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Routing Protocols
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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.
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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 - ???????)
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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
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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
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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 multiaccess networks.
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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).
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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
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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
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OSPF
 Draw a diagram showing a backbone router and an
ABR and an ASBR
 ABR = ????????????
 ASBR = ?????????????
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Configuring OSPF
 Lab_A#config t
 Lab_A(config)#router ???? ?
 Lab_A(config-router)#??????? 10.0.0.0 0.255.255.255
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OSPF
 Areas = # range
 Process ID = # range
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Wildcard Example
 192.168.10.64/28
 192.168.10.80/28
 192.168.10.96/28
 192.168.10.8/30
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OSPF
 Can load-balance only across links of equal costs
 Can’t load-balance across unequal-cost links as EIGRP
can
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OSPF – Summarization
Core(config-router)#area 1 range 192.168.10.64
255.255.255.224
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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
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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
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OSPF Questions
 Which of the following describe the process identifier
that is used to run OSPF on a router? Choose two.
A.It is locally significant.
B.It is globally significant.
C.It is needed to identify a unique instance of an OSPF
database.
D.It is and optional parameter required only if multiple
OSPF processes are running on the router.
E.All routes in the same OSPF area must have the same
Process ID if they are to exchange routing information.
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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.
A.The wildcard mask is incorrect.
B.The OSPF area is wrong.
C.The OSPF Process ID is incorrect.
D.The AS configuration is wrong..
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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
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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.
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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 protocoldependent 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
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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?
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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?
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EIGRP Questions
 Where are EIGRP successor routes stored?
A.In the routing table only
B.In the neighbor table only
C.In the topology table only
D.In the routing table and neighbor table
E.In the routing table ant the topology table
F.In the topology table and the neighbor table
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EIGRP Questions
 Which command will display all the EIGRP feasible
successor routes now to a router?
A.Show ip routes *
B.Show ip eigrp summary
C.Show ip eigrp topology
D.Show ip eigrp adjacencies
E.Show ip eigrp neighbors detail
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EIGRP Questions
 Which is true regarding EIGRP successor routes? (Choose
two)
A.A successor route is used by EIGRP to forward traffic to a
destination
B.Successor routes are saved in the topology table to be used
if the primary router fails
C.Successor router are flagged as “active” in the routing table
D.A successor route may be backed up by a feasible
successor route
E.Successor routes are stored in the neighbor table following
the discovery process
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