Chapter 12 Intro to Routing & Switching

 Upon completion of this chapter, you should be able to:  Read a routing table  Configure a static route  Compare & contrast distance vector and link state routing protocols  Describe & configure RIPv1 & v2  Describe & configure EIGRP  Describe & configure OSPF

12.1

 Routers can be used to break network smaller  Subnet  To go from router to router  Routing table  Finds route to other networks  Statically set  Dynamically learned

 Router looks at destination IP & SM  ANDing the destination IP & SM Result is a network # Looks in table for the match & forwards it out that interface No match= default route, if set  Routing Table has list of networks & paths

 Routing Table Homework

12.2

 You telling the router:  “To get to this network, go this way!”  Used so routers do less “thinking” or when there’s only one way out of a network  Stub networks or small networks  Same as default route config, but replacing quad zero with destination network address

 ip route destination_network subnet mask next hop ip or outgoing int  R1(config) #ip route What would be the static route on R2 to reach the ladies’ network?

 Handout: Create static routes  Complete the PT lab together  Configure default and static routes

12.3

 Maintain tables when changes occur  Bad cables, interfaces go down, better route learned  Best route to a network in table  Removes routes when no longer valid  When all routers agree on topology= converged  Two routers can exchange these tables as long as they use the same protocol

 Passes updates every so often to connected neighbors  Distance & Direction  Metric (hops, speed, reliability, etc)

 Directly connected network has an administrative distance of 0  Neighbors update each other & add on how far away it is Star is 0 away Star is 1 away Star is 2 away

  Activity for Routing Table  Do together on SmartBoard  Create a Diagram from Routing Tables  On paper  In groups of 2, create a topology based on Routing Table

12.4

 DV  Metric is Hops  Only15 Max; 16 is unreachable (D)  Updates every 30 seconds by default  Sends entire routing table (D)  If change, update sent immediately (triggered)  Slow to converge whole network (D)  Administrative Distance is 120

 RIPv1  Doesn’t send subnet mask in updates  Classful subnetting  RIPv2  Classless (VLSM) subnetting  Supports authentication  Otherwise, same as v1

 Router(config)#router rip  Router (config-router)#version 2  Router(config-router)#network network-number

 Ping  Show ip route  Show ip protocols  Debug ip rip

 Increased traffic every 30 seconds  Max hop count of 15  Further away is unreachable  Only considers hops, not speed  Possible routing loops

 Configure RIP  In groups of 2, using the handout  PT Lab Configure & Verify RIP  Use our in class PT lab to configure RIP & verify it.  RIP Homework

 What routing protocol uses hops for its metric and understands classless routing?  RIPv2  What is the AD of RIP?  120  What’s the purpose of entering your router’s network numbers when configuring RIP?  To tell it what networks to advertise in updates  A directly connected network has an AD of… 00  A static route has an AD of… 11

12.5

 Enhanced Interior Gateway Routing Protocol  Cisco proprietary DV (mix LS & DV)  AD of 90  Many metrics (bandwidth, delay, load, reliability)  Up to 255 hops  Routing Table, Neighbor Table, Topology Table  Updates on start of router & only when a change happens  VLSM Support

 R1(config)#router eigrp 100  R1(config-router)#network  Autonomous System #  Must be the same on all routers in the network

 Neighbor Table  Has info about neighbor direct connect routers  Topology Table  Built from advertisements of its neighbors  Contains ALL routes advertised by neighbor routers  DUAL calculates the best path to a destination and installs it into the routing table  Is able to find the best alternate path quickly when a network change occurs  If no alternate route exists it asks its neighbors to find a new path to the destination

 Show ip route  Show ip eigrp neighbors

 How do you configure EIGRP?  Router eigrp as  When viewing the routing table, what letter indicates an EIGRP route? DD  What 4 metrics are used for EIGRP?  Bandwidth, load, delay, reliability  What algorithm calculates the best path for EIGRP?  DUAL

 EIGRP Configuration Lab

 Static route  RIP  EIGRP

12.6

 Knows all routes in your network  Sends out LSA  Makes a Topological database  With info from LSAs  Uses the SPF algorithm  Each change causes new calc & database update  Map of network from point of view of the router  Info in tree is used to build the routing table  Adds best path to routing table

 Most popular interior routing protocol  Multi-vendor  Unlike Cisco’s EIGRP  Link-state  Knows map of whole network  Routing updates ONLY when change occurs

