Maximizing ICA Sessins with Limited Netwrk Bandwidth By Citrix Cnsulting Services Citrix Systems, Inc.
Ntice The infrmatin in this publicatin is subject t change withut ntice. THIS PUBLICATION IS PROVIDED AS IS WITHOUT WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT. CITRIX SYSTEMS, INC. ( CITRIX ), SHALL NOT BE LIABLE FOR TECHNICAL OR EDITORIAL ERRORS OR OMISSIONS CONTAINED HEREIN, NOR FOR DIRECT, INCIDENTAL, CONSEQUENTIAL OR ANY OTHER DAMAGES RESULTING FROM THE FURNISHING, PERFORMANCE, OR USE OF THIS PUBLICATION, EVEN IF CITRIX HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES IN ADVANCE. This publicatin cntains infrmatin prtected by cpyright. Except fr internal distributin, n part f this publicatin may be phtcpied r reprduced in any frm withut prir written cnsent frm Citrix. The exclusive warranty fr Citrix prducts, if any, is stated in the prduct dcumentatin accmpanying such prducts. Citrix des nt warrant prducts ther than its wn. Prduct names mentined herein may be trademarks and/r registered trademarks f their respective cmpanies. Cpyright 2002 Citrix Systems, Inc., 851 West Cypress Creek Rad, Ft. Lauderdale, Flrida 33309-2009 U.S.A. All rights reserved. Versin Histry Versin 1.0 Citrix Cnsulting Services March 15, 2002
Table f Cntents TABLE OF CONTENTS...III INTRODUCTION...1 PLANNING A METAFRAME DEPLOYMENT WITH REMOTE CLIENT ACCESS...2 CHOOSING THE BEST SOLUTION...2 MINIMUM ICA TRAFFIC REQUIREMENTS ON THE WAN...2 PRE-IMPLEMENTATION PLANNING...2 Hw Much Bandwidth D I Need?...3 POST-IMPLEMENTATION GROWTH AND MONITORING...4 BANDWIDTH MANAGEMENT OPTIONS...5 ADDITIONAL BANDWIDTH...5 Internatinal Challenges...5 Alternatives...5 QOS...5 Nn-Technical Intricacies...6 Which Devices Supprt Which OSI Layers?...6 COMPLEX CACHING & ENCAPSULATION...6 CONCLUSION...7 Maximizing ICA Sessins with Limited Netwrk Bandwidth iii
Intrductin Ensuring that sufficient wide-area netwrk (WAN) bandwidth is available fr ICA traffic is smetimes misunderstd and is the cre purpse f this white paper. Just like a huse needs a firm fundatin, Citrix MetaFrame envirnments require an adequate netwrk as the basis fr deplyments that include remte ffices and/r clients. When a MetaFrame administratr hears frequent cmplaints that users ICA sessins are drpped at randm, the mst cmmn reasn is insufficient netwrk bandwidth. In rder establish and maintain ICA sessins, particularly acrss WAN links, MetaFrame deplyments must have sufficient netwrk bandwidth available. T add mre users r t maximize WAN links that are already in existence, the MetaFrame/Netwrk administratr has three ptins: 1. Purchase additinal bandwidth; 2. Utilize Quality f Service (QS) fr priritizing specific types f netwrk traffic; 3. Incrprate a netwrk appliance that enables mre ICA sessins by using mre cmplex caching technlgies in cnjunctin with the ruter (Layer 3) device. Each f these ptins is discussed in detail within this white paper. Please nte that n single technlgy r slutin is right fr every client envirnment; each MetaFrame deplyment differs and requires a detailed analysis in rder t ensure that the best slutin is recmmended and implemented. Further, having a cntingency plan in the event that the primary WAN link is nt available is an imprtant cnsideratin; hwever, such is beynd the scpe f this paper. Maximizing ICA Sessins with Limited Netwrk Bandwidth 1
Planning a MetaFrame Deplyment with Remte Client Access Chsing the Best Slutin With the release f Citrix Secure Gateway in December 2001, MetaFrame and Netwrk Administratrs nw have tw ptins fr cnnecting remte ffices t Citrix MetaFrame server farms. Administratrs can chse t deply MetaFrame ver traditinal WAN Links r utilize Citrix Secure Gateway ver Internet circuits. Internet circuits are much less expensive than frame relay, ISDN, r ther traditinal WAN links. Where pssible, Citrix Secure Gateway as deplyed with Internet circuits will likely be mre cst-effective slutin. Because the deplyment f MetaFrame ver WAN links is mre cmplex and cnfusing, the majrity f this white paper is fcused n this slutin. Minimum ICA Traffic Requirements n the WAN ICA traffic is ptimized t supprt dialup