Route propagated while network is still unavailable

Discussion in 'Cisco' started by Robertas, Mar 1, 2005.

  1. Robertas

    Robertas Guest

    Hi,
    I guess this is generic problem, but I could not find information about
    it on newsgroup. Any information regarding this problem would be
    helpfull.
    I have LAN segment of 2 switches interconnected in between. Each switch
    has one router connected. Routers acts as redundant running HSRP and
    has OSPF with default timers configured. Problems ocurs when one switch
    is turned off and after while turned on again. Router connected to that
    switch will add route to its routing table as soon as link is up, but
    switch is not ready with startup yet and does not proccess traffic.
    This creates time window when router sends out route update while that
    link is not available. In my case it is 40 seconds. Switches has STP
    turned off.
    switches: Catalyst 2950-12
    routers: C2801


    Robertas
    Robertas, Mar 1, 2005
    #1
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  2. In article <>,
    "Robertas" <> wrote:

    > Hi,
    > I guess this is generic problem, but I could not find information about
    > it on newsgroup. Any information regarding this problem would be
    > helpfull.
    > I have LAN segment of 2 switches interconnected in between. Each switch
    > has one router connected. Routers acts as redundant running HSRP and
    > has OSPF with default timers configured. Problems ocurs when one switch
    > is turned off and after while turned on again. Router connected to that
    > switch will add route to its routing table as soon as link is up, but
    > switch is not ready with startup yet and does not proccess traffic.
    > This creates time window when router sends out route update while that
    > link is not available. In my case it is 40 seconds. Switches has STP
    > turned off.
    > switches: Catalyst 2950-12
    > routers: C2801


    Since the router sees carrier on the interface, it has no way to know
    that the network is not usable.

    --
    Barry Margolin,
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
    Barry Margolin, Mar 2, 2005
    #2
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  3. Robertas

    Hansang Bae Guest

    Robertas wrote:

    > Hi,
    > I guess this is generic problem, but I could not find information
    > about it on newsgroup. Any information regarding this problem would be
    > helpfull.
    > I have LAN segment of 2 switches interconnected in between. Each
    > switch has one router connected. Routers acts as redundant running
    > HSRP and has OSPF with default timers configured. Problems ocurs when
    > one switch is turned off and after while turned on again. Router
    > connected to that switch will add route to its routing table as soon
    > as link is up, but switch is not ready with startup yet and does not
    > proccess traffic. This creates time window when router sends out
    > route update while that link is not available. In my case it is 40
    > seconds. Switches has STP turned off.
    > switches: Catalyst 2950-12
    > routers: C2801


    Why do you have have STP turned off? Also, which switch port is not
    processing traffic? The uplink port to the router? Also, you should
    turn off FEC and Trunk negotiations on the uplink port to the routers.

    --

    hsb


    "Somehow I imagined this experience would be more rewarding" Calvin
    **************************ROT13 MY ADDRESS*************************
    Due to the volume of email that I receive, I may not not be able to
    reply to emails sent to my account. Please post a followup instead.
    ********************************************************************
    Hansang Bae, Mar 2, 2005
    #3
  4. Robertas

    Robertas Guest

    Hansang Bae wrote:
    > Robertas wrote:
    >
    > > Hi,
    > > I guess this is generic problem, but I could not find information
    > > about it on newsgroup. Any information regarding this problem would

    be
    > > helpfull.
    > > I have LAN segment of 2 switches interconnected in between. Each
    > > switch has one router connected. Routers acts as redundant running
    > > HSRP and has OSPF with default timers configured. Problems ocurs

    when
    > > one switch is turned off and after while turned on again. Router
    > > connected to that switch will add route to its routing table as

    soon
    > > as link is up, but switch is not ready with startup yet and does

    not
    > > proccess traffic. This creates time window when router sends out
    > > route update while that link is not available. In my case it is 40
    > > seconds. Switches has STP turned off.
    > > switches: Catalyst 2950-12
    > > routers: C2801

    >
    > Why do you have have STP turned off? Also, which switch port is not
    > processing traffic? The uplink port to the router? Also, you should
    > turn off FEC and Trunk negotiations on the uplink port to the

    routers.
    >
    > --
    >
    > hsb
    >
    >
    > "Somehow I imagined this experience would be more rewarding" Calvin
    > **************************ROT13 MY ADDRESS*************************
    > Due to the volume of email that I receive, I may not not be able to
    > reply to emails sent to my account. Please post a followup instead.
    > ********************************************************************


    STP is turned off because I am not using it and not planning to use.
    Actually, I thought it would take longer to startup if switch is using
    STP. Yes, it is uplink port that takes 40 seconds from power on to
    become usable. Port is set to static access mode and no negotiations.
    Is there any way to shorten this time window or I do have to live with
    it?
    I believe that some one had the same problem and solve it in some way.


    Robertas
    Robertas, Mar 2, 2005
    #4
  5. Robertas

    Brad Guest

    My recommendation is not to turn the switch off.
    Brad, Mar 2, 2005
    #5
  6. Robertas

    Hansang Bae Guest

    Robertas wrote:
    > STP is turned off because I am not using it and not planning to use.
    > Actually, I thought it would take longer to startup if switch is using
    > STP. Yes, it is uplink port that takes 40 seconds from power on to
    > become usable. Port is set to static access mode and no negotiations.
    > Is there any way to shorten this time window or I do have to live with
    > it?
    > I believe that some one had the same problem and solve it in some way.



    You're not planning on using it but what if someone plugs in a wrong
    cable? It's cheap insurance.

    But it looks like you are negotiating something. Configs might help.


    --

    hsb


    "Somehow I imagined this experience would be more rewarding" Calvin
    **************************ROT13 MY ADDRESS*************************
    Due to the volume of email that I receive, I may not not be able to
    reply to emails sent to my account. Please post a followup instead.
    ********************************************************************
    Hansang Bae, Mar 3, 2005
    #6
  7. Robertas

    Guest

    Or configures a dual connected windows server to bridge.

    In a recent case the network would have died forever and
    not only 'til portfast kicked out. Yes, it should have had this
    and that guard set too but it didn't.

    Can anyone point me to the right way to do
    dual homed windows devices? I will raise a thread on it.

    Back to the topic.
    As already alluded, to turn _off_ trunking, channel,
    and ethernet speed/duplex negotiation on the relevant ports.

    There is a paper on this on the cisco web site, I was
    astonished at the time outs for these phases.
    , Mar 3, 2005
    #7
  8. Robertas

    Robertas Guest

    Where is located this paper on the cisco web site?
    Robertas, Mar 4, 2005
    #8
  9. Robertas

    Guest

    Sorry, I don't know. It was a set of recommended
    configuration parameters for connecting end stations
    to switches and covered various models 6500, 4500,
    29xx, 35xx. I had a quick look but it didn't pop out.
    , Mar 4, 2005
    #9
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