 Uses SPF algorithm  Sends updates only when the topology changes  Does not send periodic updates of the entire routing table  AD of 110  Metric is cost (bandwidth)  Fast convergence, no loops  Supports VLSM/classless addressing  Provides route authentication  Multi-vendor (unlike EIGRP)

 Neighbor table  List of neighbor routers  Unique to each router  Topology table  Represents the whole network  All routers have same one  Routing Table  Routes

 Tells neighbors who they are  Is an IP address as follows:  Highest IP address on a loopback interface (virtual bc it never goes down)  No loopback= highest IP of active interfaces  Or assigned manually

 Used to establish & maintain adjacency  Helps elect Designated Router & BDR  Sent every 10 seconds to  Dead after 40 seconds  To form adjacency:  Hello, dead interval & area # must match

 One DR/BDR per multi-access area (switch)  All routers will form a full neighbor adjacency with the DR  Link updates sent to DR/BDR  Then forwards to other routers  Reduces LSA flood/traffic  Chosen by Priority #  Highest is DR, next highest is BDR  Tie breaker is highest Router ID  Default on router is 1; 0 means NEVER!

 OSPF works with the concepts of areas  Keeps the map of network smaller if you break it up into areas  By default you will always have a single area  Normally this is area 0  You can have multiple areas  They all connect to area 0 (the backbone) See picture…

 Area 0 is also known as what?  Backbone area  If multiple areas are used, where must they all connect to?  Area 0  What do you know about link state protocols?  Know whole topology, calculates shortest path, updates when change happens  To maintain connectivity to neighbors, what do OSPF routers send?  Hello packets

 How often are hello packets sent?  Every 10 seconds  What happens if you set the priority of an interface to 0?  It will NEVER be the DR/BDR  What is the metric for OSPF?  Cost  What is the AD for OSPF?  110

12.7

 Interfaces  Add a loopback interface on each  Int loopback 0  Ip address x.x.x.x y.y.y.y  Student Center  Science  Admin

 ScienceBuilding(config)#router ospf 1  ScienceBuilding(config-router)#network area 0  AdminBuilding(config)#router ospf 1  AdminBuilding(config-router)#network area 0  Process ID  Wildcard mask

 Think of a wildcard mask as the inverse of a subnet mask.  The inverse of the subnet mask is  To calculate the inverse of the subnet mask, subtract the subnet mask from : – Subtract the sm Wildcard mask

 StudentCenter#show ip ospf neighbor  AdminBuilding#show ip protocols  AdminBuilding#show ip route ospf

 PT Basic OSPF Configuration Lab

 If all OSPF routers in a single area have the same priority, what value does a router use for the OSPF router ID in the absence of a loopback interface?  Highest IP address of active interfaces  What will happen if the routers have different process-IDs?  Nothing  What is the router ID used for?  Election of the DR/BDR  What 2 things does OSPF use to build & maintain its databases?  Hello packets & LSAa

ProtocolDV or LSADMetricFeatures RIP v1DV120Hops 15 hops max RIP v2DV120Hops 15 max; VLSM EIGRP DV- Hybrid 90 Bandwidth, Load, Delay, Reliability Cisco’s; VLSM OSPFLS110Cost Multi- vendor; VLSM

 May be multiple routes to same path  Use AD (metrics) to pick best path  Lowest AD is best

 You are configuring a new router. The interfaces have been configured but no routing protocols or static routes. What routes would be in the routing table?  Directly connected ones  What would cause 2 routers to NOT form an adjacency?  The hello, dead, or area #’s don’t match  A router learns of 3 routes to one destination; they are from RIP, EIGRP, and OSPF. Which one will be put in the routing table and why?  The EIGRP one. It has the lowest AD.

 After an OSPF network has converged, what messaging gets exchanged between routers?  Hello packets  What is the default AD of OSPF?  110  What is the default priority # for Cisco routers in the DR election process? 11  What priority # would you set on a router if you did NOT want it to be a DR/BDR? 00

 An OSPF router will use a Router ID based on what?  Highest IP of loopback or highest IP of active int.  C /30 [110/782] via , 00:35:37, Serial 0 What does the 782 mean?  Cost  What address do hello packets get sent to?   What does OSPF use to calculate cost?  Bandwidth

 Complete the study guide handout  Take the quiz on netacad.com  Jeopardy review

Chapter 11 Intro to Routing & Switching