deploy eigrp

8/2/2019 Deploy Eigrp

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1216_05_2000_c1 2000, Cisco Systems, Inc.

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Deploying IGRP/E-IGRPDeploying IGRP/E-IGRP

Session 2208Session 2208


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Understanding E-IGRPUnderstanding E-IGRP

Understanding and deployingE-IGRP is like driving a car


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AgendaAgenda

Fundamentals of E-IGRP

DUAL

Summarization and Load Balancing

Query Process

Deployment Guidelines with E-IGRP

Summary


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IGRP: Interior GatewayRouting Protocol

IGRP: Interior GatewayRouting Protocol

Cisco proprietary

Distance vector

Broadcast based Utilizes link bandwidth and delay

15 hops is no longer the limit

90 seconds updates (RIP is 30 sec.)

Load balance over unequal cost paths


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IGRP/E-IGRP Metrics CalculationIGRP/E-IGRP Metrics Calculation

Metric = [K1 x BW + (K2 x BW) / (256 - Load) +K3 x Delay] x [K5 / (Reliability + K4)]

By Default: K1 = 1, K2 = 0, K3 = 1, K4 = K5 = 0

Delay is sum of all the delays of the link alongthe paths

Delay = Delay/10

Bandwidth is the lowest bandwidth of the linkalong the paths

Bandwidth = 10000000/Bandwidth


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Problems with RIP and IGRPProblems with RIP and IGRP

Slow convergence

Not 100% loop free

Dont support VLSM anddiscontiguous network

Periodic full routing updates

RIP has hop count limitation


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Advantages of E-IGRPAdvantages of E-IGRP

Advanced distance vector

100% loop free

Fast convergence

Easy configuration

Less network design constraints than OSPF

Incremental update

Supports VLSM and discontiguous network

Classless routing

Compatible with existing IGRP network

Protocol independent (support IPX and AppleTalk)


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Advantages of E-IGRPAdvantages of E-IGRP

Uses multicast instead of broadcast

Utilize link bandwidth and delayE-IGRP Metric = IGRP Metric x 256(32 bit Vs. 24 bit)

Unequal cost paths load balancing

More flexible than OSPF

Full support of distribute list

Manual summarization can be done in any

interface at any router within network


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E-IGRP PacketsE-IGRP Packets

Hello: Establish neighbor relationships

Update: Send routing updates

Query: Ask neighbors aboutrouting information

Reply: Response to query about

routing information

Ack: Acknowledgement of a reliable packet


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E-IGRP Neighbor RelationshipE-IGRP Neighbor Relationship

Two routers become neighbors when theysee each others hello packet

Hello address = 224.0.0.10

Hellos sent once every five seconds on

the following links:Broadcast Media: Ethernet, Token Ring,FDDI, etc.

Point-to-point serial links: PPP, HDLC, point-to-point frame relay/ATM subinterfaces

Multipoint circuits with bandwidth greater than

T1: ISDN PRI, SMDS, Frame Relay


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Hellos sent once every 60 seconds on the

following links:Multipoint circuits with bandwidth less than orequal to T1: ISDN BRI, Frame Relay, SMDS, etc.

Neighbor declared dead when no E-IGRPpackets are received within hold interval

Not only Hello can reset the hold timer

Hold time by default is three times thehello time


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E-IGRP will form neighbors even though

hello time and hold time dont match E-IGRP sources hello packets from

primary address of the interface

E-IGRP will not form neighbor if K-valuesare mismatched

E-IGRP will not form neighbor if ASnumbers are mismatched

Passive interface (IGRP vs. E-IGRP)


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Discovering RoutesDiscovering Routes

I am Router A, Who Is on the Link?

afadjfjorqpoeru39547439070713

11Hello

AA BB


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Update


Here Is My Routing Information (Unicast) 22



11Hello

AA BB


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Thanks for the Information!Ack


