Eigrp basic configuration and configuration commands

EIGRP: Enhanced Interior Gateway Routing Protocol is an enhanced interior gateway routing protocol. Also translated as a reinforced interior gateway routing protocol. EIGRP is a proprietary protocol of Cisco Corporation (commercialized in 2013). EIGRP combines the Cisco-specific protocol for link state and distance vector routing protocols, uses the Dispersion Correction Algorithm (DUAL) to achieve fast convergence, and does not send periodic routing updates to reduce bandwidth usage. Supports Appletalk, IP, and Novell. And various network layer protocols such as NetWare.

Basic configuration of eigrp

Experimental procedure

Step1: Configure IP

Step2: Configure EIGRP

R1(config)#router eigrp 100 //Enable eigrp

R1(config-router)#no auto-summary //Close automatic summarization

R1(config-router)#network 12.1.1.00.0.0.255 //network Target network segment anti-subnet mask

R1(config-router)#network 1.1.1.1 0.0.0.0

R2(config)#router eigrp 100

R2(config-router)#no auto-summary

R2(config-router)#network 12.1.1.00.0.0.255

R2(config-router)#network 23.1.1.00.0.0.255

R2(config-router)#network 2.2.2.2 0.0.0.0

R3(config)#router eigrp 100

R3(config-router)#no auto-summary

R3(config-router)#network 23.1.1.00.0.0.255

R3(config-router)#network 34.1.1.00.0.0.255

R3(config-router)#network 3.3.3.3 0.0.0.0

R4(config)#router eigrp 100

R4(config-router)#no auto-summary

R4(config-router)#network 34.1.1.00.0.0.255

R4(config-router)#network 4.4.4.4 0.0.0.0

Step3: Check the connectivity of the entire network

Step4: View the routing table

R3#show ip rou

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

1.0.0.0/32 is subnetted, 1 subnets

D 1.1.1.1 [90/158720] via 23.1.1.2, 00:00:22, FastEthernet0/0

2.0.0.0/32 is subnetted, 1 subnets

D 2.2.2.2 [90/156160] via 23.1.1.2, 00:00:22, FastEthernet0/0

3.0.0.0/32 is subnetted, 1 subnets

C 3.3.3.3 is directly connected, Loopback1

4.0.0.0/32 is subnetted, 1 subnets

D 4.4.4.4 [90/156160] via 34.1.1.4, 00:00:22, FastEthernet0/1

12.0.0.0/24 is subnetted, 1 subnets

D 12.1.1.0 [90/30720] via 23.1.1.2, 00:00:22, FastEthernet0/0

23.0.0.0/24 is subnetted, 1 subnets

C 23.1.1.0 is directly connected, FastEthernet0/0

34.0.0.0/24 is subnetted, 1 subnets

C 34.1.1.0 is directly connected, FastEthernet0/1

â€œDâ€ indicates the routing entry learned with EIGRP with a management distance of 90.

Step5: View the routing protocol

R3#show ip protocols

Routing Protocol is â€œeigrp 100 â€

//AS number is 100

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

EIGRPmetric weight K1=1, K2=0, K3=1, K4=0, K5=0

// Display the K value used to calculate the metric

EIGRPmaximum hopcount 100

//The maximum number of hops supported by EIGRP

EIGRPmaximum metric variance 1

//The variance value defaults to 1, which means that only the load balancing of the equivalent path is supported by default.

Redistributing: eigrp 100

Automaticnetwork summarization is not in effect

/ / Display automatic summary has been closed, the default automatic summary is turned on

Maximum path: 4

Routing for Networks:

23.1.1.0/24

34.1.1.0/24

3.3.3.3/32

Routing Information Sources:

Gateway Distance Last Update

23.1.1.2 90 0

34.1.1.4 90 10

Distance:internal 90 external 170

// EIGRP routing protocol can distinguish between internal routes and external routes. The default administrative distance for internal routes is 90, and the default management distance for external routes is 170.

