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Beginner

ISR G2 3900 and Port-channels

We have a 3900 series G2 running 15.0(1)M4. It seems there are alot of differences with the 15.0 code. I was intrigued by the ability to do a port-channel on the router instead of having to use something like HSRP or GLBP for HA.  The router is going to be a sip gateway only so I wanted to give it dual links to our core switches for extra protection. I configured the device in the following way and to my surprise it works fine. Whats scary is I would think this would cause a loop because I did not have a port-channel configured on the other side and on the router if I do a show etherchanel summary nothing is present.  Any ideas?

show run | beg interface

!
interface Port-channel1
ip address 10.1.210.15 255.255.255.0
hold-queue 150 in
!
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
channel-group 1
!
interface GigabitEthernet0/2
no ip address
duplex auto
speed auto
channel-group 1

!

show etherchannel summary
Flags:  D - down        P - in port-channel
        I - stand-alone s - suspended
        R - Layer3      S - Layer2
        U - in use
Group Port-channel  Ports
-----+------------+-----------------------------------------------------------

CORP_SIP_01#

CORP_SIP_01#show ip int brief
Interface                  IP-Address      OK? Method Status                Protocol
GigabitEthernet0/0         unassigned      YES manual down                  down   
GigabitEthernet0/1         unassigned      YES NVRAM  up                    up     
GigabitEthernet0/2         unassigned      YES NVRAM  up                    up     
Loopback0                  unassigned      YES unset  up                    up     
Port-channel1              10.1.210.15     YES manual up                    up    

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2 REPLIES 2
Hall of Fame Master

Re: ISR G2 3900 and Port-channels

You should really look at things at the switch side.

Beginner

Re: ISR G2 3900 and Port-channels

Found this article which was helpful. Still doesn't explain why the etherchannel doesn't show up in the router when I do a show etherchannel summary.

http://www.cisco.com/en/US/tech/tk389/tk213/technologies_configuration_example09186a0080094958.shtml

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