33

Update





11Hello

AA BB


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Topology

Table

TopologyTable

44




33

Update





11Hello

AA BB


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Here Is My Route Information (Unicast)Update


55

Topology

Table

TopologyTable

44 Thanks for the Information!Ack


33

Update





11


Hello

AA BB


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Converged



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TopologyTable

TopologyTable

44

AA BB

Here Is My Route Information (Unicast)Update


55



33

Update





11Hello



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AgendaAgenda

Fundamentals of E-IGRP DUAL


Query Process


Summary


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E-IGRP DUALE-IGRP DUAL

Diffusing update algorithm

Finite-State-MachineTrack all routes advertised by neighbors

Select loop-free path using a successor andremember any feasible successors

If successor lost

Use feasible successor

If no feasible successor

Query neighbors and recompute new successor


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E-IGRP Feasible Distance (FD)E-IGRP Feasible Distance (FD)

Feasible distance is the minimum

distance (metric) along a path to adestination network


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TopologyTable

DestinationDestination Feasible Distance (FD)Feasible Distance (FD) NeighborNeighbor

77

77

77

HH

BB

DD

100+20+10=130100+20+10=130

100+1+10+10=121100+1+10+10=121

100+100+20+10+10=240100+100+20+10+10=240

Feasible Distance ExampleFeasible Distance Example

Network 7

FDDI

(10)(20)

(1) GG

CC

FFEE

BB

HH

DD

AA

(100)

(10)(20)(100)

(100)

(100)


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E-IGRP Reported Distance (RD)E-IGRP Reported Distance (RD)

Reported distance is the distance(metric) towards a destination as

advertised by an upstream neighborReported distance is the distance

reported in the queries, the replies andthe updates


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DestinationDestination Reported Distance (RD)Reported Distance (RD) NeighborNeighbor

77

77

77

20+10=3020+10=30

1+10+10=211+10+10=21

100+20+10+10=140100+20+10+10=140

HH

BB

DD

Topology

Table

Reported Distance ExampleReported Distance Example

FDDI

GG

CC

FFEE

Network 7

(10)(20)

(1)(100)

(10)(20)(100)

(100)

(100) BB

HH

DD

AA


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E-IGRP Feasibility Condition (FC)E-IGRP Feasibility Condition (FC)

A neighbor meets the feasibilitycondition (FC) if the reported

distance by the neighbor is smallerthan the feasible distance (FD) ofthis router


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E-IGRP SuccessorE-IGRP Successor

A successor is a neighbor that has metthe feasibility condition and has theleast cost path towards the destination

It is the next hop for forwarding packets

Multiple successors are possible(load balancing)


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E-IGRP Feasible Successor (FS)E-IGRP Feasible Successor (FS)

A feasible successor is a neighbor

whose reported distance (RD) is lessthan the feasible distance (FD)


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12112177 BB

Router AsRouting Table

Successor ExampleSuccessor Example

B is current successor (FD = 121)

H is the feasible successor (30 < 121)

DestinationDestination NeighborNeighbor

77

77

77

HH

BB

DD

TopologyTable

FDFD RDRD

3030130130

121121

240240

2121

140140

FDDI

GG

CC

FFEE

BB

HH

DD

AA

(20)(100)

Network 7

(10)(20)

(1)(100)

(10)

(100)

(100)

P i A i d S kP i A i d S k


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Passive, Active, and Stuckin Active (SIA)

Passive, Active, and Stuckin Active (SIA)

Passive routes are routes that havesuccessor information

Passive route = Good

Active routes are routes that have lost theirsuccessors and no feasible successors areavailable. The router is actively looking foralternative paths

Active route = Bad Stuck in Active means the neighbor still has not

replied to the original query within three minutes

Stuck in active = Ugly


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Dual AlgorithmDual Algorithm

Local computation

When a route is no longer available viathe current successor, the router checksits topology table

Router can switch from successor tofeasible successor without involving

other routers in the computationRouter stays passive

Updates are sent


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DUAL: Local Computation

(1)

#2

#3

#4 #5

B C

FD E

#1

#6

GA

#7

(100)

(100) (20)

(10)

(10)

(10)

H

#8(20)

#7 121/21 B

#7 130/30 H

. . .

