1. © UNIVERSITY of NEW HAMPSHIRE INTEROPERABILITY LABORATORY IPv4 Routing Summer training 2004 Kari Revier Barbara Hill Summer training 2004 Kari Revier Barbara Hill

2. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Presentation Goals: Understand what routing is and how it is used Compare Distance Vector and Link State protocols. Learn basics of OSPF and RIP Learn how a Routing Table works Understand what routing is and how it is used Compare Distance Vector and Link State protocols. Learn basics of OSPF and RIP Learn how a Routing Table works

3. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing What is Routing? In internetworking,[Routing is] the process of moving a packet of data from source to destination. Routing is usually performed by a dedicated device called a router. Routing is a key feature of the Internet because it enables messages to pass from one computer to another and eventually reach the target machine. Each intermediary computer performs routing by passing along the message to the next computer. Part of this process involves analyzing a routing table to determine the best path. (http://www.webopedia.com/TERM/R/routing.html)

4. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Routing vs. Bridging What is the difference between Routing and Bridging?

5. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Routing vs. Bridging cont. Bridging is involved with the first two layers of the OSI model (Physical, Data link). “A bridge is a device that connects two local-area networks (LANs), or two segments of the same LAN that use the same protocol”. (http://www.webopedia.com/TERM/B/bridge.html) Though Bridges (aka Switches) are faster and less expensive than routers, Bridges don’t are not aware of IP addresses and the networking layer, and thus cannot make very well informed decisions as to the best path traffic should take. Bridging is involved with the first two layers of the OSI model (Physical, Data link). “A bridge is a device that connects two local-area networks (LANs), or two segments of the same LAN that use the same protocol”. (http://www.webopedia.com/TERM/B/bridge.html) Though Bridges (aka Switches) are faster and less expensive than routers, Bridges don’t are not aware of IP addresses and the networking layer, and thus cannot make very well informed decisions as to the best path traffic should take.

6. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Routing vs. Bridging cont. Routing is involved with the first three layers of the OIS model (Physical, Data link, network). Routers are aware and make use of IP addresses, are are able to communicate between various network and protocol types. Using a routing table, routers are able to keep track of complex network topologies, and thus efficiently choose paths through the network. Routing is involved with the first three layers of the OIS model (Physical, Data link, network). Routers are aware and make use of IP addresses, are are able to communicate between various network and protocol types. Using a routing table, routers are able to keep track of complex network topologies, and thus efficiently choose paths through the network.

7. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing So which one should I use? Bridges are best suited for small networks of a single type and, when necessary, communication between small networks of the same type. Routers, though more difficult to configure, are usually the most optimal solution as they deal in layers 1-3 and, due to their routing tables, are able to better choose routes through a network, or networks, which are not necessarily of the same type. Bridges are best suited for small networks of a single type and, when necessary, communication between small networks of the same type. Routers, though more difficult to configure, are usually the most optimal solution as they deal in layers 1-3 and, due to their routing tables, are able to better choose routes through a network, or networks, which are not necessarily of the same type.

8. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing How does a router know where to send a packet? Routing Protocols There are two types of Routing Protocols: - Distance Vector - Link State Routing Protocols There are two types of Routing Protocols: - Distance Vector - Link State

9. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Distance-Vector Routing Distance vector protocols count the number of devices data must flow through to reach a destination. Each device is referred to as a 'hop', so the total number of hops between source and destination is the 'hop count'. Routes with lower hop counts are preferred Distance Vector algorithms require very little overhead in terms of processor power and memory, compared to Link State. Distance vector algorithms calculate only the hop count to destinations and choose best routes according to the hop count metric. (http://www.inetdaemon.com/tutorials/internet/routing/dv_vs_ls.html) Distance vector protocols count the number of devices data must flow through to reach a destination. Each device is referred to as a 'hop', so the total number of hops between source and destination is the 'hop count'. Routes with lower hop counts are preferred Distance Vector algorithms require very little overhead in terms of processor power and memory, compared to Link State. Distance vector algorithms calculate only the hop count to destinations and choose best routes according to the hop count metric. (http://www.inetdaemon.com/tutorials/internet/routing/dv_vs_ls.html)

10. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Example of a Distant-Vector Routing Protocol: RIP – Routing Information Protocol Example of a Distant-Vector Routing Protocol: RIP – Routing Information Protocol

11. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Where is RIP used? RIP is used on smaller networks, with a maximum path of 15 hops. (Also known as a TTL or Time To Live of 15) –Generally, a metric (cost) of 1 is applied to each interface on a router running RIP Why is RIP used? –To recognize changes in network topology automatically and advertise these changes to other routers in the network, with a quick and simple configuration. Where is RIP used? RIP is used on smaller networks, with a maximum path of 15 hops. (Also known as a TTL or Time To Live of 15) –Generally, a metric (cost) of 1 is applied to each interface on a router running RIP Why is RIP used? –To recognize changes in network topology automatically and advertise these changes to other routers in the network, with a quick and simple configuration.

12. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing How it works: –Each RIP-enabled router keeps it’s own store of the routing information received through normal updates. –Each RIP-enabled router advertises all of it’s learned and configured addresses on each interface at every normal update interval.(A configurable interval, but the default is 30 seconds) –When a new route is received from a neighboring router, a triggered update is sent on the router’s other interfaces indicating this new route and a newly calculated metric. –Eventually each router on the network learns the existence of every other router. How it works: –Each RIP-enabled router keeps it’s own store of the routing information received through normal updates. –Each RIP-enabled router advertises all of it’s learned and configured addresses on each interface at every normal update interval.(A configurable interval, but the default is 30 seconds) –When a new route is received from a neighboring router, a triggered update is sent on the router’s other interfaces indicating this new route and a newly calculated metric. –Eventually each router on the network learns the existence of every other router.

13. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Calculating Metric How it works –Each RIP-enabled router keeps it’s own store of the routing information received through normal updates, including where it learned the route from and the cost (metric) of that route –Each time a RIP router receives a new route it transmits that information on its’ other interfaces. –Eventually each RIP-enabled router will have a routing table which lists the cost from it self to destinations in the network. How it works –Each RIP-enabled router keeps it’s own store of the routing information received through normal updates, including where it learned the route from and the cost (metric) of that route –Each time a RIP router receives a new route it transmits that information on its’ other interfaces. –Eventually each RIP-enabled router will have a routing table which lists the cost from it self to destinations in the network. G# are hosts R# are RIP enabled routers N# are individual networks Each outgoing interface has a metric of 1 G# are hosts R# are RIP enabled routers N# are individual networks Each outgoing interface has a metric of 1

14. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Disadvantages of RIP Not suited for large networks – due to the 15 hop max path Slow convergence time – It takes a while for problems to be detected and propagated throughout the network Counting to infinity – 16 is infinity in RIP. If a path becomes unavailable it won’t be removed from a router’s routing table until its cost has reached 16, this requires a lot of traffic and a lot of time. There are two common solutions to this : Split Horizon and Split Horizon with Poison Reverse. Not suited for large networks – due to the 15 hop max path Slow convergence time – It takes a while for problems to be detected and propagated throughout the network Counting to infinity – 16 is infinity in RIP. If a path becomes unavailable it won’t be removed from a router’s routing table until its cost has reached 16, this requires a lot of traffic and a lot of time. There are two common solutions to this : Split Horizon and Split Horizon with Poison Reverse.

15. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Split Horizon Split Horizon prevents routing loops from occurring in the network R4 joins the network and tells router R1 of its connection to N4 with a metric of 1 (the outgoing interface of R4 to R3) R1 notifies R2 of the newly learned route with a newly calculated metric of the original 1, plus the outgoing interface’s metric, which is also 1 = 2 R1 does not send a message to R4 advertising this route, as R1 learned the route from R4 Split Horizon prevents routing loops from occurring in the network R4 joins the network and tells router R1 of its connection to N4 with a metric of 1 (the outgoing interface of R4 to R3) R1 notifies R2 of the newly learned route with a newly calculated metric of the original 1, plus the outgoing interface’s metric, which is also 1 = 2 R1 does not send a message to R4 advertising this route, as R1 learned the route from R4 G# are hosts R# are RIP enabled routers N# are individual networks Each outgoing interface has a metric of 1 G# are hosts R# are RIP enabled routers N# are individual networks Each outgoing interface has a metric of 1

16. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Split Horizon with Poisoned Reverse Split Horizon with Poisoned Reverse further prevents routing loops from occurring in the network R4 joins the network and tells router R1 of its connection to N4 with a metric of 1 (the outgoing interface of R4 to R3) R1 notifies R2 of the newly learned route with a newly calculated metric of the original 1, plus the outgoing interface’s metric, which is also 1 = 2 R1 also sends a triggered response to R4 that its connection to N3 is unreachable (metric 16) Split Horizon with Poisoned Reverse further prevents routing loops from occurring in the network R4 joins the network and tells router R1 of its connection to N4 with a metric of 1 (the outgoing interface of R4 to R3) R1 notifies R2 of the newly learned route with a newly calculated metric of the original 1, plus the outgoing interface’s metric, which is also 1 = 2 R1 also sends a triggered response to R4 that its connection to N3 is unreachable (metric 16) G# are hosts R# are RIP enabled routers N# are individual networks Each outgoing interface has a metric of 1 G# are hosts R# are RIP enabled routers N# are individual networks Each outgoing interface has a metric of 1

