Static Routing Routing Protocols and Concepts – Chapter 2 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public ITE PC v4.0 Chapter 1 1 Objectives D e fin e th e ge n e r a l r o l e a r ou t e r p l ays in n e tw o rk s . e e e ge e a o e a ou e p ays e o s Describe the directly connected networks, different router interfaces router interfaces Examine directly connected networks in the routing table and use the CDP protocol table and use the CDP protocol Describe static routes with exit interfaces Describe summary and default route Examine how packets get forwarded when using static routes Identify how to manage and troubleshoot static routes ITE PC v4.0 Chapter 1 2 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public General Role of the Router F u n c ti o n s o f a R ou t er ucosoa oue Best Path Selections Forwarding packets to destination Routers perform packet forwarding by learning about remote networks and maintainin g routin g information. gg – The routers primary forwarding decision is based on Layer 3 information, the destination IP address. – The router's routing table is used to find the best match between the destination IP of a packet and a network address in the routing table. – The routing table will ultimately determine the exit interface to forward the packet and the router will encapsulate that packet in the appropriated data link frame for that outgoing interface ITE PC v4.0 Chapter 1 3 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public the appropriated data link frame for that outgoing interface . General Role of the Router Intr oduc in g th e T opo l ogy oduc g e opo ogy – The figure shows the topology used in this chapter. – 3 1800 series routers connected via WAN links – Each router connected to a LAN represented by a switch and a PC ITE PC v4.0 Chapter 1 4 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public General Role of the Router Connections of a Router for WAN -A router has a DB-60 port that can support 5 different cabling standards – Newer routers su pp ort the smart serial pp interface that allows for more data to be forwarded across fewer cable pins. 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, Hub-to- PC, Hub-to-Server Cross - over used to connect (pin 1 connected Cross - over used to connect (pin 1 connected to pin 3, and pin 2 connected to pin 6): -Switch-to-Switch, PC-to-PC, Switch-to- Hub , Hub-to-Hub , Route r -to-Router , PC- ITE PC v4.0 Chapter 1 5 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public , , , Router General Role of the Router in COD S m a rt Se ri a l cab l es : D C E a n d DTE S a Se a cab es C a d -Use straight cable to connect between the DTE and DCE DCE and DTE Adapter Ethernet cables: Cross-over cable: RED cable Roll-over cable: flat cables Straight cable: all other cables http://www.csdata.com/csdonline/customer/home.php ITE PC v4.0 Chapter 1 6 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public Serial Connectors DTE DCE DCE DTE DTE DCE DTE DTE DCE In our labs we will use serial DTE/DCE cables (no CSU/DSU) with a DTE cable connected to one router and DCE bl t d t th th t ITE PC v4.0 Chapter 1 7 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public a DCE ca bl e connec t e d t o th e o th er rou t er. Interfaces Ex a minin g R oute r In te rf aces a g oute te aces -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 on a condensed format Sh i fi d dt h fi ti - Sh ow runn i ng-con fi g comman d – use d t o s h ow con fi gura ti on file in RAM ITE PC v4.0 Chapter 1 8 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public Interfaces Co nfi gu rin g a n E t h e rn et in te rf ace Co gu g a t e et te ace -By default all serial and Ethernet interfaces are down -To enable an interface use the No Shutdown command •The show ip route command is used to display the routing table. •Initially, the routing table is empty if no interfaces have bfid b een con fi gure d . •Static routes and dynamic routes will not be added to th ti t bl til th th e rou ti ng t a bl e un til th e appropriate local interfaces have been configured on the router ITE PC v4.0 Chapter 1 9 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public the router . Verifying Ethernet interface Verifying Ethernet interface - Show interfaces - command shows the status and gives a detailed descri p tion for all interfaces on the route r p – Show interfaces fastEthernet 0/0 – command used to show status of fast Ethernet port R1#show interfaces fastethernet 0/0 • R1#show interfaces fastethernet 0/0 •FastEthernet0/0 is administratively down, line protocol is down • Administratively down means that the interface is currently in the shutdown mode, or turned off. • Line protocol is down means in this case that the interface is not receiving a carrier signal from • Line protocol is down means , in this case , that the interface is not receiving a carrier signal from a switch or the hub. This condition may also be due to the fact that the interface is in shutdown mode • You will notice that the show interfaces command does not show any IP addresses on R1's interfaces The reason for this is because we have not yet configured IP addresses on any of the interfaces . The reason for this is because we have not yet configured IP addresses on any of the interfaces. ITE PC v4.0 Chapter 1 10 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public [...]