Router Configuration

CISCO 2500 series router

A router is a special type of computer. It has the same basic components as a standard desktop PC. It has a CPU, memory, a system bus, and various input/output interfaces.

Router Components: RAM RAM has the following characteristics and functions: Stores routing tables Holds ARP cache Holds fast-switching cache Performs packet buffering as shared RAM Maintains packet-hold queues Provides temporary memory for the configuration file of a router while the router is powered on Loses content when a router is powered down or restarted

Router Components: NVRAM NVRAM has the following characteristics and functions: Provides storage for the startup configuration file Retains content when a router is powered down or restarted

Router Components: Flash memory Flash memory has the following characteristics and functions: Holds the IOS image Allows software to be updated without removing and replacing chips on the processor Retains content when a router is powered down or restarted Can store multiple versions of IOS software Is a type of electrically erasable programmable read-only memory (EEPROM)

Router Components: ROM ROM has the following characteristics and functions: Maintains instructions for power-on self test (POST) diagnostics Stores bootstrap program and basic operating system software Requires replacing pluggable chips on the motherboard for software upgrades

Router Components: Interfaces Interfaces have the following characteristics and functions: Connect routers to a network for packet entry and exit Can be on the motherboard or on a separate module

Console port connections

Router Configuration

Cisco IOS Software Basic routing and switching functions Reliable and secure access to networked resources Network scalability Router> show version … cisco 2620 (MPC860) processor (revision 0x102) with 59392K/6144K bytes of memory Router>show flash

Router# configure terminal Router(config)# Type exit or Ctrl-Z to return Router(config)#hostname Tokyo Tokyo(config)# Router(config)#line console 0 Router(config-line)#login Router(config-line)#password

show commands show ? – any time for help with commands type ? Router# show interfaces serial 0/1 show clock - Shows the time set in the router show hosts - Displays a cached list of host names and addresses show users - Displays all users who are connected to the router show history - Displays a history of commands show flash - information about flash memory and IOS files show version - currently loaded software version and hardware show protocols - status of configured Layer 3 protocols show startup-config - saved configuration located in NVRAM show running-config

Configuring interfaces Router(config)#interface serial 0/0 Router(config-if)# ip address Router(config)#interface serial 0/0 Router(config-if)#clock rate Router(config-if)#no shutdown Router#copy running-config startup-config Router#erase startup-config

Routing and Routing Protocols dynamic routing, static routing –ip route command to manually configure a static route. –administrative distance is an optional parameter that indicates the reliability of a route. –waycross(config)# ip route –Route can be configure by outgoing interface or next hop ip address. –default route is given by ip route [next-hop-address | outgoing interface ]

Routing and Routing Protocols

Dynamic Routing Two types of dynamic routing: Distance vector Link-state routing protocols: Routing Information Protocol (RIP) Interior Gateway Routing Protocol (IGRP) Enhanced Interior Gateway Routing Protocol (EIGRP) Open Shortest Path First (OSPF) routed protocols : Internet Protocol (IP) Internetwork Packet Exchange (IPX) Autonomous systems - 16-bit identification number –Routing protocols, e.g. Cisco IGRP, require assignment of a unique AS

Dynamic Routing

Configuring Dynamic Routing BHM(config) #router rip – Selects RIP as the routing protocol BHM(config-router) #network – Specifies a directly connected network BHM(config-router) # network – Specifies a directly connected network RIP was originally specified in RFC 1058 : –It is a distance vector routing protocol. –Hop count is used as the metric for path selection. –If the hop count is greater than 15, the packet is discarded. –Routing updates are broadcast every 30 seconds, by default. –Load balancing among multiple equidistance path

Troubleshooting ABC#show ip protocols ABC#show ip route ABC#show interface interface ABC#show ip interface interface ABC#show running-config show ip rip database show ip protocols {summary} debug ip rip {events} ip interface brief

IGRP IGRP uses the following metrics: –Bandwidth – The lowest bandwidth value in the path –Delay – The cumulative interface delay along the path –Reliability – The reliability on the link toward the destination as determined by the exchange of keepalives –Load – The load

RouterA(config) #router igrp as-number

More on Routing… OSPF and EIGRP EGP and IGP Switching VLAN Access Control List (ACL)

OSPF OSPF is a nonproprietary link-state routing protocol. –It is a link-state routing protocol. –It is an open standard routing protocol described in RFC –The SPF algorithm is used to calculate the lowest cost to a destination. –Routing updates are flooded as topology changes occur. # router ospf process-id # network net-address wildcard-mask area area-id

EIGRP EIGRP is a Cisco proprietary enhanced distance vector routing protocol. –It is an enhanced distance vector routing protocol. –It uses unequal cost load balancing. –It uses a combination of distance vector and link-state features (hybrid). –It uses Diffused Update Algorithm (DUAL) to calculate the shortest path. –Routing updates are multicast using triggered by topology changes. Max hop 255 RA(config-router)# router eigrp autonomous- system-number RA(config-router)# network network-number

BGP Border Gateway Protocol (BGP) is an exterior routing protocol. –It is a distance vector exterior routing protocol. –It is used between ISPs or ISPs and clients. –It is used to route Internet traffic between autonomous systems.