Quality of Service guidelines
320 Avaya Application Solutions IP Telephony Deployment Guide
Queuing methods
This section discusses common queuing methods and their appropriateness for voice:
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WFQ
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PQ
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Round-robin
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CB-WFQ / LLQ / CBQ
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RED / WRED
WFQ
Weighted fair queuing (WFQ) is similar to first in, first out (FIFO) queuing, except that it grants a
higher weight to small flows, and flows that are marked with higher DiffServ or IP TOS priorities.
This queuing strategy does allow smaller (for example, telnet) and higher-priority (for example,
IP Telephony) protocols to squeeze in before high-flow (for example, ftp) packets, but does not
starve off any traffic. By itself, it is not appropriate for IP Telephony traffic because high-flow
traffic can still delay IP Telephony traffic, and cause unacceptable latency and jitter.
PQ
Strict priority queuing (PQ) divides traffic into different queues. These queues are usually high,
medium, normal, and low, based on traffic type. This form of queuing services the queues in
order of priority, from high to low. If there is a packet in the high-priority queue, it will always be
serviced before the queue manager services the lower-priority queues. With priority queuing,
however, it is possible to starve out lower-priority flows if sufficient traffic enters the
high-\priority queue. This mechanism works very well for IP Telephony traffic (where IP
Telephony bearer and signaling are inserted in the high-priority queue), but might work less well
for routine data traffic that is starved out if sufficient high-priority traffic arrives.
Summary of Contents for Application Solutions
Page 1: ...Avaya Application Solutions IP Telephony Deployment Guide 555 245 600 Issue 3 4 1 June 2005 ...
Page 20: ...About This Book 20 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 21: ...Issue 3 4 1 June 2005 21 Section 1 Avaya Application Solutions product guide ...
Page 22: ...22 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 106: ...Call processing 106 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 124: ...Avaya LAN switching products 124 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 139: ...Issue 3 4 1 June 2005 139 Section 2 Deploying IP Telephony ...
Page 140: ...140 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 186: ...Traffic engineering 186 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 204: ...Security 204 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 228: ...Avaya Integrated Management 228 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 274: ...Reliability and Recovery 274 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 275: ...Issue 3 4 1 June 2005 275 Section 3 Getting the IP network ready for telephony ...
Page 276: ...276 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 356: ...Network recovery 356 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 366: ...Network assessment offer 366 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 367: ...Issue 3 4 1 June 2005 367 Appendixes ...
Page 368: ...Appendixes 368 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 394: ...Access list 394 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 414: ...DHCP TFTP 414 Avaya Application Solutions IP Telephony Deployment Guide ...