2 voice vlans on same trunk port ?

Answered Question
Sep 12th, 2006
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Hi,


Consider the senario below :-



Trunk Port--->IPPhone1----IPPhone2-->PC


Phone1 : Vlan 5 (Production)

Phone2 : Vlan 10 (Lab)

PC : Native Vlan 1 (Production)


Switch port on switch is 802.1q TRUNK,

with all vlans allowed.



Devices are dasiy chained to each other.

i.e

Switchport ---> phone1 dataport,

Ph1 PC port ---> to Ph 2 dataport

Phone2 PC port-->PC



Now, how can I set phone 1 to be in vlan 5, and phone 2 to be in vlan 10 ??


I believe on the switch (2950), I can only set a single "switchport voice vlan".



Can I set it manually on the phones, and remove the settings on the switchport ?


If yes, do I need to extend the trust boundary on the switchport, since the 2nd phone is connected to the first through its PC port ??


OR


Do I have to forego the voice vlan, have all devices on a single vlan, and use ACL's to manually set QoS / (Cos/ToS) markings based on mac addresses of the devices on the trunk ?


Thanks


Correct Answer by gpulos about 10 years 11 months ago

YEs, you need to extend the trust.


you should use the following to extend the trust for the 2nd phone connected to the secondary port:


'switchport priority extend trust'


this will queue the packets of the 2nd phone to the high priority queue, as well as continue to queue those of the first phone to the high priority queue.


please see the following link for more info:

http://www.cisco.com/en/US/products/hw/switches/ps607/products_qanda_item09186a0080116ffe.shtml#q15


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aghaznavi Mon, 09/18/2006 - 06:27
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You need to extend the trust boundary on the switchport.

gpulos Mon, 09/18/2006 - 09:00
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personally, i'd stay away from daisy chaining phones for a few reasons. but if you must then here's a few pieces of information -


there can only be one auxVLAN on the port.

(this will be used for the connection of the ip phone(s) connected to the port)


in order to get a second phone to a different VLAN than the first phone, you'll have to set the phone settings manually.

(this also requires the switch port to be in dot1q/trunk mode; as is usual with phone/pc connections to a single port)


* 'switchport access vlan 20' (used for the PC)

* 'switchport voice vlan 5' (used for the first phone); then you need the following done manually on the 2nd phone:


1) set the phone DHCP as disabled

2) set the phone TFTP server

3) set the phone ip address

4) set the phone subnet mask

5) set the phone router1 (aka default gateway)


the first ip phone will get its address for VLAN 5, as this is the voice vlan configured on the switch.


the second ip phone will get its address as it's configured statically; say vlan 10.

(your PC connected to the second phone should still be able to get its 'access vlan' ip address when connected; ie: from vlan 20)


as far as QoS, the phones will require the same settings from the network. DSCP will be marked the same, COS will be marked the same, queuing should be configured the same.

(not different QoS properties for the two different phones directly connected together)


for the phone settings configuration in ccmAdmin, you will need to set the 'forwarding delay' to YES as described in the following document:

http://www.cisco.com/en/US/products/hw/phones/ps379/products_administration_guide_chapter09186a00801ebe70.html

shahedvoicerite Mon, 09/18/2006 - 10:43
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Thanks for the details !!


Regarding QoS, are you saying that I dont need to extend trust boundary on the switch, since cdp will detect both devices as

"Cisco Phones", and automatically honour

QoS markings made by each phone ?


Thanks.

Correct Answer
gpulos Mon, 09/18/2006 - 11:52
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YEs, you need to extend the trust.


you should use the following to extend the trust for the 2nd phone connected to the secondary port:


'switchport priority extend trust'


this will queue the packets of the 2nd phone to the high priority queue, as well as continue to queue those of the first phone to the high priority queue.


please see the following link for more info:

http://www.cisco.com/en/US/products/hw/switches/ps607/products_qanda_item09186a0080116ffe.shtml#q15


(5th bullet point in the list)

shahedvoicerite Fri, 10/06/2006 - 04:18
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In response to your suggestion above, I tried setting the


switchport voice vlan


on the switch.


The result is that both IP phones take the same vlan.


Actual vlan is overridden by Admin vlan settings, as described in the link below (in Table 4-2)


I was able to solve my issue, by manually configuring the admin vlans on both phones, and removing the voice vlan on the switchport.


Thanks



http://www.cisco.com/en/US/products/hw/phones/ps379/products_administration_guide_chapter09186a00801ebe70.html

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