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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    

2 REPLIES 2
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Hall of Fame Master

You should really look at things at the switch side.

Highlighted

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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