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Is this problem due to Spanning tree root bridge being in wrong place?

Unanswered Question
Dec 16th, 2013
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Hi All,


Have an odd issue getting LAN communicating using a particulcar vlan. I will show the setup






ISP(VPN)==========>2811 Gateway=======>2960NONPOE=======> 2950 (root)========> 2960POE=======>WLC4400(10.151.220.146)


I have sub interface for vlan 20 on 2811, it's active etc:


interface FastEthernet0/0.20

encapsulation dot1Q 20

ip address 10.220.252.145 255.255.255.240


interface FastEthernet0/0.100

encapsulation dot1Q 100

ip address 10.220.252.254 255.255.255.192

ip wccp 61 redirect in



I am then trunking everything from 2960NONPOE through to the WLC4400. I already have another vlan 100 which is works fine and used for management of each of all devices except WLC4400. However when I configure the address 10.220.252.146 on the WLC the router/gateway 2811 with address 10.220.252.145  doesn't communicate with it.


The 2960POE can ping 10.220.252.145 with it's vlan 100 address which is 10.151.220.245; however it can't communicate with the WLC4400s vlan 20 address 10..220.252.146 even though the address shows on the 2960POE when using "show cdp neighbour detail"


When I put an SVi for vlan 20 on 2960POE it can ping the WLC 10.220.252.146 but instead can't communicate with vlan20 gateway 10.220.252.145 which it could before even if I use "ping 10.220.252.145 source interface vlan 100 (which was the management address used previously to communicate with it.


If I put SVI from vlan 20 on 2960NONPOE then I can ping the router but not the WLC4400.


There are no vlans being blocked by trunk.


The spanning tree root bridge for all vlans is the 2950; could this be the problem? I ask this because this whole setup was working at one stage but stopped working when someone went on site and not sure what has changed since!


Thanks for your help


Regards

Zee

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Jon Marshall Mon, 12/16/2013 - 09:17
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Zee


Your post is a bit confusing in terms of addressing eg -


The 2960POE can ping 10.220.252.145 with it's vlan 100 address which is 10.151.220.245

vlan 100 uses the subnet 10.220.252.192 255.255.255.192 (on the router) so how can the 2960POE switch be using 10.151.220.245 and be in the same vlan ? It's a completetly different subnet. Are you running multiple IP subnets within the same vlan ?


Jon

Zahan Al-Rashid Mon, 12/16/2013 - 11:51
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Hi Jon,


Sorry Jon I made a mistake, it is using 10.220.252.245, not 10.151.252.245.
Sorry for the confusion, i have now edited the original message,

Jon Marshall Mon, 12/16/2013 - 12:03
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Zee


No problem. When you configured the WLC was that interface in vlan 20 ?


Can you post "sh int trunk" and "sh spanning-tree vlan 20" from each 2960 switch ?


Jon

Zahan Al-Rashid Tue, 12/17/2013 - 08:54
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This has resolved itself after I shut down the trunk interface to WLC, left it off and re-applied trunking to WLC from 2960POE. ALthough it did not work when I shut no shut the same interface before. Really not sure what the problem was :/

Thanks for your assistance Jon

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