Shulou(Shulou.com)05/31 Report--

This article shows you how to analyze the EIGRP protocol, which is concise and easy to understand. It will definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

1. Brief introduction of EIGRP protocol

EIGRP (Enhanced Inerior Gateway Routing Protocol, enhanced Interior Gateway routing Protocol) is a balanced hybrid routing protocol, which combines the advantages of distance vector and link state routing protocols. It is also a private protocol of CISCO.

EIGRP is an efficient routing protocol with the following characteristics:

Establish and maintain neighbor relationships and exchange routing information by sending and receiving Hello packets

Routing updates using multicast (224.0.0.10) or unicast

The administrative distance of EIGRP is 90 and 170.

Use triggered updates to reduce bandwidth consumption

Variable length subnet mask (VLSM) is supported, and automatic summarization is enabled by default.

Supports multiple network layer protocols such as IP, IPX, and Apple Talk

For each network protocol, EIGRP maintains independent neighbor, topology and routing tables.

EIGRP uses Diffusing Upadte algorithm (DUAL) for fast convergence and ensures that there are no routing loops

Store the information of the entire network topology while quickly adapting to network changes

Support equivalent and non-equivalent load balancin

Using reliable Transport Protocol (RTP) to ensure the reliability of routing information transmission

Seamlessly connect data link layer protocols and topologies. EIGRP does not require layer 2 protocols of the OSI reference model to be configured.

2. Purpose of the experiment

Simply understand the following two basic knowledge points of EIGRP.

Understand neighbor tables, topology tables, and routing tables

The calculation method of EIGRP measure

3. Topology diagram

In order to establish an adjacency relationship between two adjacent routers, two conditions need to be met, which are the same AS number and the matching K value. You can view it via Show ip protocols, as follows (take R2 as an example here):

R2#show ip protocols

Routing Protocol is "eigrp 200"

Outgoing update filter list for all interfaces is not set

Incoming update filter list for all interfaces is not set

Default networks flagged in outgoing updates

Default networks accepted from incoming updates

EIGRP metric weight K1, K2, K3, K4, K5, 0

EIGRP maximum hopcount 100

EIGRP maximum metric variance 1

Redistributing: eigrp 200

Automatic network summarization is not in effect

Maximum path: 4

Routing for Networks:

192.168.10.0

192.168.20.0

192.168.40.0

192.168.50.0

0.0.0.0

Routing Information Sources:

Gateway Distance Last Update

192.168.10.2 90 330051

192.168.20.2 90 356798

192.168.40.2 90 382527

192.168.50.2 90 418109

Distance: internal 90 external 170

Since the current maximum of 4 lines is allowed for load balancing, if the router allows you to continue to add lines, you can use maximum-paths * to modify the number (* represents the unit of quantity). In addition, you can see the red font. "eigrp 200" represents the current EIGRP homemade system number 200.

EIGRP metric weight K1, K2, K3, K4, and K5 are K values, which have the following meanings:

K1 stands for bandwidth

K2 stands for load

K3 stands for delay

K4 and K5 represent reliability.

By default, EIGRP uses only bandwidth and load to calculate parameters for metrics. To change the K value, you can use the metric weights tos K1 K2 K3 K4 K5 command, where tos is used as the quality of service differentiation service level, 0 is not enabled and 1 is enabled.

(1), neighbor table

R2#show ip eigrp neighbors

IP-EIGRP neighbors for process 100

H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num

0 192.168.10.2 Se1/1 12 00:11:47 40 1000 0 78

1 192.168.20.2 Se1/0 12 00:11:20 40 1000 0 80

2 192.168.40.2 Se1/2 11 00:10:54 40 1000 0 91

3 192.168.50.2 Se1/3 14 00:10:19 40 1000 0 94

"H" indicates the order in which neighbors are learned, and 0 is the first neighbor to learn.

"Address" is the neighbor routing interface IP

"Interface" is the interface on which the local route is connected to this neighbor

"Hold" is the current hold time, which defaults to 15 seconds and is a decreasing value

"Uptime" is how long it has been since the neighbor entered the neighbor list.

"SRTT" refers to the normal round-trip time, which calculates the measurement of the average round-trip time of messages sent between routers in milliseconds.

"RTO" means to determine the value of the retransmission interval

"Q" refers to the queue count, and the column is the number of messages waiting in the send queue. If this value is higher than 0, there is congestion in the link.