17. © UNIVERSITY of NEW HAMPSHIRE INTEROPERABILITY LABORATORY IntermissionIntermission Insert cheesy movie theater music…

18. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Link State Routing Link State protocols track the status and connection type (and therefore speed) of each link, and produce a calculated metric based on these and other factors, including some set by the network administrator. Distance Vector protocols differ from link state protocols because they see all hops as equal and only the number of hops matters. Link State protocols will take a path which has more hops, but that uses a faster medium over a path using a slower medium with fewer hops. Because of their awareness of media types and other factors, link state protocols require more processing power (more circuit logic in the case of ASICs) and memory. Distance vector algorithms being simpler require simpler hardware. (http://www.inetdaemon.com/tutorials/internet/routing/dv_vs_ls.html) Link State protocols track the status and connection type (and therefore speed) of each link, and produce a calculated metric based on these and other factors, including some set by the network administrator. Distance Vector protocols differ from link state protocols because they see all hops as equal and only the number of hops matters. Link State protocols will take a path which has more hops, but that uses a faster medium over a path using a slower medium with fewer hops. Because of their awareness of media types and other factors, link state protocols require more processing power (more circuit logic in the case of ASICs) and memory. Distance vector algorithms being simpler require simpler hardware. (http://www.inetdaemon.com/tutorials/internet/routing/dv_vs_ls.html)

19. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Example of a Link State Routing Protocol OSPF – Open Shortest Path First Example of a Link State Routing Protocol OSPF – Open Shortest Path First

20. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing OSPF Terminology Hello Packets: a periodic message broadcasted by a router which allows others routers to know that it is running OSPF Hello Interval: The time between Hello packets. By default, this is set to 10 seconds. Router Dead Interval: If a router does not send out a hello packet within this interval, other routers on the same network will assume that the router is no longer on that network. By default, this is set to 40 seconds. Router ID: A number in the form of an IP address that routers use to identify each other. Flooding: When a router broadcasts an LSA from another network AS: Autonomous System – a group of routers running the same interior gateway protocol and are controlled by an administrator. ASBR: Autonomous System Border Router – when a router is located between an OSPF autonomous system and a non-OSPF network. Hello Packets: a periodic message broadcasted by a router which allows others routers to know that it is running OSPF Hello Interval: The time between Hello packets. By default, this is set to 10 seconds. Router Dead Interval: If a router does not send out a hello packet within this interval, other routers on the same network will assume that the router is no longer on that network. By default, this is set to 40 seconds. Router ID: A number in the form of an IP address that routers use to identify each other. Flooding: When a router broadcasts an LSA from another network AS: Autonomous System – a group of routers running the same interior gateway protocol and are controlled by an administrator. ASBR: Autonomous System Border Router – when a router is located between an OSPF autonomous system and a non-OSPF network.

21. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing What is OSPF used for? – It advertises routing information between routers within a single AS. The OSPF protocol is based on link-state or SPF (shortest path first) technology. – In a link-state routing protocol, each router maintains a database describing the AS’s topology. This database is referred to as the link- state database. Each participating router has an identical database. What is OSPF used for? – It advertises routing information between routers within a single AS. The OSPF protocol is based on link-state or SPF (shortest path first) technology. – In a link-state routing protocol, each router maintains a database describing the AS’s topology. This database is referred to as the link- state database. Each participating router has an identical database.

22. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing What is OSPF used for Cont. – All routers run the same algorithm, in parallel. Each router constructs a tree of shortest paths with itself as root. This shortest-path tree gives the route to each destination in the AS. – When there are multiple routes to a destination with the same preference, traffic is equally distributed between them. One measure of preference is cost. The cost of a route is described by a single dimensionless metric. What is OSPF used for Cont. – All routers run the same algorithm, in parallel. Each router constructs a tree of shortest paths with itself as root. This shortest-path tree gives the route to each destination in the AS. – When there are multiple routes to a destination with the same preference, traffic is equally distributed between them. One measure of preference is cost. The cost of a route is described by a single dimensionless metric.

23. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing What is OSPF used for Cont. – OSPF allows sets of networks to be grouped together. The group of networks is called an area. The topology of the area is hidden from the rest of the AS. This reduces traffic that is transmitted within an AS. What is OSPF used for Cont. – OSPF allows sets of networks to be grouped together. The group of networks is called an area. The topology of the area is hidden from the rest of the AS. This reduces traffic that is transmitted within an AS.

24. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing LSA - Link State Advertisement What is an LSA? An advertisement sent to describe the local state of a router or network. For a router, this includes the state of the router’s interfaces and adjacencies. There are five common types of LSA’s: 1 Router 2 network 3 summary-network 4 summary-ASBR 5 AS-external The other types of LSA’s are: Group-membership, NSSA and external-attributes What is an LSA? An advertisement sent to describe the local state of a router or network. For a router, this includes the state of the router’s interfaces and adjacencies. There are five common types of LSA’s: 1 Router 2 network 3 summary-network 4 summary-ASBR 5 AS-external The other types of LSA’s are: Group-membership, NSSA and external-attributes

25. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing The five common LSA’s Router LSA: Advertises a router’s active interfaces and neighbors Network LSA: Advertises a network segment and the routers currently attached to the network Summary-Network LSA: Advertises a route to a network Summary-ASBR LSA: Advertises a route to an ASBR AS-external LSA: Describes links that are learned outside of the AS Router LSA: Advertises a router’s active interfaces and neighbors Network LSA: Advertises a network segment and the routers currently attached to the network Summary-Network LSA: Advertises a route to a network Summary-ASBR LSA: Advertises a route to an ASBR AS-external LSA: Describes links that are learned outside of the AS

26. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Hello Packets What are Hello packets used for? Hello packets allow routers to form adjacencies (become neighbors). A Hello packet advertises a router’s router ID, hello interval, router dead interval, neighbor(s) (routers on the same network as itself), subnet mask, area ID, and the DR and BDR on the subnet. A router will only recognize and make adjacencies with routers that have the same hello interval, router dead interval, subnet mask and area ID. If any of the conditions are different, the routers will ignore each other. What are Hello packets used for? Hello packets allow routers to form adjacencies (become neighbors). A Hello packet advertises a router’s router ID, hello interval, router dead interval, neighbor(s) (routers on the same network as itself), subnet mask, area ID, and the DR and BDR on the subnet. A router will only recognize and make adjacencies with routers that have the same hello interval, router dead interval, subnet mask and area ID. If any of the conditions are different, the routers will ignore each other.

27. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing DR – Designated Router What is the purpose of a DR? The DR has two main functions: 1) The DR originates a network-LSA on behalf of the network. This LSA lists the set of routers (including the DR itself) currently attached to the network. 2) The DR becomes adjacent to all other routers on the network. Since the link state databases are synchronized across adjacencies, the DR plays a central part in the synchronization process. What is the purpose of a DR? The DR has two main functions: 1) The DR originates a network-LSA on behalf of the network. This LSA lists the set of routers (including the DR itself) currently attached to the network. 2) The DR becomes adjacent to all other routers on the network. Since the link state databases are synchronized across adjacencies, the DR plays a central part in the synchronization process.

28. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing BDR – Backup Designated Router What is the purpose of the BDR? In order to make the transition to a new DR smoother, there is a BDR for each network. The BDR is also adjacent to all routers on the network, and becomes DR when the previous DR fails. If there were no BDR, when a new DR became necessary, new adjacencies would have to be formed between the new DR and all other routers attached to the network. During this time, the network would not be available for transit data traffic. The BDR makes the need to form these adjacencies unnecessary, since they already exist. This means the period of disruption in transit traffic lasts only as long as it takes to flood the new LSAs (which announce the new DR). What is the purpose of the BDR? In order to make the transition to a new DR smoother, there is a BDR for each network. The BDR is also adjacent to all routers on the network, and becomes DR when the previous DR fails. If there were no BDR, when a new DR became necessary, new adjacencies would have to be formed between the new DR and all other routers attached to the network. During this time, the network would not be available for transit data traffic. The BDR makes the need to form these adjacencies unnecessary, since they already exist. This means the period of disruption in transit traffic lasts only as long as it takes to flood the new LSAs (which announce the new DR).

29. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing How is a Routing Table formed? A routing table is formed by advertisements that a router receives from its neighbors. Consider the diagram show below:

30. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Since Router A and Router B are both connected on network 0, they are able to learn each other’s routes in their routing table. They send advertisements that tell their neighbors what is in their routing table. Why would Router A choose the path to PC 4 with a gateway of Router B??? Since Router A and Router B are both connected on network 0, they are able to learn each other’s routes in their routing table. They send advertisements that tell their neighbors what is in their routing table. Why would Router A choose the path to PC 4 with a gateway of Router B???

31. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing Sample Routing Table ERX-00-0b-e0#show ip route Protocol/Route type codes: I1- ISIS level 1, I2- ISIS level2, I- route type intra, IA- route type inter, E- route type external, i- metric type internal, e- metric type external, O- OSPF, E1- external type 1, E2- external type2, N1- NSSA external type1, N2- NSSA external type2 L- MPLS label, V- VRF Prefix/Length Type Next Hop Dst/Met Intf ------------------ ------- --------------- ---------- ------------------------ 10.0.0.0/8 Static 10.10.10.2 1/0 FastEthernet5/0 10.0.0.0/16 Static 10.10.10.4 1/0 FastEthernet5/0 10.10.10.0/24 Connect 10.10.10.13 0/0 FastEthernet5/0 10.10.11.0/24 Connect 10.10.11.13 0/0 FastEthernet5/1 10.10.12.0/24 Connect 10.10.12.13 0/0 FastEthernet5/2 10.10.13.0/24 Connect 10.10.13.13 0/0 FastEthernet5/3 ERX-00-0b-e0#show ip route Protocol/Route type codes: I1- ISIS level 1, I2- ISIS level2, I- route type intra, IA- route type inter, E- route type external, i- metric type internal, e- metric type external, O- OSPF, E1- external type 1, E2- external type2, N1- NSSA external type1, N2- NSSA external type2 L- MPLS label, V- VRF Prefix/Length Type Next Hop Dst/Met Intf ------------------ ------- --------------- ---------- ------------------------ 10.0.0.0/8 Static 10.10.10.2 1/0 FastEthernet5/0 10.0.0.0/16 Static 10.10.10.4 1/0 FastEthernet5/0 10.10.10.0/24 Connect 10.10.10.13 0/0 FastEthernet5/0 10.10.11.0/24 Connect 10.10.11.13 0/0 FastEthernet5/1 10.10.12.0/24 Connect 10.10.12.13 0/0 FastEthernet5/2 10.10.13.0/24 Connect 10.10.13.13 0/0 FastEthernet5/3

32. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing In Summary Routing protocols are used to determine the best path for traffic through a network. There are two types of routing protocols: Distance-Vector and Link- State RIP is a small, easily configurable Distance-Vector protocol, best suited for small networks. OSPF is a example of a Link-State protocol. It keeps a database of the topology of the entire network (which requires a large amount of data storage space), allowing for well informed calculations of the shortest path, and making it well suited for large networks which require quick convergence times. Routing protocols are used to determine the best path for traffic through a network. There are two types of routing protocols: Distance-Vector and Link- State RIP is a small, easily configurable Distance-Vector protocol, best suited for small networks. OSPF is a example of a Link-State protocol. It keeps a database of the topology of the entire network (which requires a large amount of data storage space), allowing for well informed calculations of the shortest path, and making it well suited for large networks which require quick convergence times.

33. U NIVERSITY of N EW H AMPSHIRE I NTER O PERABILITY L ABORATORY IPv4 Routing ReferencesReferences http://www.webopedia.com http://www.inetdaemon.com/tutorials/internet/routing/dv_vs_ls.html OSPF_eric.ppt, Eric Barrett, UNH-IOL Routing Consortium Routing Information Protocol Version 2.ppt, Joe Scholefield, UNH-IOL Routing Consortium Routing1999.ppt, Kimo Johnso, UNH-IOL Routing Consortium RFC 2328 (OSPFv2) RFC 2453 (RIPv2) IPtraining1.ppt and IPtraining2.ppt, Ben Schultz, UNH-IOL Routing Consortium http://www.webopedia.com http://www.inetdaemon.com/tutorials/internet/routing/dv_vs_ls.html OSPF_eric.ppt, Eric Barrett, UNH-IOL Routing Consortium Routing Information Protocol Version 2.ppt, Joe Scholefield, UNH-IOL Routing Consortium Routing1999.ppt, Kimo Johnso, UNH-IOL Routing Consortium RFC 2328 (OSPFv2) RFC 2453 (RIPv2) IPtraining1.ppt and IPtraining2.ppt, Ben Schultz, UNH-IOL Routing Consortium