Prioritization and Management of VoIP & RTP s

Transcription

1 Priritizatin f VIP Priritizatin and Management f VIP & RTP s Priritizatin and Management f VIP & RTP s SkyPilt Netwrks, Inc.

2 Intrductin This dcument will utline the prcess by which the SkyPilt netwrk can be cnfigured t ptimize the perfrmance f VIP and ther Real Time Prtcls (RTP s). There are specific netwrk and link cnditins that directly cntribute t the verall perfrmance f VIP. These essentials will be cvered first. The discussin will then turn t cnfiguratin f QS fr the SkyPilt netwrk that maximizes available timeslts and end with the cnfiguratin f classifiers the criteria used t identify which packets get pririty. In the SkyPilt netwrk, it s a cmbinatin f rate limiting and priritizatin that that allw VIP and RTP perfrmance t be at its best. What Impacts VIP r RTP Perfrmance? There are several cnditins that need t be met in rder t achieve the desired perfrmance f VIP and RTP s. If these cnditins are nt met the quality f VIP, r ther RTP s, may be impacted. Link quality frm the custmer premise t the SkyGateway. The link RSSI between all SkyExtenders shuld maintain a target RSSI f 25, r abve. Mdulatin rates shuld remain static and shuld be at 36Mbps fr best perfrmance. The RSSI and mdulatin rate values fr the SkyCnnectr links shuld be similar. Lw RSSI values can mean increased susceptibility t interference generated by transmissins within the SkyPilt netwrk (self-interference) r ther terrestrial interference generated by ther 5.8GHz devices in the area lcal t a given link. Inadequate link margins mean that ne, r mre, data packets may be lst during transmissin resulting in drp-uts and pr VIP and RTP perfrmance. Adequate bandwidth must be available n all links frm the SkyGateway t the SkyCnnectr. The devices experiencing the mst impact are the first-hp SkyExtenders and the SkyGateway. If adequate bandwidth is nt available, priritizatin f VIP r ther RTP traffic will nt realize sufficient gains in perfrmance. There are tw cmmn issues that impact bandwidth availability n the SkyPilt netwrk. The first has t d with unwanted traffic n the netwrk. This traffic can be generated by users, r enter the netwrk frm the utside. Externally surced traffic can be thrttled via a packet shaping device. Anther methd used t ensure adequate bandwidth centers arund assigning asymmetrical traffic rates fr users. The typical rati is fr every 10 bits per secnd (bps) dwnstream, the custmer is assigned 1bps upstream. A mre symmetrical rati f 5bps t 1bps will als yield gd results but sacrifice twice as many upstream time slts per active custmer. End-t-End QS shuld be managed frm the VIP, r RTP, gateway/server all the way t the client CPE device. Once priritized traffic exits the SkyGateway it must be priritized by the netwrk hardware between the SkyGateway and the VIP Sft Switch r RTP server in the netwrk. The same requirement may als apply t traffic exiting the SkyCnnectr at the custmer premise. Netwrk latency must be managed. Latency within the SkyPilt netwrk is a functin f available timeslts within a devices scheduler. The mst heavily utilized devices, in the SkyPilt netwrk, are the first-hp SkyExtenders and the SkyGateway servicing thse SkyExtenders. The latency, t the end-user, can be mnitred thrughut the day using a ping graphing agent such as SmkePing. This applicatin shuld be cnfigured t use ping packets that are the same size as thse used in the critical RTP applicatins. If the latency t the CPE device cnsistently exceeds the maximum jitter buffer size fr the prtcl being used, additinal bandwidth must be added and/r netwrk traffic must be additinally filtered/shaped t ensure adequate available bandwidth. Priritizatin and Management f VIP and RTP s SkyPilt Netwrks, Inc.

