2 voice vlans

[clark_white]

Hello Dears

I have created 2 voice vlan vlan A and vlan B in Hp switches but only vlan A  is working, vlan B cisco ip phones are not receiving IP address from the DHCP server.

What is the soluiton to make two voice vlan work in the network, I doing this as if now my users have increased more than  254 host.

Thanks

[Peter_Debruyne]

Hi,

just use the voice command under the 2 vlans.

Next step is to control per port which voice vlan will be announced through LLDP-MED on that port.

For this, the switch simply checks the tagged vlan membership of the port, so if you only allow the vlan you want on these ports it should work.

Sample config, assumes 1 switch with 48 ports, assume 1 user data vlan (untagged) and 2 voice vlans.

vlan 11

 name data

 untag 1-48

vlan 21

 name voice1

 voice

 tag 1-24

vlan 22

 name voice2

 voice

 tag 25-48

Phones connected to first 24 ports supporting LLDP-MED will get to vlan 21, last 24 ports to vlan 22.

Hope this is what you were looking for,

Peter.

[clark_white]

Hello,

This is what thinking what i was having , but it did'nt worked , My half of the switch ports are in voice vlan A and another half in voice vlan B , voice vlan B ports are not working they are not getting IP addess from DHCP.

Thanks

[paulgear]

Hi clark_white,

Have you considered changing the netmask of your voice VLAN and adjusting the pool size on your DHCP server? At one of my clients, we ran 10.x.0.0/16 for all our VLANs, even though very few of them had more than 200 hosts.

[clark_white]

Dear Paul,

I have been to one website subnet calculator i have specified a subnet 10.21.41.0/23 this includes 512 host starts from 10.21.41.1 till 10.21.42.254 but the calculator is showing me 10.21.40.1 - 10.21.41.254

why that so, please find the attached.

[paulgear]

Hi clark_white,

You can't start a /23 subnet on an odd number - 10.21.41.0/23 is always going to be from 10.21.40.0-10.21.41.255; if you 've already used 10.21.40.0/24, then you need to move your voice subnet to something like 10.21.42.0/23, which gives you 10.21.42.0-10.21.43.255, or 10.21.44.0/22, which gives you 10.21.44.0-10.21.47.255.

Or better still, move it to 10.22.0.0/16, then you'll never have to think about it again. :-)

[clark_white]

Dear Paul,

If suppose if i want a /22 subnet i can start with 10.21.42.0/22 that will include 42,43,44 

AND

If suppose if i want a /21 subnet can i start with 10.21.42.0/21 that will include 42,43,44,45

please reply

Thanks

[paulgear]

Hi clark_white,

You can't decide to start a range at an arbitrary point - the mask affects where you must place the start.

For /24s, you can start at anything that ends in .0 - e.g. 10.21.42.0/24

For every bit that you take from the mask, you must make the start of the mask an even multiple of 2 to the power of that number; e.g.

/23s must have an even number (divisible by 2) as the network address.  e.g. 10.21.42.0/23 is the start, but 10.21.43.0 can't be the start of a /23

/22s must have a multiple of 4 as the network address.  e.g. 10.21.42.0 can't be the start of a /22; it must be 10.21.40.0/22 or 10.21.44.0/22

/21s must have a multiple of 8 as the network address.  e.g. 10.21.44.0 can't be the start of a /21; it must be 10.21.40.0/21 or 10.21.48.0/21

... and so on with /20, /19, etc. up to the next octet boundary.

This is something that's worth studying until you can nail it every time.  I found the Cisco CCNA official certification guide by Wendell Odom a really good resource on this, but i'm sure HP have something as well.  There are plenty of free resources on the Internet: just search for "learn to subnet" or something like that.  Plenty of videos may be found on Youtube as well.

Good luck!

[clark_white]

Thank for very good explanation Paul,

I have configured the subnet according to your explanation, but still phone's are getting IP address. If i put a static IP address fromthe voice vlan in my PC i am able to ping the DHCP but when phones are connected they get nothing by dhcp

Thanks