Routing Protocols

Routing Protocols

There are 2 classes of routing protocols: • ???????? • Finds the best path to a remote network by judging distance. The route with the least number of hops to the network is determined to be the best route. • ???????? • Create different tables. One of these keeps track of directly attached neighbors, one determines the topology of the entire network, and one is used for routing.

Routed or Routing Protocols??? • ???????? • Used by routers to dynamically find all the networks and to ensure that all routers have the same routing table. (Examples – ??????) • ???????? • Assigned to an interface and determine the method of packet delivery. (Examples - ???????)

OSPF, EIGRP, Rip V1, Rip V2???? • Open Standard Routing Protocol • Uses Dijkstra Algorithm • Supports multiple equal cost routes to the destination • Consists of areas • Minimizes routing update traffic • Unlimited hop count • Designed in a hierarchical fashion (decreases routing overhead, speeds up convergence, confines network instability) • More elaborate and difficult to configure

OSPF Terms • ???? – a network or router interface assigned to any given network. Has state information with it (up or down) as well as IP address. • ?????? ?? – IP address used to identify the router. • ??????? – Two or more routers that have an interface on a common network. (point-to-point serial link) • ??????? – A relationship between 2 OSPF routers that permits the direct exchange of route updates. • ????? Protocol – Provides dynamic neighbor discovery and maintains neighbor relationships. Addressed to 224.0.0.5

OSPF Terms • Link State Advertisement – OSPF data packet containing link-state and routing information that’s shared among OSPF routers. • Designated Router – Elected on broadcast networks. Router with highest priority, Router ID is used as a tiebreaker. • Backup Designated Router – Hot standby for the DR, receives all routing updates from OSPF adjacent routers but doesn’t flood LSA updates. • OSPF area – Routers within the same area have the same topology table. Must be an area 0! • DR and BDR elected on broadcast and non-broadcast multi-access networks.

OSPF Terms • ??????? – Refers to a type of network topology consisting of a direct-connection between two routers. • ???????? – Refers to a type of network topology consisting of a series of connections between a single interface on one router and multiple destination routers. • ????? – 10^8 / bandwidth * NOTE – Picture each router in an area constructing a tree – much like a family tree – where the router is the root and all other networks are arranged along the branches and leaves. Known as the shortest path tree (SPF).

OSPF Terms • Broadcast network – Ethernet • Non-broadcast network – Frame Relay, ATM • Point-to-Point – no DRs and BDRs • Point-to-multipoint – no DRs and BDRs

OSPF Terms • Authentication – Configuration of a password for a specific area, in order for routers to become neighbors, need to have the same password on a segment. • Hello and Dead intervals – number of seconds between Hello packets, must be the same between two neighbors. (show ip ospf interface) • Adjacencies – next step after neighboring process, proceed into the database exchange process (DR and BDR relay information to everybody else) • Loopback interfaces – logical interfaces which are virtual, highest IP will become a router’s RID

OSPF • Draw a diagram showing a backbone router and an ABR and an ASBR • ABR = ???????????? • ASBR = ?????????????

Configuring OSPF • Lab_A#config t • Lab_A(config)#router ???? ? • Lab_A(config-router)#??????? 10.0.0.0 0.255.255.255

OSPF • Areas = # range • Process ID = # range

Wildcard Example • 192.168.10.64/28 • 192.168.10.80/28 • 192.168.10.96/28 • 192.168.10.8/30

OSPF • Can load-balance only across links of equal costs • Can’t load-balance across unequal-cost links as EIGRP can

OSPF – Summarization • Core(config-router)#area 1 range 192.168.10.64 255.255.255.224

OSPF – Exam Objectives • Configure, verify, and troubleshoot OSPF • Be able to configure a single-area OSPF • Router ospf process-id • Network x.x.x.x y.y.y.y.y area Z • Be able to verify the operation of OSPF

OSPF • Show ip ospf • Contains router IR, area information, SPF statistics, and LSA timer information • Show ip ospf database • Command will give you info about the number of routers in the internetwork • Show ip ospf interface • Displays all interface-related ospf information • Show ip ospf neighbor • Show ip protocols

OSPF Questions • Which of the following describe the process identifier that is used to run OSPF on a router? Choose two. • It is locally significant. • It is globally significant. • It is needed to identify a unique instance of an OSPF database. • It is and optional parameter required only if multiple OSPF processes are running on the router. • All routes in the same OSPF area must have the same Process ID if they are to exchange routing information.

OSPF Questions • You get a call from a network administrator who tells you that he typed the following into his router; • Router(config)#router ospf 1 • Router(config-router)#network 10.0.0.0 255.0.0.0 area 0 • He tells you he still can’t see any routes in the routing table. What configuration error has been made. • The wildcard mask is incorrect. • The OSPF area is wrong. • The OSPF Process ID is incorrect. • The AS configuration is wrong..

OSPF, EIGRP, Rip V1, Rip V2???? • Classless • Enhanced distance-vector protocol • Cisco proprietary • Maximum hop-count 255 • Provides routing support for multiple network layer protocols (IP, IPX, AppleTalk and IPv6) through the use of protocol-dependent modules • Reliable Transport Protocol (RTP) – manages communication • DUAL – Diffusing Update Algorithm

EIGRP • There are three conditions that must be met for neighborship establishment • Hello or ACK received • AS numbers match • Identical metrics (K values) • NOTE: The only time EIGRP advertises its entire routing table is when it discovers a new neighbor and forms an adjacency with it through the exchange of Hello packets.

EIGRP Terms • ????? distance – Best metric along all paths to a remote network. Considered the best best. • ??????? Distance – Metric of a remote network as reported by a neighbor. • Neighbor Table – One neighbor table for each protocol-dependent module. • ?????? Table – Contains all destinations advertised by neighboring routers, holding each destination address and a list of neighbors that have advertised the destination. • Feasible __________= Path whose reported distance is less than the feasible distance. (Keep up to 6.) Show ip eigrp topology • ???????? – Best router to a remote network

EIGRP Terms • Neighbor table – records info about routers with whom neighborship relationships have been formed • Topology Table – stores the route advertisements about every router • ???? Table – stores the current routes • Load balance across up to 6 links • Metrics – B?, D?, L?, R?

EIGRP Questions • Where are EIGRP successor routes stored? • In the routing table only • In the neighbor table only • In the topology table only • In the routing table and neighbor table • In the routing table ant the topology table • In the topology table and the neighbor table

EIGRP Questions • Which command will display all the EIGRP feasible successor routes now to a router? • Show ip routes * • Show ip eigrp summary • Show ip eigrp topology • Show ip eigrp adjacencies • Show ip eigrp neighbors detail

EIGRP Questions • Which is true regarding EIGRP successor routes? (Choose two) • A successor route is used by EIGRP to forward traffic to a destination • Successor routes are saved in the topology table to be used if the primary router fails • Successor router are flagged as “active” in the routing table • A successor route may be backed up by a feasible successor route • Successor routes are stored in the neighbor table following the discovery process

Routing Protocols