(2), routing table

R2#show ip route

Codes: C-connected, S-static, I-IGRP, R-RIP, M-mobile, B-BGP

D-EIGRP, EX-EIGRP external, O-OSPF, IA-OSPF inter area

N1-OSPF NSSA external type 1, N2-OSPF NSSA external type 2

E1-OSPF external type 1, E2-OSPF external type 2, E-EGP

I-IS-IS, L1-IS-IS level-1, L2-IS-IS level-2, ia-IS-IS inter area

*-candidate default, U-per-user static route, o-ODR

P-periodic downloaded static route

Gateway of last resort is not set

10.0.0.0/16 is subnetted, 5 subnets

D 10.2.0.0 [90/20640000] via 192.168.10.2, 00:13:00, Serial1/1

D 10.5.0.0 [90/20640000] via 192.168.20.2, 00:12:48, Serial1/0

C 10.6.0.0 is directly connected, Loopback0

D 10.11.0.0 [90/20640000] via 192.168.50.2, 00:12:23, Serial1/3

D 10.12.0.0 [90/20640000] via 192.168.40.2, 00:12:35, Serial1/2

192.168.10.0/30 is subnetted, 1 subnets

C 192.168.10.0 is directly connected, Serial1/1

192.168.20.0/30 is subnetted, 1 subnets

C 192.168.20.0 is directly connected, Serial1/0

192.168.30.0/30 is subnetted, 1 subnets

D 192.168.30.0 [90/21024000] via 192.168.40.2, 00:12:35, Serial1/2

[90/21024000] via 192.168.50.2, 00:12:23, Serial1/3

192.168.40.0/30 is subnetted, 1 subnets

C 192.168.40.0 is directly connected, Serial1/2

192.168.50.0/30 is subnetted, 1 subnets

C 192.168.50.0 is directly connected, Serial1/3

If "D *. * / * is a summary, 00:15:00, Null0" appears in the routing table, it is a route generated by automatic summarization. By default, both EIGRP and RIP are automatically summarized at the boundary of the main network, but the difference is that EIGRP will generate an automatically summarized route locally, and the data sent to the empty interface (Null0) directed to the empty interface will be discarded. This can effectively avoid the generation of routing loops, that is, each link will have such an automatic summary record. In fact, this can be cancelled with no auto-summary, without automatic summary.

D 192.168.30.0 [90Universe 21024000] via 192.168.40.2, 00:12:35, Serial1/2 this is a final route learned through EIGRP, D stands for is learned through EIGRP, you can see that the link 192.168.30.0amp 30 is aggregated, and 90 in [90Universe 21024000] is the default administrative distance for EIGRP, followed by a measure. From this route, it can be seen that the link to 192.168.30.0swap 30 can be reached from any R4 or R5 router.

(3), topology table

R2#show ip eigrp topology

IP-EIGRP Topology Table for AS 200

Codes: P-Passive, A-Active, U-Update, Q-Query, R-Reply

R-Reply status

P 10.2.0.0/16, 1 successors, FD is 20640000

Via 192.168.10.2 (20640000 pound 128256), Serial1/1

P 10.5.0.0/16, 1 successors, FD is 20640000

Via 192.168.20.2 (20640000 pound 128256), Serial1/0

P 10.6.0.0/16, 1 successors, FD is 128256

Via Connected, Loopback0

P 10.11.0.0/16, 1 successors, FD is 20640000

Via 192.168.50.2 (20640000 pound 128256), Serial1/3

Via 192.168.40.2 (21152000 Universe 2297856), Serial1/2

P 10.12.0.0/16, 1 successors, FD is 20640000

Via 192.168.40.2 (20640000 pound 128256), Serial1/2

Via 192.168.50.2 (21152000 Universe 2297856), Serial1/3

P 192.168.10.0/30, 1 successors, FD is 20512000

Via Connected, Serial1/1

P 192.168.20.0/30, 1 successors, FD is 20512000

Via Connected, Serial1/0

P 192.168.30.0/30, 2 successors, FD is 21024000

Via 192.168.40.2 (21024000 Universe 2169856), Serial1/2

Via 192.168.50.2 (21024000 Universe 2169856), Serial1/3

P 192.168.40.0/30, 1 successors, FD is 20512000

Via Connected, Serial1/2

P 192.168.50.0/30, 1 successors, FD is 20512000

Via Connected, Serial1/3

Where P represents a passive route, that is, the route is steadily available.

Successors is the main route to the remote network, and there can be four successor routes for any particular route.