netwrk bandwidth speeds as lw as 28.8 Kbps; hwever, an average minimum f 20 Kbps per ICA sessin shuld be included in planning and design fr WAN links. While it is pssible that less bandwidth may actually be required t supprt each ICA sessin, fr planning purpses, the full 20 Kbps shuld be alltted fr ICA sessins acrss WAN links. Pre-Implementatin Planning When planning a MetaFrame deplyment, there are several factrs that must be cnsidered with regard t the remte site(s). Each f these items listed belw will have a direct impact n the number f cncurrent ICA sessins that can successfully be maintained: Number f cncurrent ICA sessins per site An average minimum f 20 Kbps shuld be allcated per ICA sessin If mre bandwidth exists, ICA will actually use up t the full amunt available Typical habits f users Nrmal (ne r tw cncurrent applicatins) r Pwer (several cncurrent applicatins) Will the user be accessing applicatins hused n tw r mre MetaFrame servers? If s, sessin sharing cannt be emplyed and multiple ICA sessins will be used. Number f cncurrent lgns Available bandwidth If raming prfiles are being used, these must be cpied t the designated MetaFrame server. If the raming prfiles are stred n a file server that is remte, this will add additinal traffic. Multiple lgns will mmentarily spike the CPU f the designated MetaFrame server. Cmmitted Infrmatin Rate (CIR) r guaranteed/cntracted speed frm service prvider, nt the burst rate. Maximizing ICA Sessins with Limited Netwrk Bandwidth 2
Printing All print traffic must traverse the WAN link, and heavy traffic has a great impact. Physical Lcatin/Latency Printer bandwidth thrttling can regulate this traffic, but print jbs will be slwed. Rund-trip time fr packets Packets must still physically mve frm ne lcatin t the next, and rund-trip time can impact perfrmance as much as insufficient bandwidth Other Traffic Additinal traffic that is als traversing the WAN link, such as dmain cntrller replicatin, file transfers, internet traffic, etc. Mappings Disabling all unused mappings will result in less bandwidth utilizatin. Fr example, by nt disabling clipbard mapping, clients are able t cut and paste t and frm a MetaFrame applicatin. Especially when graphic files are used, a greater impact will be bserved. Much like CPU usage, a successful remte ffice implementatin des nt include a design that immediately plans fr 100% utilizatin. Accrding t Cisc, WAN links shuld be cnsidered saturated when netwrk utilizatin reaches 70% 1. Fr example, if a 128 Kbps CIR frame relay link r bth channels f an ISDN BRI link are being designated between a remte ffice and a headquarters lcatin, 30% r 38 Kbps shuld nt be allcated, leaving 90 Kbps available. Using 20 Kbps as the average minimum bandwidth, nly 4.5 ICA sessins wuld be available n this link. While it may be pssible t successfully achieve a higher number f ICA sessins acrss the WAN link, the impact f the cnsideratins described abve will accunt fr variances. It is best t plan fr a full 20 Kbps per ICA sessin. Hw Much Bandwidth D I Need? General frmula: Example Cntracted bandwidth (CIR r ther fixed minimum) 128 Kbps ISDN r frame relay CIR - 30% (assuming 70% is cnsidered full capacity) -30% x available bandwidth 90 Kbps - ther (FTP, printing, ther traffic) - 30 Kbps (assuming 1/3 traffic is FTP & printing*) y 60 Kbps / 20 Kbps (each ICA sessin) /20 Kbps z = number f ICA sessins 3 ICA sessins *Each client situatin is different and this number may be much higher r lwer depending n the envirnment; this number is used fr purpses f this example nly. Maximizing ICA Sessins with Limited Netwrk Bandwidth 3
While it may be pssible t actually get a higher number f ICA sessins using the available bandwidth, fr planning purpses, 20 Kbps shuld be used as the average minimum bandwidth. Pst-Implementatin Grwth and Mnitring If additinal users are added t remte site(s), reviewing the available bandwidth alng with the factrs listed abve will determine whether the WAN links can successfully supprt the expansin. In additin, cntinuusly mnitring the WAN links t ensure that retransmissins and drpped ICA sessins d nt exist will ensure that the user experience is satisfactry. 1 Cisc Certified Design Prfessinal Study Guide, Page 62 Maximizing ICA Sessins with Limited Netwrk Bandwidth 4
