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http://www.3com.com/ Par t No. DU A173 0-0 BAA0 1 Publ ished Apr il 2002 Sup erStac k ® 3 Swit ch Im ple me nt ati on Guide Generic guide for units in the SuperStack 3 Swi tc h 4200 Series: 3C1 7300,.
3Com Cor poration 5400 Bayfr ont Plaza Santa Cl ara, Cali fornia 95052- 8145 Copyri ght © 200 2, 3Com T echno logies . All r ight s reserved . No part of this do cume ntation ma y be reprodu ced in a.
C ONTEN TS A BOUT T HIS G UIDE Conventions 8 Related Doc umentation 9 Documentation Comme nts 9 Product Regi s trati on 1 0 1 S WITCH F EATURES O VERVIEW What is Management Softw ar e? 13 Swit ch Feat.
3 U SING M ULTICAST F IL TERING Wha t is an IP Multic ast ? 2 7 Benefits o f Multicast 28 M ult ica st F ilter ing 28 Mult ica st Filt erin g an d Y our Swit ch 2 9 IG MP Mu ltic ast Filt er ing 3 0 4.
7 S TATUS M ONI TORIN G AND S TATIST ICS RMON 53 What is RMON? 53 The RMON Groups 54 Benefits o f RMON 54 RMON and the Switch 55 Alar m Events 5 6 The Defa u lt Al arm Settings 56 The Audi t Log 57 Em.
Configuration Rules w ith Full Duplex 77 B N ETWORK C ONF IGURATIO N E XAMPLE S Simple Network Configuration Exam ples 80 Segmen tation Swi tch Example 80 Collapsed Backbo ne Switch Examp le 81 Desk t.
A BOUT T HI S G UI DE This gui de describ es the features of the Super Stack ® 3 S w itch 4 200 Series and outl ines how to use the se featur es to optimize th e perf ormance of yo ur netwo rk. This gu ide is intend ed for the system or ne twor k admini strator who is r esponsible for c onfiguring, u sing, and managing the Switches.
8 A BOU T T HIS G UID E Conve ntions Ta b l e 1 an d Ta b l e 2 li st conve ntions t hat ar e used th r ough out this gui de. Ta b l e 1 Notice Icons Ic on Notice Type Descripti on In form atio n note.
Relat ed Docume ntation 9 Related Do cumen tati on In addi tion t o thi s gu ide, ea ch Sw itch docum en tat ion set incl ude s the fo llow i ng : ■ Gett ing Start ed Guide This gui de contains: ■.
10 A BOU T T HIS G UID E Pl ease include th e followi ng informat ion when co ntacting us: ■ Document title ■ Do cu ment par t n umb er ( on t he t it l e pag e) ■ Page numb er (if appr opria te.
I S WITCH F EAT UR E S Chapter 1 Swi tch Featur es Overvi ew Chapter 2 O pti mi zi ng B and wi dth Chapter 3 Using M ulticast Filteri ng Chapter 4 Using Re silience Fe atures Chapter 5 Using the Swit .
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1 S WITCH F EA TURES O VERV IEW This c hapt er conta ins int ro ductory inform ation ab out the Sup erStac k ® 3 Switch mana g ement software a nd suppor ted fe atures.
14 C HAPTER 1: S W ITCH F EATURES O VER VIE W Automatic IP Conf igur ati on By def ault th e Swit ch tries to confi g ur e i tself wi th IP in format ion with out r eq uesting user interven tion.
Swit ch Fea tures Expl ained 15 F or de tai l s of th e aut o- ne go ti ati on f ea tu re s s upp o rt ed b y y our Swit ch , please refe r to the Get ting Star ted Guid e that acc ompanies yo ur Switch. Ports o perat ing at 10 00 M bps on ly sup port full du plex m ode.
16 C HAPTER 1: S W ITCH F EATURES O VER VIE W Spannin g T r ee Pr otocol and Rapi d Span ning T ree Pr otocol Spann ing T ree Pro tocol (STP) and Rapid Span ning T r ee Protocol (R STP) ar e brid ge-b.
Swit ch Fea tures Expl ained 17 This sy stem is compatib le with the r elevant section s of the I EEE 802.1D/D17 stan dard (inc orporating IEEE 802.1p). For more inform atio n about 802.1 D and traffi c prio riti zati on, see Chapter 6 “ U si ng T ra ffic P rio ri ti zat io n” .
