PLUG AND PLAY SERVER LOAD BALANCING AND GLOBAL SERVER LOAD BALANCING FOR TACTICAL NETWORKS

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1 PLUG AND PLAY SERVER LOAD BALANCING AND GLOBAL SERVER LOAD BALANCING FOR TACTICAL NETWORKS William V. Wollman, Harry Jgr, Maurn Loftu, Calb Wan Th MITRE Corporation 12 Chritophr Way Eatontown, NJ ABSTRACT Srvr Load Balancing (SLB) tchnology a dcribd by [1] ha providd a fundamntal cornrton ncary to th ucc of th Intrnt. Global Srvr Load Balancing (GSLB) a dcribd in [2, 3] nhanc application prformanc by allowing th clint rvr lction to b bad upon rvr prformanc, ntwork prformanc and th approximat ntwork location of th clint and th rvr. To hlp nabl thi tchnology for th tactical nvironmnt w hav cratd th Srvr Load Balancing Rgitration Protocol 1. INTRODUCTION Thi Srvr Load Balancing Rgitration Protocol allow rvr to rgitr and coordinat thir rvic with a Srvr Load Balancr (SLB) managr application. Th SLB managr u th rgitration mag to automatically configur a SLB to upport th rvic providd by a ral rvr. Coordination btwn ral rvr and th SLB managr will includ rvic dfinition(), dynamically aignd or pr-plannd tatic Virtual IP (VIP) addr, and rvr application halth monitoring. Th SLB managr will alo rgitr dynamically-aignd VIP addr with th Domain Nam Sytm (DNS)-bad GSLB, upport VIP addr rout injction, and provid rvic halth tatitic to DNS-bad GSLB application. Thi protocol prmit a rvr to roam into any ntwork and maintain th am VIP addr. Allowing th rvr to maintain th am VIP addr that i not corrlatd to th location of th rvr within a ntwork topology aily nabl th u of ntwork layr anycat tchnology [4]. Alo, nabling plug and play SLB configuration will dcra th tim, cot, and managmnt rquird whn dploying rvr farm, implify anycat dploymnt, and alo minimiz th amount of oldir training rquird to upport ntwork. 1 Pr MITRE Public Rla Mmorandum thi papr i Approvd for Public Rla; Ditribution Unlimitd. Thi papr will dcrib th SLB Rgitration Protocol and an initial Java-bad implmntation. Th papr documnt how th SLB managr can b ud to provid tatitic to an implmntation of a DNS-bad GSLB. Nxt, th papr will dcrib how th SLB and GSLB application can b ud to nabl plug and play anycating. Th papr will alo dcrib two anycat Addr Rolution Protocol (ARP) implmntation to upport clint rquiring rvr connction to application that u dynamic port numbr aignmnt (.g., th H.323 protocol). PROTOCOL DESCRIPTION AND OPERATION A rvr will initiat a connction to a SLB managr via Tranmiion Control Protocol (TCP) to rgitr rvic. Th SLB managr will accpt rgitration from th ral rvr and communicat th xitnc of th rvr VIP addr to th GSLB application and ntwork infratructur quipmnt. Whn th rvic upportd by th rvr fail, th SLB and GSLB will rmov rvic availability from th infratructur. REAL SERVER AND SLB MANAGER COMMUNICATIONS Th typical qunc of mag xchang btwn a ral rvr, th SLB managr, and a GSLB application i hown in Figur 1. Firt a rvr will rgitr with th SLB managr. Th SLB managr will acknowldg rgitration of th rvr. If th rvr rquir a VIP addr, th rvr will rqut to la a VIP from th SLB managr. Onc th VIP ha bn providd to th rvr, th rvr will intall th VIP addr a a loopback intrfac. Nxt, th rvr will rgitr it rvic with th SLB managr. Onc it proc th rvic rgitration rqut, th SLB managr will prform a halth chck on th rvic. If uccful, th SLB managr program th SLB to rprnt th rvic providd by th rvr. Th SLB 2003, Th MITRE Corporation. ALL RIGHTS RESERVED. 1 of 5