Bandwidth Management Optins Additinal Bandwidth In mst cases, purchasing additinal bandwidth is the simplest slutin; hwever, it is generally als the least feasible frm a cst standpint. IT rganizatins typically spend the majrity f their budgets n WAN links and must exhaust all ther pssibilities befre cntracting fr higher capacity links t supprt additinal users. When researching r negtiating frame relay link csts, there are tw parameters cmmnly used: CIR and Burst. Cmmitted Infrmatin Rate (CIR) is the guaranteed minimum thrughput that is cntracted, whereas Burst is the thrughput that will be prvided if available. Please nte that there are n guarantees assciated with the Burst rate and that it shuld NOT be used fr planning purpses. WAN links are cstly. There are three factrs that cmprise the mnthly expense fr WAN links: prt, access, and PVC. The prt and access fees are generally fixed fees, whereas the PVC fee increases as the bandwidth increases. As an example, a 128 Kbps frame relay link frm Flrida t Califrnia csts apprximately $2400 per mnth. T upgrade that link t 384 Kbps, the mnthly fee increases t apprximately $3500 r the equivalent f a 46% increase. Internatinal Challenges Outside f the United States, additinal netwrk capacity is extremely expensive and increasing bandwidth may be cst prhibitive. Als, the differences in services available frm the netwrk service prvider must be cnsidered. Fr example, T-1 cnnectins (1.544 Mbps/24 channels) are used in the US and Canada, J-1 cnnectins are used in Japan (2.048 Mbps/30 channels), and E-1 cnnectins (2.048 Mbps/30 channels) are used in Eurpe, Suth America, and mst f the rest f the wrld. Alternatives Sme ptential alternatives t purchasing additinal bandwidth are: Dial-up cnnectins If nly a few ccasinal users are being added, it may be mre csteffective t use analg mdem dialup t a Remte Access Server (RAS). If a RAS server is nt available, an asynchrnus cnnectin via a TAPI mdem can be made straight int a specific MetaFrame server. Lad balancing wuld be affected because the Zne Data Cllectr is nt making the MetaFrame server selectin based n the least-busy server; cnnectin t a specific server is being frced and will impact lad balancing. Further, security implicatins shuld be cnsidered. Citrix Secure Gateway and VPN cnnectins Bth Citrix Secure Gateway and VPN cnnectins, such as Citrix Extranet, use the netwrk bandwidth f an Internet service prvider. Thus, s lng as Internet cnnectivity is available frm the remte lcatin, via whatever means, users can cnnect t the MetaFrame server farm withut a direct cnnectin t that physical lcatin. QS Quality f Service (QS) is the priritizatin f ne r several types f netwrk traffic abve all thers. There are a variety f priritizatin techniques, and mst use TCP and/r UDP prt numbers as the basis fr priritizatin. Fr example, if it is fund that the priritizatin f MetaFrame traffic is desired, then TCP prt 1494 culd be priritized. Maximizing ICA Sessins with Limited Netwrk Bandwidth 5
Hwever, because cmmunicatins between the client and server are made via a dynamically chsen prt, the return traffic will nt be priritized n the ruter unless sme type f advanced QS mechanism, such as Cisc s Netwrk- Based Applicatin Recgnitin technlgy, is used. QS des nt actually create any additinal bandwidth nr increase the capacity f the WAN link in any way. It instead priritizes certain type(s) f traffic s that the netwrk device places it in frnt f ther the traffic. Fr example, if a remte ffice has a 256 Kbps Cmmitted Infrmatin Rate (CIR) link t its hme ffice that supprts multiple MetaFrame sessins and nn-critical Internet brwsing, then priritizing the ICA traffic is likely an excellent slutin. Of curse, this assumes that Internet brwsing packets can be drpped withut an adverse user reactin. At the ruter level, the implementatin f QS requires that the ruter analyze each packet as it traverses the ruter t determine if and hw it shuld be queued. Depending n the queuing technique