... Public 25 Routing Table Concepts Purpose of the debug ip routing command Allows you to view changes that the router performs when adding or removing routes in real time 3 disable interfaces with the shutdown command 1 enable debugging with the debug ip routing command Configuring the IP address and Subnet Mask g g 4 Check the routing table 2 Check the routing table Disable debug ip by using 5 routingthe... Inc All rights reserved Cisco Public 33 Static Routes A router can learn about remote networks in one of two ways: y –Manually, from configured static routes –Automatically, from a dynamic routing protocol •Dynamic routing protocols are introduced in the next chapter D i ti t l i t d d i th t h t Purpose of a static route –A manually configured route used when routing from a network to a stub A network... reserved Cisco Public 24 Routing Table C R ti T bl Concepts t The show ip route command reveals the content of the routing table –The main purpose of a routing t bl i t provide th router with paths t Th i f ti table is to id the t ith th to different destination networks The routing table consists of a list of "known" network addresses –directly connected, di tl t d –configured statically, –learned dynamically... Never use the debug all command on the production router ITE PC v4.0 Chapter 1 ip routing command or the “undebug all” command © 2007 Cisco Systems, Inc All rights reserved Cisco Public 26 Routing Table and CDP Protocol When a router only has its interfaces configured & no other routing protocols are configured then: -The routing table contains only the directly connected networks -Only devices on the... Cisco Public 14 Interfaces Reading the Routing Table 172.16.0.0/24 is subnetted, 1 subnets –Having a single route represent an entire network of host IP addresses makes the routing table smaller, with fewer routes, which results in faster routing table lookups •It means that this route matches all packets with a destination address belonging to this network –The routing table could contain all 254 individual... Cisco Public 28 Routing Table and CDP Protocol Checking each route in turn –The ping command is used to check end to end connectivity –Ping 172.16.3.1 failed •Route does not match any route in the routing table –Ping 192.168.1.1 succeed •192.168.1.0/24, matches the first 24 bits of the destination IP address ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 29 Routing Table... destinations beyond R2 •Therefore, network 172.16.3.0 is a stub network and R1 is a stub router •Running a routing protocol between R1 Running and R2 is a waste of resources ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 34 Static Routes IP route command oute co a d To configure a static route use the following command: ip route Example: -Router(config)# ip route network-address... used to make the connections, –the model numbers of the devices –…… ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 30 Routing Table and CDP Protocol Concept of neighbors -2 types of neighbors Layer 3 neighbors At Layer 3, routing protocols consider neighbors to be devices th t share th same network address space d i that h the t k dd R1 and R2 are neighbors Both are members... p g configured interfaces are "up" and "up" ITE PC v4.0 Chapter 1 POP Quiz: Why pings failed? © 2007 Cisco Systems, Inc All rights reserved Cisco Public 27 Routing Table and CDP Protocol When a router only has its interfaces configured, and the routing t bl contains th di tl connected networks b t ti table t i the directly t d t k but no other routes, only devices on those directly connected networks... with your typing ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 13 Interfaces Verifying Ethernet interface -Show interfaces fastEthernet 0/0 Reading the Routing Table –Now look at routing table shown in the figure Notice R1 now has a "directly connected" FastEthernet 0/0 interface a new network –The interface was configured with the 172.16.3.1/24 IP address which makes . Static Routing Routing Protocols and Concepts – Chapter 2 © 2007 Cisco Systems, Inc. All rights reserved address. – The router's routing table is used to find the best match between the destination IP of a packet and a network address in the routing table. – The routing table will ultimately. show ip route command is used to display the routing table. •Initially, the routing table is empty if no interfaces have bfid b een con fi gure d . Static routes and dynamic routes will not