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I have 2 Catalyst 3560 switches. Several switches in Bldg A, but only one in Bldg B.

I had fiber run between the two buildings.

When I connect the 2 3560's using Fiber/GBIC connectors GLC-SX-MM, the network gets flaky and some of the VLAN even go down.

This is how I have the ports on each end configured:

interface GigabitEthernet0/50

description ToBuildingX

switchport trunk encapsulation dot1q

switchport mode trunk

switchport nonegotiate

Any ideas? I'd appreciate any suggestions.

18 Replies 18

After connecting the 2 switches together, can you post the output of

show spanning-tree?

afpicore3560g-01>sh spanning-tree

VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 0
Address 0017.a405.3b40
Cost 20019
Port 48 (GigabitEthernet0/48)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address b414.8929.ec00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi0/48 Root FWD 19 128.48 P2p
Gi0/51 Desg FWD 4 128.51 P2p
Po10 Desg FWD 3 128.136 P2p

VLAN0010
Spanning tree enabled protocol ieee
Root ID Priority 32778
Address 0008.30a4.1380
Cost 4
Port 51 (GigabitEthernet0/51)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32778 (priority 32768 sys-id-ext 10)
Address b414.8929.ec00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi0/34 Desg FWD 4 128.34 P2p Edge
Gi0/36 Desg FWD 19 128.36 P2p Edge
Gi0/37 Desg FWD 4 128.37 P2p Edge
Gi0/38 Desg FWD 4 128.38 P2p Edge
Gi0/48 Desg FWD 19 128.48 P2p
Gi0/51 Root FWD 4 128.51 P2p
Po4 Desg FWD 3 128.88 P2p
Po5 Desg FWD 3 128.96 P2p
Po6 Desg FWD 3 128.104 P2p
Po10 Desg FWD 3 128.136 P2p

VLAN0100
Spanning tree enabled protocol ieee
Root ID Priority 32868
Address 0008.30a4.1380
Cost 4
Port 51 (GigabitEthernet0/51)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32868 (priority 32768 sys-id-ext 100)
Address b414.8929.ec00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi0/48 Desg FWD 19 128.48 P2p
Gi0/51 Root FWD 4 128.51 P2p
Po10 Desg FWD 3 128.136 P2p

VLAN0104
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address a4ba.db8a.b5ed
Cost 8
Port 46 (GigabitEthernet0/46)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32872 (priority 32768 sys-id-ext 104)
Address b414.8929.ec00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi0/46 Root FWD 4 128.46 P2p
Gi0/48 Desg FWD 19 128.48 P2p
Gi0/51 Desg FWD 4 128.51 P2p
Po10 Desg FWD 3 128.136 P2p

VLAN0105
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address a4ba.db8a.b5ed
Cost 8
Port 47 (GigabitEthernet0/47)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32873 (priority 32768 sys-id-ext 105)
Address b414.8929.ec00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi0/47 Root FWD 4 128.47 P2p
Gi0/48 Desg FWD 19 128.48 P2p
Gi0/51 Desg FWD 4 128.51 P2p
Po10 Desg FWD 3 128.136 P2p

VLAN0110
Spanning tree enabled protocol ieee
Root ID Priority 32878
Address 0008.30a4.1380
Cost 4
Port 51 (GigabitEthernet0/51)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32878 (priority 32768 sys-id-ext 110)
Address b414.8929.ec00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi0/2 Desg FWD 4 128.2 P2p Edge
Gi0/9 Desg FWD 4 128.9 P2p Edge
Gi0/10 Desg FWD 4 128.10 P2p Edge
Gi0/13 Desg FWD 4 128.13 P2p Edge
Gi0/14 Desg FWD 4 128.14 P2p Edge
Gi0/15 Desg FWD 4 128.15 P2p Edge
Gi0/16 Desg FWD 4 128.16 P2p Edge
Gi0/17 Desg FWD 4 128.17 P2p Edge
Gi0/19 Desg FWD 4 128.19 P2p Edge
Gi0/48 Desg FWD 19 128.48 P2p
Gi0/51 Root FWD 4 128.51 P2p
Po1 Desg FWD 3 128.64 P2p
Po10 Desg FWD 3 128.136 P2p

VLAN0111
Spanning tree enabled protocol ieee
Root ID Priority 32879
Address 0008.30a4.1380
Cost 4
Port 51 (GigabitEthernet0/51)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32879 (priority 32768 sys-id-ext 111)
Address b414.8929.ec00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi0/22 Desg FWD 4 128.22 P2p Edge
Gi0/23 Desg FWD 19 128.23 P2p Edge
Gi0/25 Desg FWD 19 128.25 P2p Edge
Gi0/29 Desg FWD 19 128.29 P2p Edge
Gi0/48 Desg FWD 19 128.48 P2p
Gi0/51 Root FWD 4 128.51 P2p
Po10 Desg FWD 3 128.136 P2p

VLAN0112
Spanning tree enabled protocol ieee
Root ID Priority 32880
Address 0008.30a4.1380
Cost 4
Port 51 (GigabitEthernet0/51)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32880 (priority 32768 sys-id-ext 112)
Address b414.8929.ec00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi0/48 Desg FWD 19 128.48 P2p
Gi0/51 Root FWD 4 128.51 P2p
Po10 Desg FWD 3 128.136 P2p