Step6: View EIGRP neighbors

R3#show ip eigrp neighbors

IP-EIGRP neighbors for process 100

H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num

0 23.1.1.2 Fa0/0 10 00:06:54 40 1000 0 9

1 34.1.1.4 Fa0/1 10 00:06:54 40 1000 0 11

The meanings of the above output fields are as follows:

1 H: indicates the order in which the session is established with the neighbor;

2 Address: Interface address of the neighbor router;

3 Interface: The interface from the local to the neighbor router;

4 Hold: The maximum time that the neighbor relationship can be waited for;

5 Uptime: From the establishment of the neighbor relationship to the current time;

6 SRTT: is the time to send a packet to the neighbor router and the router receives the acknowledgement packet;

7 RTO: The time the router waits for an ACK before retransmitting the packet;

8 Q Cnt: queue waiting to be sent;

9 Seq Num: Serial number of the transmitted packet received from the neighbor.

Step7: View the topology

R3#show ip eigrp topology

IP-EIGRP Topology Table for AS100/ID (3.3.3.3)

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

r - Reply status

P 1.1.1.1/32, 1 successors, FD is 158720

Via 23.1.1.2 (158720/156160), FastEthernet0/0

P 2.2.2.2/32, 1 successors, FD is 156160

Via 23.1.1.2 (156160/128256), FastEthernet0/0

P 3.3.3.3/32, 1 successors, FD is 128256

Via Connected, Loopback1

P 4.4.4.4/32, 1 successors, FD is 156160

Via 34.1.1.4 (156160/128256), FastEthernet0/1

P 12.1.1.0/24, 1 successors, FD is 30720

Via 23.1.1.2 (30720/28160), FastEthernet0/0

P 23.1.1.0/24, 1 successors, FD is 28160

Via Connected, FastEthernet0/0

P 34.1.1.0/24, 1 successors, FD is 28160

Via Connected, FastEthernet0/1

You can clearly see the FD and RD values â€‹â€‹of each routing entry.

Step8: View the EIGRP interface

R3#show ip eigrp interfaces

IP-EIGRP interfaces for process 100

Xmit Queue Mean Pacing Time Multicast Pending

Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes

Lo1 0 0/0 1236 0/10 0 0

Fa0/0 1 0/0 1236 0/10 0 0

Fa0/1 1 0/0 1236 0/10 0 0

The meaning of each field is as follows

1 Interface: The interface that runs the EIGRP protocol.

2 Peers: number of neighbors on the interface;

3 Xmit Queue Un/Reliable: The number of packets that remain in the unreliable/reliable queue;

4 Mean SRTT: average round trip time in seconds;

5 Pacing Time Un/Reliable: used to determine the interval at which packets in the unreliable/reliable queue are sent out of the interface;

6 Multicast Flow Timer: The longest waiting time before the multicast packet is sent;

7 Pending Routes: Waiting for the routing entries carried in the transmitted packets in the transmit queue.

Step9: View the situation of EIGRP sending and receiving packets

R3#show ip eigrp traffic

IP-EIGRP Traffic Statistics for process 100

Hellos sent/received: 566/377

Updates sent/received: 12/11

Queries sent/received: 0/0

Replies sent/received: 0/0

Acks sent/received: 10/7

Input queue high water mark 1, 0 drops

SIA-Queries sent/received: 0/0

SIA-Repliessent/received: 0/0

Step10: debug eigrp neighbors

This command can dynamically view the EIGRP neighbor relationship. Shut down the f0/0 interface on router R1.

Then no shutdown, you can see the process of EIGRP neighbor establishment.

EIGRP routing configuration command

It is Cisco's private routing protocol, which combines the advantages of distance vector and link state. Its features include: 1. Fast convergence

Link-state packets (LSPs) are forwarded without relying on routes, so large networks can converge faster. It only announces the link and link status without declaring the route, so even if the link changes, it will not cause the route of the link to be announced. However, the link state routing protocol uses the Dijkstra algorithm, which is more complicated and accounts for CPU and memory resources compared with other routing protocols. EIGRP uses diffing calculations (diffusingcomputations) to route through multiple routers in parallel. Calculated so that it can converge quickly without loops. 2. Reduce bandwidth usage

