vtp issue or something else

Sheraz.Salim · ‎12-09-2015

Hi please help here as my senior team getting angry with me for the change of network switch.

we are running a C2950 Software (C2950-I6Q4L2-M), Version 12.1(22)EA6. This switch is cause an issue. the issue it has it restart once in a month itself this been happening long time ago. i was given a task to find and fix why this is happening. i look into the switch config and find out the trunk interface has unncessary vlan on both side (from core to end switch). however the switch was running on vlan 87,235 only with managment vlan2. so i remove all the unnecessary vlan on the trunk port and left on vlan 87,235 and also the managment vlan 2. from both end switch and the core. Note. we only have a flat network where running a core and all access switch are connected to the core.

i also change the vtp of this switch 2950 from client to transparent. just for not to receive any new vlan from the core. these two change i made only. now some user (on this switch 2950) on the vlan 235 can not talk to each other. but when i ping these clinet on vlan 235 i can ping them from switch 2960 CLI the once i made changes.

my managment is accusing me for me why i made these change and my changes were wrong. could please some one guide me if i made it wrong change. I only put the right trunk vlan on both side with managment vlan. I beleive it wont made any different if the switch is in client or in transpormt mode.

please give feedback on this suitation.

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nspasov · ‎12-09-2015

Hi there, I don't see VTP being the problem here but I will need some more information. Here my questions/requests:

- Please post the output from the following commands from both the access and core switch:

show vtp status

show interface trunk

show ip interface brief | excl unass

show spanning-tree root

show spanning-tree

show spanning-tree blockedports

shwo spanning-tree vlan 235

- Are users connected on VLAN 235 on the new access switch able to communicate

- Are users connected on VLAN 235 on the other access switches able to communicate

- Can you ping users on VLAN 235 that are on the new switch from the core

Let's start here and see if we can narrow this issue down 🙂

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Sheraz.Salim · ‎12-09-2015

show vtp status
VTP Version                     : 2
Configuration Revision          : 482
Maximum VLANs supported locally : 250
Number of existing VLANs        : 215
VTP Operating Mode              : Client
VTP Domain Name                 : xxxxx
VTP Pruning Mode                : Enabled
VTP V2 Mode                     : Enabled
VTP Traps Generation            : Enabled
MD5 digest                      : 0x18 0x4C 0x8E 0x0E 0xF4 0x91 0xA6 0xF9
Configuration last modified by 192.168.250.6 at 10-22-15 10:46:28

show interfaces trunk

Port        Mode         Encapsulation Status        Native vlan
Gi0/1       desirable    802.1q         trunking      1
Gi0/2       desirable    802.1q         trunking      1

Port      Vlans allowed on trunk
Gi0/1       1-2,83,283
Gi0/2       2,83,283

Port        Vlans allowed and active in management domain
Gi0/1       1-2,83,283
Gi0/2       2,83,283

Port        Vlans in spanning tree forwarding state and not pruned
Gi0/1       1-2,83,283

#show ip interface brief | exclude unass
Interface IP-Address OK? Method Status Protocol
Vlan2 192.168.250.83 YES NVRAM up up

show spanning-tree root

                                        Root Hello Max Fwd
Vlan                   Root ID          Cost Time Age Dly Root Port
---------------- -------------------- ------ ----- --- --- ----------------
VLAN0001          8193 0024.f9e2.1400    100    2   20 15 Gi0/1
VLAN0002          8194 0024.f9e2.1400    100    2   20 15 Gi0/1
VLAN0083          8275 0024.f9e2.1400    100    2   20 15 Gi0/1
VLAN0283          8475 ec30.91e1.8300    101    2   20 15 Gi0/1

Estates_48-G_1#show spanning-tree

VLAN0001
Spanning tree enabled protocol rstp
Root ID    Priority    8193
             Address     0024.f9e2.1400
             Cost        100
             Port        49 (GigabitEthernet0/1)
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    32769 (priority 32768 sys-id-ext 1)
             Address     000a.b71c.4a00
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi0/1            Root FWD 100       128.49   P2p

--More--

Estates_48-G_1#
Estates_48-G_1#show spanning-tree

VLAN0001
Spanning tree enabled protocol rstp
Root ID    Priority    8193
             Address     0024.f9e2.1400
             Cost        100
             Port        49 (GigabitEthernet0/1)
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    32769 (priority 32768 sys-id-ext 1)
             Address     000a.b71c.4a00
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi0/1            Root FWD 100       128.49   P2p

