Ch!"ther 1 $und!ment!ls %evie&
CCNP R&S SWITCH: Implementing IP Switching
Chapter 1 Objectives
S&itch '"er!tion, (!yer 2 S&itch '"er!tion, )r!ns"!rent *ridging
+thernet 'vervie&, S&itch Port Conigur!tion
*!sic -einition /(As !nd )runs, )r!dition!l S"!nning )ree Protocol, Aggreg!ting S&itch (ins, S&itch Port Aggreg!tion Aggreg!tion &ith +therCh!nnel. +therCh!nnel.
*!sic -einition ultil!yer S&itch '"er!tion
3ubs !nd S&tiches, *ridges !nd S&itches, *ro!dc!st -om!ins, )he *!sic +thernet $r!me $orm!t, *!sic S&itching $unction, /(As, )he S"!nning )ree Protocol, )runing, Port4Ch!nnels, ulti(!yer S&itching 5(S6
Ch!"ther 1 $und!ment!ls %evie&
a!er " Switch Operati#n An +thernet s&itch o"er!tes !t 'SI (!yer 2, m!ing decisions !bout or&!rding r!mes b!sed on the destin!tion AC !ddresses ound &ithin the r!mes. )his me!ns th!t the +thernet medi! is no longer sh!red !mong connected devices. Inste!d, !t its most b!sic level, !n +thernet s&itch "rovides isol!tion bet&een connected hosts in sever!l &!ys
)he collision dom!in9s sco"e is severely limited. 3ost connections c!n o"er!te in ull4du"le: mode bec!use there is no contention on the medi!. *!nd&idth is no longer sh!red +rrors in r!mes !re not "ro"!g!ted ;ou c!n limit bro!dc!st tr!ic to ! volume threshold.
Transparent $ri%ging A (!yer 2 s&itch is b!sic!lly ! multi"ort tr!ns"!rent bridge, &here e!ch s&itch "ort is its o&n +thernet (A segment, isol!ted rom the others. $r!me or&!rding is b!sed com"letely on the AC !ddresses cont!ined in e!ch r!me, such th!t the s&itch &ill not or&!rd ! r!me unless it no&s the destin!tion9s loc!tion.
Transparent $ri%ging
thernet Overview +thernet is ! (A technology b!sed on the Institute o +lectric!l !nd +lectronics +ngineers 5I+++6 =02. st!nd!rd. +thernet oers ! s"eciic b!nd&idth bet&een end users. In its most b!sic orm, +thernet is ! sh!red medium th!t becomes both ! collision !nd ! bro!dc!st dom!in. +thernet is b!sed on the c!rrier sense multi"le !ccess collision detect 5CSA>C-6 technology,&hich re?uires th!t tr!nsmitting st!tions b!c o or ! r!ndom "eriod o time &hen ! collision occurs. I ! st!tion must &!it its turn to tr!nsmit, it c!nnot tr!nsmit !nd receive !t the s!me time. )his is c!lled half-duplex o"er!tion.
thernet Overview )y"ic!lly, e!ch gener!tion o +thernet oers ! ten4old b!nd&idth im"rovement. +ven so, the +thernet c!bling schemes, CSA>Co"er!tion, !nd !ll u""er4l!yer "rotocol o"er!tions !re m!int!ined &ith e!ch gener!tion. )he net result is the s!me d!t! lin edi! Access Control 5AC6 l!yer 5'SI (!yer 26 merged &ith ! ne& "hysic!l l!yer 5'SI (!yer16.
thernet Overview $!st +thernet 104ig!bit +thernet
ig!bit +thernet
'irt(al )Ns *y deinition, ! /(A is ! single bro!dc!st dom!in. All devices connected to the /(A receive bro!dc!sts sent by !ny other /(A members. 3o&ever, devices connected to ! dierent /(A &ill not receive those s!me bro!dc!sts.
')N *embership Bhen ! /(A is "rovided !t !n !ccess l!yer s&itch, !n end user must h!ve some me!ns o g!ining membershi" to it. )&o membershi" methods e:ist on Cisco C!t!lyst s&itches
St!tic
/(A
conigur!tion
St!tic
/(As
oer
"ort4b!sed
membershi", in &hich s&itch "orts !re !ssigned to s"eciic /(As.
-yn!mic /(A !ssignment -yn!mic /(As "rovide membershi" b!sed on the AC !ddress o !n end4user device, r!ther th!n the s&itch "ort &here it is connected.
I +,"-1. Overview
A robust net&or design not only includes eicient tr!nser o "!cets or r!mes, but !lso considers ho& to recover ?uicly rom !ults in the net&or. In ! (!yer environment, the routing "rotocols in use ee" tr!c o redund!nt "!ths to ! destin!tion net&or so th!t ! second!ry "!th c!n be used ?uicly i the "rim!ry "!th !ils. (!yer routing !llo&s m!ny "!ths to ! destin!tion to rem!in u" !nd !ctive, !nd !llo&s lo!d sh!ring !cross multi"le "!ths. In ! (!yer 2 environment 5s&itching or bridging6, ho&ever, no routing "rotocols !re used, !nd !ctive redund!nt "!ths !re neither !llo&ed nor desir!ble. Inste!d, some orm o bridging "rovides d!t! tr!ns"ort bet&een net&ors or s&itch "orts. )he S"!nning )ree Protocol 5S)P6 "rovides net&or lin redund!ncy so th!t ! (!yer 2 s&itched net&or c!n recover rom !ilures &ithout intervention in ! timely m!nner. )he S)P is deined in the I+++ =02.1- st!nd!rd.
