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QoS on SkyWay 7000. 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. - PowerPoint PPT Presentation
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QoS on SkyWay 7000
David GellVP 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.
66
33
55
44
22
11
Inputtraffic
Outputtraffic
HighPriorityQueue
LowPriorityQueue
123456
PriorityEngine
PriorityEngine
12 345 6
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
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
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
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.
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
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.