18 C HAPTER 1: S W ITCH F EATURES O VER VIE W VLANs A V irtua l LA N (V LAN ) is a flexib le g r o up o f de vices t hat can b e l ocat ed any where in a net work, but which communic ate as i f they ar e on the same ph ysical segm ent.
2 O PTIM IZIN G B ANDWIDTH There are m any wa ys you c an op timize the b a ndwidt h on y our netw ork and im prove n etw ork pe rfo rma nce. If you u til ize cer tain S witc h fe atures you ca n prov.
20 C HAPTER 2: O PTIMIZING B ANDWIDTH If t he dev ices a t eithe r end o f a link do no t suppo rt a uto-ne gotia tion, both en ds m ust be man ually se t to full duple x or hal f dup lex acc ordingly . Ports o perat ing at 10 00 M bps sup por t full du plex m ode o nly .
Po rt F eatur es 21 port and react acc ordingly . In other words, a uto- negotia tion ma y “ag ree” upon a con figurat ion that th e cable cann ot sustain ; smart au to-sens ing can det ect this an d adjust the l ink accor dingly .
22 C HAPTER 2: O PTIMIZING B ANDWIDTH Aggr egated Lin ks Aggr egated lin ks are c onnectio ns that all ow devic es to communicat e using up to tw o links in paral lel.
Ag g re gat ed Li nks 23 ■ I f p or ts of a di ffe ren t speed ar e aggr eg ated togeth er , t he higher speed links ca rry the tr aff ic. The lo wer speed lin ks onl y carry the traf fic if t he higher sp eed lin ks fail . ■ The aggr egated link d oes not support securit y .
24 C HAPTER 2: O PTIMIZING B ANDWIDTH T raff ic D istr ibu tion an d Link Fail ur e on A ggr egat ed Lin ks T o maximi ze thro ughput , all traf fic is di stri buted acr oss the indiv idual li nks that m ak e up an agg regat ed link.
Ag g re gat ed Li nks 25 Agg r egate d Link Exam ple The example sh own in Figu re 3 il lustrat es an 2 Gbps aggr egated l ink be twe en t wo S wi tch u ni ts. Figure 3 A 2 Gbps aggrega ted link between two S witch units T o set u p this config urati on: 1 Add t he 1000B ASE-T ports on the upper u nit to the ag gr egated link.
26 C HAPTER 2: O PTIMIZING B ANDWIDTH.
3 U SING M ULTICA ST F ILTERING Mul ticast f iltering improve s the p erf ormanc e of net works t hat ca rry mu lt ica st tr a ffic . This cha pter explains m ult icasts, mult icast fi ltering, and h ow mult icast filter ing c an be i mpl ement ed on yo ur Sw itch .
28 C HAPTER 3: U SING M ULTIC AST F ILTERING A multic ast packet is identi fied by t he presen ce of a multi cast gr oup addr ess in th e destinat ion addr ess fi eld of the pac ket’ s IP header .
Mult ic ast Filt erin g 29 Figure 4 The ef fect of mult icast filter ing Mult icast Fi lterin g and Y our Switc h Y our Switch pr ovides auto m at ic multi cast fil tering sup port usi ng IGMP (Inter net Group M anage m ent P r otoc ol) Sno oping . It also supp orts I GMP query m od e.
30 C HAPTER 3: U SING M ULTIC AST F ILTERING comma n d will c onfigure t he Sw itch 42 00 Series to auto mat ically nego tiate wi th c omp atible devic es on V LAN 1 to beco me t he qu erier . The Swit ch 4200 Serie s is compatible with any device that confo rms to the IGMP v2 protoco l.
IG MP Mult ic ast Filt erin g 31 I f IGMP mult icast l earn ing i s not enabled t hen I P multi cast tr aff ic is alway s forwa rded, th at is, it floods t he net wor k.
32 C HAPTER 3: U SING M ULTIC AST F ILTERING.
4 U SING R ESILIENC E F EA TUR ES Settin g up resilie nce o n your net work helps prote ct cri tical link s agai nst failure, prote cts aga inst ne twork l oops, a nd reduc es ne twork d ownt ime to a mi nimum. This c hapter ex plains th e featur es suppor ted by the Swi tch that pr o vide resi lie n ce fo r y o ur ne two rk .