')N Tr(n/s
')N 0rame I%entiicati#n /(A identiic!tion c!n be "erormed using t&o methods, e!ch using ! dierent r!me identiier mech!nism
Inter4S&itch (in 5IS(6 "rotocol "rotocol is ! Cisco4"ro"riet!ry method or "reserving the source /(A identiic!tion o r!mes "!ssing over ! trun lin.
')N 0rame I%entiicati#n /(A identiic!tion c!n be "erormed using t&o methods, e!ch using ! dierent r!me identiier mech!nism
I+++ =02.1 "rotocol )he I+++ =02.1 "rotocol !lso c!n c!rry /(A !ssoci!tions over trun lins.
)ggregating Switch in/s
Cisco oers !nother method o sc!ling lin b!nd&idth by !ggreg!ting, or bundling, "!r!llel lins, termed the EtherChannel technology. )&o to eight lins o either $!st +thernet 5$+6, ig!bit +thernet 5+6, or 104ig!bit +thernet 510+6 c!n be bundled !s one logic!l lin o $!st +therCh!nnel 5$+C6, ig!bit +therCh!nnel 5+C6, or 104ig!bit +therch!nnel 510+C6, res"ectively.
*(ltila!er Switch Operati#n !ny Cisco C!t!lyst s&itches c!n !lso or&!rd r!mes b!sed on (!yers !nd 8 inorm!tion cont!ined in "!cets. )his is no&n !s
multilayer switching 5(S6. !tur!lly, (!yer 2 s&itching is "erormed !t the s!me time bec!use even the higher4l!yer enc!"sul!tions still !re cont!ined in +thernet r!mes.
T!pes # *(ltila!er Switching: C!t!lyst s&itches h!ve su""orted t&o b!sic gener!tions or ty"es o (S
route c!ching 5irst4gener!tion (S6 !nd
5second4gener!tion (S6.
to"ology b!sed
*(ltila!er Switch Operati#n
R#(te caching: )he irst gener!tion o (S, re?uiring ! route "rocessor 5%P6 !nd ! s&itch engine 5S+6. )he %P must "rocess ! tr!ic lo&9s irst "!cet to determine the destin!tion. )he S+ listens to the irst "!cet !nd to the resulting destin!tion, !nd then sets u" ! DshortcutE entry in its (S c!che. )he S+ or&!rds subse?uent "!cets belonging to the s!me tr!ic lo& b!sed on shortcut entries in its c!che.
*(ltila!er Switch Operati#n )o"ology b!sed )he second gener!tion o (S, utiliFing s"eci!liFed h!rd&!re, is !lso org!niFed &ith distinct %P !nd S+ unctions. )he %P uses (!yer routing inorm!tion to build !nd "re"o"ul!te ! single d!t!b!se o the entire no&n net&or to"ology. )his d!t!b!se becomes !n eicient t!ble loou" in h!rd&!re, !nd is consulted so th!t "!cets c!n be or&!rded !t high r!tes by the S+. )his ty"e o (S is no&n !s Cisco +:"ress $or&!rding 5C+$6. A routing "rocess running on the s&itch do&nlo!ds the current routing t!ble d!t!b!se into the $or&!rding Inorm!tion *!se 5$I*6 !re! o h!rd&!re.
Ch!"ther 1 $und!ment!ls %evie&
Tcl Script Reerence an% .em#nstrati#n )cl scri"ts c!n be cre!ted to !ccom"lish routine !nd re"etitive unctions &ith Cisco I'S4b!sed net&oring devices. )o construct ! sim"le connectivity veriic!tion scri"t, do the ollo&ing. '"en ! te:t editor !nd cre!te ! ne& te:t ile. Gsing ! te:t ile s!ves time, es"eci!lly i you !re "!sting the )cl scri"t into multi"le devices. St!rt &ith the tclsh comm!nd to enter )cl shell mode in &hich you c!n use n!tive )cl instructions lie ore!ch or issue +H+C mode comm!nds. ;ou c!n !lso !ccess conigur!tion mode rom &ithin the )cl shell !nd issue conigur!tion comm!nds rom their res"ective menus, !lthough these e!tures !re not e:"lored in this l!b.
Tcl Script Reerence an% .em#nstrati#n %1# tclsh %15tcl6# *egin ! loo" using the #reach instr(cti#n- The l##p iterates #ver a
se2(ence # val(es3 e4ec(ting a deined se?uence o instructions once for each value. Think of it as “for each value in alues, do each
instruction in !nstructions." #or each iteration of the loop, $identifier reflects the current value in alues. The foreach instruction uses the following model
Tcl Script Reerence an% .em#nstrati#n The foreach instruction uses the following model #reach identifier { v!lue1 v!lue2 ... v!lueH J instruction1 Instruction2 ... instruction; #reach a%%ress 5 1,-1-1-1 1,-1-"-1 1,-1-6-1 1,-"-1-1 1,-"-"-1 1,-"-6-1 J ping 7a%%ress 8
Chapter 1 S(mmar! *!sic -einition *ridges !nd S&itches, *ro!dc!st -om!ins, AC Addresses, )he *!sic +thernet $r!me $orm!t, *!sic S&itching $unction, /(As, )he S"!nning )ree Protocol )runing, Port4Ch!nnels, ulti(!yer S&itching 5(S6
ote
AC Address det!ils !nd
det!ilsK )his is ! CCA4(evel )!s
r!me orm!t
Chapter 1 abs
Ch!"ter 1 (!b 4 Pre"!ring the S&itch
