Dynamic Routing All Algorithms, Working And Basics

A computer network or data network is a telecommunications network that
allows computers to exchange data.

ADVANTAGES
•Connectivity
•Sharing
•Updates
•Information

PROBLEMS WITH
THIS NETWORK
•Concession Control
•Sender And Destination
•Speed degradation
•Security
•If One Route is Destroyed
•Efficiency

ENHANCED INTERIOR GATEWAY
ROUTING PROTOCOL (EIGRP)
(The protocol was designed by Cisco Systems as a proprietary protocol, available only
on Cisco routers, but Cisco converted it to an open standard in 2013.)

Security
Congestion Handling Algorithm
Efficiency
Best Routing Finding Logic
Minimal Database
Dual algorithm
Supports IPv4 IPv6 etc
Another Root Finding Logic
(loop free)

It is the process of selecting best paths in a network.
Routing is performed for All Kind Of Networks.
TECHNICALY:
It is the process of determining, selecting the best outgoing path that a
packet has to take in a Network.
Ex: What Player Do in Football Game?
TWO TYPES OF ROUTINGS ARE
•Static (Non Adaptive)
•Dynamic(Adaptive)

 non-adaptive routing
 networks may use manually
configured routing tables.
 suitable on small networks
 public switched telephone
network (PSTN).
 adaptive routing
 constructing routing tables
automatically
 Small+Large Networks
 RIP , OFPS , ISIS , BGP
etc.

A routing protocol is a set of processes, algorithms, and messages that
are used to exchange routing information
PURPOSE
•Discovery of remote networks
•Maintaining up-to-date routing
information
•Choosing the best path to destination
networks
•Ability to find a new best path if the
current path is no longer available

•Interior Routing Protocols
•Used within an autonomous system
•Used within an area of administrative
control
•Exterior Routing Protocols
•Used between autonomous systems
•Used to peer with networks in which
you have no administrative control
Ethernet
Router
Ethernet
Ethernet
RouterRouter
Ethernet
Ethernet
EthernetRouter
Router
Router
Autonomous
System2
Autonomous
System1

RIPv1:
• (RIP version 1) defined in RFC 1058.
• There is no support for VLSM (variable length subnet masks)
•There is also no support for authentication.
RIPv2:
• (RIP version 2) is defined in RFC 2453.
•There is support for authentication.
• It uses hop count as routing metric with that it is also slow to converge
• Not very scalable.
• Still it is limited to 15 hops only.
RIPng:
• (RIP next generation), defined in RFC 2080.
•It has support of IPv6.

•shortest paths from a single source vertex.
•It is slower than Dijkstra's algorithm
•More versatile, as edge weights are
negative numbers.

•Invented by Cisco to overcome limitations of RIP
•Allows for hop count up to 255
•Allows for multiple route METRICS
1. Bandwidth
2. Delay
3. Load
4. MTU
5. Reliability
•Classful, no support for VLSM

A metric is a variable assigned to routes as a means of ranking them
from best to Worst
•Hop Count: Simply counts router hops
•Bandwidth: Choose a higher-bandwidth path over a lower-bandwidth.
•Delay: Delay is a measure of the time a packet takes to traverse a route
•Cost: It is determined by the preferable route.
•Reliability: Reliability measures the likelihood that the link will fail in
some way and can be either variable or fixed.

•VERSION: RFC 2328(OSPFv2), 1998.
•USES: Dijkstras Algorithm
•DRAWBACK: Designing can be complicated
•SUPPORTS:
1. Internet Protocol Version 4 (IPv4)
2. Internet Protocol Version 6 (IPv6)
3. Variable Length subnet masking (VLSM)
4. Classless Inter-Domain RouTing(CIDR).
•METRICS
1. Intra-area
2. Inter-area
3. External Type 1
4. External Type 2

VERSION: RFC 1142, 1990
USES: Dijkstra Algorithm
•Mainly used by large service providers
•Does not use IP to carry routing information
•Classless, supports VLSM

• With distance vector routing, each node has information
only about the next hop:
• Node A: to reach F go to B
• Node B: to reach F go to D
• Node D: to reach F go to E
• Node E: go directly to F
• Distance vector routing makes
poor routing decisions if
directions are not completely
correct
(e.g., because a node is down).
• If parts of the directions incorrect, the routing may be incorrect until the
routing algorithms has re-converged.
20
AA BB CC
DD EE FF

•IF One Node Gets Down
Then Whole Network
Shuts Down

•LINK-STATE = OSPF + ISIS
•ONLY 5 STEPS
1.Determining The Neighbors Of Each Node (HELLO)
2.Determine the cost of each path (ECHO)
3.Flooding ALGORITHM
4.Creating The Map And Tables
5.Calculating The Shortest Paths
AA BB CC
DD EE FF

◦ Relationship (“adjacency”) with neighbors
◦ Generates link state advertisements
LSA = (Link Id, State Of The Link, Cost, Neighbors Of The Link)
◦ Topological database and link state database.
23

• Each node has a complete map of the topology.
• If a node fails, each node can calculate the new route.
• DIFFICULTY: All nodes need to have a consistent view of the
network.
24
AA BB CC
DD EE FF
A B C
D E F
A B C
D E F
A B C
D E F
A B C
D E F
A B C
D E F
A B C
D E F

EIGRP = The concepts of ( RIP + IGRP + OSOS + ISIS
+ Distance Vector + Link State + New Concepts)
A HYBRID NETWORK…!!!

