Cisco 2 - Routers Perrine modified by Brierley Page 13/21/2016 Chapter 4 Module 6 Routing & Routing Protocols

Cisco 2 - Routers Perrine modified by Brierley Page 23/21/2016 Chapter 4 Routing Protocols Important function of a router (layer 3 device): Examine incoming data packets & make path selection based on: information stored in its routing tables Router evaluates the available paths to a destination & establishes the best path for routing a packet. Most routing protocols use the shortest & best path - but each use different methods.

Cisco 2 - Routers Perrine modified by Brierley Page 33/21/2016 Chapter 4 The Routing Process The physical address (MAC) changes at each hop A5-C3-26-6B E C A-5F-0D-09-8B-AA BC F-FF-AA The protocol address (IP) always remains the same.

Cisco 2 - Routers Perrine modified by Brierley Page 43/21/2016 Chapter 4 Static Routing Characteristics of static routes: administrators establish static routing table maps routes do not change, unless changed by an administrator used in environments where network traffic is predicable & network design is simple can’t react quickly to network changes; hence are considered unsuitable for today’s LANs

Cisco 2 - Routers Perrine modified by Brierley Page 53/21/2016 Chapter 4 Static Routing Static route can be defined in global config mode: RouterA(config)# ip route Router A Router B Network s0 RouterA(config)# ip route RouterA(config)# ip route s0

Cisco 2 - Routers Perrine modified by Brierley Page 63/21/2016 Chapter 4 Static Routing Router A Router B Network s0 RouterA(config)# ip route e0 The command for a static address from to get to network is: net RouterA(config)# ip route s0

Cisco 2 - Routers Perrine modified by Brierley Page 73/21/2016 Chapter 4 Static Routing Router A Router B Network s0 RouterA(config)# ip route RouterA(config)# ip route s0 In the routing table, the above example will have an administrative distance of 1. In the routing table, the above example will have an administrative distance of 0.

Cisco 2 - Routers Perrine modified by Brierley Page 83/21/2016 Chapter 4 Static Routing Router A Router B Network s0 RouterA(config)# ip route If the network goes down for any reason, the static address on RouterA will be removed from the routing table.

Cisco 2 - Routers Perrine modified by Brierley Page 93/21/2016 Chapter 4 Default Static Route (Gateway of Last Resort) If router doesn’t know where to send a packet, it can use a default route: RouterA(config)# ip route Router A Internet s0 RouterA(config)# ip route RouterA(config)# ip route s0

Cisco 2 - Routers Perrine modified by Brierley Page 103/21/2016 Chapter 4 Default/Static Route Verify a static route or default route with the commands: show running-config (s run) Or show ip route (s ip route) Test a static route or default route with the commands: ping Or traceroute

Cisco 2 - Routers Perrine modified by Brierley Page 113/21/2016 Chapter 4 Configuring Static Routes with Outgoing Interface Administrative distance of 0 Outgoing interface

Cisco 2 - Routers Perrine modified by Brierley Page 123/21/2016 Chapter 4 Configuring Static Routes with Next-hop IP Address Administrative distance of 1 - default Next hop interface

Cisco 2 - Routers Perrine modified by Brierley Page 133/21/2016 Chapter 4 Routed vs. Routing Protocols Routed vs. Routing: Routed protocols are protocols that are moved over a network. (PCs use routed protocols to talk to each other.) TCP/IP IPX Apple Talk …

Cisco 2 - Routers Perrine modified by Brierley Page 143/21/2016 Chapter 4 Routed vs. Routing Protocols Routed vs. Routing: Routing protocols route routed protocols through a network. (Routers use routing protocols to talk to each other about networks & paths.) RIP (Routing Information Protocol) -- RIP Ver2 IGRP (Interior Gateway Routing Protocol) EIGRP ( Enhanced IGRP) BGP (Border Gateway Protocol) OSPF (Open Shortest Path First) APPN (Advanced Peer-to-Peer Networking) IS-IS (Intermediate System-to Intermediate System)

Cisco 2 - Routers Perrine modified by Brierley Page 153/21/2016 Chapter 4 Autonomous Systems An autonomous system (AS) is a collection of networks under a common administration. The American Registry of Internet Numbers (ARIN) assigns an identifying number to each AS. AS is a 16 bit number. Some routing protocols such as IGRP, EIGRP requires AS.

Cisco 2 - Routers Perrine modified by Brierley Page 163/21/2016 Chapter 4 Routing Protocols When all routers in an internetwork are operating with the same knowledge of the routes available in a network it is said to have converged. Fast convergence is desirable because it reduces the period of time in which routers would continue to make incorrect routing decisions.

