mix copper- and optical-ports in port-channel on Cisco 3750 series

m4rtinm4rtin Senior MemberMember Posts: 170
While I know that under Cisco 6000/6500 series Ethernet interfaces that participate in a port-channel can include both the copper and fiber-optic ports, then is this allowed on Cisco 3750 platform as well?


  • inscom.brigadeinscom.brigade I like soup Member Posts: 400 ■■■□□□□□□□
    I think we got some in our new data center, not sure. I saw tons of fiber go in, today when I am doing show interface status I see lots of portchannel groups.

    Portchannel is a protocol, not hardware; Could a portchannel group contain copper and fiber both? seems like it

    how bout this martin


    On different Cisco switches it is possible to create logical connections that
    are made-up off different fysical interface. It is needed that these interface
    do have the same speed.

    Most Cisco switches support max 64 etherchannels. These interfaces do not have to be contiguous.
    or even on the same module. Each channel must be made up of min 2, max 8 interfaces.
    The best is to use 2 ,4 or 8 interfaces. This will give the perfect load-balancing.

    The load-balancing can be bases on layer 2/3 or 4 information.
    It is not possible to have different load-balancing methods for different Etherchannels
    on one switch. If the load-balancing method is change, it is applicable for all.
    The load-balancing method can be:
    - src-mac
    - dst-mac
    - src-dst-mac
    - src-ip
    - dst-ip
    - src-dst-ip
    - src-port
    - dst-port
    - src-dst-port

    By using <port-channel load-balance {option}> it is possible to change to method.
    If a single header is used to load-balance the low-order bits is used to dictate to
    witch interface the frame is send. If two headers are used a XOR function is used on
    the low-order bits.

    It is possible to change what path with-in the etherchannel a frame takes by used the following command:
    <test etherchannel load-balance interface port-channel [#] ip [src] [dst]>

    to assign a physical interface towards a port-channel use the following command:
    channel-group [#] mode on

    There are two type of dynamic protocols to negotiate an etherchannels: PAgP and LACP 8021.AD
    PAgP is Cisco proprietary
    When these protocols start to communicate there is an exchange of information before the port-channel can be formed. The following items must match before a port-channel can form:
    - same speed/duplex
    - Access VLAN (if not trunked)
    - Same trunking type, allowed VLAN and native VLAN (if trunked)
    - Each port must have the same STP cost per VLAN with-in the portchannel
    - No SPAN ports

    channel-group [#] mode on (disables PAgP en LACP)
    channel-group [#] mode off (disables PAgP en LACP and prevent the ports to form a port-channel)
    channel-group [#] mode auto (use PAgP in a passive mode, it will wait until a PAgP packet will be send)
    channel-group [#] mode passive (use LACP in a passive mode, it will wait until a PAgP packet will be send)
    channel-group [#] mode desirable (use PAgP in an active mode, it will start to send PAgP packets)
    channel-group [#] mode active (use LACP in an active mode, it will start to send LACP packets)

    3750(config)#interface range gigabitethernet 1/0/2 - 4
    3750(config-if-range)#channel-group 1 mode on
    3750(config-if-range)#switchport trunk encapsulation dot1q
    3750(config-if-range)#switchport mode trunk
    First type the channel-group command. After that all interface commands will be automatically duplicated on all the interfaces group in the channel-group.
    With LACP it is possible to create a port-channel on a stack (3560/3750 switches).
    This is based on IOS version 12.2(25)SEE

    Show command’s
    · show interfaces port-channel I]channel-group-number[/I
    · show etherchannel I]channel-group-number[/I summary
    Verify command’s
    • test etherchannel load-balance interface port-channel [#] ip [src] [dst

    This is maybe why we instal SFP modulas to aquire the same speed ports huh?
Sign In or Register to comment.