3 Implementing QS Rates fr Effective Bandwidth Management The first cnfiguratin parameters t be addressed are QS rates. QS helps t maintain satisfactry thrughput fr every custmer attached t the SkyPilt netwrk. The SkyPilt netwrk utilizes Time Divisin Duplex (TDD) fr data transmissin. TDD cnsists f a single data channel resurce that is shared in time. There are 1250 available timeslts, each secnd, fr utilizatin by the netwrk. Each active child nde receives equal numbers f timeslts each scheduling perid but nt necessarily equal bandwidth (bandwidth t a child nde is a functin f the mdulatin rate t the nde). When a child nde is active bth upstream and dwnstream, the scheduled timeslts will be alternated between transmissin and receptin f data. If the bandwidth, assigned t a SkyCnnectr, is asymmetrical (e.g. 1Mbps x 128Kbps) this alternatin ccurs less frequently, and mre verall bandwidth is available t all users, as a result f the ability t use fewer timeslts fr upstream transmissin. Dwnstream t Upstream Bandwidth As nted abve it is preferred that the bandwidth assigned t SkyCnnectrs be asymmetrical with the dwnstream rate greater than the upstream rate. Typical internet file transfers average a rati f 50 dwnstream bytes received per upstream byte transmitted. Bandwidth settings shuld typically be 10:1, r 5:1 (maximum), dwnstream t upstream rati. This prvides mre than adequate bandwidth t the subscriber fr all file transfers. It als prvides adequate upstream bandwidth fr upstream transfers. It als limits a given custmers the ability t hst services n their netwrk. It is imprtant t cnfigure EVERY custmer n the netwrk with asymmetrical QS rates in rder t effectively manage bandwidth t all ndes within the SkyPilt netwrk. Cnfiguring just VIP custmers in this manner will result in ther custmers utilizing available timeslts, reducing the ttal number f pprtunities available t critical VIP custmers. When netwrks are servicing predminantly business custmers, there is a strnger demand fr mre symmetrical traffic rates. In these situatins bandwidth management in the distributin netwrk, utilizing packet shapers r ther bandwidth cntrl mechanisms, becmes a pririty. Symmetrical bandwidth cnfiguratins (e.g. 1Mbps x 1Mbps) will typically hst fewer custmers befre experiencing jitter/latency beynd what can be tlerated by VIP r ther RTP flws. When assigning bandwidth fr VIP r RTP custmers these ratis may change t accmmdate the added bandwidth requirements fr VIP r RTP cnnectins. Fr a custmer using a VIP prtcl that requires 64Kbps, the upstream rate wuld typically be cnfigured t 1/10 r 1/5 the dwnstream value PLUS 64Kbps t accmmdate the VIP traffic. In the dwnstream directin, cnfigured traffic rates are typically much higher, (512Kbps, 756Kbps, 1Mbps, 1.5Mbps, etc) and shuld nt require any changes. Hw D I Knw When I ve Exceeded System Capacity t Handle VIP r RTP? The best way t determine if system capacity has been exceeded is t watch the statistics n the VIP gateway r the RTP server. These devices reprt n the quality f cnnectins with statistics such as buffer verrun, buffer errred secnds, underruns, jitter, packet lss, ut-f-rder packets, etc. This data represents the quality f the data flws between the client and the terminatin device. As these values increase it signals that the data path between the VIP Sft Switch r RTP server, and the CPE device is being cmprmised. Anther indicatr f this issue is displayed using the shw link stats cmmand n the SkyGateway, SkyExtender and SkyCnnectrs in questin. RED Drps is the stat yu re lking fr. If this value increments every pll, queued data is being drpped by the device. This data culd be internet traffic, VIP r RTP traffic. RED stands fr Randm Early Discard and it is implemented in bth the pririty and the nrmal queues n all SkyPilt devices. Priritizatin and Management f VIP & RTP s SkyPilt Netwrks, Inc.

4 What Other Traffic Management Issues Shuld I Be Aware Of? VIP and ther RTP streams usually present a flw rate t the interface that des nt vary ver time. Internet traffic, n the ther hand, ccurs in bursts f packets n an interface. There may be situatins when a burst f internet traffic, fr end-users, enters the SkyGateway. Depending n the number f users t be serviced by that burst, and their lcatin in the SkyPilt netwrk, it culd cause a significant jitter f dwnstream VIP r RTP data streams. A traffic shaper can be utilized, prir t the SkyGateway, t manage the packet burst rate t the SkyGateway. This will reduce the therwise significant variatins in latency that might ccur during perids f heavy bursts f traffic frm the internet. This is mre apparent when TCP Synchrnizatin ccurs as a result f queuing, r bandwidth issues between the client and the server. The SkyGateway and SkyExtenders will prtin ut an equal number f timeslts fr all active child ndes, during a scheduling interval. When the child nde is scheduled the high-pririty queue will be serviced first, and the nrmal pririty queue will be serviced secnd. Child ndes with high pririty data may nt be serviced befre child ndes with nrmal pririty data. Scheduling is nt based n pririty; it s based n equal pprtunity t all active child ndes. If a child nde requires data transmissin bth upstream and dwnstream every ther scheduled pprtunity, fr that child nde, will be alternated between upstream and dwnstream. Priritizatin and Management f VIP and RTP s SkyPilt Netwrks, Inc.

