Cisco Networking Academy Program Semester 5 : Routing

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Cisco Networking Academy Program Semester 5
Routing

• Chapter 6 EIGRP

EIGRP Features, components and operation EIGRP
Configuration Monitoring EIGRP
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EIGRP Features

• Hybrid protocol (Cisco Proprietary)
• Advanced Distance-Vector protocol
• Supports CIDR and VLSM
• Faster convergence and more scalable than IGRP
• No hierarchy
• Multi-protocol
• Simple to implement

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EIGRP and IGRP

• EIGRP and IGRP exchange routing information when
  in same AS.
• EIGRP sees IGRP routes as external routes.

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EIGRP advantages

• Rapid convergence Diffusing Update Algorithm
  (DUAL) recalculates routes and diffuses them.
• Efficient use of bandwidth with partial updates
• sent only to the routers that need the
  information (bounded updates)
• Hello packets keep the contact between routers
• Supports VLSM and CIDR by exchanging subnet
  information
• Multiple network-layer support through the use of
  protocol dependent modules (PDM)

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IPX RIP redistribution in EIGRP

• EIGRP can redistribute IPX RIP and SAP info
• Updates become incremental
• Starting IOS Ver. 11.1, EIGRP redistribute NLSP

• EIGRP also redistribute Apple Routing Table
  Maintenance Protocol (RTMP)

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EIGRP Terminology

• Neighbour table
• Topology table
• Routing table
• Successor
• Feasible successor

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EIGRP Terminology

• Neighbour table equivalent to OSPF adjacency
• Topology table Contains all the routes that the
  router has learned, for each protocol
• Routing table contains the best routes
  calculated from the topology table

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EIGRP Terminology

• Successor
• The Neighbor with the best route to a destination
• Appears in the routing table
• Think about successful route
• Feasible successor
• The Neighbor with the next best route (or backup
  route)
• Could be more than one
• Remains in the topology table

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EIGRP Technologies
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Neighbor Discovery

• Neighbor discovery allows routers to
• Dynamically learn of new routes that join their
  network
• Identify routers that become either unreachable
  or inoperable
• Rediscover routers that had previously been
  unreachable

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Reliable Transport Protocol

• EIGRP uses its own proprietary transport-layer
  protocol to guarantee delivery of routing
  information RTP.
• Not used with Hello packets
• Retransmits routing information right away if
  data is lost.

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Dual Finite State Machine

• DUAL tracks all the routes advertised by
  neighbors and uses the composite metric of each
  route to compare them.
• guarantees that each path is loop-free
• Lowest-cost paths are then inserted into the
  routing table

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Feasible And Advertised Distance

• To be a feasible successor, a route must have an
  AD smaller than the FD through the successor
• A router views its feasible successors as
  neighbors that are downstream, or closer, to the
  destination than it is.

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Protocol Dependant Modules

• Each PDM is responsible for all functions related
  to its specific routed protocol.

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EIGRP Packet types

• Hello
• Acknowledgment
• Update
• Query
• Reply

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EIGRP Hello Packets

• EIGRP relies on hello packets to discover,
  verify, and rediscover neighbor routers
• Multicast on 224.0.0.10
• Hello and dead interval dont have to be the same
  on all routers

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EIGRP Acknowledgement Packets

• Acknowledgement Packets are dataless unicast
  hello packets
• They can piggyback on other packets
• Hello packets dont require acknowledgement

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EIGRP Updates Packets

• Update packets are unicast packets used to send
  the topology table to a new neighbor.
• Update packets are also used when a router
  detects a topology change (multicast to all
  neighbors).

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Query And Reply Packets

• Query packets (Unicast or Multicast) are used by
  routers that needs specific information on a
  route.
• Triggered by route loss with no feasible
  successor
• Reply packets (Unicast) carry the answer to the
  query.

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EIGRP Neighbor Table

• The neighbor table keeps track of the directly
  connected neighbors
• Supports reliable, sequenced delivery of packets

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EIGRP Routing Table

• The routing table contains the routes installed
  by DUAL as the best loop-free paths to a given
  destination

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EIGRP Topology Table

• Stores all the information it needs to calculate
  a set of distances and vectors to all reachable
  destinations

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Passive and Active Routes

• A passive a route is stable and available for
  use.
• If a route disappears, the routers looks for the
  next feasible successor available.
• If no feasible successor, the route goes into
  active mode (query and reply states to identify a
  new route)
• If no response is received before the end of the
  active time (180 sec.), the route becomes Stuck
  in Active.

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Route tagging

• Tags identify a route as internal or external,
  and may include other information as well.
• Could be used to implement routing policy.

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Configuring EIGRP

• router(config) router eigrp autonomous-system-num
  ber
• router(config-router) network network-number
• router(config-if) bandwidth kilobits
• router(config-if) eigrp log-neighbor-changes(opt
  ional)

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Bandwidth And Frame Relay
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Bandwidth Percent Command

• Allows the adjustment of the percentage of the
  bandwidth used by EIGRP

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No auto-summary

• EIGRP automatically summarizes network addresses
  to the classful boundaries
• To deactivate itrouter(config-router)no
  auto-summary

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Manual Summarization

• RTC(config)router eigrp 2446
• RTC(config-router)no auto-summary
• RTC(config-router)exit
• RTC(config)interface serial0
• RTC(config-if)ip summary-address eigrp 2446
  2.1.0.0 255.255.0.0

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Show Commands
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Debug Commands