11-12-2007 03:26 PM - edited 03-05-2019 07:23 PM
Hi all,
Just wondering if someone can provide some assistance with my issue.
Just installed a new 2851. Both ethernet interfaces (gi0/0 & gi0/1) are configured for a bridge-group. Both of these ports are connected to a 3750 switch.
The issue is when I connect both physical cables to the gi0/0 and gi0/1 it creates a loop. Disconnect one of them and it's fine. It appears as though spanning-tree is not working properly.
Can anyone suggest a place for me to look at within my config? (Router or switch). Some of the config below:
2851 router:
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
no mop enabled
bridge-group 140
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
no mop enabled
bridge-group 140
interface BVI140
description VLAN 140
ip address 10.1.1.70 255.255.248.0
no ip proxy-arp
ip nat inside
ip ips sdm_ips_rule out
ip virtual-reassembly
zone-member security in-zone
ip route-cache flow
3750:
interface GigabitEthernet2/0/31
description Cisco 2851 Router
switchport access vlan 140
switchport mode access
switchport block multicast
switchport block unicast
srr-queue bandwidth share 10 10 60 20
srr-queue bandwidth shape 10 0 0 0
queue-set 2
mls qos trust cos
auto qos voip trust
storm-control broadcast level 1.00
spanning-tree guard root
interface GigabitEthernet2/0/32
description Cisco 2851 Router
switchport access vlan 140
switchport mode access
switchport block multicast
switchport block unicast
srr-queue bandwidth share 10 10 60 20
srr-queue bandwidth shape 10 0 0 0
queue-set 2
mls qos trust cos
auto qos voip trust
storm-control broadcast level 1.00
spanning-tree guard root
Thanks
Solved! Go to Solution.
11-12-2007 04:56 PM
The router isn't running any spanning-tree therefore the switch is not able to block one port to prevent the loop.
Can you post the router's entire config ?
You must have
bridge 140 protocol ieee
bridge irb
bridge route ip
on the router's config.
11-12-2007 04:48 PM
Can we see the show spanning-tree output from both devices ?
11-12-2007 04:52 PM
output from 2851: (however only one interface out of the two is currently active)
2851-01#sh spanning-tree
No spanning tree instances are running.
output from 3750: (the 2851 is connected to gi2/0/31 and gi2/0/32)
VLAN0140
Spanning tree enabled protocol rstp
Root ID Priority 140
Address 0013.c386.ab40
Cost 3
Port 616 (Port-channel1)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32908 (priority 32768 sys-id-ext 140)
Address 0014.a9ec.fd00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi1/0/16 Desg FWD 19 128.16 Edge P2p
Gi1/0/17 Desg FWD 19 128.17 Edge P2p
Gi1/0/18 Desg FWD 19 128.18 Edge P2p
Gi1/0/19 Desg FWD 100 128.19 Edge Shr
Gi1/0/21 Desg FWD 19 128.21 Edge P2p
Gi1/0/40 Desg FWD 19 128.40 P2p
Gi1/0/42 Desg FWD 19 128.42 P2p
Gi1/0/44 Desg FWD 19 128.44 P2p
Po1 Root FWD 3 128.616 P2p
Po2 Desg FWD 3 128.624 P2p
Po3 Desg FWD 3 128.632 P2p
Gi2/0/9 Desg FWD 4 128.61 Edge P2p
Gi2/0/10 Desg FWD 19 128.62 Edge P2p
Gi2/0/11 Desg FWD 19 128.63 Edge P2p
Gi2/0/12 Desg FWD 4 128.64 Edge P2p
Gi2/0/13 Desg FWD 4 128.65 Edge P2p
Gi2/0/14 Desg FWD 4 128.66 Edge P2p
Gi2/0/17 Desg FWD 4 128.69 Edge P2p
Gi2/0/18 Desg FWD 19 128.70 Edge P2p
Gi2/0/19 Desg FWD 4 128.71 Edge P2p
Gi2/0/22 Desg FWD 4 128.74 Edge P2p
Gi2/0/31 Desg FWD 4 128.83 P2p
Gi2/0/39 Desg FWD 4 128.91 Edge P2p
Gi2/0/40 Desg FWD 19 128.92 P2p
Gi2/0/41 Desg FWD 4 128.93 Edge P2p
Gi2/0/42 Desg FWD 19 128.94 P2p
Gi2/0/44 Desg FWD 19 128.96 P2p
11-12-2007 04:56 PM
The router isn't running any spanning-tree therefore the switch is not able to block one port to prevent the loop.
Can you post the router's entire config ?
You must have
bridge 140 protocol ieee
bridge irb
bridge route ip
on the router's config.
11-12-2007 06:02 PM
Ok, I had:
bridge irb
and
bridge 140 route ip
However I didn't have:
bridge 140 protocol ieee
I added the above into the config, and spanning-tree kicked in. Then connected the second physical link to the router and spanning-tree blocked the second port. All working perfectly now.
Thanks a lot for your help!
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