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Dear Friends,

1. I have the attached Network Switch setup in our office.i am just new to this place and trying to understand the topology.we have more than 25 vlans in our network and VTP enbaled in it.manually spanning-tree root switch has not been configured hence it took the lowest mac-address bearing switch as its root switch which is very old switch. do we face any issue/latency in reaching other subnet through this root switch?

2. Right now we dont have IP phones in our network. we use Nortel PBX with phone. now our company has decided to implement Avaya IP phones in our network. with this current set up can i implement IP phones in our network.can we enable QOS in this switches? Do we need to create separate Vlan for Voice?

Please suggest some ideas and configurations



Re: Switch-connectivity-Spanning-tree-IP-phones


1- I wouldnt keep it like this, for Optimal design and Network path flow, the appropriate is to set the Root Switch to be at the distribution layer, following the CISCO three Hierarchical design. Since you have only CORE and the Core acting as a distribution , i will set the root bridge to be that switch. its also capable interms of device hardware capability.

2- Yes, you need to configure a single vlan to be used for voice communication, and you would need to implement QoS if you have bandwidth limitation or if you want to gurantee latency for Voice traffic.



Hall of Fame Super Silver

Re: Switch-connectivity-Spanning-tree-IP-phones

Hello Shibu,

1) main C4507 should be made root switch in place of current because STP for each instance is rooted at root bridge.

Also notice that you haven't a fault tolerant design if main c4507 fails your network becomes partitioned you should provide an alternate path to connect to.

Ideally a second distribution switch with each switch having an uplink to each distribution node would be the ideal solution (it is expensive I know)

The two distrib switches could be root bridge each for a different subset of vlans

you can use spanning-tre root primary and spanning-tree root secondary macro commands for this.

2) usage od dedicated voice vlan(s) is recommended to be able to implement QoS end to end and for security reasons.

Hope to help


Community Member

Re: Switch-connectivity-Spanning-tree-IP-phones

Dear Both,

Thanks for the quick reply.

1.At the moment i cannot change anything in the network as i have to run the show with the current setup for another few months.

2.Will there be any downtime occur when the current Root switch goes down? current root switch is very old switch will it with stand when we add Voice vlan ?

3. usage od dedicated voice vlan(s) is recommended to be able to implement QoS end to end and for security reasons? can u please explain little more about this?

Can i have some configuration examples of Voice vlan and Qos for cisco switch 4507& 2950.

Thanks for understanding

Community Member

Re: Switch-connectivity-Spanning-tree-IP-phones


1. When my current Spanning-tree Root switch goes down what will be the impact in the network? will the next switch with lowest mac-address become root switch?

2. Right now users vlans are cofigured with DHCP and its been configured in the DC. should i create the new Voice vlan DHCP scope in the DC?

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