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New Member

DHCP and voice vlan on Cisco 3560 switch

Greetings,

I'm setting up a Cisco 3560 switch for voice and data comms. I'm looking for documentation with best practice guidelines for the following requirements.

1. Using the Cisco 3560 as a DHCP server - Config examples.  Do I need to use different subnets for the voice and data vlans?

2. Layer 2 CoS QoS  - I'm connecting Aastra phones as well as notebooks - I've been told that Aastra also makes use of the voice vlan config through LLDP and that Aastra phones supports CDP.

Your assistance will be appreciated.

6 REPLIES
New Member

Re: DHCP and voice vlan on Cisco 3560 switch

Hi ,


Cisco recommends that you have a separate vlan for  voice and data with different ip subnets for voice and data. You will need to configure the dhcp pool accordingly.

Here is the config guide for setting up IOS DHCP server:

http://www.cisco.com/en/US/docs/ios/12_0t/12_0t1/feature/guide/Easyip2.html

Here is the LAN qos recommendations:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/7x/netstruc.html#wp1044009

New Member

Re: DHCP and voice vlan on Cisco 3560 switch

Thanks for the info.

I would like to use the 3560 switch to be the DHCP server for both the voice and data networks. If I'm using different subnets for my voice and data, how would the switch know how to differentiate between voice and data devices?

Regards,

Super Bronze

Re: DHCP and voice vlan on Cisco 3560 switch

Hi

Just create a DHCP pool for each VLAN.

You will then need an SVI for each VLAN (e.g. int vlan 1  and int vlan 2), and depending on which VLAN the DHCP request comes from the switch will receive it on the SVI for that VLAN. It uses the IP associated with the SVI to decide which DHCP pool to serve an IP address from.

Regards

Aaron

Please rate helpful posts...

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!
New Member

Re: DHCP and voice vlan on Cisco 3560 switch

Hi,

Did not see your post, thanks for the info.

New Member

Re: DHCP and voice vlan on Cisco 3560 switch

Hi,

Is it a good idea to create 2 SVI's one for voice and the other for data and use the SVI addresses as the ip-helper addresses for each vlan?

Regards,

Werner le Grange

New Member

Re: DHCP and voice vlan on Cisco 3560 switch

Thanks for the advice.

I'll configure my switchports with ex..

Fa0/1
switchport access vlan 1  
switchport voice vlan 2
auto qos voip trust

Do I require any config relating to the L2 voice markings on my trunk interfaces?

When voice traffic gets to my PE router, do I have to match traffic on the cos value or can I match on EF?

Regards,

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