Cisco 2 - Routers Perrine modified by Brierley Page 173/21/2016 Chapter 4 Routing protocols are divided into 2 classes: Interior and Exterior interior - used for routing information within networks that are under a common network administrator RIP IGRP OSPF EIGRP

Cisco 2 - Routers Perrine modified by Brierley Page 183/21/2016 Chapter 4 Routing protocols are divided into 2 classes: Interior and Exterior Exterior - used for routing information between networks that do not share a common administrator. EGP (exterior gateway protocol) BGP (border gateway protocol)

Cisco 2 - Routers Perrine modified by Brierley Page 193/21/2016 Chapter 4 Classes of Routing Protocols distance-vector - determines the direction & distance IGRP RIP link-state (also called shortest path first) re- creates the exact topology of the entire network). OSPF IS-IS

Cisco 2 - Routers Perrine modified by Brierley Page 203/21/2016 Chapter 4 Distance Vector Routing Protocols Distance vector routing algorithms pass periodically copies of a routing table from router to router. These regular updates are based on the routing algorithm know as Bellman-Ford algorithm. However a distance vector algorithms do not allow a router to know the exact topology of an internetwork as each router only sees its neighbor routers.

Cisco 2 - Routers Perrine modified by Brierley Page 213/21/2016 Chapter 4 Link-state Routing Protocol Link-state algorithms are also known as Dijkstras algorithm or SPF (shortest path first) algorithm. Link-state routing algorithms maintain a complex database of topology information. It maintains full knowledge of distant routers and how they are interconnected. Link-state routing uses: Link-state Advertisements (LSAs) Small packets of routing info that are sent between routers SPF algorithm (shortest path first) Topological database Routing tables

Cisco 2 - Routers Perrine modified by Brierley Page 223/21/2016 Chapter 4 Link-state Routing Protocol Link-state makes an update only when there is a topology change. Link-state concerns itself with minimizing: processor overhead memory requirements bandwidth consumption

Cisco 2 - Routers Perrine modified by Brierley Page 233/21/2016 Chapter 4 RIP routing protocol Characteristics of RIP are: distance vector metric is hop count if the hop count is greater than 15, the packet is discarded table is updated every 30 seconds Each router that a message has to go through to get to its destination is considered one hop count. If the message pass through 2 routers the hop count is 2. If the destination is the next router, then the hop count is 0.

Cisco 2 - Routers Perrine modified by Brierley Page 243/21/2016 Chapter 4 IGRP Routing Protocol IGRP: must be assigned an AS (autonomous system number - 16 bit number) Cisco proprietary distance-vector metrics delay bandwidth (1200 bps - 10 Gbps) reliability (1-224) (higher the number, more reliable) load (1-244) (higher the number, the more load carried) sends updates every 90 seconds maximum hop count is 255 (default 100)

Cisco 2 - Routers Perrine modified by Brierley Page 253/21/2016 Chapter 4 OSPF Routing Protocol Characteristics of OSPF: link-state routing protocol open standard uses the SPF algorithm to calculate the lowest cost to a destination routing updates are flooded as topology changes occur.

Cisco 2 - Routers Perrine modified by Brierley Page 263/21/2016 Chapter 4 EIGRP Routing Protocol Characteristics of EIGRP are: distance-vector Cisco proprietary uses load balancing uses a combination of distance vector & link-state features use Diffused Update Algorithm (DUAL) to calculate the shortest path updates broadcast every 90 seconds

Cisco 2 - Routers Perrine modified by Brierley Page 273/21/2016 Chapter 4 BGP Routing Protocol Characteristics of BGP are: distance vector exterior routing protocol used between ISP and clients used to route internet traffic between AS (autonomous systems)

Cisco 2 - Routers Perrine modified by Brierley Page 283/21/2016 Chapter 4 Configure routing protocols RouterA#config t RouterA(config)# router [AS number] RouterA(config-router)# network As an example: RouterA(config)# router rip RouterA(config-router)# network As an example: RouterA(config)# router igrp 100 RouterA(config-router)# network

Cisco 2 - Routers Perrine modified by Brierley Page 293/21/2016 Chapter 4 Configure routing protocols RouterA# config t s0 s1 e net net net RouterA(config-router)# network RouterA(config-router)# network RouterA(config-router)# network RouterA(config)# router rip Router A

Cisco 2 - Routers Perrine modified by Brierley Page 303/21/2016 Chapter 4 Autonomous systems have an identifying number, which is assigned to it by the American Registry of Internet Numbers (ARIN) or a provider. This autonomous system number is a 16-bit number. Border Gateways & Autonomous Systems

Cisco 2 - Routers Perrine modified by Brierley Page 313/21/2016 Chapter 4 Module 6 Routing & Routing Protocols END