EIGRP does not perform periodic updates, it only makes partial updates after the path and degree of the route changes. When the path information changes, DUAL only sends the update that the routing information changed, instead of sending the entire routing table. Compared to updating the link state routing protocol transmitted to all routers in an area, DUAL only sends updates to the routers that need the update information. On the WAN low-speed link, EIGRP may occupy a large amount of bandwidth. By default, only the link bandwidth is 50%. The IOS that is released later can use the ip bandwidth-percent eigrp command to modify this default value. 3. Support multiple network layer protocols

EIGRP supports protocols such as IPX, ApplleTalk, IP, IPv6, and NovellNetware by using a protocol-dependent module (PDM). 4. Seamlessly connect data link layer protocols and topologies

EIGRP does not require special configuration of the Layer 2 protocol of the OSI Reference Model. Unlike OSPF, OSPF does different configurations for different Layer 2 protocols, such as Ethernet and Frame Relay. EIGRP can work effectively in LANs and WANs, and EIGRP ensures that the network does not loop-free; And it's simple to configure; it supports VLSM; it uses multicast and unicast, does not use broadcast, which saves bandwidth; it uses the same degree of algorithm as IGRP, but is 32 bits long; it can be non-equivalent The load balancing of the path. Four components

1. Protocol-Dependent Module (PDM)

2. Reliable Transport Protocol (RTP) 3. Neighbor discovery/recovery

4. Diffusing Update Algorithm (DUAL) RTP-EIGRP reliable transmission protocol

RTP is responsible for the sequential (reliable) transmission and reception of EIGRP packets (described below). This reliable guarantee is implemented by a proprietary Cisco algorithm, reliable multicast, using the multicast address 224.0.0.10, which is received by each neighbor. In this reliable multicast packet, the unicast is used as the acknowledgment. The sequential transmission is implemented by the two serial numbers in the packet. Each packet contains one serial number assigned by the sender, and the sender sends each sequence. Packet, the serial number is incremented by 1. In addition, the sender also puts the serial number of the packet recently received from the target router in the packet to be sent. In some cases, the RTP can also use the acknowledgment. Unreliable transmission, and the use of this unreliable transmission of the packet does not contain the serial number. The first transmission of EIGRP is in multicast form, and the retransmission is unicast. EIGRP-Metric calculation method

EIGRP selects a primary route (best route) and a backup route on the topology table (EIGRP supports up to 6 links to the destination). It supports several routing types: internal, external (non-EIGRP) and summary routing. EIGRP uses mix.

i. Five standards of EIGRP Metric 1. Bandwidth

The 7th power of 10 divided by the lowest bandwidth between source and destination multiplied by 256 2. Delay (delay)

The cumulative delay of the interface is multiplied by 256 in units of 10 microseconds. 3. Reliability

The value of the most unreliable reliability between source and destination based on keepalive. 4. Loading

The value of the worst load between source and destination based on packet rate and interface configuration bandwidth. 5. Maximum Transmission Unit (MTU)

The smallest MTU.MTU in the path is included in the EIGRP routing update, but generally does not participate in the EIGRP degree operation.

Ii. Calculation of EIGRP Metric

The EIGRP metric is calculated as: 256*{K1(10^7/bandwidth)+K2(10^7/bandwidth)/(256-load)+K3(delay)+K5/(reliability+K4)}

By default, K1 and K3 are 1, and the other K values â€‹â€‹are 0.

So usually, the metric = 256 Ã— (10 ^ 7 / minimum bandwidth + cumulative delay)

By configuring the weight (K value), you can modify the EIGRP metric calculation method. You can use the command in EIGRP configuration mode: Metric weight Tos K1 K2 K3 K4 K5 to modify the K value. Tos has only one valid value of 0, otherwise it will be ignored.