34 C HAPTER 4: U SING R ESILIENCE F EATURES Rapi d Spa nnin g T re e Protoco l (RSTP) The Rapid Spannin g T ree (RSTP) is an enh anced Spanni ng T r ee featu re. RSTP imp lements the Spa nning T ree Algori thm and Pr otocol, as defined in the I EEE 802.
What is STP? 35 Figure 5 A network configurat ion that cr eates l oops Figu r e 6 shows the r esult of enabl ing STP on t he bri dges in the conf igurati on. STP detec ts the d uplicat e paths and p revent s, or block s , one of them fr om forwar ding traf fic, so this c onfiguration will work sat isfact orily .
36 C HAPTER 4: U SING R ESILIENCE F EATURES Figure 7 T raf f i c flowing through Br idge B STP det ermines whi ch is the most effi c ie nt path bet ween each bridge d segm ent and a specifi c al ly assig ned re fere n ce poi nt on the netwo rk. Once the most ef ficient path has b een determ ined, all other p aths ar e blocked.
How STP Wor ks 37 cost , the l ess eff ic ient the li nk. T able 3 shows the default port c osts for a Swi tch. Ta b l e 3 De fault p ort co sts STP C al culation The fi rst stage in th e S TP proces s is the c alculatio n stage.
38 C HAPTER 4: U SING R ESILIENCE F EATURES STP Co nfigura tion After al l the brid ges on the n etwork hav e agreed on the identit y of the Root B ridg e, and have est ablish ed the othe r relevant p.
How STP Wor ks 39 Figure 8 Po rt cost s in a netw ork ■ Bri dge A has the lowest Bridge Ident ifi er in the n etwork, and has ther efore been selected as the Root Bri dge. ■ Becau se Bridge A is t he Ro ot Brid ge, it is also the D esignated Br idge for LAN segment 1.
40 C HAPTER 4: U SING R ESILIENCE F EATURES ■ Bri dge C has been selected as the De signated Bridge fo r LAN segmen t 3, be cause i t offers th e low est Root Pa th Cos t for LAN Segme nt 3 : ■ the route through Bridges C and B costs 20 0 (C to B=1 00, B to A =100) ■ the rout e through Bridge s Y and B co sts 300 (Y to B =200, B to A =1 00).
How STP Wor ks 41 Figure 9 STP configur ations.
42 C HAPTER 4: U SING R ESILIENCE F EATURES Def ault Behavio r This sec tion con tains impor tant infor mation to note whe n using the RSTP and Fast Start fea tures, parti cularly if you alr eady have exist ing Switc h 4200 u nits in you r networ k wi th an ol der v ersion of soft ware.
Usin g STP on a Netwo rk with Multi ple VLANs 43 Figur e 10 Configuration tha t separates VLANs T o avoid any VLAN subdivisi on, it is r ecommended that all inter -Switch co nnect ions are made mem bers of all avai lable 802.1Q VLAN s to en sure connec tivit y at all times.
44 C HAPTER 4: U SING R ESILIENCE F EATURES.
5 U SING THE S WITCH D AT A BAS E What is th e Swit ch Dat abase? The Swit ch Database is u sed by the Swit ch to determ ine wher e a packet should be forwa rded t o, an d which port sh ould tran smit the packe t if it is to be fo rwar d ed.
46 C HAPTER 5: U SING THE S W ITCH D ATABASE Swit ch Dat abase En try St a te s Da ta b ase s en tr i es ca n h a ve th ree sta t es: ■ Lear ned — The Switch has plac ed the ent ry into the Switch Da tabase when a packet was r eceived fr o m an endstat ion .
6 U SING T RA F F IC P RIORITIZA TION Using t he t raffic pri oritiza tion ca pab ilities of your Swi tch al lows yo ur netwo rk tra f fic to be pri orit ized to ensu re th at hig h prio rity da ta is tra ns m itte d w ith m in imu m de la y .
48 C HAPTER 6: U SING T RA F FI C P RIOR ITIZA TION ■ Res our ce p lann ing appl ica tions — Use d by org aniza tions t hat r eq uir e p r edict able and r eli able acce s s to enter prise r es ource p lanning applic ations s uch as SAP .