2 managr will alo alrt th routing damon to advrti th aignd VIP addr to th ntwork. At thi point, th rvr will dlivr rvic halth tatu mag to th SLB managr. Th SLB managr will alo prform it own indpndnt halth chck on th rgitrd rvic. If a rvic halth failur occur, th SLB managr will automatically rmov th rvr from th rvr farm. Upon halth failur of th lat rvr within a common local rvr farm, th SLB managr will alrt th local routing damon to rmov th VIP addr from th routing infratructur. Srvr Load Ral Srvr Balancr Srvr Rgitration Acknowldgmnt VIP Rqut VIP Rpon Srvic Rgitration Srvic Halth Chck Srvic Rg Ack Srvic Halth Hartbat Hartbat Ack Srvic Halth Chck Srvic Halth Hartbat Hartbat Ack Srvic Halth Chck Rout Injction GSLB Notification Halth Poll Rpon GSLB Notification Halth Poll Rpon Wid Ara Ntwork GSLB Srvr Halth Poll GSLB Srvr Halth Poll Global Srvr Load Balancr Figur 1. Srvr and SLB Managr Mag Flow SLB MANAGER AND GSLB APPLICATION COMMUNICATION Th SLB managr will alo provid a GSLB application with information about th xiting rvic of it rgitrd ral rvr. In thi ca, onc th SLB managr complt th rgitration of a rvic, it will notify on or mor application of th nw rvic and th nw VIP addr aociatd with th rvic. Thi notification i tranmittd a an IP multicat datagram. Th GSLB i a DNS rvr that i configurd to b authoritativ for on or mor pcific zon. Th GSLB will rgitr with it local routr to rciv th multicat rvic notification. Each notification includ th uniqu IP addr of th SLB that gnratd th rvic notification a wll a th uniqu DNS nam and VIP addr rquird by th rvic. Th GSLB will inrt th ntry into it DNS databa to track what rvic ach SLB maintain. At thi point th GSLB will bgin P r i o d i c M a g to priodically poll th SLB for th information concrning th halth of th rvic. Upon rcption of a poll from th GSLB, th SLB managr will rpond with a cor that dcrib th halth of th rvic. Thi cor i normalizd and account for th numbr of rvr upporting th rvic and a wightd tim avrag of th numbr of connction. Whn th GSLB larn of multipl diprd VIP addr that upport th am rvic (i.., idntifid by th DNS nam), th GSLB will u th information providd by th diffrnt SLB managr to influnc it DNS rpon. Th GSLB application can alo b configurd to collct othr ntwork prformanc information, uch a prcnt bandwidth utilization for ky communication link and round trip tim maurmnt btwn Tactical Opration Cntr (TOC) and ky information rvr. IMPLEMENTATION An initial Java-bad implmntation of th SLB Rgitration Protocol ha bn compltd. It ha bn writtn to work with an implmntation of th Opn Sourc Linux Virtual Srvr (LVS) [5] and with an xprimntal vrion of th Cico IOS that includ an mbddd Java Virtual Machin 2. Th SLB Rgitration Protocol implmntation ha bn dignd to prmit th SLB managr to aily connct to diffrnt SLB implmntation and intrfac. A impl diagram dcribing th componnt dignd to upport th SLB Rgitration Protocol i providd by Figur 2. Th modul highlightd within Figur 2 illutrat th componnt dvlopd to upport th SLB Rgitration Protocol. Th Commrcial off th Shlf (COTS) SLB and th ral rvr hown within Figur 2 rprnt xtrnal componnt that would intrfac with th SLB Rgitration Protocol. For th lat 2 modul, th ral rvr i th rvr bing managd and th COTS SLB i th SLB application or applianc bing configurd by th SLB managr. 2 Thi i a pr-production vrion of Cico IOS with an mbddd Java Virtual Machin. Thi Cico IOS i currntly not availabl on any bai for commrcial u, howvr, Cico i willing to dicu acc to pr-rla IOS imag for rarch and xprimntation. 2003, Th MITRE Corporation. ALL RIGHTS RESERVED. 2 of 5

3 Srvic to Clint Routr Commrcial off th Shlf SLB Ral Srvr (Wb Srvr) 1..N Ral Srvr RS LAN SLB MGR Ral Srvr Rgitration RS MGR GSLB Notification NETWORK PERFORMANCE INFORMATION AND GSLB Our GSLB implmntation lvrag a partial DNS rvr calld Load Balanc Namd (LBNamd) [7]. W modifid LBNamd to accpt rvic rgitration and prformanc information from th SLB managr oftwar and to accpt ntwork prformanc information from Cico routr. Th Cico routr xcut a Java program to gathr and puh ntwork prformanc information to th GSLB. Figur 2. SLB Rgitration Protocol Softwar Componnt ROUTE INJECTION IMPLEMENTATION Th SLB managr will configur th local OSPF implmntation to injct a rout to