EIGRP requires that both routers have the same K value to be a neighbor. In addition, K2, K4, and K5 are best not set, because setting these parameters to non-zero will cause the load and reliability of the excuses to be considered when calculating the metrics, and the load and reliability will change with time, which will result in EIGRP re-floating topology data may also cause routers to continually select different routes, which may result in network instability. EIGRP Packet

EIGRP uses multiple types of packets, which are identified by protocol number 88 in the IP header information: 1. Hello packet

Used to discover and recover neighbors, send them by multicast, and use unreliable sending. 2. ACK (acknowledgement) packet

A Hello packet that does not contain data (data) is sent unreliably using unicast.

3. Update packet

Propagating routing update information, sent irregularly, such as through network links. When only one router needs routing updates, update is sent by unicast; when multiple routers need routing updates, they are sent by multicast. 4. Query & Reply packet

The DUAL finite state machine is used to manage the diffusion calculation. The query packet can be multicast or unicast; the response packet is sent by unicast, and the method is reliable. 5. Request packet

Originally intended to be used by the routing server (server), but never implemented. Neighbor Discovery/Recovery Protocol

The EIGRP Update package is sent aperiodically.

1. Hello packets in a general network (such as point-to-point) are multicast once every 5 seconds (to randomly subtract 1 small time to prevent synchronization);

2. On multipoint X.25, Frame Relay (FR) and ATM interfaces (such as ATM SVC) and ISDN PRI interfaces, the Hello packet transmission interval is 60 seconds.

In all cases, the Hello package does not need to be confirmed. You can change the default interval for sending Hello packets on the interface in interface configuration mode. The command is ip hello-interval eigrp.

When a router receives a Hello packet from a neighbor, the Hello packet contains a holdown time, which tells the router the maximum time to wait for the subsequent Hello packet. If no subsequent Hello packets are received before this holdown time is exceeded, the neighbor is declared unreachable and DUAL is notified that the neighbor has been lost. The default hold time is 3 times the Hello packet transmission interval, the higher link -- the default Hello interval and hold time is 5s and 15s T1 or lower than the T1 link -- 60s and 180s respectively can be modified in interface configuration mode The default holdown time, the command is ip hold-time eigrp.

EIGRP neighbor information is recorded in the neighbor table. Use the show ip eigrp neighbors command to view the IP EIGRP neighbors. EIGRP solution to the loop

Eigrp basic configuration and configuration commands

EIGRP LOOP

If EIGRP does not consider the loop problem, then when the line connecting routes 3 and 4 in the figure on the right is disconnected, it will not be able to get network a and route 1-3 to query each other how to go to network a to generate a loop. Therefore, EIGRP considers two aspects of loop prevention:

1. Split Horizon

2. Route poison reverse (Poison reverse)

The interface that receives the routing information, and then advertises that the route just learned is unreachable.

When two routers initiate neighbor initialization, they will advertise each other with the largest metric value (route poisoning).

When the topology changes, the split horizon and poison reverse are temporarily turned off, and the topology is re-learned.

When sending a query request, it will cause horizontal splitting. For example, when a router queries an unknown network segment, he will want each neighbor to send a query. The successor in the network segment will return a query to the router. The router will feed back a query result to other neighbors, and will not tell the successor that the network segment should be re-distributed through its own route.

In some large networks, there are often different autonomous regions that need to be interconnected. Eigrp basic configuration and configuration commands

EIGRP redistribution

. For example, in the case of the right picture, the two EIGRPs with the AS number of 1000 must communicate with the two EIGRPs with the AS number of 2000. You only need to configure redistribution in the intermediate router. Pay attention to configuring redistribution and avoid routing loops. Example:

Router One

Router eigrp 2000 network 172.16.1.0 0.0.0.255 Router Two

Router eigrp 2000 redistribute eigrp 1000 route-map to-eigrp2000

Network 172.16.1.0 0.0.0.255--Define the network segment of AS=1000 to AS=2000 in AS=2000!

Router eigrp 1000

Redistribute eigrp 2000 route-map to-eigrp1000--Define the network segment where AS=2000 goes to AS=1000 in AS=1000

Network 10.1.0.0 0.0.255.255 route-map to-eigrp1000 deny 10 match tag 1000 !

Route-map to-eigrp1000 permit 20 set tag 2000 !

Route-map to-eigrp2000 deny 10 match tag 2000 !

