IGRP and EIGRP. Comparison between traditional Distance Vector Routing Protocols and Enhanced Distance Vector Routing Protocols. EIGRP Message Format and Packet Header. EIGRP Parameters (K1,K2, K3, K4, K5, Reserved, and Hold Time). Protocol Dependent Modules (PDM). Reliable Transport Protocol (RTP). EIGRP Packet Types (Hello Packets, Update packets, Acknowledgment packets, Query and Reply packets). EIGRP Bounded Updates. Introduction to DUAL Algorithm. EIGRP Administrative Distance. The router eigrp Command, the network command with a Wildcard Mask, Verifying EIGRP and using the Bandwidth command EIGRP Metric Calculation, EIGRP uses Bandwidth, delay, reliability, and load in its metric. DUAL Concepts, successor, Feasible distance (FD), Feasible successor (FS), Reported distance (RD)/ AD and Feasibility Condition (FC). DUAL Finite State Machine, Null0 Summary Route, Disabling Automatic Summarization, Manual Summarization and EIGRP default route

1. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Routing Protocols and Concepts
Abdelkhalik Mosa
abdu.elsaid@yahoo.com
abdu.elsaid@gmail.com

2. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Introduction
• EIGRP is a Classless DV “not hybrid” routing protocol.
• Cisco proprietary, Released in 1992 with IOS 9.21.
• The main purpose was to create a classless version of IGRP.
 IGRP:1985, overcome RIPv1’s metric and network size.
 Classful DV routing protocol uses Bellman-Ford algorithm.
 Both IGRP & EIGRP use composite metric
 Discontinued support starting with IOS 12.2.
• EIGRP new features that are not found in other DV Protocols
 RTP Provides reliable & unreliable delivery of EIGRP packets.
 Bounded Updates.
 DUAL guarantees loop-free paths and backup paths.
 Establishing Adjacencies, Neighbor and Topology Tables.

3. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
IGRP to EIGRP
Enhanced Distance Vector
Routing Protocol
Traditional Distance Vector
Routing Protocols
1. DUAL algorithm
2. Route entries doesn’t age
out, Uses Hello protocol
to monitor connection
status.
3. No periodic updates.
1. Bellman-Ford or Ford-
Fulkerson algorithm.
2. Age out routing entries.
3. Use periodic updates.
Algorithm
1. Topology table contains
best path and loop-free
backup path.
2. DUAL uses backup path in
case of unavailable route.
1. Keep track of only the best
routes.
2. The router must wait for a new
routing update in case of
unavailable route.
Path
determination
Faster convergenceSlower convergence due to
hold-down timers.
Convergence

4. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
EIGRP Message Format

5. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
EIGRP Packet Header
• Opcode: specifies the EIGRP packet type:
 Update (1).
 Query (3).
 Reply (4).
 Hello (5).
• Autonomous System (AS): Number specifies the EIGRP
routing process, also called “Global Process ID”.
 ID for EIGRP Routing process, Cisco routers can run multiple instances of EIGRP.

6. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
TLV: EIGRP Parameters
• The EIGRP parameters message includes the weights that
EIGRP uses for its composite metric.
• K1 field for bandwidth and the K3 for delay are both set to 1.
• The Hold Time is the maximum time router should wait for
the next hello.

7. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
TLV: IP Internal
• The IP Internal message is used to advertise EIGRP routes
within an autonomous system.
• Delay: sum of delays from source to destination in units of 10
microseconds.
• Bandwidth is the lowest configured bandwidth of any
interface along the route.

8. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
TLV: IP External
• The IP External message is used when external routes are
imported into the EIGRP routing process.

9. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Protocol Dependent Modules (PDM)
• EIGRP uses PDM to route several different protocols “IP, IPX &
AppleTalk”.
• PDMs are responsible for the specific routing task for each
network layer protocol.

10. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Reliable Transport Protocol (RTP)
• RTP: is the protocol used by EIGRP for the delivery and
reception of EIGRP packets.
• EIGRP was designed as a Network layer independent routing
protocol.
• EIGRP replaces TCP with RTP.
• Involves both reliable “ack” &
unreliable “no ack” delivery
of EIGRP packets.
• RTP Packets can be sent
either Unicast or Multicast
“224.0.0.10”.

11. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
EIGRP Packet Types
• Hello packets
Used to discover neighbors & form adjacencies with those
neighbors.
 Multicasts and use unreliable delivery.

12. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
EIGRP Packet Types
• Update packets
Used to propagate routing information.
Are Triggered, Partial, Bounded and not Periodic.
Use reliable delivery.
Multicast / Unicast.
• Acknowledgement packets
Used to acknowledge
receipt of update, query &
reply packets.
Use unreliable delivery.
 Always Unicast.

13. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
EIGRP Packet Types
• Query & Reply packets
Query Packet: used by DUAL for searching for networks.
Reply Packet: automatically sent in response to query.
Both use reliable delivery.
Query packets are either Unicast or Multicast.
Reply packet are only Unicast.

14. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Purpose of Hello Packet
• To discover & establish adjacencies with neighbor routers.
• Time interval for sending hello packet
5 seconds: High bandwidth (greater than T1)
60 seconds: Low bandwidth, NBMA networks (T1 or slower ).
• Holdtime: the maximum time the router should wait to receive
the next Hello before declaring that neighbor as unreachable.
• Holdtime = 3 times hello interval.

15. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
EIGRP Bounded Updates
• EIGRP uses the term partial or bounded when referring to its
update packets.
Partial: update only includes information about route
changes “not the full routing table”.
Bounded only routers affected by the change will receive the
update .
• The partial update is automatically "bounded“.
• EIGRP minimizes the bandwidth required to send EIGRP
packets.
‫به‬ ‫مجازى‬ ‫فإنك‬ ‫شئت‬ ‫ما‬ ‫واعمل‬ ،‫مفارق‬ ‫فإنك‬ ‫شئت‬ ‫من‬ ‫وأحبب‬ ،‫ميت‬ ‫فإنك‬ ‫شئت‬ ‫ما‬ ‫عش‬

16. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
DUAL: An Introduction
• DUAL: is the convergence algorithm used by EIGRP.
• Provides for fast convergence time by keeping a list of loop-
free backup routes.
• The decision process for all route computations is done by the
DUAL FSM.
• FSM: is a model of behavior composed of a finite number of
states, transitions between those states, and events or actions
that create the transitions.

17. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Administrative Distance (AD)
• the trustworthiness “preference” of the source route.

18. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Authentication
• EIGRP can
Encrypt routing information.
Authenticate routing information.
• Note: Authentication does not encrypt the router's routing
table.

19. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
EIGRP Network Topology

20. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Basic EIGRP configuration: AS & Process ID
• AS is a collection of networks under the control of a single
authority that presents a common routing policy to the
Internet. (RFC 1930).
 AS Numbers are assigned by IANA.
 Prior to 2007, AS numbers were 16-bit numbers.
 Now 32-bit AS numbers are assigned.
 Entities needing AS numbers: ISP

21. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Basic EIGRP configuration: AS & Process ID
• EIGRP AS number actually functions as a Global process ID.
• Process ID represents an instance of the routing protocol
running on a router.

22. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
The Router EIGRP Command
• router eigrp autonomous-system
• All routers in the EIGRP routing domain must use the same
process ID number (AS Number)

23. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
The Network Command
• Functions of the network command
1. Enables interfaces that belong to the advertised network to send &
receive EIGRP updates.
2. Includes network or subnet in EIGRP updates.
• Router(config-router)#network classful_network_address.

24. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
The Network Command with a Wildcard Mask
• Wildcard mask is used when the network administrator does
not want to include all interfaces within a network when
enabling EIGRP.
• Think of a wildcard mask as the inverse of a subnet mask.
255.255.255.255
-255.255.255.252
-----------------------
0. 0. 0. 3 “Wildcard mask”
• Router(config-router)#network network-address [wildcard-mask]

25. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Verifying EIGRP
• EIGRP routers must establish adjacencies using Hello with their
neighbors before any updates can be sent or received.
• To view neighbor table use: show ip eigrp neighbors
• Common Adjacency problems
1.Different process ID.
2.Incorrect network command.
3.Passive-interface.

26. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Verifying EIGRP
• The show ip protocols: used to verify that EIGRP is enabled.

27. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
EIGRP Metric Calculation
• EIGRP uses Bandwidth, delay, reliability, and load in its metric:
• Verifying the K Values

28. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Examining the Metric values
• Bandwidth: The value of the bandwidth may or may not reflect
the actual physical bandwidth of the interface.
Most serial interfaces use a default bandwidth value of 1.544Mbps (T1)
• Delay: a measure of the time it takes for a packet to traverse a
route.

29. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Examining the Metric values
• Reliability: how often the link has experienced errors.
Reliability is expressed as a fraction of 255.
The higher the value, the more reliable the link.
• Load: reflects the amount of traffic utilizing the link.
Load is expressed as a fraction of 255.
A lower load value is more desirable because it indicates less
load on the link.

30. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Using the Bandwidth Command
• The bandwidth command only modifies the bandwidth metric
used by routing protocols not the physical metric.
• Verifying the bandwidth

31. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Calculating the EIGRP metric

32. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Calculating the EIGRP metric

33. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
DUAL Concepts
• Successor: The next hop in the best path.
• Feasible distance (FD): Best Path metric.

34. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
DUAL Concepts
• Feasible successor (FS): The next hop in the backup path.
• Reported distance (RD)/ AD :The distance (metric) from the
next hop to the destination network.
• Feasibility Condition (FC): RD<FD.

35. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
DUAL Concepts

36. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Topology Table: Successor and Feasible Successor

37. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Topology Table: Successor and Feasible Successor

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Topology Table: Successor and Feasible Successor

39. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
DUAL Finite State Machine
• FSMs are used to describe how a device, computer program, or
routing algorithm will react to a set of input events.

40. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
DUAL Finite State Machine

41. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
The Null0 Summary Route
• By default, EIGRP uses the Null0 interface to discard any
packets that match the parent route but do not match any of
the child routes
• EIGRP automatically includes a null0 summary route as a child
route whenever both of the following conditions exist
1. There is at least one subnet that was learned via EIGRP.
2. Automatic summarization is enabled.

42. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Disabling Automatic Summarization

43. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Disabling Automatic Summarization

44. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Disabling Automatic Summarization

45. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Manual Summarization

46. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Manual Summarization

47. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
EIGRP Default Route

48. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy
Fine-tuning EIGRP
• EIGRP Bandwidth Utilization
 By default, EIGRP will use only up to 50 percent of the
bandwidth of an interface for EIGRP information.
• Configuring Hello Intervals and Hold Times

49. Suez Canal University – Faculty of Computers & Informatics - Cisco Local Academy