5 Cnfiguring QS Bandwidth This is a list f steps t be used t cnfigure QS Rates fr individual SkyCnnectrs Click SkyPrvisin Click the + next t QS. Click Traffic Rate Cntrl Click ADD Enter the values fr the specified QS Rate(s) example shwn belw. Click OK When cnfiguring traffic rates fr custmers that will be utilizing bth VIP and Internet prtcls at the same time, it is essential t cnfigure a QS rate which will allw the VIP flw and the Internet flw t ccur simultaneusly. As an example, fr a VIP stream which requires 64Kbps, it might be advisable t cnfigure an upstream rate f 128Kbps, 64Kbps fr the pririty VIP traffic and 64Kbps fr any internet traffic the user might generate during the VIP phne call. Priritizatin and Management f VIP & RTP s SkyPilt Netwrks, Inc.

6 The Classifiers The next step in the priritizatin f VIP and ther RTP traffic is the cnfiguratin f classifiers. Classifiers are used t identify which fields, within an IP packet, are t be used t priritize that packet fr transmissin t the SkyCnnectr r the SkyGateway. Classifiers are defined and then appended t the SkyCnnectr nde prfile. If the SkyCnnectr is in manual mde, classifiers can be cnfigured thrugh the SkyCnnectr CLI. The SkyCnnectr will frward the infrmatin, fr traffic rates and classifiers, t the SkyGateway and its parent nde during the registratin prcess. Hw t Determine Classifier Directinality Classifiers can be cnfigured as either upstream r dwnstream. In rder t priritize VIP and ther RTP prtcls, bth an upstream and a dwnstream classifier must be used. There are several ways that traffic can be classified and priritized. We re ging t discuss the mst cmmn methd, utilizatin f the VIP Gateway, r RTP server s IP address. In the abve example, the VIP Sft Switch has an IP address f When the VIP Sft Switch sends traffic t a VIP phne it will cnstruct an IP packet with a Surce IP Address f (VIP Sft Switch) and a Destinatin IP Address f the VIP phne. Every packet sent by the VIP Sft Switch t VIP phnes, n the SkyPilt netwrk will have the same Surce IP Address f and different Destinatin IP Addresses. When the VIP phne, at the custmer premise, sends data t the VIP Sft Switch, it will cnstruct an IP Packet with its unique Surce IP Address. The Destinatin IP Address, in this packet, will be the IP Address f the VIP Sft Switch. Every packet sent by a VIP Phne, n the SkyPilt netwrk, will have the same Destinatin IP Address that f the VIP Sft Switch. The classifiers need t be cnfigured in the fllwing way: Type f Classifier Directin IP Address IP Mask Surce IP Address Dwnstream Destinatin IP Address Upstream NOTE: Other classifiers that might be used include the Differentiated Services Cde Pint (DSCP) typically used fr QS classificatin in many enterprise netwrks. In sme VIP implementatins, multiple servers might be used and DSCP may be the best classifier t use. The DSCP field is smetimes called TOS (Type Of Service) and is referenced as such in the SkyPilt EMS Classifier cnfiguratin. Surce r Destinatin UDP prts are smetimes used as classifiers. Priritizatin and Management f VIP and RTP s SkyPilt Netwrks, Inc.

7 Cnfiguring VIP r RTP Classifiers This is a list f steps t be used t cnfigure classifiers thrugh the SkyPilt EMS: Click SkyPrvisin Click the + next t QS. Click Classifier Click ADD Enter the data as shwn belw bth upstream and dwnstream classifiers must be specified. The value fr Name can be any value that allws yu t identify the classifier cnfigured. Click OK The fllwing screenshts depict the cnfiguratin f a Upstream and Dwnstream Classifier fr the SkyCnnectr. Nte that the Upstream Classifier uses the Destinatin IP Address fr the Classifier and the Dwnstream Classifier uses the Surce IP Address fr the Classifier. It is critical t the prper implementatin f the Classifiers that crrect directinality be specified. Classifier cnfiguratin is nt yet cmplete. This step identifies the criteria used by the SkyGateway and SkyCnnectr t separate pririty traffic frm nrmal traffic. Directinality must be specified, in an additinal step. Priritizatin and Management f VIP & RTP s SkyPilt Netwrks, Inc.

