VoIP and RTP

rakemrakem Member Posts: 800
Does RTP do sequencing??

If yes, i assume this means that VoIP packets can arrive out of order?
CCIE# 38186
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Comments

  • Met44Met44 Member Posts: 194
    Yes, RTP does sequencing.

    VoIP clients usually have a jitter buffer feature. Softphones I have seen are usually around 20ms. Within that 20ms buffer, RTP re-orders voice packets (if necessary) and spaces them out so we hear a steady stream of voice.
  • kryollakryolla Member Posts: 785
    it time stamps the packets
    Studying for CCIE and drinking Home Brew
  • mzinzmzinz Member Posts: 328
    What does Cisco consider the highest amount of allowable latency between two VoIP hosts?
    _______LAB________
    2x 2950
    2x 3550
    2x 2650XM
    2x 3640
    1x 2801
  • networker050184networker050184 Mod Posts: 11,962 Mod
    The recommendation is that delay should not exceed 150ms one way (from mouth to ear). I have ran VoIP networks that were upwards of 300ms delay one way with success though.
    An expert is a man who has made all the mistakes which can be made.
  • rakemrakem Member Posts: 800
    The recommendation is that delay should not exceed 150ms one way (from mouth to ear). I have ran VoIP networks that were upwards of 300ms delay one way with success though.

    Yea Cisco say 150 but i have read other places that say 250. I would say that getting higher than 300 would definitely start to cause some issues.
    CCIE# 38186
    showroute.net
  • AlanJamesAlanJames Member Posts: 230
    rtp = real time. The end user needs to receive them in order, so it has to be time stamped :P
    What does Cisco consider the highest amount of allowable latency between two VoIP hosts?
    250ms




    If you have call manager across sites, it needs to be 40ms round trip delay for successful coms between servers.
  • kryollakryolla Member Posts: 785
    I was just in a class about setting up a Satellite link to replace our backhaul in case it goes down and this would introduce a delay of 250ms one-way which they said was acceptable but needed an echo can. Did anybody else have to put an echo can for the increase in delay? THanks
    Studying for CCIE and drinking Home Brew
  • rakemrakem Member Posts: 800
    kryolla wrote: »
    I was just in a class about setting up a Satellite link to replace our backhaul in case it goes down and this would introduce a delay of 250ms one-way which they said was acceptable but needed an echo can. Did anybody else have to put an echo can for the increase in delay? THanks

    wtf is an echo can?
    CCIE# 38186
    showroute.net
  • shodownshodown Member Posts: 2,271
    AlanJames wrote: »
    rtp = real time. The end user needs to receive them in order, so it has to be time stamped :P


    250ms




    If you have call manager across sites, it needs to be 40ms round trip delay for successful coms between servers.


    Only if they are in the same cluster. You can have trunks to other sites that have there own cluster and this problem goes away.
    Currently Reading

    CUCM SRND 9x/10, UCCX SRND 10x, QOS SRND, SIP Trunking Guide, anything contact center related
  • networker050184networker050184 Mod Posts: 11,962 Mod
    rakem wrote: »
    wtf is an echo can?

    Echo canceler, which basically removes echo from voice calls by removing redundant signals.

    If you are using Cisco the echo cancellation will take place in the DSPs. I have never had to use it on satellite links, your millage may vary.
    An expert is a man who has made all the mistakes which can be made.
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