168.135.151 192.168.130.1
    TCP 52053 > tdbm [ACK] Seq=1 Ack=1 Win=8192 Len=0
    60 47.095506 192.168.135.151 192.168.130.1
    SKINNY AlarmMessage
    61 47.095807 192.168.135.151 192.168.130.1
    SKINNY AlarmMessage
    63 47.230405 192.168.135.151 192.168.130.1
    SKINNY RegisterMessage
    64 47.293941 192.168.130.1 192.168.135.151
    TCP tdbm > 52053 [ACK] Seq=1 Ack=273 Win=3856 Len=0
    65 47.372566 192.168.130.1 192.168.135.151
    SKINNY RegisterAckMessage
    66 47.372780 192.168.130.1 192.168.135.151
    SKINNY CapabilitiesReqMessage
    67 47.771395 192.168.135.151 192.168.130.1
    SKINNY IpPortMessage
    68 47.771586 192.168.135.151 192.168.130.1
    SKINNY ButtonTemplateReqMessage
    69 47.771588 192.168.135.151 192.168.130.1
    SKINNY SoftKeyTemplateReqMessage
    70 47.771793 192.168.135.151 192.168.130.1
    SKINNY SoftKeySetReqMessage
    71 47.771795 192.168.135.151 192.168.130.1
    SKINNY ConfigStatReqMessage
    72 47.772209 192.168.135.151 192.168.130.1
    SKINNY CapabilitiesResMessage
    73 47.772211 192.168.135.151 192.168.130.1
    SKINNY HeadsetStatusMessage
    76 47.875883 192.168.130.1 192.168.135.151
    TCP [TCP segment of a reassembled PDU]
    82 48.310389 192.168.135.151 192.168.130.1
    TCP 52053 > tdbm [ACK] Seq=513 Ack=538 Win=8192 Len=0
    83 48.378127 192.168.130.1 192.168.135.151
    SKINNY SoftKeyTemplateResMessage
    84 48.379981 192.168.130.1 192.168.135.151
    TCP [TCP segment of a reassembled PDU]
    85 48.380194 192.168.130.1 192.168.135.151
    SKINNY SoftKeySetResMessage
    87 48.630168 192.168.130.1 192.168.135.151
    TCP tdbm > 52053 [FIN, PSH, ACK] Seq=1501 Ack=513 Win=3616 Len=0
    88 48.850357 192.168.135.151 192.168.130.1
    TCP 52053 > tdbm [ACK] Seq=513 Ack=1501 Win=8192 Len=0
    89 49.120218 192.168.135.151 192.168.130.1
    TCP 52053 > tdbm [FIN, ACK] Seq=513 Ack=1502 Win=8192 Len=0
    90 49.120926 192.168.130.1 192.168.135.151
    TCP tdbm > 52053 [ACK] Seq=1502 Ack=514 Win=3616 Len=0



    Look at packet number 87. This is the first place an unsuccessful
    registration differs. Note that the router (192.168.130.1) is dropping
    the control connection ~240 mS after sending a SoftKeySetResMessage.
    Also note that the ACK does come, but after 470 mS.

    Is there a way to make the router more tolerant of high latency
    links???
     
    Thrill5, Jan 12, 2008
    #4
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