advrti a nw VIP addr. To upport OSPF with th Linux Virtual Srvr w lvragd th opn ourc Zbra [6] routr implmntation. Th Java-bad SLB managr will automatically configur th Zbra OSPF to advrti th appropriat VIP rout for th Linux implmntation. For th Cico-bad SLB managr implmntation, w automatically configur th Cico to advrti a VIP rout via OSPF. On diffrnc btwn th LVS and Cico IOS SLB implmntation i aociatd with how th VIP i rprntd by th diffrnt ytm. Th LVS SLB implmntation rprnt a VIP addr a a condary IP addr on on of th computr ntwork intrfac card. Thi implmntation allow Zbra a OSPF to advrti th VIP addr a an intrnal OSPF rout. Cico IOS SLB implmntation rprnt th VIP a a tatic rout to a null intrfac. Thi rquir th VIP tatic rout to b rditributd into th routing protocol. For OSPF, thi man th VIP rout i advrtid a an xtrnal rout. By dfault, OSPF prfr an intrnal rout whn compard to a cond rout to th am dtination that i markd a xtrnal. Thrfor, whn uing ntwork layr anycat within a mixd LVS/Zbra and Cico IOS nvironmnt, all LVS SLB will b ud prior to any Cico IOS routr. OSPF do not prmit thi bhavior to b aily modifid. Othr routing protocol may b mor conduciv to avoiding thi limitation. Thi information includ th 5-minut input and output data rat for ky communication link. Th Java program on th Cico routr will alo intruct ky TOC WAN dg routr to rciv th multicat SLB Managr rvic notification mag. Onc th Cico routr rciv thi notification mag it will configur itlf to collct tranaction round trip tim (RTT) maurmnt btwn itlf and th nw rvic announcd. Obtaining RTT maurmnt data i nabld through th u of th Cico Srvic Auranc Agnt (SAA) [8]. Thi RTT data i providd to th GSLB. Clint Connction Clint DNS-Bad GSLB Srvr Load Balancr (SLB) Srvr Halth Rport Ral Srvr Srvr Rgitration Evnt DNS Rqut Srvic Halth Poll Srvr Halth Chck DNS Rpon VIP Halth Notification (DNS Rpon i bad upon rcivd SLB halth rport and rportd VIP RTT from Clint TOC Routr) VIP Halth Notification WAN Link Prformanc Rport Clint TOC Routr VIP RTT Maurmnt WAN Routr Figur 3. GSLB Componnt Intraction In addition to obtaining thi ntwork data and RTT data from ntwork ourc, th GSLB will b populatd with data that dcrib th ntwork topology. In particular, thi will includ information that map local DNS rvr addr to thir upportd IP ubntwork addr and WAN acc routr. Thi data will prmit th GSLB to aociat ntwork topology information with clint and rvr location. Combining thi information with ntwork and rvr prformanc maurmnt prmit th GSLB to provid clint with DNS rpon 2003, Th MITRE Corporation. ALL RIGHTS RESERVED. 3 of 5

4 that can lad to optimal clint-rvr rpon tim [9]. Figur 3 illutrat th flow btwn th variou ntwork componnt that affct th GSLB dciion proc. ENABLING ANYCAST Th Srvr Load Balancing Rgitration Protocol can b ud to automat upport for anycat tchnology. Sinc th protocol allow ditributd rvr to rgitr th am VIP addr with gographically diprd SLB Managr, ntwork layr anycat can b aily dployd. Each SLB Managr will injct th anycat VIP addr into th OSPF routing tabl from thir diprd location. Th OSPF routing protocol will b ud to automatically connct clint to th clot rvr. Thi implifi rvr location iu aociatd with finding ky rvr uch a DNS and othr dirctory rvr. In addition, thi protocol can prmit rvr to roam into diffrnt wirl cll without changing it VIP addr. If ach wirl cll i aociatd with a diffrnt IP ubnt, th rvr can gt a nw local IP addr via DHCP and till maintain a contant VIP addr by rgitring with a local SLB managr. If ncary, HTTP rdirct tchnology or anycat ARP can b ud to aociat a VIP-aignd wb rvr with a rvr uniqu ral IP addr. Th Srvr Load Balancing Rgitration Protocol can alo b ud to automat upport for application layr anycat a wll. In thi ca, parat diprd SLB managr will aign uniqu VIP to gographically diprd rvr providing th am or imilar rvic. Automatic inrtion of th VIP