From: Marcus Jensen (marcus@pobox.com)
Date: Sun Jul 27 2003 - 13:26:37 GMT-3
Timothy,
I don't think you need to use the the encap dot1q and native vlan commands
for setting voice vlans with IP phones. I see often configs with these extra
commands posted, but here is some testing I did without using native vlan or
encap dot1q commands.
Two 7960 phones connected to 3550 set up for dhcp. Factory reset, config
erased.
3 Hosts, 150.1.1.1/2/3. Two are connected to the phones, one is on its own
port on the switch.
Call manager set up as dhcp server as well connected to 3550 using different
subnet 192.168.0.254
(All PCs are routers with no ip routing)
First, just the PCs configured for connectivity, no voice vlans, all static
access ports.
------sw1
en
vlan data
vtp server
vtp domain VTP
vlan 200 name PreferredVoice200
vlan 100 name PreferredData100
exit
conf t
int fast 0/5
description Port to single PC
sw mode access
sw access vlan 100
spann portfast
int fast 0/19
description port to Phone A with PC off its Access Port
sw mode access
sw access vlan 100
spann portfast
int fast 0/20
description Phone B with PC off its Access Port
sw mode access
sw access vlan 100
spann portfast
end
-----------------------
Power up phones. I look at the phones and they endlessely search for ip
address and won't resolve a vlan from the switch either in the network
settings. But the hosts all have connectivity. (I should mention that if I
put the dhcp server in the same vlan 100, then the phones would resolve an
address, but we're talking about separating the voice and data traffic into
different vlans here).
r1#p 150.1.1.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.2, timeout is 2 seconds:
!!!!!
r1#p 150.1.1.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.2, timeout is 2 seconds:
!!!!!
----------------------
r2#p 150.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.1, timeout is 2 seconds:
!!!!!
r2#p 150.1.1.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.3, timeout is 2 seconds:
!!!!!
-----------------
r3#p 150.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms
r3#p 150.1.1.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.2, timeout is 2 seconds:
!!!!!
------------
Now add in the voice vlans.
conf t
int fast 0/19
description port to Phone A with PC off its Access Port
sw mode access
sw access vlan 100
sw voice vlan 200 <---only command added
spann portfast
int fast 0/20
description Phone B with PC off its Access Port
sw mode access
sw access vlan 100
sw voice vlan 200 <---only command added
spann portfast
int fast 0/4
description This is port to CALL Manager also acting as dhcp server
sw mode access
spann portfast
sw access vlan 200 <--needs access to the vlan 200 to control phones, but
call manager regular PC so access vlan, not voice vlan
end
-----------------
Before these config additions int fast 0/19, 0/20 were in access mode so any
encapsulated frames would have been dropped, but when we add the voice vlan
command, it does two things as far as I can tell. It tells the switch to
not drop vlan 200 tagged frames. And also tells the switch to instruct the
phone to send voice related packets (including dhcp requests for the phone)
encapsulated as dot1q tagged vlan 200. This also shows up as "operational
vlan id 200" in the network settings panel on the phone.
At this point, the phones resolve an address from dhcp server, and register
themselves automatically with call manager. I can then make phone calls
between the phones, and still ping from any to any host.
r1#p 150.1.1.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.2, timeout is 2 seconds:
!!!!!
----------------------
r2#p 150.1.1.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.3, timeout is 2 seconds:
!!!!!
-----------------
r3#p 150.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.1, timeout is 2 seconds:
!!!!!
Now test the dot1q config. If I erase the switch config and do this,
conf t
default int fast 0/19
default int fast 0/20
int range fast 0/19 -20
sw trunk encap dot1q
sw trunk native vlan 100
sw voice vlan 200
sw mode trunk
end
Then I can still make calls just fine, and I can ping from the hosts on the
phones to each other, but the third host on its own access port is now not
accessible.
r1#p 150.1.1.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.2, timeout is 2 seconds:
!!!!! <-------------ping to other phone's host
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/8 ms
r1#p 150.1.1.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.3, timeout is 2 seconds:
..... <------------------failed ping to single host on its own port
If I do this now,
conf t
default int fast 0/5
int fast 0/5
sw trunk encap dot1q
sw trunk native vlan 100
sw mode trunk
end
Then a ping works, but kinda a clunky solution when working with just access
ports, probably just extra voice vlan command is the way to go I think.
Marcus
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On
> Behalf Of Timothy Snow
> Sent: Saturday, July 26, 2003 1:50 AM
> To: ccielab@groupstudy.com
> Subject: 3550 - Voice Trunks?
>
>
> I was wondering if anyone could explain the difference between the
> following two voice enabled ports. The require on this lab
> stated to do
> it this way, and it appears that my config matches the
> solution but I'm
> wondering if the interface fa0/11 would work as it's not defined as a
> trunk???
>
>
> interface FastEthernet0/11
> switchport access vlan 102
> switchport voice vlan 101
> switchport trunk encapsulation dot1q
> !
> interface FastEthernet0/12
> switchport trunk encapsulation dot1q
> switchport trunk native vlan 202
> switchport mode trunk
> switchport voice vlan 201
> !
>
>
> Tim
>
>
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