VLAN0002
Spanning tree enabled protocol rstp
Root ID    Priority    8194
             Address     0024.f9e2.1400
             Cost        100
             Port        49 (GigabitEthernet0/1)
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    32770 (priority 32768 sys-id-ext 2)
             Address     000a.b71c.4a00
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi0/1            Root FWD 100       128.49   P2p
Gi0/2            Desg FWD 200       128.50   P2p

VLAN0083
Spanning tree enabled protocol rstp
Root ID    Priority    8275
             Address     0024.f9e2.1400
             Cost        100
             Port        49 (GigabitEthernet0/1)
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    32851 (priority 32768 sys-id-ext 83)
             Address     000a.b71c.4a00
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/47           Desg FWD 19        128.47   Edge P2p
Fa0/48           Desg FWD 19        128.48   Edge P2p
Gi0/1            Root FWD 100       128.49   P2p
Gi0/2            Desg FWD 200       128.50   P2p

VLAN0283
Spanning tree enabled protocol rstp
Root ID    Priority    8475
             Address     ec30.91e1.8300
             Cost        101
             Port        49 (GigabitEthernet0/1)
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    33051 (priority 32768 sys-id-ext 283)
             Address     000a.b71c.4a00
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1            Desg FWD 100       128.1    Edge P2p
Fa0/2            Desg FWD 19        128.2    Edge P2p
Fa0/5            Desg FWD 19        128.5    Edge P2p
Fa0/8            Desg FWD 100       128.8    Edge P2p
Fa0/10           Desg FWD 100       128.10   Edge P2p
Fa0/11           Desg FWD 19        128.11   Edge P2p
Fa0/15           Desg FWD 100       128.15   Edge P2p
Fa0/16           Desg FWD 100       128.16   Edge P2p
Fa0/18           Desg FWD 100       128.18   Edge P2p
Fa0/19           Desg FWD 100       128.19   Edge P2p
Fa0/20           Desg FWD 19        128.20   Edge P2p
Fa0/21           Desg FWD 19        128.21   Edge P2p
Fa0/25           Desg FWD 19        128.25   Edge P2p
Fa0/28           Desg FWD 19        128.28   Edge P2p
Fa0/29           Desg FWD 19        128.29   Edge P2p
Fa0/30           Desg FWD 19        128.30   Edge P2p
Fa0/31           Desg FWD 19        128.31   Edge P2p
Fa0/33           Desg FWD 100       128.33   Edge P2p
Fa0/34           Desg FWD 100       128.34   Edge P2p
Fa0/35           Desg FWD 19        128.35   Edge P2p
Fa0/38           Desg FWD 100       128.38   Edge P2p
Fa0/41           Desg FWD 19        128.41   Edge P2p
Fa0/42           Desg FWD 19        128.42   Edge P2p
Fa0/43           Desg FWD 19        128.43   Edge P2p
Gi0/1            Root FWD 100       128.49   P2p
Gi0/2            Altn BLK 200       128.50   P2p

Estates_48-G_1#

#show spanning-tree blockedports

Name Blocked Interfaces List
-------------------- ------------------------------------
VLAN0283 Gi0/2

