Traffic Classification Design
Services carried on large and medium-sized campus network include voice, video, and data services and network protocol control signaling required for transmitting service data. QoS indicators of various services include the bandwidth, packet loss rate, latency, and jitter. In terms of the network layer, except the bandwidth, it is difficult to specify the packet loss rate, latency, and jitter based on explicit parameters. In practice, QoS is deployed based on engineering experience, as shown in Table 3-24.
Service Category |
Typical Application or Protocol |
Packet Loss Tolerance |
Latency Tolerance |
Jitter Tolerance |
|---|---|---|---|---|
Network protocol |
Link-layer loop prevention protocols for network interconnection and interoperability, routing protocols, and multicast group management protocols, such as STP, OSPF, and IGMP. |
Low |
Low |
Permit |
Management protocol |
Protocols used by network administrators for monitoring network devices, delivering configurations, and diagnosing faults, for example, ICMP, SNMP, Telnet, and XMPP. |
Low |
Low |
Permit |
VoIP data flow |
Real-time voice calls over IP networks. The network must provide low latency and low jitter to ensure service quality. |
Very low |
Very low |
Very low |
Voice signaling |
Signaling protocols for controlling VoIP calls and establishing communication channels, for example, SIP, H.323, H.248, and Media Gateway Control Protocol (MGCP). Signaling protocols have a lower priority than VoIP data flows because call failure is often considered worse than intermittent voices. |
Low |
Low |
Permit |
Multimedia conference |
Multiple parties can share camera feeds and screens over IP networks. Protocols or applications can adapt to different network quality levels by adjusting the bitrate (image definition) to ensure the smoothness. |
Low or medium |
Very low |
Low |
Gaming |
The network is required to provide online interactive applications with low packet loss rate, latency, and jitter to ensure fast and accurate response during gaming. For example, online games that transmit operation instructions through RTP or UDP pose higher requirements on the network. |
Low |
Very low |
Low |
Streaming media |
Online audio and video streaming. Audio and video programs are made in advance and then cached on local terminals before being played. Therefore, the requirements on the network latency, packet loss, and jitter are reduced. |
Low or medium |
Medium |
Permit |
Online live broadcast |
Unlike streaming media, data of online live broadcast is sent and received in real time. Though terminals provide the cache mechanism, the network is required to provide the low packet loss rate and jitter to meet real-time requirements and ensure good experience. |
Very low |
Medium |
Low |
Delay-sensitive data service |
Data services that are sensitive to delay. For example, long delay on an online ordering system may reduce the revenue and efficiency of enterprises. |
Low |
Low or medium |
Permit |
Bandwidth-intensive services |
Network services that involve the transmission of a large amount of data for a long period of time, such as File Transfer Protocol (FTP), database backup, and file dump. |
Low |
Medium or high |
Permit |
Common services |
Basic services that have no special requirements on enterprise networks, such as email and web browsing. |
No requirement |
No requirement |
No requirement |
Low-priority services |
Services that are not important to enterprises, such social network and entertainment applications |
High |
High |
Permit |