Ho w Tr af fi c Prio r iti zati o n Wo rks 49 Y ou cannot alt er the mappi ng of the p riorities . These ar e fixed to the traf fic ty pes a s shown in Figure 1 1 .
50 C HAPTER 6: U SING T RA F FI C P RIOR ITIZA TION Figur e 12 DSCP Service Le vel Mapping Figu r e 1 2 ill ustrates h ow DiffSer v code point (DSCP) s ervice lev els are mapped to the two T raff ic Queue s. The DSCP servi ce level of the packet i s not alter ed by the Switc h 4200.
Tr af fi c Pr iori ti zati on and yo ur Sw itc h 51 How t raf fic is pr ocessed to pr ovide Qual ity of Serv ice A rec eived packet at the ing ress port is checked for it s DSCP and IEEE 802.1 D attribu tes to de termine t he level o f serv ice that t he packet should re c e i v e .
52 C HAPTER 6: U SING T RA F FI C P RIOR ITIZA TION somewher e else in the netwo rk and not in th e Switch 4200 . Note also tha t 802.1 D ser vice le vels a r e f ixed and c annot be altered. 3 Create Prof iles The next st ep i s to crea te a pro file, wh ich a sso ciat es classifier s with service levels.
7 S TA TUS M ONIT ORING AND S TA TIS TIC S This c hapter c ontains det ails of th e featur es t hat assist y ou with st atus moni toring and statistic s.
54 C HAPTER 7: S TATUS M ONI T ORI NG AND S TATISTICS the sa me net wor k as th e Sw itch and can m anage the S witc h by i n-band or out -of-ba nd co nnec tion s.
RMON and the Swit ch 55 addit ion, p r o bes reco rd the beh avior of yo ur ne tw ork, so th at you can analy ze the causes of pr oblems. ■ It r educ es the lo ad on t he netw ork and the mana geme .
56 C HAPTER 7: S TATUS M ONI T ORI NG AND S TATISTICS Alar m Events Y ou can defi ne up to 200 alar ms for th e S witch. The ev ents th at you ca n defi ne for eac h alarm and th eir r esulti ng action s are li sted in T able 5.
RMON and the Swit ch 57 The A udit Log The Switch keeps an audit lo g o f all manageme nt user session s, pro viding a record of a v arie ty of ch a nges, in cluding ones relating to RM ON . The log c an on ly be read b y u sers at th e security access leve l u si ng an SNMP Netwo rk Ma nag eme nt appl icatio n.
58 C HAPTER 7: S TATUS M ONI T ORI NG AND S TATISTICS Y ou can con figure the e mail address to w hic h you wi sh th e not ificatio ns to be sent. H ow ever , y ou ca nnot chang e th e fac tory defau lt no tifica tion mess ages fo r event ema ils. RMO N traps c onti nue to b e se nt, in a dditi on to an y em ail no tific ations you ma y re cei ve.
Hardwar e Stat us M onito ring 59 Figur e 13 Example C LI scr een te xt Figur e 14 Example of an indi vidual unit sy stem summary scr een ■ Via th e w e b. On th e Web int e rf ace , a n i nd ic ati on o f a ge ne r al ha rdw a re fa il ure w ill be pr ovided thr ough th e top-lev el System Su mmary inform ation screen.
60 C HAPTER 7: S TATUS M ONI T ORI NG AND S TATISTICS Figur e 15 Example device summary web page ■ RMO N T rap See “Events” on pa ge 54 fo r detail s of th is feat ure o f your Swit ch.
8 S E TTI NG U P V IRTUAL LAN S Sett ing up Vi rtual LA N s (VLAN s) on you r Swi tch r edu ce s the t ime and ef fort r equir ed by many net work administ rati on tasks, and incr eases th e efficie ncy of yo ur net work. This chapter explain s mor e abou t the c oncept of V LANs and exp lains ho w the y can be imp lem ented on your Sw itch.
62 C HAPTER 8: S ETTING U P V IRTUAL LAN S Figur e 16 A network setup showing thr ee VLANs Benefits of VLANs The main benef it of VLANs i s th at they pr o vid e a network seg m e ntati on sys tem that is far mor e fl exible than any tr aditi onal network.
VLAN s and Your Swit ch 63 ■ VLAN s he lp to control tra ffic W ith t radit ional netw orks, conge stion can be c ause d by broad cast traffic tha t is directe d to al l net work dev ices w hethe r th ey require it or not.
