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  • S i R iStatic Routing

    Routing Protocols andRouting Protocols and Concepts Chapter 2

    2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1

  • ObjectivesDefine the general role a router plays in networks.

    Describe the directly connected networks, different router interfaces

    E i di tl t d t k i th tiExamine directly connected networks in the routing table and use the CDP protocol

    Describe static routes with exit interfacesDescribe static routes with exit interfaces

    Describe summary and default route

    E i h k t t f d d h iExamine how packets get forwarded when using static routes

    Identify how to manage and troubleshoot static routes

    ITE PC v4.0Chapter 1 2 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Identify how to manage and troubleshoot static routes

  • General Role of the RouterFunctions of a Router

    B t P th S l tiBest Path SelectionsForwarding packets to destination

    Introducing the TopologyIntroducing the Topology3 1800 series routers connected via WAN linksEach router connected to a LAN represented by a switch and a PC

    ITE PC v4.0Chapter 1 3 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • General Role of the RouterConnections of a Router for WAN

    A t h DB 60 t th t t 5 diff t bli-A router has a DB-60 port that can support 5 different cabling standards

    Connections of a Router for Ethernet-2 types of connectors can be used: Straight through and Cross-over Straight through used to connect:Straight through used to connect:

    -Switch-to-Router, Switch-to-PC, Router-to-Server, Hub-to-PC, Hub-to-Server

    Cross-over used to connect: -Switch-to-Switch, PC-to-PC, Switch-to-Hub, Hub-to-Hub, Router-to-Router

    ITE PC v4.0Chapter 1 4 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • InterfacesExamining Router Interfaces

    Sh IP t d d t i ti t bl-Show IP router command used to view routing table-Show Interfaces command used to show status of an

    interface-Show IP Interface brief command used to show a portion of

    the interface information-Show running-config command used to show configuration g g g

    file in RAM

    ITE PC v4.0Chapter 1 5 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • InterfacesConfiguring an Ethernet interface

    B d f lt ll i l d Eth t i t f d-By default all serial and Ethernet interfaces are down-To enable an interface use the No Shutdown command

    ITE PC v4.0Chapter 1 6 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • InterfacesInterfacesVerifying Ethernet interface

    -Show interfaces for fastEthernet 0/0d d t h command used to show

    status of fast Ethernet port

    Sh i i t f b i f-Show ip interface brief-Show running-config

    Ethernet interfaces participate in ARPEthernet interfaces participate in ARP

    ITE PC v4.0Chapter 1 7 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • InterfacesConfiguring a Serial interface

    -Enter interface configuration mode-Enter in the ip address and subnet mask-Enter in the no shutdown command-Enter in the no shutdown command

    Example:-R1(config)#interface serial 0/0-R1(config-if)#ip address 172.16.2.1 255.255.255.0-R1(config-if)#no shutdown

    ITE PC v4.0Chapter 1 8 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • InterfacesExamining Router Interfaces

    Ph i ll ti WAN I t f-Physically connecting a WAN Interface. -A WAN Physical Layer connection has sides:

    Data Circuit-terminating Equipment (DCE) This is the g q p ( )service provider. CSU/DSU is a DCE device. Data Terminal Equipment (DTE) Typically the router is the

    DTE device.

    ITE PC v4.0Chapter 1 9 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • InterfacesConfiguring serial links in a lab environment

    O id f i l ti t b id d DCEOne side of a serial connection must be considered a DCEThis requires placing a clocking signal use the clock rate

    command.Example:

    -R1(config)#interface serial 0/0R1(config if)#clockrate 64000-R1(config-if)#clockrate 64000

    Serial Interfaces require a clock signal to control the timing of h ithe communcations.

