Port looses VLAN setting

Discussion in 'Cisco' started by Ned, Feb 18, 2009.

  1. Ned

    Ned Guest

    I'm trying to find out if it is somehow possible for some switch
    (Cisco 3750-48) ports to "loose" their "switchport access VLAN 123"
    setting. I had a switch recently which had 40 ports in VLAN 44 and 8
    ports in VLAN 123. I got a call to say the users in the VLAN 123 had
    lost their connection - when I checked (maybe an hour later) I found
    these 8 ports also had "access VLAN 44" in the config. If 44 was the
    native VLAN, could the switch somehow, if there was some error,
    reconfigure the ports access VLAN 44.
    My guess is that someone actually reconfigured the ports to access
    VLAN 44 but there are only one or two people who could do this and
    neither of them are owning up.
    TIA, Ned
     
    Ned, Feb 18, 2009
    #1
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  2. "Ned" <> wrote in message
    news:...
    > I'm trying to find out if it is somehow possible for some switch
    > (Cisco 3750-48) ports to "loose" their "switchport access VLAN 123"
    > setting. I had a switch recently which had 40 ports in VLAN 44 and 8
    > ports in VLAN 123. I got a call to say the users in the VLAN 123 had
    > lost their connection - when I checked (maybe an hour later) I found
    > these 8 ports also had "access VLAN 44" in the config. If 44 was the
    > native VLAN, could the switch somehow, if there was some error,
    > reconfigure the ports access VLAN 44.
    > My guess is that someone actually reconfigured the ports to access
    > VLAN 44 but there are only one or two people who could do this and
    > neither of them are owning up.
    > TIA, Ned


    Do you have some 802.1x in your switch config or any other kind of VLAN
    autoassignment?
     
    Igor Mamuzic aka Pseto, Feb 18, 2009
    #2
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  3. Ned

    Trendkill Guest

    Re: Port looses VLAN setting

    On Feb 18, 10:27 am, "Igor Mamuzic aka Pseto"
    <-com.hr> wrote:
    > "Ned" <> wrote in message
    >
    > news:...
    >
    > > I'm trying to find out if it is somehow possible for some switch
    > > (Cisco 3750-48) ports to "loose" their "switchport access VLAN 123"
    > > setting. I had a switch recently which had 40 ports in VLAN 44 and 8
    > > ports in VLAN 123. I got a call to say the users in the VLAN 123 had
    > > lost their connection - when I checked (maybe an hour later) I found
    > > these 8 ports also had "access VLAN 44" in the config. If 44 was the
    > > native VLAN, could the switch somehow, if there was some error,
    > > reconfigure the ports access VLAN 44.
    > > My guess is that someone actually reconfigured the ports to access
    > > VLAN 44 but there are only one or two people who could do this and
    > > neither of them are owning up.
    > > TIA, Ned

    >
    > Do you have some 802.1x in your switch config or any other kind of VLAN
    > autoassignment?


    As the other poster pointed out, 802.1x or secondary vlans could be at
    play, but much more likely to be a changed config or an unsaved config
    w/ a reboot.
     
    Trendkill, Feb 18, 2009
    #3
  4. Ned

    Ned Guest

    Re: Port looses VLAN setting

    On Feb 18, 3:27 pm, "Igor Mamuzic aka Pseto"
    <-com.hr> wrote:
    > "Ned" <> wrote in message
    >
    > news:...
    >
    > > I'm trying to find out if it is somehow possible for some switch
    > > (Cisco 3750-48) ports to "loose" their "switchport access VLAN 123"
    > > setting. I had a switch recently which had 40 ports in VLAN 44 and 8
    > > ports in VLAN 123. I got a call to say the users in the VLAN 123 had
    > > lost their connection - when I checked (maybe an hour later) I found
    > > these 8 ports also had "access VLAN 44" in the config. If 44 was the
    > > native VLAN, could the switch somehow, if there was some error,
    > > reconfigure the ports access VLAN 44.
    > > My guess is that someone actually reconfigured the ports to access
    > > VLAN 44 but there are only one or two people who could do this and
    > > neither of them are owning up.
    > > TIA, Ned

    >
    > Do you have some 802.1x in your switch config or any other kind of VLAN
    > autoassignment?


    Yes, I have 802.1 trunks on this switch
     
    Ned, Feb 18, 2009
    #4
  5. Ned

    Ned Guest

    Re: Port looses VLAN setting

    On Feb 18, 4:04 pm, Ned <> wrote:
    > On Feb 18, 3:27 pm, "Igor Mamuzic aka Pseto"
    >
    >
    >
    > <-com.hr> wrote:
    > > "Ned" <> wrote in message

    >
    > >news:....

    >
    > > > I'm trying to find out if it is somehow possible for some switch
    > > > (Cisco 3750-48) ports to "loose" their "switchport access VLAN 123"
    > > > setting. I had a switch recently which had 40 ports in VLAN 44 and 8
    > > > ports in VLAN 123. I got a call to say the users in the VLAN 123 had
    > > > lost their connection - when I checked (maybe an hour later) I found
    > > > these 8 ports also had "access VLAN 44" in the config. If 44 was the
    > > > native VLAN, could the switch somehow, if there was some error,
    > > > reconfigure the ports access VLAN 44.
    > > > My guess is that someone actually reconfigured the ports to access
    > > > VLAN 44 but there are only one or two people who could do this and
    > > > neither of them are owning up.
    > > > TIA, Ned

    >
    > > Do you have some 802.1x in your switch config or any other kind of VLAN
    > > autoassignment?