used and the respective cnfiguratin, the higher pririty packets are ruted first, and all ther packets wait r even get drpped if there is cntentin fr netwrk bandwidth. Nn-Technical Intricacies The plitics assciated with QS implementatin shuld be cnsidered. By priritizing ne r mre types f netwrk traffic, the remaining traffic falls farther back in the queue and culd be drpped, delayed, r cmpletely discarded when there is cntentin. Determining exactly which types f traffic are priritized while thers are nt is an extremely plitically sensitive issue within mst rganizatins. As a result, QS implementatins are ften slw and difficult, and few cmpanies have implemented QS t date. Which Devices Supprt Which OSI Layers? Mst ruters include sme basic QS capabilities within the perating system. This enables QS implementatin up t Layer 4, i.e., TCP and/r UDP prts. Netwrk appliances that can utilize higher layers f the OSI mdel are available frm vendrs such as Packeteer, Sitara, Netwrk Appliance, and Cisc. Cmplex Caching & Encapsulatin Expand Netwrks ffers netwrk appliances that use patented caching technlgies that transparently maximize netwrk bandwidth. This technlgy inherently includes numerus ICA-related features. While the ICA prtcl caches n a per-sessin basis, Expand takes that ne step further by caching unchanged prtins f the screen fr multiple sessins based n the entire lcatin. Thus, if users typically access ne r few applicatins, it is likely that many f the screen bitmaps are hused n the lcal Expand device clsest t the clients. Further, Expand encapsulates multiple ICA packets s that fewer large packets traverse the WAN link instead f many small packets. When testing Expand under ptimal cnditins (nly ICA traffic and n printing), it was fund that as many as three times the number f ICA sessins culd successfully be supprted n lw-bandwidth (64 and 128 Kbps) cnnectins. Typical client envirnments include many types f WAN traffic, thus the actual number f additinal ICA sessins that can be supprted may vary. WAN emulatin shuld be fully tested under cnditins that clsely resemble the prductin envirnment. Particularly where WAN links are very expensive, such as utside f the United States, the cst/benefit f an Expand Netwrks slutin may be an effective alternative t purchasing additinal bandwidth. Hardware is required at each remte lcatin, and these netwrk appliances require cnfiguratin using a Cisc IOS-like perating system. Expand netwrk appliances inherently autmatically sense ne anther, enabling this technlgy t be implemented at sme remte lcatins (such as internatinal ffices) and nt thers (such as US dmestic sales ffices). Maximizing ICA Sessins with Limited Netwrk Bandwidth 6
Cnclusin Frm a cst standpint, there is n single silver bullet slutin t maximizing the number f ICA sessins acrss limited WAN links. The least expensive slutin frm a cst standpint, if available, is t use the Quality f Service (QS) capabilities f the netwrk ruters already in existence. This may require an upgrade f the ruter perating system, but this is generally free r very inexpensive. Althugh this slutin has little r n financial impact, the plitical cst may be significant. If cntacting fr additinal bandwidth is nt an ptin, the remaining ptins require the implementatin f additinal hardware. Optins include engaging a third-party vendr that ffers mre cmplex QS such as Packeteer, Sitara, Netwrk Appliance, r Cisc r t emply a cmplex caching technlgy such as that ffered by Expand Netwrks. Citrix Secure Gateway represents a slutin wherein nly Internet circuits are required, nt pint-t-pint links, such as frame relay. Thus, if WAN links will be used nly t supprt ICA traffic, a mre cst-effective slutin may be t cntract with a lcal service prvider fr Internet circuits nly and utilize Citrix Secure Gateway fr MetaFrame server farm access. Each client envirnment shuld be reviewed in detail t determine the existing cnstraints and the slutin that best addresses the initial and nging financial, plitical, and maintenance csts. Maximizing ICA Sessins with Limited Netwrk Bandwidth 7
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