Presentation on theme: "SkyWay 4000 & 7000 QoS systems David Gell VP Engineering."— Presentation transcript:
SkyWay 4000 & 7000 QoS systems David Gell VP Engineering
New Applications The Internet and private enterprise intranets have been evolving steadily over the last 5-10 years and are responsible for the effective communication of ever-growing applications. Three of the fastest growing are real time voice, video and wireless communication.
Video Tremendous gains in standardized video compression and IP conversion technologies has created an important, but difficult to implement purpose for IP networks – real time video transport. Applications include CCTV and IP camera-based surveillance, video conferencing and video streaming. While the technology to convert video to and from IP packets is highly standardized (e.g. – Motion JPEG, MPEG2, MPEG4, H.264), the ability to transport such IP packets in a timely manner has been left to other technologies.
VoIP International groups (ITU, IETF) have standardized a series of end-to-end protocols for IP based telephony. Such standards encompass and address necessary functions at OSI layer 4 and above (e.g. – H.323, SIP, RTP, H.245, G.711, G.72x) Like with real-time video, the technology to convert voice to and from IP packets is highly standardized but the ability at layer 3 and below to deliver IP packets in a timely manner has been left to other technologies.
The need for QoS… It is clear that in both voice and video standardization, the means to assure timely and error free packet delivery is left to other, QoS technologies. When combined with Broadband Wireless systems, it becomes clear that an effective mechanism is needed…
Main Site … … PSTN Internet Satellite Office A … … Satellite Office B … … ‘Typical’ Enterprise BWA application In this example, how can VoIP intranet performance be properly managed?....
Congested Networks Despite gains in throughput performance, a long-distance, fixed wireless system can often become a network bottleneck during peak times of network usage. At such times, latency and packet-loss sensitive payload, such as voice or video can suffer significant degradation.
Priority Queuing Conceptually simple, priority queuing uses multiple queues to allow higher priority traffic to ‘jump ahead’ of lower priority traffic Input traffic Output traffic High Priority Queue Low Priority Queue Priority Engine Priority Engine
Dest Addr. Src Addr TPID CFI TCI Len Data FCS SFD PRE Priority VID Priority Tagging Multiple approaches are available to tag frames with desired priority: Ethernet frame tagging (802.1q) Ethernet Frame 3 bits: 0-7
Dest Addr. Src Addr TPID TCI Len Data FCS SFD PRE ToS Len Iden Flags TTL Protocol IHL Vers H Cksm Src Dest Opt Data Frag Ethernet Frame IP Packet Priority Tagging, cont. IP frame tagging via ToS (RFC 791) 3 priority bits: 0-7
Priority Tagging, cont. IP frame tagging via DiffServ (RFC 2474) Redefines ToS byte as DS byte. Supercedes ToS definition Dest Addr. Src Addr TPID TCI Len Data FCS SFD PRE DS Len Iden Flags TTL Protocol IHL Vers H Cksm Src Dest Opt Data Frag Ethernet Frame IP Packet 6 priority bits: 0-63
SkyWay QoS Features Priority Queuing System 4 Queues. From highest priority to lowest: Voice, Video, Best Effort, Background Line speed packet inspection supports the three most common tagging methods: 1) 802.1p VLAN tag priority bits 2) IP ToS field 3) IP Diffserv Note: QoS requires end-to-end network support. SkyWay will prioritize traffic but will not actually tag the data. Endpoint devices/appliances are responsible for tagging data.
SkyWay Queue mapping VoiceVideoBest EffortBackground 802.1q bits:0x6, 0x7 0x3, 0x4, 0x0 0x1, 0x2 0x5 IP ToS/Diffserv Byte: 0x30, 0xe0 0x28, 0x88, Default 0x08, 0x20 0xa0 Note: If a frame has multiple tags, then the tag with the highest priority will establish queue assignment
SkyWay System Design for QoS The SkyWay system provides support for QoS, but the proper, end- to-end network design is critical for QoS performance. Tagging device: the closer to the data source the better. Ideally, the voice or video generation device itself will tag frames. Examples: Uniden VoIP phones Vbrick CCTV/IP converter Polycom Video Conferencing systems QoS-enabled network. For best results all switches, routers and gateways should be QoS enabled.