802.1q trunk from Cisco 3550 to Extreme Alpine

Discussion in 'Cisco' started by Illusion, Oct 28, 2003.

  1. Illusion

    Illusion Guest


    I am trying to setup a VLAN trunk between a Cisco Catalyst 3550 and an
    Extreme Alpine switch but have not been able to get it working.

    I d/l'ed a config from a Catalyst 2950 (which I have been able to get
    trunking working on no problem simply by using 'switchport mode trunk') to
    the 3550 but then realised that it would need more configuring due to the
    3550 being able to do ISL trunks.

    I dont have access to the config currently so cant paste in full but
    basically I modified the config by issuing the following commands on the
    g0/1 interface:

    switchport trunk encapsulation dot1q
    switchport mode trunk

    However this does not seem to work. Untagged traffic is fine but I can not
    ping the IP on the Cisco vlan100 which is the VLAN I am trying to trunk
    across the link.

    I think my Alpine config is fine because it is configured the same way for
    the trunk with the 2950 which works OK. It seems as if the Cisco is trying
    to use an ISL trunk even though I have forced it to 'dot1q' ?

    Any info would be greatly appreciated.

    Cheers, Dan
    Illusion, Oct 28, 2003
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  2. Have you tried fixing the Extreme to 802.1q as well? If I recall correctly
    Extreme also understands ISL.

    Erik Tamminga, Oct 28, 2003
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  3. Illusion

    l0stbyte Guest

    Make sure that native VLANs match

    l0stbyte, Oct 28, 2003
  4. Illusion

    Andre Beck Guest

    Have you created the VLAN 100 in the Cisco's VLAN database? If not, it
    will probably not pass the trunk.
    switchport trunk encaps dot1q
    switchport mode trunk
    switchport nonegotiate

    Strongly recommended, if you ask me ;)
    Andre Beck, Nov 1, 2003
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