ip routing. chapter 8 objectives understanding ip routing static routing dynamic routing –rip...
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IP Routing
Chapter 8 Objectives
• Understanding IP routing• Static routing• Dynamic routing
– RIP– RIPv2– OSPF– EIGRP
• Verifying routing• Router Security
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To route a router need to know:– Remote Networks
– Neighbor Routers
– All Possible routes to remote network
– The absolute best route to all remote networks
– Maintain and verify the routing information
What is Routing?
C B AD
To route a router need to know:– Remote Networks
– Neighbor Routers
– All Possible routes to remote network
– The absolute best route to all remote networks
– Maintain and verify the routing information
What is Routing?
C B AD
Basic Path Selection
What interface will the router send out a packet if it has destination address of 10.10.10.10?
Simple IP Routing
>ping 172.16.20.2>ping 172.16.20.2
Routing/PDU Example:
3. The destination port number in a segment header will have a value of __
1. The destination address of a frame will be the _______________________2. The destination IP address of a packet will be the IP address of the________________________________
Host A Web browses to the HTTP Server….
172.16.3.2
SO
Static Routes
172.16.1.0
B172.16.3.1
A B
Stub Network
172.16.2.0
SOA
Routes must be unidirectional
ip route remote network
[mask]
{address|interface}
[distance]
[permanent]
Router(config)#ip route remote_network mask next_hop
Static Route Configuration
ip route 172.16.1.0 255.255.255.0 172.16.3.2or
ip route 172.16.1.0 255.255.255.0 s0
Static Route Example
172.16.3.2
SO
172.16.1.0
B172.16.3.1
A B
Stub Network
172.16.2.0
SO
Default Routes
172.16.3.2
SO
172.16.1.0
B172.16.3.1
A B
Stub Network
172.16.2.0
SO
ip route 0.0.0.0 0.0.0.0 172.16.3.1
ip classless
• Routing protocols are used between routers to: – Determine the path of a packet through a network– Maintain routing tables– Examples?
• Routed protocols are:– Assigned to an interface– Once the path is determined by the Routing
protocol, determines method of delivery– Examples?
Routing vs. Routed
Autonomous System 1 Autonomous System 2
IGPs: RIP, IGRP EGPs: BGP
Routing Protocols
• An autonomous system is a collection of networks under a common administrative domain.
• IGPs operate within an autonomous system.
• EGPs connect different autonomous systems.
Classful Routing Overview
Classful routing protocols do not include the subnet mask with the route advertisement.
– Within the same network, consistency of the subnet masks is assumed.
– Summary routes are exchanged between foreign networks.
– Examples of classful routing protocols:• RIP Version 1 (RIPv1)• IGRP
Classless Routing Overview
Classless routing protocols include the subnet mask with the route advertisement.
– Classless routing protocols support variable-length subnet masking (VLSM).
– Summary routes can be manually controlled within the network.
– Examples of classless routing protocols:• RIP Version 2 (RIPv2)• EIGRP• OSPF• IS-IS
IGRPAdministrative Distance=100
Router D
Router BRouter A
Router C
RIPAdministrative Distance=120
Default Administrative Distance• Directly Connected: 0• Static Route: 1• RIP: 120• IGRP: 100• EIGRP: 90• OSPF: 110
Administrative Distance
C B AD
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
Distance—How farVector—In which direction
Distance—How farVector—In which direction
Distance vector algorithms do not allow a router to know the exact topology of an internetwork.
All routers just broadcast their entire routing table out all active interfaces on periodic time intervals
Distance Vector
Discovering RoutesDiscovering Routes
Discovering RoutesDiscovering Routes
Routing Loops
Router LoopPrevention
• Maximum Hop Count• Split Horizon• Route Poisoning• Holddowns
64kbps
T1
T1 T1
– Hop count metric selects the path, 16 is unreachable
– Full route table broadcast every 30 seconds
– Load balance maximum of 6 equal cost paths (default = 4)
– RIPv2 supports VLSM and Discontiguous networks
RIP Overview
Router(config)#router rip
Router(config-router)#network network-number*
network 172.16.0.0network 192.168.10.0
router RIPnetwork 172.16.0.0network 10.0.0.0
router RIP
*Network is a classful network address.
Every device on network uses the same subnet mask
172.16.10.0 192.168.10.010.3.5.0
RIP Routing Configuration
RIP Version 2• Allows the use of variable length subnet
masks (VLSM) by sending subnet mask information with each route update
• Distance Vector – same AD, and timers.• Easy configuration, just add the command
“version 2” under the router rip configuration
router ripnetwork 10.0.0.0version 2
Discontiguous Addressing
• Two networks of the same classful networks are separated by a different network address
192.168.10.0/24
10.1.1.0/24
192.168.10.0/24
– RIPv1 and IGRP do not advertise subnet masks, and therefore cannot support discontiguous subnets.
– OSPF, EIGRP, and RIPv2 can advertise subnet masks, and therefore can support discontiguous subnets.
Passive Interface
Maybe you don’t want to send RIP updates out your router interface connected to the Internet. Use the passive-interface command:Router(config)#router rip
Router(config-router)#passive-interface serial0
This allows a router to receive route updates on an interface,
but not send updates via that interface
S0 GatewayInternet
Updates
XX
Verifying RIP
Router#show ip protocols
Router#show ip route
Router#debug ip rip
Router#undebug all (un all)
Summary
– Open your books and go through all the written labs and the review questions.
– Review the answers in class.
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