64 C HAPTER 8: S ETTING U P V IRTUAL LAN S VLANs: T agged a nd Unt agged Mem bership Y ou r Swi tch su pport s 802.1Q VLA N tag ging, a syst em tha t allows t raffic for mult iple VLANs to be carried on a single ph ysical (backbone) link. When settin g up V LANs yo u nee d to und erstand wh en t o use u ntagge d and ta gged me mbe rship of VLANs.
VLAN s and Your Swit ch 65 Conne cti ng VL ANS to Other VLANS I f the devices p laced in a VLAN need to communicate to devices in a different LAN , e ach VLA N requi re s a con nect ion to a router or Lay er 3 switchin g device.
66 C HAPTER 8: S ETTING U P V IRTUAL LAN S VLAN Config uration Exam ple s This se ction c onta ins exa mpl es of sim ple V LAN configu rat ions. It descri bes ho w to se t up y our switc h to su pport si mple u ntag ged an d tagge d conn ection s.
VLAN Confi gurati on Exampl es 67 2 Add p orts to the VLA Ns Ad d p or ts 10 , 11 an d 1 2 of the Swi t ch a s un t agg ed mem be rs t o VLA N 2. Usin g 802.1Q T ag ged Con necti ons In a netwo rk where t he VLANs are d istrib uted amongst more t han one Switch , you must use 802 .
68 C HAPTER 8: S ETTING U P V IRTUAL LAN S 3 Add port 12 o n Sw itch 1 to the V LAN s A dd por t 12 o n Sw itch 1 as a tagge d m ember of bo th V LANs 1 and 2 so that all VLAN traf f i c is passed over t he lin k to Switc h 2. 4 Co nfi gur e t he VLANs on Swi tch 2 Define VLAN 2.
9 U SING A UTO M ATI C IP C ONFIGURATIO N This c hapter ex plains mor e about IP addr esses and how t he automati c conf igur ation opt ion works . It co vers th e follo wing to pics: ■ How Y our Sw.
70 C HAPTER 9: U SING A UTOMA TIC IP C ONFIGU RATI ON How Y our Swi tch Obtains IP In formati on Y ou can use on e of the following met hods to alloc ate IP i nform ation to yo ur Swit ch (e sse ntial.
How Automat ic IP Confi guration Works 71 Autom atic Process T o de tect it s IP in formati on usi ng the a utom atic con figurat ion process, the S witch goes throu gh the f ollowi ng seq uence of st.
72 C HAPTER 9: U SING A UTOMA TIC IP C ONFIGU RATI ON Importa nt Conside ration s This se ction c onta ins som e impo rtant point s to no te wh en using the autom atic IP c onfigur ation feat ur e. The dynam ic nature of automatic ally configu red IP inform ation means that a Swit c h may change its IP ad dress whils t in use.
II A PP ENDI C ES AND I NDEX App endix A C onf igur ati on R ul es App endix B Network Confi guration Exampl es App endix C I P Addressing Glossary In de x.
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A C ONFIGURATIO N R ULES Config uration Rul es fo r Gig a b it Eth er net G ig abi t Et hern et is de sig ned t o run ov er se ver al me di a: ■ Singl e-mode fibe r opt ic cab le, w ith conn ect ions up to 5 km (3.1 mi les). S uppor t for d istances o ver 5 km is supp orted d epe ndin g on t he mo dule sp ecifi cation.
76 A PPENDIX A: C ON FI GUR A TI ON R ULES Config uration Rul es fo r Fas t E th er ne t The t opolo gy rule s for 100 M bps Fa st Ether net are slight ly different to those f or 10 M bps E ther n et. Figu r e 20 illust rates th e key t opology r ules and pr o vid es examples o f how they all ow for large-s cale Fas t Ethernet netw orks.
Confi gurati on Rul es f or F ast E therne t 77 colla psed backbo ne). F or e xamp le, a 225 m ( 738 ft) fib er link from a r ep eater to a r out er or sw itch, plus a 100 m (32 8 ft) UTP link from a r ep eater out to t he endst ation s.
