why can I see a UDP Unicast from a third machine not involved in this conversation?

Posted on 2011-10-05
Last Modified: 2012-05-12
while doing regular packet troubleshooting I could see a UDP Unicast traffic from third machine NOT involved in this conversation, and I could not understand why ... could anyone explain?


A <-------------------> B
Machine C could see some unicast traffic from A to B .
Happens from time to time in a VOIP traffic ... is this normal ?
Question by:LRBED
    LVL 39

    Accepted Solution

    Most likely:
    If a switch has no knowlegde of where the packet really needs to go (The destination of that packet has not sent a packet recently)
    then the switch will broadcast it. Any return traffic will setup the mac/cam table with the right interface for that MAC address.

    Less likely: (because you only see one packet):
    It might indicate that your switch lacks enough power to handle the traffic. [ to smal a mac/cam table, to match mac addresses to interfaces ]
    If one interface overflows the machine on filtering & routing, then the swith will start broadcasting a packet.

    Author Closing Comment

    Thank you NOCI

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