    >
    > Yes, I have 802.1 trunks on this switch


    I don't think there was a reboot - when I was fixing the problem
    (switchport access vlan 123) from the console, I'm fairly sure I saw a
    console message "VLAN1 interface down" ... followed soon by an "VLAN1
    interface up". Can you explain further what you mean by "802.1x or
    secondary vlans...". I would love to be able to recreate the problem
    and prove nobody was messing with the config... Ned
     
    Ned, Feb 18, 2009
    #5
  6. Re: Port looses VLAN setting

    Ned <> writes:
    >On Feb 18, 4:04=A0pm, Ned <> wrote:
    >> On Feb 18, 3:27=A0pm, "Igor Mamuzic aka Pseto"
    >> <-com.hr> wrote:
    >> > "Ned" <> wrote in message

    >>
    >> >news:..=

    >.
    >>
    >> > > I'm trying to find out if it is somehow possible for some switch
    >> > > (Cisco 3750-48) ports to "loose" their "switchport access VLAN 123"
    >> > > setting. I had a switch recently which had 40 ports in VLAN 44 and 8
    >> > > ports in VLAN 123. I got a call to say the users in the VLAN 123 had
    >> > > lost their connection - when I checked (maybe an hour later) I found
    >> > > these 8 ports also had "access VLAN 44" in the config. If 44 was the
    >> > > native VLAN, could the switch somehow, if there was some error,
    >> > > reconfigure the ports access VLAN 44.
    >> > > My guess is that someone actually reconfigured the ports to access
    >> > > VLAN 44 but there are only one or two people who could do this and
    >> > > neither of them are owning up.
    >> > > TIA, Ned

    >>
    >> > Do you have some 802.1x in your switch config or any other kind of VLAN
    >> > autoassignment?

    >>
    >> Yes, I have 802.1 trunks on this switch


    >I don't think there was a reboot - when I was fixing the problem
    >(switchport access vlan 123) from the console, I'm fairly sure I saw a
    >console message "VLAN1 interface down" ... followed soon by an "VLAN1
    >interface up". Can you explain further what you mean by "802.1x or
    >secondary vlans...". I would love to be able to recreate the problem
    >and prove nobody was messing with the config... Ned


    I've never seen a cisco switch change its VLAN settings in the 10+
    years I've been using Cisco switches doing VLANs across thousands of
    ports that I've configured.

    RANCID is great at tracking changes for your switches/routers.
    It doesn't log every command, there are other solutions for that, but
    knowing when something changed is good. Make sure you use seperate
    admin usernames and you pick up the last person who did make a change
    in comments at the top of the config as well.
     
    Doug McIntyre, Feb 18, 2009
    #6
  7. Ned

    Trs80 Guest

    its loses
    "Ned" <> wrote in message
    news:...
    > I'm trying to find out if it is somehow possible for some switch
    > (Cisco 3750-48) ports to "loose" their "switchport access VLAN 123"
    > setting. I had a switch recently which had 40 ports in VLAN 44 and 8
    > ports in VLAN 123. I got a call to say the users in the VLAN 123 had
    > lost their connection - when I checked (maybe an hour later) I found
    > these 8 ports also had "access VLAN 44" in the config. If 44 was the
    > native VLAN, could the switch somehow, if there was some error,
    > reconfigure the ports access VLAN 44.
    > My guess is that someone actually reconfigured the ports to access
    > VLAN 44 but there are only one or two people who could do this and
    > neither of them are owning up.
    > TIA, Ned
     
    Trs80, Feb 19, 2009
    #7
  8. Ned

    donjohnston

    Joined:
    Jun 28, 2008
    Messages:
    38
    If you do a "show version", about halfway down will show how long the switch has been up.

    A "show log" should indicate the last time the config was changed.

    To my knowledge, there is no protocol that will change a VLAN assignment in the configuration.
     
    donjohnston, Feb 19, 2009
    #8
  9. Ned

    Barry OGrady Guest

    On Wed, 18 Feb 2009 07:05:54 -0800 (PST), Ned <> wrote:

    >I'm trying to find out if it is somehow possible for some switch
    >(Cisco 3750-48) ports to "loose" their "switchport access VLAN 123"
    >setting.


    By "loose" do you mean broadcast the seeting for others to see?

    >I had a switch recently which had 40 ports in VLAN 44 and 8
    >ports in VLAN 123. I got a call to say the users in the VLAN 123 had
    >lost their connection - when I checked (maybe an hour later) I found
    >these 8 ports also had "access VLAN 44" in the config. If 44 was the
    >native VLAN, could the switch somehow, if there was some error,
    >reconfigure the ports access VLAN 44.
    >My guess is that someone actually reconfigured the ports to access
    >VLAN 44 but there are only one or two people who could do this and
    >neither of them are owning up.


    It sounds like it didn't loose its setting at all, but rather it did lose its setting.

    >TIA, Ned


    Barry
    =====
    Home page
    http://members.iinet.net.au/~barry.og
     
    Barry OGrady, Feb 19, 2009
    #9
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