. . .

. . .

#7 121/21 B

#7 130/30 H

. . .

. . .

. . .

FDDI

XX


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Dual AlgorithmDual Algorithm

Diffused Computation

When a route is no longer available via its

current successor and no feasible successor isavailable, queries are sent out to neighborsasking about the lost route

The route is said to be in active state

Neighbors reply to the query if they haveinformation about the lost route. If not, queriesare sent out to all of their neighbors.

The router sending out the query waits for all ofthe replies from its neighbors and will makerouting decision based on the replies


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(1)

#2

#3

#4 #5

B C

FD E

#1

#6

GA

#7

(100)

(100) (20)

(10)

(10)

(10)

H

#8(20)

#7 121/21 B

#7 130/30 H

. . .

. . .

. . .

#7 121/21 B

#7 130/30 H

. . .

. . .

. . .

FDDI

XX

DUAL: Diffused Computation

XX


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D E-IGRP Topology(a) Cost (2) (fd)

via B Cost (2/1) (Successor)via C Cost (5/3)



E E-IGRP Topology(a) Cost (3) (fd)

via D Cost (3/2) (Successor)

via C Cost (4/3)



via C Cost (4/3)

C E-IGRP Topology(a) Cost (3) (fd)

via B Cost (3/1) (Successor)via D Cost (4/2) (fs)via E Cost (4/3)



(1)

DUAL ExampleDUAL Example

XXX

(1)

(1)

(1)

(2)(2)

A

D

EC

B

(a)


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D E-IGRP Topology(a) **ACTIVE** Cost (-1) (fd)

via E (q)via C Cost (5/3) (q)


via E (q)via C Cost (5/3) (q)



via C Cost (4/3)



via C Cost (4/3)


via B Cost (3/1) (Successor)via Dvia E Cost (4/3)


via B Cost (3/1) (Successor)via Dvia E Cost (4/3)

(1)

(1)

(1)

(2)(2)

A

D

EC

B

(a)


QQQQQQ


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via E (q)via C Cost (5/3)



E E-IGRP Topology(a) **ACTIVE** Cost (-1) (fd)

via D

via C Cost (4/3) (q)

E E-IGRP Topology(a) **ACTIVE** Cost (-1) (fd)

via D

via C Cost (4/3) (q)


via B Cost (3/1) (Successor)via Dvia E




RRR

QQQ

(1)

(1)

(1)

(2)(2)

A

D

EC

B

(a)


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via C Cost (4/3) (Successor)

via D



via D






RRR

(1)

(1)

(1)

(2)(2)

A

D

EC

B

(a)


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via C Cost (5/3) (Successor)via E Cost (5/4) (Successor)





via D



via D






RRR

(1)

(1)

(1)

(2)(2)

A

D

EC

B

(a)


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via D



via D






(1)

(1)

(1)

(2)(2)

A

D

EC

B

(a)


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(1)

(1)

(1)

(1)

(2)(2)

A

D

EC

B

(a)



via C Cost (4/3)



via C Cost (4/3)









DUAL Example (Start)DUAL Example (Start)


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(1)

(1)

(1)

(2)(2)

A

D

EC

B

(a)



via D



via D









DUAL Example (End)DUAL Example (End)

E IGRP ReliableE IGRP Reliable


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E-IGRP ReliableTransport Protocol


E-IGRP reliable packets are packets thatrequires explicit acknowledgement:

Update

Query

Reply

E-IGRP unreliable packets are packets that

do not require explicit acknowledgement:

Hello

Ack



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The router keeps a neighbor list and aretransmission list for every neighbor

