Re: need clarification on trunking and setting up port-channel

On May 22, 12:00 am, Adam Przestroga <aprzestr...@xxxxx> wrote:
flamer die.s...@xxxxxxxxxxx wrote:
config:
interface GigabitEthernet0/1
 switchport trunk allowed vlan 2-4094
 switchport mode trunk
 channel-group 1 mode desirable

interface GigabitEthernet0/2
 switchport trunk allowed vlan 2-4094
 switchport mode trunk
 channel-group 1 mode desirable

a few points:
* config must match exactly on the two ports
* allowed vlans at either end must have the exact same range
* channel-group number (port channel number) must match all on
interfaces and be unique

you should either configure port channel or spanning tree, you might
as well double your bandwidth and use a port channel.

traffic will still get across one link if the other goes down so you
aren't losing out on diversity.

Flamer,

Thank you for the provided information. Please allow me to ask a few
more follow up questions.
1. I understand that the configuration on each port (within a switch)
must match, but what  about the other switch? Do I need to configure
port channel on the other switch as well? If so, what are the
requirements for it then?
2. Is it required to use the "switchport trunk allowed vlan 2-4094"
statement? I think, that skipping it will allow vlans.
3. What does the "mode desirable" stand for? I googled it, but could not
find anything that I could easily comprehend.
4. If I understood it correctly, the "Port-channel1" interface will be
created automatically when I add the first physical interface to the
"channel-group 1"? Do I need to tweak the settings of the
"Port-channel1" interface once it is created?
5. Without creating the "channel-group" (etherchannel), and having 2
wires connecting the two switches the throughput between the two
switches will be equal to the speed of a single interface and only one
of them will be active at a time? What happens when this link fails? Is
there a downtime till the link is established over the other wire?

Thank you in advance for additional clarification.

Regards,
AP

Thanks,
AP

http://www.cisco.com/en/US/products/hw/switches/ps5304/products_configuration_guide_chapter09186a00800f0a17.html

And yes, you need to configure the channel on both sides/switches. If
you don't, it works as you say, and yes there will be downtime as
spanning-tree runs since one of those links should be blocking. With
the channel, it's only one logical link, so there really isn't any
disadvantages to the channel in a small network (other than your
switches may not be able to push the throughput).
.

Relevant Pages

  • Re: Clarification on VLANS native and management
    ... VLAN in bridge-group 1, so nobody on the wired side is going to be able ... ~ in) a 2950 switch and a 1231 Access Point. ... ~ place all trunk ports in a VLAN that is not being used on any other ... ~ Interface VLAN2 ...
    (comp.dcom.sys.cisco)
  • Clarification on VLANS native and management
    ... In our company we have a Cisco 871 router (with the 4-port switch built ... place all trunk ports in a VLAN that is not being used on any other ... Interface VLAN2 ...
    (comp.dcom.sys.cisco)
  • Re: Newbie Question: 802.1q and VLAN interfaces on 877w
    ... in the Native VLAN, the phones in a trunked VLAN. ... Each interface is configured as a dot1q trunk with a sub-interface ... Check that your router supports dot1q trunking, and check its Config ... Guide for the exact format for creating a dot1q trunk. ...
    (comp.dcom.sys.cisco)
  • Re: 2924 + vlans
    ... need a subinterface on the router with dotq encap and a vlan ... switchport trunk allowed vlan 1,2,1002-1005 ... interface FastEthernet1/2 ...
    (comp.dcom.sys.cisco)
  • Re: Etherchannel problem
    ... I am assuming it should be a trunk, I was just trying to allow the ... channel to pass only traffic on that vlan. ... no switchport access vlan 4 ...
    (comp.dcom.sys.cisco)