and rvic into th GSLB databa allow th opration of plug and play application layr anycat a wll. Th GSLB application will thn work to dirct clint to an optimal rvr. Th VIP addring, naming and prformanc information will b dicardd by th GSLB upon notification from th SLB managr or lot communication btwn th GSLB and SLB managr. Additional information on lvraging GSLB concpt for anycat ntwork with QoS can alo b found in [10]. ANYCAST ARPS Vido Tlconfrncing (VTC) can b upportd whn H.323 clint rgitr with H.323 Multipoint Control Unit (MCU). Anycat tchniqu will allow roaming H.323 clint to find th clot MCU. Alo, whn uing th SLB Rgitration Protocol th MCU rvr can roam anywhr in th ntwork and rgitr it anycat IP addr with a local SLB. Howvr, H.323 ignaling tchniqu allocat voic and vido UDP port numbr dynamically. Thi limit our ability to tak advantag of gnric rvr load balancing of MCU. In liu of uing load balancing to upport MCU H.323 connction, w can lvrag ntwork layr anycat ARP to allow th H.323 clint to find th uniqu addr of th MCU. Th clot SLB managr upporting th anycat IP addr will rpond to th anycat ARP rqut with th individual IP addr of all MCU locally rgitrd. Th lit will includ an MCU halth cor for ach rgitrd MCU. Th H.323 clint can pick a prfrrd MCU from thi lit and connct to th uniqu addr of th MCU. With thi prviou xampl, th H.323 clint mut know th IP anycat addr of th MCU. If thi i not known or poibl, an altrnativ anycat ARP implmntation will prmit th H.323 clint to rqut a lit of MCU anycat addr dirctly from th GSLB. In thi implmntation, th rpon from th GSLB will includ th uniqu addr of th SLB managr that maintain rgitrd MCU. Th GSLB will prioritiz th information within th rpon with a halth cor aociatd with ach SLB. Th clint can thn pick a prfrrd SLB managr and addr th anycat ARP dirctly to th SLB managr. Th SLB managr will rpond with th uniqu IP addr of th SLB dirctly attachd MCU. What mak our anycat ARP uniqu i that th clint rqut includ not only th anycat IP addr, but alo th rqutd application protocol (.g., HTTP or DNS), tranport protocol port numbr (.g., 80, 8080, 53), a wll a th tranport protocol typ (.g., ithr TCP or UDP). In liu of including thi dtaild information in th anycat ARP, a wildcard ntry will allow th SLB managr or GSLB to includ all rvic and aociatd halth cor for th anycat addr within th rpon. CONCLUSION Th SLB Rgitration Protocol i a impl and fficint way to automat anycat addring. By lvraging plug and play SLB configuration concpt, w ignificantly hlp to rduc complxity aociatd with rvr mobility in th battlfild. Through plug and play GSLB w hav nabld optimal rvr lction by uing both ntwork and rvr prformanc attribut. Our anycat ARP implmntation alo prmit protocol not normally upportd by SLB to function vry wll within our nvironmnt. 2003, Th MITRE Corporation. ALL RIGHTS RESERVED. 4 of 5

5 REFERENCES [1] T. Schrodr, S Goddard, B. Ramamurthy, Scalabl Wb Srvr Clutring Tchnologi, IEEE Ntwork, May/Jun 2000, pp [2] E. Zgura, M. Ammar, Z. Fi, S. Bhattacharj, Application Layr Anycating: A Srvr Slction Architctur and U in a Rplicatd Wb Srvic, IEEE/ACM Tranaction on Ntworking, Vol. 8, No. 4, Augut 2000, pp [3] J. Dilly, B. Magg, J. Parikh, H. Prokop, R. Sitaraman, B. Wihl, Globally Ditributd Contnt Dlivry, IEEE Intrnt Computing, Sptmbr/Octobr 2002, pp [4] Chri Mtz, IP Anycat Point-to-(Any) Point Communication, IEEE Intrnt Computing, March/April 2002, pp [5] [6] [7] /lbnamd/lbnamd.html/ [8] iowrl/p1830/product_fatur_guid09186a a78.html [9] R. Cartr and M. Crovlla, Dynamic Srvr Slction uing Bandwidth Probing in Wid Ara Ntwork, Computr Scinc Dpartmnt, Boton Univrity, BU-CS , March 18, [10] Fang Hao and Elln W. Zgura, QoS Routing for Anycat Communication: Motivation and an Architctur for DiffSrv Ntwork, IEEE Communication Magazin, Jun 2002, pp , Th MITRE Corporation. ALL RIGHTS RESERVED. 5 of 5