Each reliable packet (Update, Query,Reply) will be retransmitted when packet

is not acked

E-IGRP transport has window size of one

(stop and wait mechanism)Every single reliable packet needs to beacknowledged before the next sequenced

packet can be sent



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With reliable multicast traffic, one mustwait to transmit the next reliable multicastpackets, until all peers haveacknowledged the previous multicast

If one or more peers are slow inacknowledging, all other peers sufferfrom this

Solution: The nonacknowledged multicastpacket will be retransmitted as a unicast to

the slow neighbor



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Per neighbor, retransmission limit

is 16 Neighbor relationship is reset when

retry limit (limit = 16) for reliablepackets is reached


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AgendaAgenda



Query Process


Summary


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E-IGRP SummarizationE-IGRP Summarization

Purpose: Smaller routing tables, smallerupdates, query boundary

Auto summarization:

On major network boundaries, networks are

summarized to the major networks

Auto summarization is turned on by default

192.168.1.x

192.168.1.0

192.168.2.x


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Manual summarization

Configurable on per interface basis in anyrouter within network

When summarization is configured on an interface, therouter immediate creates a route pointing to null zerowith administrative distance of five

Loop prevention mechanism

When the last specific route of the summary goes away,the summary is deleted

The minimum metric of the specific routes is used asthe metric of the summary route


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192.168.9.X

192.168.10.X

192.168.8.0/22

interface s0ip address 192.168.11.1 255.255.255.252ip summary-address E-IGRP 1 192.168.8.0 255.255.252.0

S0

AS 1


Manual summarization command:

ip summary-address E-IGRP

192.168.8.X


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E-IGRP Load BalancingE-IGRP Load Balancing

Routes with equal metric to the

minimum metric, will be installed inthe routing table (Equal Cost LoadBalancing)

There can be up to six entries in the

routing table for the same destination(default = 4)

ip maximum-paths

E-IGRP UnequalE-IGRP Unequal


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E-IGRP UnequalCost Load Balancing

E-IGRP UnequalCost Load Balancing

E-IGRP offers unequal cost load

balancing feature with the command:Variance

Variance command will allow the routerto include routes with a metric smallerthan multiplier times the minimum

metric route for that destination, wheremultiplier is the number specified by

the variance command


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10

20

10

10

20

25

A

B

C

D

E

Variance 2

Variance ExampleVariance Example

Router E will choose router C to get tonet X FD=20

With variance of 2, router E will also chooserouter B to get to net X

Router D will not be used to get to net X

Net X


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AgendaAgenda



Query Process


Summary


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Have You Seen My Sparky?

E-IGRP Query ProcessE-IGRP Query Process

E-IGRP is Advanced

Distant Vector. It relies onits neighbor to providerouting information

If a route is lost and nofeasible successor isavailable, E-IGRP needs toconverge fast, its only

mechanism for fastconvergence is to activelyquery for the lost route toits neighbors


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Queries are sent out when a route is lost

and no feasible successor is available The lost route is now in active state

Queries are sent out to all of its neighborson all interfaces except the interface tothe successor

If the neighbor does not have the lostroute information, queries are sent out to

their neighbors

E IGRP Q P


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The router will have to get ALL of the

replies from the neighbors before the routercalculates the successor information

If any neighbor fails to reply the query inthree minutes, this route is stuck in activeand the router resets the neighbor that fails

to reply Solution is to limit query range to be

covered later in presentation

G QE IGRP Q R


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A

AS 1AS 2

C

Network X

Query for XQuery for XReply for XReply for XQuery for XQuery for X

E-IGRP Query RangeE-IGRP Query Range

Autonomous System Boundaries

Contrary to popular belief, queries are notbounded by AS boundaries. Queries from AS 1will be propagated to AS 2

B

XX

E IGRP Q RE IGRP Q R


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A CB130.130.1.0/24

B Summarizes 130.0.0.0/8 to A

130.x.x.x

Reply with Infinity and theQuery Stops Here!