78 A PPENDIX A: C ON FI GUR A TI ON R ULES.
B N ETW ORK C ONFIGURATI ON E XAMPLES Th is ch ap te r co n tai n s th e fol lo wi ng s e ct io ns : ■ Simple Net w or k Configurat ion Examples ■ Segmen tation Switch Ex ample ■ Collapsed Backb.
80 A PPENDIX B: N ETWORK C O NF IGU R AT ION E XAM PLE S Sim ple Netw ork Config uration Exam ple s The foll ow ing illu strations show some simp le examples of how the Switch 4200 f amil y and 4900 f amil y can be us ed in y our ne twor k.
Simpl e Network Conf igura tion Ex amples 81 Coll aps ed Back bone Switc h Exa m ple The example i n Figu r e 2 2 shows how a Switch 4 200 stack can ac t as a backb one f or bo th sha r ed and switch ed net wor k segment s.
82 A PPENDIX B: N ETWORK C O NF IGU R AT ION E XAM PLE S D eskt op S wi tch Exam ple The example i n Figu r e 2 3 sh ows ho w a Sw itch 42 00 ca n be used for a group of user s tha t require dedicat ed 10 M bps or 100 Mbps con nectio ns to th e deskto p.
Advanc ed Network Conf igura tion Ex amples 83 Ad vance d Ne twor k Config uration Exam ple s This sec tion s hows some netwo rk examples that il lustr ate how you can set up y our ne twor k for o ptimum perfor manc e using som e of th e feature s suppor ted by your Swi tch.
84 A PPENDIX B: N ETWORK C O NF IGU R AT ION E XAM PLE S Enhanc ing t h e Perform ance o f Y ou r Ne twork Figu r e 2 5 show s how you ca n se t your n etwor k up to e nhance its perfor mance .
C IP A DD R ESSIN G This ch ap ter provid es som e background detai l on the IP i nfor matio n tha t needs to be assi gned to you r Switch to ena ble you to man age it acr oss a networ k.
86 A PPENDIX C: IP A DDR ESSING 192.16 8.10 0. X (wh ere X is a nu mber betw een 1 a nd 25 4) wi th a su bnet mask 25 5.25 5.25 5.0. If yo u are usin g SLIP , u se the def ault SLIP add r ess of 192.16 8.10 1.1 with a su bnet mask o f 255. 255 .255.0.
IP A ddre sses 87 Dotted D ecim al Notation The actu al IP addr ess is a 3 2-bit nu mber that is sto red in binary f ormat. These 32 bi ts are segm ented into 4 groups of 8 bit s — each g r oup is r eferred to as a fi eld or a n oc te t .
88 A PPENDIX C: IP A DDR ESSING Subne ts and Subnet Masks Y ou can divide your IP netw ork into sub- netw orks also kn own as subn ets. Supp ort for subne ts is imp ortant bec ause the nu mber of bit s assigned t o the dev ice pa rt of an I P addr ess limit s the numbe r of devi ces that m ay be addr essed on an y given network.
Sub nets and Subn et Mask s 89 As sho wn in this ex ample , the 32 bits of an I P addr ess and subn et mask are u sually w ritten using an integ er shortha nd. T his n otation t ranslate s f our con sec ut iv e 8- bi t gr oup s (oc te t s) i nto f ou r in t ege rs th at r ang e fr om 0 thro ugh 255 .
90 A PPENDIX C: IP A DDR ESSING The sub net mask 25 5.25 5.255.2 55 is r eser ved as the defau lt broad cast addre ss. D e fau l t Ga te w ay s A gate way i s a dev ice on you r ne two rk wh ich is use d to forwa rd IP pac kets to a rem ote desti n atio n.
G LOSSARY 3Com N etwor k Supe rvis or The 3C om netwo rk m anageme nt ap plication used t o ma nage 3Com ’ s netw orking solutions. 10B ASE -T The IEEE specif ication fo r 10 Mbps Ethernet over Category 3, 4 or 5 twist ed pai r ca ble. 100B A SE-FX The IEEE sp ecific ation f or 100 Mbps Fast Ethernet over fiber -optic cable.
92 G LOSSARY Fast E ther net is 100 Mbp s, and the bandw idth of Gigabi t Eth erne t i s 10 00 Mbps . baud Th e signalli n g rat e of a line, that is, the number o f transi tions (volta ge or frequ ency chan ges) m ade pe r seco nd. Also k now n as line speed .