VLAN0120
Spanning tree enabled protocol ieee
Root ID Priority 32888
Address 0008.30a4.1380
Cost 4
Port 51 (GigabitEthernet0/51)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32888 (priority 32768 sys-id-ext 120)
Address b414.8929.ec00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi0/18 Desg FWD 4 128.18 P2p Edge
Gi0/20 Desg FWD 4 128.20 P2p Edge
Gi0/48 Desg FWD 19 128.48 P2p
Gi0/51 Root FWD 4 128.51 P2p
Po10 Desg FWD 3 128.136 P2p

VLAN0124
Spanning tree enabled protocol ieee
Root ID Priority 32892
Address 00cc.fcfd.d000
Cost 3
Port 136 (Port-channel10)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32892 (priority 32768 sys-id-ext 124)
Address b414.8929.ec00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi0/35 Desg FWD 19 128.35 P2p Edge
Gi0/48 Desg FWD 19 128.48 P2p
Gi0/51 Desg FWD 4 128.51 P2p
Po10 Root FWD 3 128.136 P2p

Now mind you, I don't have the two connected cuz I don't want to bring users down again.

Can you provide the show commands when you have a maintenance window and the 2 switches are connected together, so you don't bring down the network?

Here's what I get when they are plugged connected:

(I connected both sides with fiber.

Hurried and did a sh int gi 0/50

Then disconnected before people noticed they were down. :)

Here's what I got:

afpicore3560g-01#sh int gi 0/50
GigabitEthernet0/50 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is b414.8929.ec32 (bia b414.8929.ec32)
Description: TruckShopSwitch
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseSX SFP
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:01, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 2000 bits/sec, 1 packets/sec
5 minute output rate 2000 bits/sec, 2 packets/sec
34682292664 packets input, 46898058598400 bytes, 0 no buffer
Received 24178074 broadcasts (10471019 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 10471019 multicast, 0 pause input
0 input packets with dribble condition detected
15558616726 packets output, 3092966805686 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
2412428 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out

Also, the fiber cables are fixed together so they cannot be swapped.

Am I using the right GBIC Connectors?: GLC-SX-MM (CNUIAFJAAA)

Hi Linda,

Out of interest, it may be worth you setting both the speed and duplex statically on both switch interfaces. I have seen auto/auto on fibre interfaces cause issues historically.

I would suggest the following next steps;

1. Statically assign the speed and duplex. In interface configuration mode (in your case Gi0/50 on one switch) type the following commands;

!

speed 1000

duplex full

!

[Ensure this is completed on both sides of the trunk]

2. Before enabling the interfaces, please provide a "show spanning-tree" output for both switches (each side for the trunk)

3. Finally, have you configured which VLANs are permitted to use the trunk, or have you allowed all VLANs to traverse the trunk link?

Hello,

If possible, post running configs from both switches. Based on your postings, it sounds like STP issue.

Thx

MS

Unfortunately, I don't have a maint. window. We are a 24/7 operation.

Before connect the switch make sure

1 the switch in vtp transparent mode

Thanks for your help but I’m not sure how to do this.

2 make these switches with higher spanning root priority

Would this fix the priority issue:

priority-queue out

3 make sure trunk is up and notice the interface by looking to lights of interface maybe you have a loop in some where

Can’t be a loop since nothing is plugged into the switch in bldg. 2 yet. Yes, the green lights do come on, on both ends.

I connected both sides with fiber.

Hurried and did a sh int gi 0/50

Then disconnected before people noticed they were down. :)

Here's what I got:

afpicore3560g-01#sh int gi 0/50
GigabitEthernet0/50 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is b414.8929.ec32 (bia b414.8929.ec32)
Description: TruckShopSwitch
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseSX SFP
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:01, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 2000 bits/sec, 1 packets/sec
5 minute output rate 2000 bits/sec, 2 packets/sec
34682292664 packets input, 46898058598400 bytes, 0 no buffer
Received 24178074 broadcasts (10471019 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 10471019 multicast, 0 pause input
0 input packets with dribble condition detected
15558616726 packets output, 3092966805686 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
2412428 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out

Make it as transparent

Vtp mod transparent

Set spanning tree

Spanning-tree vlan (valn numbers) priority? And see the highest number

Hi Linda,

Could you send me the output for the following;

sh int Gi0/50

Would be good to see this from either side of the trunk link.

Both Switches have port 50 configured the same, just the description differs:

afpicore3560g-01#sh run int gi 0/50
Building configuration...

Current configuration : 151 bytes
!
interface GigabitEthernet0/50
description TruckShopSwitch
switchport trunk encapsulation dot1q
switchport mode trunk
switchport nonegotiate
end

Hi,

Can you provide the output without, the "run" statement.

Oh...gotcha.

Here you go:

afpicore3560g-01#sh int gi 0/50
GigabitEthernet0/50 is down, line protocol is down (notconnect)
Hardware is Gigabit Ethernet, address is b414.8929.ec32 (bia b414.8929.ec32)
Description: TruckShopSwitch
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Auto-duplex, Auto-speed, link type is auto, media type is 1000BaseSX SFP
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 01:22:56, output 01:22:39, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
34682292655 packets input, 46898058594413 bytes, 0 no buffer
Received 24178065 broadcasts (10471010 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 10471010 multicast, 0 pause input
0 input packets with dribble condition detected
15558616653 packets output, 3092966796971 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
2412428 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out
afpicore3560g-01#

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