Ccnav2 Chapter 4 Notes - C4

Chapter 4 2/9/2016  CCNA 2 Chapter 4 - Routers Routers: - Route outerrs are are Compu omputters ers It has has a CPU CPU,, OS (Rou (Router ters s use Cisc Cisco o IOS) IOS),, Memor Memory y & Stora Storage ge (RAM/ROM/NRAM/!"AS#/#$) Importa%t a'e a'e - Router Compo%e%ts (o Memory) RAM oatie - Ru%%i%g IOS Ru%%i%g Co%ig !ie IP Routi%g &  ARP a'e a'e Pac*et +u +uer   ROM No%-oatie NRAM No%-oatie +oo*up I%structio%s +asic $i $iag%ostic Sotare "imite IOS - Startup Co%ig !ies IO IOS Other Sy System !ie !"AS# No%-oatie Routers use speciai.e ports a% %etor* i%terace cars to i%terco%%ect to other %etor*s - Rout Router ers s co% co%%e %ect ct mut mutip ipe e %et %etor or*s *s Router Routers s ha0e mut mutip ipe e i%ter i%terace aces, s, each each o% a ier iere%t e%t IP IP %eto %etor* r* 1 Routers Choose Best Paths Routers use static routes a% y%amic routi%g protocos to ear% a'out remote %etor*s a% 'ui their routi%g ta'es Routers use routi%g ta'es to etermi%e the 'est path to se% pac*ets Routers e%capsuates the pac*et a% orars it to the i%terace i%icate i% the routi%g ta'e 1 Packet Forwarding Methods Process Switching A% oer pac*et orari%g mecha%ism sti a0aia'e or Cisco router Fast Switching A commo% pac*et orari%g mecha%ism hich uses a ast-sitchi%g cache to store %e2t-hop i%ormatio% Cisco Epress Forwarding !CEF" he most rece%t, astest, a% preerre Cisco IOS pac*et-orari%g mecha%ism a'e e%tries are %ot pac*et-triggere i*e ast sitchi%g 'ut cha%ge-triggere 1 #e$au%t &atewa's o e%a'e %etor* access e0ices must 'e co%igure ith the ooi%g IP aress i%ormatio%3 IP Aress Ie%tiies u%i4ue host o% oca %etor* Su'%et Mas* Ie%tiies the host5s %etor* su'%et $eaut 6ateay "$R 7#o to get out o the %etor*8 1 Ena(%e )P on a *ost - - 1 Statica%%' Assigned )P Address Ma%uay assig%e IP Use to ie%tiy speciic %etor* resources such as ser0ers/pri%ters Ca% 'e use i% sma %etor*s ith itte amou%t o hosts #'na+ica%%' Assigned )P Address Automaticay o'tai%e IP aress !rom $#CP Ser0er Most hosts ac4uire their IP aress i%ormatio% through $#CP #e,ice E#s - "ights o% the 'ac* o the router pro0ie i%ormatio% i %eee 1 Conso%e Access - Co%soe Access re4uires9 A computer ith proper sotare (see thir item3 termi%a emu) - Co%soe Ca'e (R:-;< to $+= Co%soe Ca'e) ermi%a >muatio% Sotare3 eraerm/ Pu?/ #yperermi%a 1 Ena(%ing )P on a Switch I%rastructure e0ices re4uire IP aresses Ma%ageme%t IP aresses is assig%e o% a 0irtua i%terace 1 Con$igure Basic Router Settings Name the $e0ice $isti%guish the router5s %ame rom other routers Secure Ma%ageme%t Access Secure pri0iege e2ec, user e2ec, te%et access, a% e%crypte passors 1 Con$igure )P,4 Router )nter$ace o Co%igure3 - Co%igure ith a% IP & Su'%et Aress Must use @%o shuto%5 Seria Ca'e usi%g @$C>5 must ha0e a coc* rate Pro0ie a escriptio% 1 Con$igure )P,. Router )nter$ace o Co%igure3 Use IP0 aress (i%* oca / eui-;) Acti0ate usi%g @%o sh5 IP0 supports more tha% o%e aress Co%igure a speciie go'a u%icast aress (ar/e%gth) Co%igure a go'a IP0 Aress ith a% I%terace I$ i% the o orer ; 'its Co%igure a i%*-oca aress 1 Con$igure a oop(ack Address A oop'ac* i%terace is a ogica i%terace that is i%ter%a to the router It is %ot assig%e to a physica port, it is co%siere a sotare i%terace A oop'ac* i%terace is use or testi%g It is importa%t i% the OSP! routi%g process 1 /eri$' )nter$ace Settings Sho comma%s are use to 0eriy operatio% a% co%iguratio% o i%terace3 sho ip i%t 'rie  sho ip route - sho ru%%i%g-co%ig sho i%terace 9 sho ip i%teraces - ?ou ca% iter sho comma%s Use the @termi%a e%gth B%um'er15 comma% to speciy the %um'er o i%es to 'e ispaye o iter out speciic output o comma%s, use the 78 pipe character Ca% use parameters to iter3 sectio%, i%cue, e2cue, a% 'egi% 1 Best Path +est path is seecte 'y a routi%g protoco 'ase o% the 0aue or metric it uses to etermi%e the ista%ce o a %etor* A metric is the 0aue use to measure the ista%ce to a gi0e% %etor* +est path to a %etor* is the path ith the oest %etor* $y%amic routi%g protocos use their o% rues a% metrics to 'ui a% upate ta'es3 Routi%g I%ormatio% Protoco (RIP) - #op Cou%t Ope% Shortest Path !irst (OSP!) - Cost-'ase o% cumuati0e 'a%ith rom source to esti%atio% >%ha%ce I%terior 6ateay Routi%g Protoco (>I6RP) +a%ith, eay, oa, reia'iity 1 oad Ba%ancing Dhe% a router has to or more paths to a esti%atio% ith e4ua cost metrics, the% the router orars the pac*ets usi%g 'oth paths e4uay3 >4ua cost oa 'aa%ci%g ca% impro0e %etor* perorma%ce >4ua cost oa 'aa%ci%g ca% 'e co%igure to use 'oth  y%amic routi%g protoco a% static routes 1 Ad+inistrati,e #istance I mutipe paths to a esti%atio% are co%igure o% a router, the path i%stae i% the routi%g ta'e is the o%e ith the oest  Ami%istrati0e $ista%ce (A$) A static route ith a% A$ o E is more reia'e tha% a% >I6RP isco0ere route ith a% A$ o =F A irecty co%%ecte route ith a% A$ o F is more reia'e tha% a static route ith a% A$ o E $iagram3 - 1 1 Routing 0a(%e Sources show ip route $ispay the co%te%ts o the routi%g ta'e %oca% route inter$aces Ae to the routi%g ta'e he% a% i%terace is co%igure direct%' connected inter$aces Ae to the routi%g ta'e he% a% i%t is co%igure a% acti0e static routes Ae he% a route is ma%uay co%igure a% the e2it i%terace is acti0e d'na+ic routing protoco% Ae he% >I6RP or OSP! are impeme%te %etor*s are ie%tiie Static Routes - Static routes a% eaut static routes ca% 'e impeme%te ater irecty co%%ecte i%teraces are ae to the routi%g ta'e 1 #'na+ic Routing - Dhere the routers 7o the or* or us8 $y%amic routi%g is use 'y routers to share i%ormatio% a'out the reacha'iity a% status o remote %etor*s It perorms %etor* isco0ery a% mai%tai%s routi%g ta'es >I6RP - OSP! - IS-IS - etc
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Chapter 4

