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Using Enterprise Edge Services 31

P0910464 Issue 01 Enterprise Edge Networking Operations Guide

DiffServ Networks

For DiffServ networks, Enterprise Edge:

• Intercepts all H.323 traffic

• Identifies call setup packet

• Performs admission control based on the WAN link usage

• Marks the packets as premium once admitted

Enterprise Edge implements the DiffServ queuing model that includes a premium

queue and eight best-effort queues. The premium queue has a stricter high priority

than the best-effort queues. The eight best-effort queues are scheduled by a

weighted-fair-queuing (WFQ) algorithm. Since best-effort traffic is not shaped and

does not go through the admission control process, the WFQ is needed to avoid

starvation of low priority packets.

Currently, H.323 traffic is allowed to get into the premium queue. Users can allow

other traffic to be premium by setting up priority filters on the web-based GUI using

the following filter criteria:

• Source IP address (with mask)

• Destination IP address (with mask)

• IP protocol ID (e.g. TCP, UDP, or ICMP)

• Source port range

• Destination port range

• Incoming TOS field

Note: There is no traffic shaping mechanism implemented in this version. Be

cautious when setting up premium priority filters. If the traffic is high

volume and with high bursts, it may impact VoIP quality. Unless necessary,

Nortel Networks recommends that you allocate traffic to the high priority

best-effort queues instead of the premium queue.

Legacy Network

In a legacy network, Enterprise Edge assumes that network devices, such as routers

and switches, do not recognize the IP header TOS field (as defined by DiffServ) and

do not perform the corresponding priority processing. However, most of the current

installed routers, including those from Cisco and Nortel Networks, allow

administrators to set up priorities by IP addresses, port numbers or protocol types,

which is similar to the priority filters described above.

Note: This information is specific to H.323 traffic in legacy networks.

In this environment, Enterprise Edge allows H.323 voice (and optional video)

packets to travel across the WAN link with high priority in both directions using

existing router features.

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Avaya EE Networking Betriebsanweisung Seite 31