Route-map to-eigrp2000 permit 20 set tag 1000

- When the network segment with AS=1000 is marked with a tag of 1000, when AS=2000 is redistributed into AS=1000, the routing information marked with 1000 will be rejected to prevent loops; AS=2000 is also true. Router Three

Router eigrp 1000network 10.1.0.0 0.0.255.255 Now routes between 1 and 3 can be accessed. Definition of Terms

1. Introduction to the diffusion update algorithm

(Diffusion update algorithm can guarantee 100% loop-free loopfree) In order to enable DUAL to operate correctly, the lower layer protocol must meet the following conditions:

1. A node has to detect the existence of a new neighbor or the loss of a connection with a neighbor for a limited time. All information transmitted on the link must be received in the correct order for a limited time

3. All messages, including link cost changes, link failures, and new neighbor discovery, should be processed in a limited time, one by one, processing Cisco's EIGRP using neighbor discovery/recovery and RTP to ensure the above prerequisites. 2.adjacency (adjacent)

At the time of startup, the router uses the Hello packet to discover neighbors and identify itself for neighbor identification. When a neighbor is discovered, EIGRP forms an adjacency between them. Adjacency refers to the formation of a virtual link (virtual link) between two neighbors. When the adjacencies are formed, they can send routes update to each other. These updates include all the links that the router knows and their metrics. For each route, the router will base its neighbors on the distance and arrival. The cost of the link of that neighbor to calculate a distance

3.Feasible Distance (FD, feasible distance)

The smallest metric to reach each target network will be the FD of that target network. For example, the router may have three routes to the network 172.16.5.0, metrics are 380672, 12381440 and 660868, then 380672 becomes FD.

4. Feasible Condition (FC, feasible condition)

The neighbor announces that the distance to the target network is less than the FD AD of the local router to reach the target network. FD = "FC=ture.

5.Feasible Successor (FS, feasible successor route)

If a neighbor announces that the distance to the target network meets the FC, then the neighbor becomes the FS. For example, the FD of the router reaching the target network 172.16.5.0 is 380672, and the distance that the neighbor announces to reach the target network is 355072, and the neighbor router satisfies FC, it becomes FS; if the neighbor router announces that the distance to the target network is 380928, that is, FC is not satisfied, then the neighbor router cannot become FS, FS and FC are core technologies to avoid loops, and FS is also downstream router (downstream) Router), because the distance from the FS to the target network is smaller than the FD of the local router reaching the target network.

Router eigrp 1000network 10.1.0.0 0.0.255.255 Now routes between 1 and 3 can be accessed. Definition of Terms

1. Introduction to the diffusion update algorithm

(Diffusion update algorithm can guarantee 100% loop-free loopfree) In order to enable DUAL to operate correctly, the lower layer protocol must meet the following conditions:

3.Feasible Distance (FD, feasible distance)

4. Feasible Condition (FC, feasible condition)

The neighbor announces that the distance to the target network is less than the FD AD of the local router to reach the target network. FD = "FC=ture.

5.Feasible Successor (FS, feasible successor route)

6. Topology Table

The topology table includes the following: FD of the target network. All FDs.

The distance that each FS announces to reach the target network.

The distance calculated by the local router after each FS reaches the target network, that is, the distance that the FS announces to reach the target network and the cost of the link that the local router reaches the FS. The interface connecting the FS network is found.

7. Neighbor Table

A table of neighbor address and interface information is stored in the RAM of each router.