Query for130.130.1.0/24

E-IGRP Query RangeE-IGRP Query Range

Summarization point

Auto or manual summarization bound queriesRequires a good address allocation scheme

XX129.x.x.x

Query for130.130.1.0/24

E IGRP B d id h U ili iE IGRP B d idth Utili ti


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E-IGRP Bandwidth UtilizationE-IGRP Bandwidth Utilization

E-IGRP by default will use up to 50%

of the link bandwidth forE-IGRP packets

This parameter is manuallyconfigurable by using the command:

ip bandwidth-percent E-IGRP

Use for greater E-IGRP load control

B d id h WAN I fB d idth WAN I t f


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Bandwidth over WAN InterfacesBandwidth over WAN Interfaces

Bandwidth utilization over point-to-point subinterface Frame Relay

Treats bandwidth as T1 by default

Best practice is to manually configurebandwidth as the CIR of the PVC

B d idth WAN I t fB d idth WAN I t f


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Bandwidth over multipoint Frame Relay,ATM, SMDS, and ISDN PRI:

E-IGRP uses the bandwidth on the maininterface divided by the number of neighborson that interface to get the bandwidth

information per neighbor

B d idth WAN I t fB d idth WAN I t f


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Each PVC might have different CIR, this

might create E-IGRP packet pacing problemMultipoint interfaces:

Convert to point-to-pointBandwidth configured = (lowest CIR x numberof PVC)

ISDN PRI:

Use Dialer Profile (treat as point-to-point link)

A dA d


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AgendaAgenda



Query Process


Summary

Factors That InfluenceFactors That Influence


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Factors That InfluenceE-IGRP Scalability

Factors That InfluenceE-IGRP Scalability

Keep in mind that E-IGRP is not plugand play for large networks

Limit E-IGRP query range!

Quantity of routing informationexchanged between peers

Limiting Updates/QueriesLimiting Updates/Queries


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10.1.8.0/24

RTRB

RTRA

RTRC

RTRD

RTRE

Distribution Layer Remote Sites

Limiting Updates/QueriesExample

Limiting Updates/QueriesExample

Limiting Size/Scope ofLimiting Size/Scope of


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Limiting Size/Scope ofUpdates/Queries

t g S e/Scope oUpdates/Queries

Evaluate routing requirements

What routes are needed where?

Once needs are determinedUse summary address

Use new E-IGRP Stub feature(To be discussed later)

Use distribute lists

Limiting Updates/Q eries E ampleLimiting Updates/Queries Example


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10.1.8.0/24

RTRB

RTRA

RTRC

RTRD

RTRE


XQueriesQueriesRepliesReplies

Limiting Updates/QueriesExampleLimiting Updates/QueriesExample

Limiting Updates/Queries SummaryLimiting Updates/Queries Summary


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Limiting Updates/QueriesSummaryLimiting Updates/QueriesSummary

Remote routers fully involvedin convergence

Most remotes are never intendedto be transit

Convergence complicated throughlack of information hiding

Limiting Updates/Queries BetterLimiting Updates/Queries Better


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10.1.8.0/24

RTRB

RTRA

RTRC

RTRD

RTRE


XQueriesQueriesRepliesReplies

IP summary-address E-IGRP 1 10.0.0.0 255.0.0.0on all outbound interfaces to remotes

Limiting Updates/QueriesBetterLimiting Updates/QueriesBetter



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Convergence simplified by addingthe summary-address statements

Remote routers just reply

when queried

Limiting Updates/QueriesLimiting Updates/Queries


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g pNew Featureg pNew Feature

New E-IGRP STUB command is now

available (12.0.7T and higher)

[no] E-IGRP stub [receive-only]

[connected] [static] [summary]

Only specified routes are advertised.