    ITE PC v4.0Chapter 1 10 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Routing Table and CDP ProtocolPurpose of the debug ip routing command

    All t i h th t th t f hAllows you to view changes that the router performs when adding or removing routesExample:

    -R2#debug ip routing-IP routing debugging is on

    ITE PC v4.0Chapter 1 11 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Routing Table and CDP ProtocolTo configure an Ethernet interface

    E lExample:-R2(config)#interface fastethernet 0/0-R2(config-if)#ip address 172.16.1.1 255.255.255.0( g ) p-R2(config-if)#no shutdown

    ITE PC v4.0Chapter 1 12 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Routing Table and CDP ProtocolWhen a router only has its interfaces configured & no other routing protocols are configured then:other routing protocols are configured then:

    -The routing table contains only the directly connected networks-Only devices on the directly connected networks are reachable

    ITE PC v4.0Chapter 1 13 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Routing Table and CDP Protocol

    ITE PC v4.0Chapter 1 14 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Routing Table and CDP ProtocolRouting Table and CDP Protocol

    Checking each route in turnroute in turn

    The pingcommand is used to checkused to check end to end connectivity

    ITE PC v4.0Chapter 1 15 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Routing Table and CDP ProtocolPurpose of CDP

    A l 2 i i t t l d t th i f ti b tA layer 2 cisco proprietary tool used to gather information about other directly connected Cisco devices.

    Concept of neighborsp g-2 types of neighbors

    Layer 3 neighborsLayer 2 neighbors

    ITE PC v4.0Chapter 1 16 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Routing Table and CDP ProtocolCDP show commands

    Sh d i hb dShow cdp neighbors command-Displays the following information:

    Neighbor device IDgLocal interfaceHoldtime value, in secondsNeighbor device capability codeNeighbor hardware platformNeighbor remote port IDg p

    Show cdp neighbors detail command -Useful in determining if an IP address configuration error

    ITE PC v4.0Chapter 1 17 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Routing Table and CDP ProtocolDisabling CDP

    T di bl CDP l b ll th f ll i dTo disable CDP globally use the following commandRouter(config)#no cdp run

    ITE PC v4.0Chapter 1 18 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Static Routes with Exit InterfacesPurpose of a static route

    A ll fi d t d h ti f t kA manually configured route used when routing from a network to a stub network

    ITE PC v4.0Chapter 1 19 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Static Routes with Exit InterfacesIP route command

    T fi t ti t th f ll i d i tTo configure a static route use the following command: ip routeExample:

    -Router(config)# ip route network-address subnet-mask {ip-( g) p { paddress | exit-interface }

    ITE PC v4.0Chapter 1 20 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Static Routes with Exit InterfacesDissecting static route syntax

    i t St ti t dip route - Static route command172.16.1.0 Destination network address 255.255.255.0 - Subnet mask of destination network172.16.2.2 - Serial 0/0/0 interface IP address on R2, which is

    the "next-hop" to this network

    ITE PC v4.0Chapter 1 21 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Static Routes with Exit InterfacesConfiguring routes to 2 or more remote networks

    U th f ll i d f R1Use the following commands for R1-R1(config)#ip route 192.168.1.0 255.255.255.0 172.16.2.2-R1(config)#ip route 192.168.2.0 255.255.255.0 172.16.2.2( g) p

    ITE PC v4.0Chapter 1 22 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Static Routes with Exit InterfacesZinins 3 routing principles

    P i i l 1 "E t k it d i i l b dPrinciple 1: "Every router makes its decision alone, based on the information it has in its own routing table.Principle 2: "The fact that one router has certain information in

    it ti t bl d t th t th t h thits routing table does not mean that other routers have the same information.Principle 3: "Routing information about a path from one

    t k t th d t id ti i f ti b tnetwork to another does not provide routing information about the reverse, or return path."

    ITE PC v4.0Chapter 1 23 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Static Routes with Exit InterfacesUsing Zinins 3 routing principles, how would you answer the following?answer the following?-Would packets from PC1 reach their destination?

    Yes, packets destined for 172.16.1.0/24 and 192.168.1.0/24 networks would reach their destination.

    -Does this mean that any packets from these networks destined for 172.16.3.0/24 network will reach their destination?No, because neither R2 nor R3 router has a route to the

    172.16.3.0/24 network.

    ITE PC v4.0Chapter 1 24 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

  • Static Routes with Exit InterfacesResolving to an Exit Interface

    Recursive route lookup Occurs when the router has to perform-Recursive route lookup - Occurs when the router has to perform multiple lookups in the

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