8. Successor routing (Successor)

Also known as the "Secessful", it is the best route to reach a remote network. It is the route EIGRP uses to forward traffic, which is stored in the routing table. Advantages and Disadvantages of EIGRP Routing Protocol (1) Main Advantages of EIGRP Routing Protocol

Precise route calculation and multi-route support. The biggest advantage of the EIGRP protocol inheriting the IGRP protocol is the vector routing right. EIGRP protocol comprehensively considers factors such as network bandwidth, network delay, channel occupancy rate and channel credibility in route calculation. Therefore, EIGRP routing calculation is more accurate and can better reflect the actual situation of the network. At the same time, the EIGRP protocol supports multiple routes, so that routers can perform load sharing according to different paths. Less bandwidth is used. The peer routers that use the EIGRP protocol periodically send small hello packets to ensure the validity of the previously sent packets. The route is sent using the incremental sending method, that is, only the changed route is sent at a time. The sent routing update message is transmitted reliably. If no confirmation message is received, it is resent until it is confirmed. EIGRP can also control the transmission of EIGRP packets, reducing the bandwidth usage of EIGRP packets on the interface, thus avoiding the continuous transmission of a large number of routing packets and affecting normal data services.

Fast convergence. The loop-free and route convergence speed of route calculation is an important indicator of route calculation. Due to the use of the DUAL algorithm, the EIGRP protocol makes it impossible for EIGRP to generate loop routes in route calculation, and the convergence time of route calculation is also guaranteed. Because the DUAL algorithm makes EIGRP only recalculate the changed route when calculating the route; for a route, only the router affected by this route will intervene in the recalculation of the route.

MD5 certification. To ensure the correctness of the route, you can configure MD5 authentication between the routers that run the EIGRP process to discard the packets that do not meet the authentication, thus ensuring the security of the routes.

Route aggregation. EIGRP can be configured to aggregate routes of any EIGRP route with arbitrary mask lengths, thus reducing routing information transmission and saving bandwidth.

Implement load sharing. Routes to the same destination can be automatically generated based on the rate, quality, and reliability of the interface. The packets can be automatically matched to the interface traffic based on the information. purpose.

Simple configuration. Using EIGRP to form a network, the router configuration is very simple, it does not have complex locales, and there is no need to implement different configuration methods for different network interface types. To use the EIGRP protocol, simply use the router eigrp command to start the EIGRP routing process on the router, and then use the network command to enable the network-wide interface. (2) Main disadvantages of EIGRP routing protocol

There is no regional concept. EIGRP has no concept of area, and OSPF can plan and limit the size of the network by dividing the area in the case of large-scale networks. Therefore, EIGRP is applicable to networks with relatively small network scales, which is also the limitation of vector-distance routing algorithms (RIP protocol is used). Send HELLO packets periodically. Routers running EIGRP must periodically send HELLO packets to maintain neighbor relationships. This kind of neighbor relationship needs to send HELLO packets periodically even on the dial-up network. This makes it impossible to locate on the dial-on-demand network. The service packet is also a timing polling message sent by EIGRP, which may trigger the dial-up network to initiate a connection, especially on the backup network, causing unnecessary trouble. Therefore, the router running EIGRP generally needs to configure the dialer list and the dialer group on the dial-up backup port to filter unnecessary packets or run the TRIP protocol. This increases the overhead of the router. OSPF can provide on-demand dial-up support for dial-up networks. It can meet the needs of various leased line or dial-up network applications with only one routing protocol.

Based on the distributed DUAL algorithm. The loop-free calculation and convergence speed of EIGRP is based on the distributed DUAL algorithm, which actually spreads the indeterminate routing information (query packets to the neighbors) and obtains confirmation from all neighbors (reply message). In the process of reconvergence, the neighbor repeats the dissemination without determining the reliability of the routing information. Therefore, in some cases, the routing information may always be active (this route is called an active routing stack). And, if the measurement of the successor to the route changes during the DUAL calculation of the active route, it will enter multiple calculations, which will affect the convergence speed of the DUAL algorithm. The OSPF algorithm does not have such a problem, so from the perspective of convergence speed, although the overall is similar, in some special cases, EIGRP has an unsatisfactory situation.

EIGRP is a proprietary protocol of Cisco Corporation. Cisco is the inventor of the agreement and the only vendor with the right to interpret and modify the agreement. If you want to support the EIGRP protocol, you need to purchase the corresponding copyright from Cisco, and Cisco has no obligation to notify the other company and the users who use the agreement. OSPF is an open protocol and is a standard published by the IETF. The world's major network equipment manufacturers support the agreement, so its interoperability and reliability are guaranteed by the public, and with the support of many manufacturers, the agreement will continue to be more perfect.