93 DHCP Dyn ami c H ost Cont rol Protocol. A prot ocol th at le ts you cen trally manag e a nd au tomate t he assign ment of Int erne t Protoco l (IP) addresses in a n org aniza tion's n etwor k . DNS Do main Name System. This s ystem maps a numerical In ternet Pr otocol (IP) addr ess to a mor e meanin g f ul and easy-to -r emember nam e.
94 G LOSSARY gat eway See rou ter . GBIC Gigabit In terface Conv erter . Giga bit Eth ernet I EEE standar d 802.3z fo r 1000 Mbps Ethernet; i t is compatible wit h existing 10/100 M bps Ether net stand ar d s. half du ple x A sy stem that all ows pac kets to t ransmi tted an d receive d, but not at the sam e time.
95 Inte rne t Grou p Manage ment Pr otocol Inter ne t Gr ou p Manage me nt Pr o tocol (IGMP) is a protoco l t hat runs betwe en hosts an d their im mediate neig hboring multi c ast rout ers. The protoco l allows a host to inf orm it s local router that it w ishes to r ec eive transm issions addresse d to a specific multi cast group.
96 G LOSSARY lo op An event t hat occur s when two network devi ces are connected by mor e than one pa th, ther eby causing pa ckets to r epeatedly cyc le ar o und the netwo rk and not r eac h their d es tination.
97 POS T Power On Se lf T est. An intern a l test that a Switch carries out wh en it is powered- up. QoS Profile Con si sts of multiple sets of rul es (classi f ier pl u s ser vice level combin ations) . The QoS profil e is assig ned to a port(s) . pr oto col A set of ru les for c omm unica tion be tween devi ces on a n etwo rk.
98 G LOSSARY st andar d servi ce level s, for ex ample, best e ffort , busines s crit ical, ne twork control, a nd so on. SLIP Se rial Li ne Int erne t P rot o col. A protoc ol tha t allow s IP to run over a serial line (con sole po rt) conne ction . SMTP Sim ple Ma il T ransfer Protocol.
99 TC P rel a tes to th e c on te n t o f th e d a ta tra v e lli ng thro u gh a ne two rk — ensu ring that th e infor mation sent ar rives in one piece when it r eaches i ts destinat ion. IP r elates to the addr ess of the endst ati on to which d ata is bei ng sen t, as w ell as the address of the de stination n etwo rk.
100 G LOSSARY.
I NDEX Numbers 802.1 D prio rity le vel s 48 tr affic cl as si fica ti on 4 8 802.1 Q t aggin g 64 A addr esses cla sses 87 IP 85 aggr eg ated l inks 14, 22 ex am pl e 25 agin g time, definit ion 4 6 .
102 I NDEX IGM P mu ltic a st fi lter in g 3 0 Inte rnet ad dres ses 85 In terN IC 86 IP ( Internet Pr otocol) ad dres ses 86 IP add res s 14, 70, 85 clas se s of 87 defi ned 86 deri vati on 86 divi s.
I NDEX 103 Root Por t 37 using on a networ k with mul tiple VL ANs 42 su bnet mask 88 defi ned 88 exam ple 88 numbe ring 89 su bnets 88 su bnetwork ing defi ned 88 su bnet mask 88 su b-networ ks. See su bnets Switc h Databas e 45 T topol ogy rul es for Fast E thernet 76 topol ogy rul es wit h full dupl ex 77 traf fic c l as sif icati on 802.
An important point after buying a device 3Com 3 (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
If you have not bought 3Com 3 yet, this is a good time to familiarize yourself with the basic data on the product. First of all view first pages of the manual, you can find above. You should find there the most important technical data 3Com 3 - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, 3Com 3 you will learn all the available features of the product, as well as information on its operation. The information that you get 3Com 3 will certainly help you make a decision on the purchase.
If you already are a holder of 3Com 3, but have not read the manual yet, you should do it for the reasons described above. You will learn then if you properly used the available features, and whether you have not made any mistakes, which can shorten the lifetime 3Com 3.
However, one of the most important roles played by the user manual is to help in solving problems with 3Com 3. Almost always you will find there Troubleshooting, which are the most frequently occurring failures and malfunctions of the device 3Com 3 along with tips on how to solve them. Even if you fail to solve the problem, the manual will show you a further procedure – contact to the customer service center or the nearest service center