• BANDWIDTH: Minimum Bandwidth (in kilobits per second) along
the path from router to destination network.
• LOAD: Number in range 1 to 255; 255 being saturated.
• TOTAL DELAY: Delay, in 10s of microseconds, along the path
from router to destination network.
• RELIABILITY: Number in range 1 to 255; 255 being the most
reliable.
• MTU: Minimum path Maximum Transmission Unit (MTU) (never
used in the metric calculation).
• HOP COUNT: by default it is set to 100 and can be changed to any
value between 1 and 255.

• SUCCESSOR :The best, least cost route to the destination
installed in the routing table; multiple successors can be installed
for load balancing
• FEASIBLE SUCCESSOR: A next-hop alternative route to the
destination kept in the topology table, ready to be installed if the
successor fails; feasible successors are only in the topology table
• ACTIVE STATE: EIGRP is still trying to calculate the best
path for the specific route
• PASSIVE STATE: that EIGRP has determined the path for the
specific route and has finished processing

1. Like OSPF, EIGRP maintains three unique tables to assist
in routing traffic.
•Neighbor Table
•Topology Table
•Routing Table
2. EIGRP maintains one table of each for each routed protocol
configured on the router.
•3 Neighbor Tables
•3 Topology Tables
•3 Routing Tables

• Use the command
show ip eigrp neighbors
• Similar to OSPF’s Adjacencies database:
1. Contains a list of all neighbors discovered through
hellos
2. Maintains hello and holdtime intervals on each
neighbor
Router#show ip eigrp neighbors
IP-EIGRP neighbors for process 100
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
0 192.168.224.2 Se0 13 00:01:28 930 5000 0 30
1 192.168.208.2 Se1 11 00:02:20 35 1140 0 21

Router#show ip eigrp topology
IP-EIGRP Topology Table for process 100
Codes: P – Passive, A – Active, U – Update, Q – Query, R – Reply,
r – Reply status
P 192.150.42.120 255.255.255.248, 1 successors, FD is 2172416
via 192.150.42.9 (2172416/2169856), Fddi0
P 192.150.42.8 255.255.255.248, 1 successors, FD is 28160
via Connected, Fddi0
Feasible Distance
Reported Distance
• Use the command to view the table
show ip eigrp topology
• Similar to LINK-STATE database:
Contains all routes the router has learned about from its neighbors
and all the information necessary to calculate a set of distances and
vectors to all reachable destinations
1. FD—Feasible Distance: lowest calculated metric to reach a
destination as opposed to.
2. RD—Reported Distance: distance to the destination reported
by the neighbor.

• Use the command to view table
show ip route
• Like ALL ROUTING protocols:
EIGRP maintains a routing table with best routes to destination
networks

REPORTED DISTANCE:
Destination: Router A
•via D: RD(4)
•via C: RD(3)
The route via C have lowest cost.
FEASIBLE DISTANCE:
•via D: RD(4), FD(5)
•via C: RD(3), FD(6)
DUAL therefore finds that:
•via D: RD(4), FD(5) successor
•via C: RD(3), FD(6) feasible successor

 It supports classless interdomain routing (CIDR) and variable-length
subnet masks (VLSM).
 It sends routing updates only when network topology changes
instead of its entire routing table at regular intervals.
 It is less CPU intensive.
 It supports IPX and AppleTalk. OSPF supports only IP.
 EIGRP supports unequal-cost load balancing.
 OSPF propagates network changes to all routers in an area. EIGRP
has much better convergence time than OSPF/ISIS.
 Loop control that Distance vector / Link State Doesn’t have.

• Dynamic Routers are worldwide by nearly every organization or
individual which uses internet. Following are the network hardware
vendors that make these algorithms practically possible in real life.
i. CISCO Systems (uses EIGRP)
ii. D- Link
iii. Dell
iv. Juniper Networks
v. Huawei
vi. Telco System
vii. HP
• Upcoming The Darkest Algorithm by convergEX group.(rumors)

IT IS CISCO PROPRIETARY
If you are working in a mixed environment, then
it does not interoperate with other vendors' devices.
IN A POORLY DESIGNED NETWORK:
One malfunctioning router can trigger bad router problem much better.
A chain reaction that brings an entire network down
ISIS-OFPS handles the Situation However,
if EIGRP is properly designed, this problem can be overcome.

[1].Wikipedia. “Routing” http://en.m.wikipedia.org/wiki/Router_(computing). October
2014.
[2]. Sumitha J. “Routing Algorithms in Networks” Research Journal of Recent
Sciences Vol.3(ISC-2013), 1-3. February 2014.
[3]. B, Richard . "On a routing problem". Quarterly of Applied Mathematics 16: 87–90.
[4]. CISCO. “Enhanced Interior Gateway Routing Protocol”
http://www.cisco.com/c/en/us/support/docs/ip/ Interior Gateway Routing Protocol-
eigrp/16406-eigrp-toc.html. 2014
[5]. Wikipedia. “Adaptive Routing” http://en.m.wikipedia.org/wiki/Adaptive_routing.
October 2014.

Dynamic Routing All Algorithms, Working And Basics

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