IGRP and EIGRP routing protocols

IGRP (Interior Gateway Routing Protocol) is a Cisco-specific distance vector-based routing protocol. Although it is also applied to smaller LANs, it is different from RIP routing protocols. IGRP uses IP layer. Port number 9 performs packet exchange, while RIP uses port 520 for message exchange.

IGRP is also a dynamic distance vector routing protocol designed by Cisco in the mid-1980s. It uses hop counts to determine the best path to a network, using latency, bandwidth, reliability, and load to determine optimal routing. . By default, IGRP sends a route update broadcast every 90 seconds, and within 3 update cycles (ie 270 seconds), if the update is not received from the first router in the route, the router is declared inaccessible. After 7 cycles (ie 630 seconds), the Cisco IOS (Internet Operating System) software clears the route from the routing table.

EIGRP combines the Cisco-specific protocol for link state and distance vector routing protocols, uses the Dispersion Correction Algorithm (DUAL) to achieve fast convergence, and does not send periodic routing updates to reduce bandwidth usage. Supports Appletalk, IP, and Novell. And various network layer protocols such as NetWare. Since the birth of the EIGRP routing protocol, IGRP routing protocols have rarely been used. Basic configuration r1(config)#router eigrp 1

R1 (config-router) #net 192.168.1.0 activation interface, downlink equivalent command r1 (config-router) #net 192.168.1.1 0.0.0.255

R1(config-router)#passive-interface fastEthernet 0/1 does not send Hello packet from F0/1 neib 192.168.1.2 / lo 0 unicast

Variance "multiplier" non-equivalent load balancing bandwidth "kbps" bandwidth

Ip bandwidth-parcent AS occupied bandwidth key chain "name" MD5 verification key "ID"

Key-string "string"

Ip authenticatian mode eigrp "AS" md5

Ip authentication key-chain eigrp "AS" "name-of-chain" show command:

Show ip eigrp int / nei / top / tra/

Show ip pro

Detailed EIGRP metric

1. EIGRP metric = (IGRP metric) * 256 IGRP metric is 24 bits in length. EIGRP metric is 32 bits in length.

2. K1 :: Bandwidth = (10,000,000 / bandwidth on interface, kbps) * 256 56K 45714176 1.544M 1657856 (10,000,000 / 1544 = 6476) * 256 10M 256000 100M 25600 1G 2560

3. K2 :: Loading 4. K3 :: Delay sum of delays in the path, in tens of microseconds, mutliplied by 256 Delay = [(sum of the DLY, in microseconds) / 10] * 256 where DLY is sent from the local interface, all along the way DLY of the source interface, for example: DLY=8000usec DLY=10000usec. . . DLY=20000usec. DLY=5000usec. . . . . . 12.0.0.0/24. . |---lo0-( R1 )-s0/0------------------s0/0-( R2 )-lo0---| . . . . . . . . . . . . . BW=1544Kbit BW=1544Kbit. . . . . . . BW=8000000Kbit BW=8000000Kbit. . . . 1.1.1.0/24 2.2.2.0/24 The metric value of the route to 2.2.2.0/24 obtained by show ip route on R1 is 2,297,856 Bandwidth = (10,000,000 / 1544) * 256 = 6476 * 256 = 1,657,856 Delay = [(20000 + 5000)/10] * 256 = 2500 * 256 = 640,000 metric = K1*BW + K3*Delay = 1657856 + 256000 = 2,297,856 at R2 The metric value of the route to 1.1.1.0/24 obtained by show ip route is 2,118,656 Bandwidth = (10,000,000 / 1544) * 256 = 6476 * 256 = 1,657,856 Delay = [( 10000 + 8000) / 10] * 256 = 1800 * 256 = 460,800 metric = K1*BW + K3*Delay = 1657856 + 460800 = 2,118,656 - By observing the metrics of the above 2 routes, it can be seen that although It is only the route between two loopback interfaces of two routers, and the metric obtained is the same when the link bandwidth is the same. The reason is that the DLY value obtained by EIGRP in calculating the metric is the DLY value of the source port of all links in the routing path. Since the DLY values â€‹â€‹of the 2-terminal interface on one link are different, the two directions are different. The metric results. In fact, the value of bandwidth is not the minimum bandwidth on the link. This is wrong in many books. In EIGRP metric calculation, bandwidth is only a performance reference value and does not reflect real bandwidth. It is the local interface. The BW value displayed on it can be modified by the interface command bandwidth. For example: R2(config)#int

