Specifications

Installation Examples
305
These steps are to set up QoS on the Catalyst 3550 and create the Voice VLAN.
Interface fa0/2 is connected to the 3300 ICP which does not send VLAN tagged Ethernet frames.
Hence the 802.1p value is set manually. The mls qos trust dscp pass-through cos interface
command allows the DSCP value and 802.1p value to remain unchanged.
Interface fa0/4 is connected to a MiVoice IP Phone that is capable of sending VLAN tagged
Ethernet frames. When learning the voice VLAN via CDP (as configured) an 802.1p value of
5 is initially assumed. However, if the Mitel proprietary DHCP option 133 is used then this will
overwrite the initial value. Mitel recommends an 802.1p value of 6 (unless using Cisco auto-qos).
By default 802.1p value 6 is a member of queue number 4. This is the expedited queue created
by the priority-queue out command on a Catalyst 3550. This interface configuration assumes
that DHCP option 133 is set to 6. If an alternate value (e.g. 5) is used then the queue members
need further defining.
Switch1(config)# interface fa0/2 [the connection to the 3300 controller]
Switch1 (config-if)# no cdp enable [turn off unrequired CDP on this interface]
Switch1(config-if)# description "Connection to Mitel
3300 ICP"
Switch1(config-if)# switchport mode access [port defaults to standard Ethernet frame]
Switch1(config-if)# switchport access vlan 100 [sets the VLAN]
Switch1(config-if)# mls qos cos 6 [sets the Ethernet priority (802.1p) to 6]
Switch1(config-if)# priority-queue out [makes queue 4 a strict priority queue]
Switch1(config-if)# mls qos trust dscp pass-through
cos
[required to allow DSCP & 802.1p through]
Switch1(config-if)# spanning-tree portfast [bypasses the spanning the startup
procedure]
Switch1(config-if)# exit
Switch1(config)# interface fa0/4 [the connection to the ext. 2001]
Switch1(config-if)# description "Connection to
Ext.2001"
Switch1(config-if)# switchport mode access [port defaults to standard Ethernet frame]
Switch1(config-if)# switchport voice vlan 100 [allows the IP set to learn the VLAN via CDP]
Switch1(config-if)# mls qos trust dscp pass-through
cos
[required to allow DSCP & 802.1p through]
Switch1(config-if)# priority-queue out [makes queue 4 a strict priority queue]
Switch1(config-if)# spanning-tree portfast [bypasses the spanning the startup procedure]
Switch1(config-if)# spanning-tree bpdufilter enable [stops spanning tree messages from being sent]
Switch1(config-if)# exit
Switch1(config)# interface fa0/5 [the VLAN trunk connection to Switch 2]
Switch1(config-if)# description "Connection to Switch 2"
Switch1(config-if)# switchport trunk encapsulation dot1q [Forces 802.1Q frame]