Section 9.9. Key Issues: Quality of Service


9.9. Key Issues: Quality of Service

  • Quality of Service is decreased when packet loss, jitter, and latency increase

  • There are two styles of Quality-of-Service mechanisms to deal with the problem: CoS and QoS

  • CoS solutions are coarsely grained, best-effort approaches the rely on packet prioritization

  • CoS solutions are best in situations in which voice traffic represents 30% or less of the total traffic, such as enterprise networks

  • 802.1p and DiffServ are the two most common CoS solutions for Voice over IP

  • QoS solutions are finely grained, guaranteed -delivery approaches that reserve bandwidth across the network

  • QoS solutions are best when there is limited bandwidth, or in carrier-grade networks

  • COPS is a system for centrally storing and maintaining QoS and CoS policies

  • RSVP is the most common QoS solution for enterprise-grade voice services over IP

  • Some ISPs offer QoS services to facilitate the use of the Internet and/or VPN for voice applications.

  • Many small-office and residential broadband routers support 802.1p, and a few even support DiffServ

  • Linux's kernel-based firewall, Netfilter, can be used as a DiffServ edge router if the Linux Traffic Control components are compiled into the Linux kernel

  • In Windows NT, 2000, and XP, the QoS Packet Scheduler provides packet prioritization for API-compliant Windows applications such as a softPBX

  • The Windows RSVP service provides an RSVP policy enforcement point for voice and video software running on Windows servers

  • pathping is a Windows utility that can help you determine how well WAN call paths support QoS measures



Switching to VoIP
Switching to VoIP
ISBN: 0596008686
EAN: 2147483647
Year: 2005
Pages: 172

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