8 Cnfiguratin f Classifier Directin The next step in cnfiguring the classifiers is t set directinality. This is accmplished by assigning the apprpriate Classifiers t the Nde Prfile(s) fr all assciated SkyCnnectrs and SkyExtender Ethernet prt. T perfrm this functin fllw these steps: Click the + next t SkyPrvisin. Click Nde Prfile. Select a Nde Prfile fr a SkyCnnectr yu wish t priritize VIP fr. Frm the menu n the lwer prtin f the screen click the Attributes buttn. Select Classifier frm the tabs at the tp f the Attributes screen. Click the bx in the Selected clumn fr bth yur Upstream and Dwnstream classifiers yu wish t use. In the Type clumn cnfigure the directin fr each classifier. THIS STEP IS CRITICAL! Once the tw classifiers have been selected AND the prper directin has been specified Click Apply. Rebt the SkyCnnectr(s), OR lg in t the device and type relad, frm the CLI. These steps apply the changes t the SkyCnnectr(s) Nde Prfile and lad the changes t the SkyCnnectr and the SkyGateway. VIP traffic destined fr and surced frm will be priritized fr SkyCnnectrs cnfigured with the mdified Nde Prfile. Traffic surced frm, r destined tward, frm SkyCnnectrs that d nt have this classifier assigned t their Nde Prfile will nt be priritized. Priritizatin and Management f VIP and RTP s SkyPilt Netwrks, Inc.

9 QS and Classifier Quick Reference Sheet This sectin will prvide a quick checklist fr the user t verify/validate the cnfiguratin f their SkyPilt netwrk hardware. These practices shuld be applied t every cnnectr n the SkyPilt netwrk. QS Cnfiguratin Parameters ALL CUSTOMERS Dwnstream t Upstream Rati shuld be 10:1, r 5:1 minimum, fr all custmers nt using VIP t cntrl unnecessary upstream bandwidth. An example wuld be 1Mbps Dwnstream and 128Kbps Upstream. Bradcast Rate can be set t 10Kbps r less. A typical PC sends ne 64-byte bradcast packet every 10 secnds which translates int 52bps. This will significantly reduce the impact f rgue bradcasts generated by a user. Bradcast rate limiting is applied t the dwnstream at the SkyGateway. Classifiers All Custmers with VIP r Other RTP s Upstream rates assigned t custmers with VIP shuld be assigned at the rate f the VIP prtcl being used PLUS 1/10, r 1/5 f the assigned dwnstream rate f transfer. As per example abve, 1Mbps x 128Kbps with VIP these values change t 1Mbps x 192Kbps. Add classifiers t use. The typical classifier used is the Surce IP and Destinatin IP Address fr the VIP r RTP terminatin. Determined the directin t be used by the classifier. Typically, Surce IP address classifiers will be used fr dwnstream and Destinatin IP Address classifiers will be used fr upstream. IP TOS (a.k.a. DSCP), Surce TCP/UDP prt and ther fields can als be utilized fr classificatin. Cnfigure the classifier Bth and Upstream and a Dwnstream Classifier must be cnfigured. (SkyPrvisin QOS Classifier) Assign Classifier t Already Prvisined Nde Prfile(s). SkyPrvisin Nde Prfile Select Nde Prfile t change. Click Attributes buttn. Click the Classifier tab. Select bth Upstream and Dwnstream by putting a in the bx under the Selected clumn. Ensure that the Type clumn matches the prper directin. Apply Applying Classifiers Rebt the nde(s) t which classifiers were added t the nde prfile. OR Telnet t nde(s) and lgin t the CLI. cnfiguratin. Type: relad t have the unit relad its Priritizatin and Management f VIP & RTP s SkyPilt Netwrks, Inc.

10 2055 Laurelwd Rad Santa Clara, CA US Tll Free 866 SKYPILOT 2005 SkyPilt Netwrks, Inc. All rights reserved. SkyCnnectr, SkyCntrl, SkyExtender, SkyGateway, SkyPilt, SkyPilt Netwrks, SkyPrvisin, the SkyPilt lg, and ther designated trademarks, trade names, lgs, and brands are the prperty f SkyPilt Netwrks, Inc. r their respective wners. Prduct specificatins are subject t change withut ntice. This material is prvided fr infrmatinal purpses nly; SkyPilt assumes n liability related t its use and expressly disclaims any implied warranties f merchantability r fitness fr any particular purpse. Priritizatin and Management f VIP and RTP s SkyPilt Netwrks, Inc. 9/05