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Issue 6 January 2008 293
e. Apply the configured VLANs to the port, and permit only those VLANs (bind-to-all permits
all VLANs and not just the configured) by typing set port vlan-binding-mode <mod/
port> bind-to-configured
3. For simplicity, Avaya recommends using the static option for IP Telephony. If the port is
connected to a router or to another switch, trunking must be enabled with the command set
trunk <mod/port> dot1q, which causes all egress frames to be tagged. However, if the
port is connected to an Avaya IP Telephone with an attached personal computer, trunking
must not be enabled so that none of the egress frames are tagged. This is necessary
because most personal computers cannot understand tagged frames.
Setting the priority without trunking
or VLAN binding (single-VLAN scenario)
With Avaya, it is possible to set the Layer 2 priority on the IP Telephone, even if the telephone is
not connected to a trunk or multi-VLAN port. That is, the Avaya switch does not need to be
explicitly configured to accept priority-tagged Ethernet frames on a port with only the port VLAN
or the native VLAN configured. This is useful if the telephone and the attached personal
computer are on the same VLAN (same IP subnetwork), but the telephone traffic requires
higher priority. Enable 802.1Q tagging on the IP phone, set the priorities as desired, and set the
VID to zero. Per the IEEE standard, a VID of zero assigns the Ethernet frame to the port VLAN
or the native VLAN.
Cisco switches behave differently in this scenario, depending on the hardware platforms and
OS versions.
Note:
Note: Setting a Layer 2 priority is useful only if QoS is enabled on the Ethernet switch.
Otherwise, the priority-tagged frames are treated no differently than clear frames.
WAN
Because of the high costs and lower bandwidths available, there are some fundamental
differences in running IP Telephony over a Wide Area Network (WAN) versus a LAN. Because
of the resource scarcity, it is important to consider network optimizations and proper network
design, because problems are more likely to manifest themselves in a WAN environment.
Topics covered include:
● Overview
● Frame Relay
● MPLS