Any neighbor receiving stubinformation from a neighbor will not

query those routers for any routes

Limiting Updates/Queries BestLimiting Updates/Queries Best


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Limiting Updates/QueriesBestLimiting Updates/QueriesBest

Best practice is to combineSummarization and E-IGRP STUBcommand

Limiting Updates/Queries BestLimiting Updates/Queries Best


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10.1.8.0/24

RTRB

RTRA

RTRC

RTRD

RTRE


XQueriesQueries

RepliesReplies

IP summary-address E-IGRP 1 10.0.0.0 255.0.0.0 E-IGRP stub connectedon all outbound interfaces to remotes on all remote routers C, D, and E

Limiting Updates/QueriesBestLimiting Updates/QueriesBest

Hierarchy/AddressingHierarchy/Addressing


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Hierarchy/AddressingHierarchy/Addressing

Permits maximum information hiding

Advertise major net or default routeto regions or remotes

Provides adequate redundancy

E IGRP ScalabilityE IGRP Scalability


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E-IGRP ScalabilityE-IGRP Scalability

E-IGRP is a very scalable routing

protocol if proper design methodsare used:

Good allocation of address space

Each region should have an uniqueaddress space so route summarization

is possibleHave a tiered network design model(Core, Distribution, Access)

E IGRP ScalabilityE IGRP Scalability


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E-IGRP ScalabilityE-IGRP Scalability

Use of E-IGRP Stub command if possible

Proper network resources

Sufficient memory on the router

Sufficient bandwidth on WAN interfaces

Proper configuration of the bandwidthstatement over WAN interfaces, especially

over Frame Relay Avoid blind mutual redistribution between

two routing protocols or two E-IGRP processes

Tiered Network DesignTiered Network Design


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DistributionLayer

Access Layer

Summarized RoutesSummarized Routes

Summarized RoutesSummarized RoutesSummarized RoutesSummarized Routes

Summarized RoutesSummarized Routes

Summarized RoutesPossible stub

Summarized RoutesPossible stub

Summarized RoutesPossible Stub

Summarized RoutesPossible Stub

Tiered Network DesignTiered Network Design

OtherRegions

OtherRegions

OtherRegions

OtherRegions

Core

Nonscalable NetworkNonscalable Network


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Core

TokenRing

TokenRing

3.3.4.01.1.1.0

3.3.4.0

1.1.4.0

3.3.3.0

2.2.1.0

1.1.3.0

3.3.1.0

1.1.2.02.2.3.0

2.2.2.0

TokenRing

TokenRing

TokenRing

TokenRing

1.1.1.0

1.1.2.02.2.3.03.3.4.0

2.2.1.0

3.3.2.03.3.3.01.1.4.0

3.3.1.02.2.2.01.1.3.0

Nonscalable NetworkNonscalable Network

Bad addressing scheme

Subnets are everywhere throughout entire network Queries not bounded

Scalable NetworkScalable Network


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Core

3.0.0.0

2.0.0.0

TokenRing

TokenRing

1.1.4.01.1.1.0

3.3.4.0

3.3.4.0

3.3.3.0

3.3.1.0

2.2.3.0

2.2.1.0

1.1.2.01.1.3.0

2.2.2.0

1.0.0.0

TokenRing

TokenRing

TokenRing

TokenRing

Scalable NetworkScalable Network

Readdress networkEach region has its own block of address

Queries bounded by using ip summary-address E-IGRP command

SummarySummary


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SummarySummary

Query range

Best way to limit query is through route summarization

and new E-IGRP Stub command

E-IGRP is not plug and play for large networks

Its a very scalable protocol with little design requirement

Optimizing E-IGRP network

Limiting query range

Route summarizationTiered network design

Use of E-IGRP Stub command

Sufficient network resources


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Deploying IGRP/E-IGRPDeploying IGRP/E-IGRP

Session 2208Session 2208

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Please Complete Your

Evaluation Form

Please Complete Your

Evaluation FormSession 2208Session 2208

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deploy eigrp

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