S0/0R2(config-if)#bandwidth 1000R2(config-if)#do sh ip routeCodes: C -

Connected, S - static, 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 i - IS-IS, su - IS-IS summary, 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

1.0.0.0/24 is subnetted, 1 subnetsD 1.1.1.0 [90/3020800] via 10.1.1.1, 00:00:21, Serial0/0 2.0.0.0/24 is subnetted, 1 subnetsC 2.2.2.0 is directly connected , Loopback0 12.0.0.0/24 is subnetted, 1 subnetsC 12.1.1.0 is directly connected, Serial0/0

å¯ä»¥çœ‹åˆ°ï¼Œ 1.1.1.0 çš„metric å·²ä»Ž2ï¼Œ118ï¼Œ656 å˜ä¸º3ï¼Œ020ï¼Œ800 5. K4 ï¼šï¼š Reliability Can be observed at the result of show interface 6ï¼Ž K5 ï¼šï¼š MTU

7. K1~K5 ---ã€‹ BLDRM ---ã€‹ BLack DReaM ï¼ˆè¿™æ˜¯æˆ‘çš„ä¸€ä¸ªè®°å¿†æŠ€å·§ï¼‰

8. Formula with default K values ï¼ˆK1=1ï¼Œ K2=0ï¼Œ K3=1ï¼Œ K4=0ï¼Œ K5=0ï¼‰ï¼š metric = K1*BW + ï¼ˆï¼ˆK2*BWï¼‰/ï¼ˆ256-loadï¼‰ï¼‰ + K3*delay = BW + delay

9. If K5 is not equal to 0ï¼š metric = metric * ï¼» K5/ï¼ˆreliability + K4ï¼‰ ï¼½ 10ï¼Ž K values are carried in EIGRP hello packets.

11. Mismatched K values can cause a neighbor to be reset. EIGRPå¸¸ç”¨æŽ’é”™å‘½ä»¤

show run | begin router eigrp//æŸ¥çœ‹é…ç½®æ–‡ä»¶ä¸eigrpçš„é…ç½®å‘½ä»¤show ip protocols//æŸ¥çœ‹å½“å‰è·¯ç”±å™¨è¿è¡Œçš„eigrpåè®®çŠ¶æ€show ip route summary//æŸ¥çœ‹eigrpè·¯ç”±æ±‡æ€»çŠ¶æ€show ip eigrp neighbors//æŸ¥çœ‹eigrpé‚»å±…çŠ¶æ€

show ip eigrp interface//æŸ¥çœ‹å„ä¸ªè¿è¡Œeigrpçš„çŠ¶æ€

show ip eigrp interface detail//æŸ¥çœ‹å„ä¸ªè¿è¡Œeigrpçš„è¯¦ç»†çŠ¶æ€show ip route eigrp//æŸ¥çœ‹eigrpåè®®å¦ä¹ åˆ°çš„è·¯ç”±è¡¨show ip eigrp topology//æŸ¥çœ‹eigrpçš„æ‹“æ‰‘è¡¨

show ip eigrp topology all-links//æŸ¥çœ‹eigrpå®Œæ•´çš„æ‹“æ‰‘è¡¨

show ip eigrp topology 10.1.1.0 255.255.255.0//äº§çœ‹æŒ‡å®šçš„æŸä¸ªç½‘ç»œå‚æ•°ä¿¡æ¯

debug eigrp packets//è°ƒè¯•eigrpçš„æŸ¥è®¯åŒ…

debug eigrp fsm //è°ƒè¯•eigrpçš„dualç®—æ³•è°ƒè¯•ä¿¡æ¯

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