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Hi all... quick question about discards

Discussion in 'Routing & Switching' started by azrael2000, Jul 8, 2008.

  1. azrael2000

    azrael2000 New Member

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    Hi All.

    Just saying "hello"

    I'm a regular schmoe trying to get certified, while being dropped into a work environment that is not very "helpful" if you know what I mean

    Can someone please give me a little information on how I can find out, in a 3750 switch, why i'm getting packet discards?

    My understanding is that if the switch doesn't know where the packet is supposed to go, it get's held until the buffer fills up, and then get's turfed.

    Is this correct?

    Is there more information out there? I've searched the cisco site to no avail...

    Regards
     
  2. Fergal1982

    Fergal1982 Petabyte Poster

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    A quick google on packet discards

    turned up this as the first result.

    Edit: Welcome to the forums by the way.
     
    Certifications: ITIL Foundation; MCTS: Visual Studio Team Foundation Server 2010, Administration
    WIP: None at present
  3. azrael2000

    azrael2000 New Member

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    Thanks for the response.

    I read over what was written and it appears to deal more with VoIP as opposed to my problem, which according to my switch is discards on a data network...

    Input queue: 0/75/2312964/0 (size/max/drops/flushes); Total output drops: 0

    Now this is what I found on the Cisco site....

    “When a packet enters the router, the router attempts to forward it at interrupt level. If a match cannot be found in an appropriate cache table, the packet is queued in the input queue of the incoming interface to be processed. Some packets are always processed, but with the appropriate configuration and in stable networks, the rate of processed packets must never congest the input queue. If the input queue is full, the packet is dropped.”
    These are the conditions for input queue drop counter. They usually occur when the router receives bursty traffic and cannot handle all packets

    Now, I have a little bit of an idea of what is happening but my superior, who is a CCIE, knows so much, sometimes the info doesn't filter down well to an "almost" CCNA like myself...

    I just need a little more info / explanation... so he doesn't yell at me.

    <smile>

    Regards, and thanks for the response...
     
  4. Fergal1982

    Fergal1982 Petabyte Poster

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    Dont be afraid to ask questions of your Superior. After all, they are paying you to do a job, if you dont understand something, they want to ensure that you are trained/shown the solution (after trying to find it for yourself, if you can). Sure, it may take them time to do it now, but in the long term it saves them more time.

    It could take some of the guys at my work 5 mins to do something they will take 2 hours showing me everything I need to know to do it. But next time it comes round, I may only need 10 minutes of their time. And the time after that, none at all. Its just how training works.

    Dont be afraid to look stupid. The only stupid people in the world are those who are afraid to ask a question in case they look stupid (well... there are some plain morons in the world too, but im ignoring them here, work with me!). Your superior wont always have had this knowledge, he had to learn it somewhere too. And if you dont understand the answer, tell them, and ask for more detail.

    On this particular topic, I'm limited - its not my field unfortunately. I just pointed out the google site since it seemed to define the meaning of packet discard in a suitable context. I may be wrong, but dont get caught up that everything relating to cisco is a cisco only term. Sure that site dealt with VoIP, but its still switches, etc, so it likely applies. Otherwise, someone else will be along shortly to correct me.
     
    Certifications: ITIL Foundation; MCTS: Visual Studio Team Foundation Server 2010, Administration
    WIP: None at present

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