For example, 192.168.10.0 successors is the best way to get to 192.168.10. FD is the feasible distance.

(4) the calculation method of EIGRP measurement.

EIGRP uses composite metrics to calculate the best path to the destination address, which is a combination of bandwidth, delay, reliability, and load. Under the premise that K1, K2, K3, K4 and K5 are not zero, the calculation formula of compound measure:

Metric= [K1roomBandwidth+ (K2*Bandwidth) / (256-Load) + K3*Delay] * [K5 / (Reliability+K4)]

Among them, K1 affects bandwidth (Bandwidth), K2 affects load (Load), K3 affects delay (Delay), K4 and K5 affect reliability (Reliability).

In general, Cisco routers only use K1 and K3 to calculate composite metrics, so the formula can also use the following formula:

Metric= (lowest link bandwidth between 10000M/ source and destination + sum of all link delays between source and destination / 10) * 256

The lowest link bandwidth between source and destination is in M; the sum of all link delays between source and destination is in microseconds (usec); so why should I use the sum of delays divided by 10? that's because 10 microseconds is used in the EIGRP metric calculation.

Let's take a look at the experiment, for example, how to calculate the composite metric of the loopback0 interface from R2 to R1?

First of all, we need to pay attention to the metrics of the loopback0 interface from R2 to R1, and use the bandwidth and delay of the exit interface from R2 to the loopback0 interface of R1 as parameters:

R2#show int se1/1

Serial1/1 is up, line protocol is up (connected)

Hardware is HD64570

Internet address is 192.168.10.1/30

MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec

As shown above, you can see that the parameter of R2's Serial 1ax 1 interface is 0.128m such as BW bandwidth, and the delay is 20000 microseconds.

R1#show int loopback0

Loopback0 is up, line protocol is up (connected)

Hardware is Loopback

Internet address is 10.2.0.2/16

MTU 1514 bytes, BW 8000000 Kbit, DLY 5000 usec

These are the parameters of the loopback0 interface of R1, with a bandwidth of 8000m and a latency of 5000 microseconds.

Then according to the formula "Metric= (lowest link bandwidth between 10000M/ source and destination + sum / 10 of all link delays between source and destination) * 256", if the Serial1/1 of R2 goes to the loopback0 interface of R1, the lowest link bandwidth is 0.128m, and the sum of the delay is the delay of Serial1/1 + the delay of R1 loopback0 interface = 20000 to 5000, which is calculated in the formula:

[10000/R2 serial1/1 interface bandwidth (in M) + (R2 serial1/1 interface delay + R1 loopback0 interface delay) / 10] * 256

That is, [10000Universe 0.128+ (20000 million 5000) / 10] * 256

[781252500] * 25620640000

Let's verify that R2 goes to the loopback0 port of R1.

R2#show ip eigrp topology

IP-EIGRP Topology Table for AS 200

Codes: P-Passive, A-Active, U-Update, Q-Query, R-Reply

R-Reply status

P 10.2.0.0/16, 1 successors, FD is 20640000

Via 192.168.10.2 (20640000 pound 128256), Serial1/1

P 10.5.0.0/16, 1 successors, FD is 20640000

Via 192.168.20.2 (20640000 pound 128256), Serial1/0

P 10.6.0.0/16, 1 successors, FD is 128256

Via Connected, Loopback0

P 10.11.0.0/16, 1 successors, FD is 20640000

Via 192.168.50.2 (20640000 pound 128256), Serial1/3

Via 192.168.40.2 (21152000 Universe 2297856), Serial1/2

P 10.12.0.0/16, 1 successors, FD is 20640000

Via 192.168.40.2 (20640000 pound 128256), Serial1/2

Via 192.168.50.2 (21152000 Universe 2297856), Serial1/3

P 192.168.10.0/30, 1 successors, FD is 20512000

Via Connected, Serial1/1

P 192.168.20.0/30, 1 successors, FD is 20512000

Via Connected, Serial1/0

P 192.168.30.0/30, 2 successors, FD is 21024000

Via 192.168.40.2 (21024000 Universe 2169856), Serial1/2

Via 192.168.50.2 (21024000 Universe 2169856), Serial1/3

P 192.168.40.0/30, 1 successors, FD is 20512000

Via Connected, Serial1/2

P 192.168.50.0/30, 1 successors, FD is 20512000

Via Connected, Serial1/3

The above content is how to analyze the EIGRP protocol. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.