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Page 1: QoS on SkyWay 7000

QoS on SkyWay 7000

David GellVP Engineering

Page 2: QoS on SkyWay 7000

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.

Page 3: QoS on SkyWay 7000

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.

Page 4: QoS on SkyWay 7000

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.

Page 5: QoS on SkyWay 7000

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…

Page 6: QoS on SkyWay 7000

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?....

Page 7: QoS on SkyWay 7000

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.

Page 8: QoS on SkyWay 7000

Priority Queuing Conceptually simple, priority queuing uses multiple queues

to allow higher priority traffic to ‘jump ahead’ of lower priority traffic.

66

33

55

44

22

11

Inputtraffic

Outputtraffic

HighPriorityQueue

LowPriorityQueue

123456

PriorityEngine

PriorityEngine

12 345 6

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Dest Addr.Dest Addr. Src AddrSrc Addr TPIDTPID

CFICFI

TCITCI LenLen DataData FCSFCSSFDSFDPREPRE

PriorityPriority VIDVID

Priority Tagging Multiple approaches are available to tag frames with desired

priority:

Ethernet frame tagging (802.1q)

Ethernet Frame

3 bits: 0-7

Page 10: QoS on SkyWay 7000

Dest Addr.Dest Addr. Src AddrSrc Addr TPIDTPID TCITCI LenLen DataData FCSFCSSFDSFDPREPRE

ToSToS LenLen IdenIden FlagsFlags TTLTTL ProtocolProtocolIHLIHLVersVers H CksmH Cksm SrcSrc DestDest OptOpt DataDataFragFrag

Ethernet Frame

IP Packet

Priority Tagging, cont. IP frame tagging via ToS (RFC 791)

3 priority bits: 0-7

Page 11: QoS on SkyWay 7000

Priority Tagging, cont. IP frame tagging via DiffServ (RFC 2474)

Redefines ToS byte as DS byte. Supercedes ToS definition

Dest Addr.Dest Addr. Src AddrSrc Addr TPIDTPID TCITCI LenLen DataData FCSFCSSFDSFDPREPRE

DS DS LenLen IdenIden FlagsFlags TTLTTL ProtocolProtocolIHLIHLVersVers H CksmH Cksm SrcSrc DestDest OptOpt DataDataFragFrag

Ethernet Frame

IP Packet

6 priority bits: 0-63

Page 12: QoS on SkyWay 7000

SkyWay 7000 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 7000 will

prioritize traffic but will not actually tag the data. Endpoint

devices/appliances are responsible for tagging data.

Page 13: QoS on SkyWay 7000

SkyWay 7000 Queue mapping

Voice Video Best Effort Background

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

Page 14: QoS on SkyWay 7000

SkyWay 7000 System Design for QoS

The SkyWay 7000 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.


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