Number of blocked ports (segments) in the system : 1

show spanning-tree vlan 283

VLAN0283
Spanning tree enabled protocol rstp
Root ID    Priority    8475
             Address     ec30.91e1.8300
             Cost        101
             Port        49 (GigabitEthernet0/1)
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    33051 (priority 32768 sys-id-ext 283)
             Address     000a.b71c.4a00
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1            Desg FWD 100       128.1    Edge P2p
Fa0/2            Desg FWD 19        128.2    Edge P2p
Fa0/5            Desg FWD 19        128.5    Edge P2p
Fa0/8            Desg FWD 100       128.8    Edge P2p
Fa0/10           Desg FWD 100       128.10   Edge P2p
Fa0/11           Desg FWD 19        128.11   Edge P2p
Fa0/15           Desg FWD 100       128.15   Edge P2p
Fa0/16           Desg FWD 100       128.16   Edge P2p
Fa0/18           Desg FWD 100       128.18   Edge P2p
Fa0/19           Desg FWD 100       128.19   Edge P2p
Fa0/20           Desg FWD 19        128.20   Edge P2p
Fa0/21           Desg FWD 19        128.21   Edge P2p
Fa0/25           Desg FWD 19        128.25   Edge P2p
Fa0/28           Desg FWD 19        128.28   Edge P2p
Fa0/29           Desg FWD 19        128.29   Edge P2p
Fa0/30           Desg FWD 19        128.30   Edge P2p
Fa0/31           Desg FWD 19        128.31   Edge P2p
Fa0/33           Desg FWD 100       128.33   Edge P2p
Fa0/34           Desg FWD 100       128.34   Edge P2p
Fa0/35           Desg FWD 19        128.35   Edge P2p
Fa0/38           Desg FWD 100       128.38   Edge P2p
Fa0/39           Desg FWD 100       128.39   Edge P2p
Fa0/41           Desg FWD 19        128.41   Edge P2p
Fa0/42           Desg FWD 19        128.42   Edge P2p
Fa0/43           Desg FWD 19        128.43   Edge P2p
Gi0/1            Root FWD 100       128.49   P2p
Gi0/2            Altn BLK 200       128.50   P2p

I can ping to vlan 283 from the switch and also from the core switch. i can also ping the vlan 283 end client from the core swtich.

i can not answer the remaing two question as this is the all information i have. i have not been on site i was checking it remotely. its used when the managment team getting angry on me i lose my focus.

thank you.

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Richard Bradfield · ‎12-09-2015

so the problem is Vlan 283 not 235, and the main problem is the switch restarts about once a month?

I don't know why you would think VTP to be the problem, the first thing I would do would be upgrade the OS to Version 12.1(22)EA14

I also notice on Gi0/2 the native vlan is 1 but it is not one of the allowed vlans on that trunk. I know on some of the older switches you must always have vlan1 even if it wasn not used.

HTH

Richard

Sheraz.Salim · ‎12-09-2015

sorry Richard it was a typo error the correct vlan is 283 not 235. in the beginning of the post instead of writing 283 i wrote 235.

i also remove the vlan 1 from the core interface toward the access layer switch. and also remove the vlan 1 from access trunk layer.

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Richard Bradfield · ‎12-09-2015

can you put vlan 1 back on those trunks, as that is configured as the native vlan for those trunks

Sheraz.Salim · ‎12-09-2015

ok i will do and let you know. just curious to know you mention to upgrade it to 12.1(22)EA14. is it a stable version.

Also yes this switch once in a month reboot itself. also when i was change vtp mode back to client and than again client to transparent mode. the switch rebooted itslef.

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Richard Bradfield · ‎12-09-2015

12.1(22)EA14 is the last version of code for the 2950 and has been around for over 5 years so should be good. I know from experience that with problems like reloading itself the first thing Cisco recommned is upgrading to current version of OS

Rolf Fischer · ‎12-09-2015

show vtp status
VTP Version                     : 2
Configuration Revision          : 482
Maximum VLANs supported locally : 250
Number of existing VLANs        : 215
VTP Operating Mode              : Client
VTP Domain Name                 : xxxxx
VTP Pruning Mode                : Enabled

Before you change the VTP mode to transparent, you should disable VTP Pruning. Otherwise the neighbor switch could assume that the now transparent switch does not request any VLAN (because it has stopped transmitting Join messages) and therefore prunes all the VLANs on that trunk (except VLAN 1). This would explain the behavior you've experienced.

On the (non-transparent) neighbor switch you can check this with 'show interface [<interface>] pruning':

Port                Vlans pruned for lack of request by neighbor
Gi0/1               2,4

Port                Vlan traffic requested of neighbor
Gi0/1               1

Afterwards you could re-enable Pruning again, although it's not really recommendable when some of the switches are in transparent mode.

HTH
Rolf

Sheraz.Salim · ‎12-12-2015

Hi i solved the problem.

The isssue was

interface GigabitEthernet0/1
description SX-Fibre-to-GHB
switchport trunk allowed vlan 2,83,283

switchport mode trunk (THIS WAS MISSING IT) once i write this command all get good. no keepalive
mls qos trust dscp
spanning-tree cost 100

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nspasov · ‎12-14-2015

Nice, good job resolving the issue! Also, thank you for taking the time to update everyone here (+5)!

Now, if your issue is resolved, you should mark the thread as "answered" 🙂

Thank you for rating helpful posts!