CCNA 2 Chapter 4 - Routers

Routers are Computers
- It has a CPU, OS (Routers use Cisco IOS), Memory & Storage

Important Table - Router Components (of Memory)



Running IOS
Running Config

- IP Routing &
ARP Table
- Packet Buffer




- Bookup
- Basic Diagnostic
- Limited IOS

Startup Config


Other System



Routers use specialized ports and network interface cards to interconnect to other networks.


Routers connect multiple networks.
Routers have multiple interfaces, each on a different IP network.

Default Gateway . Table entries are not packet-triggered like fast switching but change-triggered.Subnet Mask .Process Switching . .Routers use routing tables to determine the best path to send packets. .From DHCP Server. Device LEDs - Lights on the back of the router provide information if needed.Can be used in small networks with little amount of hosts.Identifies the host’s network subnet.Identifies unique host on local network.An older packet forwarding mechanism still available for Cisco router. fastest. > Default Gateways .Fast Switching . .TLDR “How to get out of the network”. > Packet Forwarding Methods .Cisco Express Forwarding (CEF) . .Routers encapsulates the packet and forwards it to the interface indicated in the routing table. Dynamically Assigned IP Address .The most recent.Manually assigned IP.Automatically obtained IP address.Used to identify specific network resources such as servers/printers.A common packet forwarding mechanism which uses a fast-switching cache to store next-hop information.Routers use static routes and dynamic routing protocols to learn about remote networks and build their routing tables. . . . . . and preferred Cisco IOS packet-forwarding mechanism.To enable network access devices must be configured with the following IP address information: .> Routers Choose Best Paths .IP Address . . .Most hosts acquire their IP address information through DHCP. > Enable IP on a Host - - > Statically Assigned IP Address .

Configure a global IPv6 Address with an Interface ID in the low order 64 bits. . telnet access. Terminal Emulation Software: TeraTerm/ PuTTY/ HyperTerminal.Secure Management Access .Use IPv6 address (link local / eui-64).Infrastructure devices require IP addresses. .It is important in the OSPF routing process.A loopback interface is a logical interface that is internal to the router. .A computer with proper software (see third item: terminal emu). and encrypted passwords. > Configure Basic Router Settings .Configure a specified global unicast address (addr/length). > Verify Interface Settings . . it is considered a software interface. > Configure IPv6 Router Interface .Configure a link-local address. Must use ‘no shutdown’. .Secure privileged exec. > Configure a Loopback Address . .A loopback interface is used for testing. Serial Cable using ‘DCE’ must have a clock rate.To Configure: . .show ip int brief . . > Configure IPv4 Router Interface .Show commands are used to verify operation and configuration of interface: .Distinguish the router’s name from other ip route .IPv6 supports more than one address.Activate using ‘no sh’.To Configure: - Configured with an IP & Subnet Address.It is not assigned to a physical port.Management IP addresses is assigned on a virtual interface. - Console Cable (RJ-45 to DB9 Console Cable). > Enabling IP on a Switch . .> Console Access - Console Access requires… . Provide a description. user exec.Name the Device . .

When a router has two or more paths to a destination with equal cost metrics.Diagram: .Open Shortest Path First (OSPF) . > Administrative Distance . the path installed in the routing table is the one with the lowest Administrative Distance (AD).Dynamic routing protocols use their own rules and metrics to build and update tables: .Can use parameters to filter: . . reliability.A static route with an AD of 1 is more reliable than an EIGRP discovered route with an AD of 90. exclude.- show running-config show interface … show ip interfaces - You can filter show commands. use the “|” pipe character. .Best path to a network is the path with the lowest network.Cost-based on cumulative bandwidth from source to destination. .Routing Information Protocol (RIP) . . .To filter out specific output of commands.section.Equal cost load balancing can be configured to use both dynamic routing protocol and static routes.Enhanced Interior Gateway Routing Protocol (EIGRP) Bandwidth. .A metric is the value used to measure the distance to a given network. > Load Balancing . .Hop Count . load. delay.Use the ‘terminal length <number>’ command to specify the number of lines to be displayed. then the router forwards the packets using both paths equally: .If multiple paths to a destination are configured on a router. . include. . .Equal cost load balancing can improve network performance.Best path is selected by a routing protocol based on the value or metric it uses to determine the distance of a network.A directly connected route with an AD of 0 is more reliable than a static route with an AD of 1. and begin > Best Path . .

.dynamic routing protocol . .Added to the routing table when an interface is configured.local route interfaces .- > > Routing Table Sources .Added when a route is manually configured and the exit interface is active.directly connected interfaces .show ip route . . .Display the contents of the routing table.Added to the routing table when an int is configured and active.static routes . Static Routes .Added when EIGRP or OSPF are implemented networks are identified.

.- Static routes and default static routes can be implemented after directly connected interfaces are added to the routing table. > Dynamic Routing - Where the routers “do the work for us”.

. EIGRP - OSPF - IS-IS - etc.Dynamic routing is used by routers to share information about the reachability and status of remote networks. It performs network discovery and maintains routing tables....