Implementing and configuring EIGRP
Hello, the Cisco blog is rarely replenished, you need to fix it.
ABOUT! I can’t publish in it so far, so it's personal.
I want to talk about the EIGRP protocol: how to configure, where to implement;)
EIGRP is a proprietary cisco-dynamic routing protocol.
In general, routing is the process of determining the route of information in communication networks. (via wikipedia)
The main point is that when using static routing, you need to manually prescribe routes, implement spare links using spanning tree / etherchannel; when using dynamic routing, the devices independently compile the network routing table, choose the shortest path to the point by the specified parameters, balance the load across several channels.
')
Application area - networks with a large number of routing nodes (on the bsci course, the instructor spoke about dozens of devices). Naturally, if you have one router on the network, there is no talk about the dynamics. Nuance - all devices must be Cisco;) You also need to understand that there should be no stretched VLANs. Each router must have its own unique VLANs.
A stretched VLAN is a VLAN, the devices in which are randomly scattered throughout the network.
We have just such a L2 network (by the way, it was not taken from the head, but actually exists, though they didn’t implement EIGRP, the customer decided, the reasons at the end). Three core switches are connected by a ring, the links between them are Etherchannels. All routing, all main VLAN gateways are raised to Core_SW1.
And after the implementation of EIGRP, we get such a scheme. The three core switches are interconnected by L3 links, the shortest route is dynamically determined by EIGRP, and the traffic is balanced between all links. In general, all connections are used, in contrast to what was where the lines worked, uncutted Spanning Tree.
EIGRP works as follows. A hello-packages are sent to the L3 link (with a specified frequency). After the device receives a response, it establishes "neighbor" relations and begins to exchange information about the networks connected to it. When all devices see each other and establish a neighbor relationship, each of them will have the entire network routing table. It is worth noting the following - if during the hold-timer a hello packet is not received from a neighbor, it is considered dead and its routes are deleted from the routing table.
You must specify IP addresses for L3 interfaces. By the way, the interfaces on the routers are already L3, on the switches with the routing function they are the same as the default L2 interfaces. To make them L3 and set IP, you need to enter a command on the interface:
no switchport
ip address [IP address] [mask]
After configuring the interfaces, run EIGRP
Cisco_2811_ons (config) #router eigrp [autonomous system number]]
Cisco_2811_ons (config-router) #eigrp router-id [IP-address] / it is possible to set the IP-address by which this device will be identified
We set networks (VLAN'Y) about which we will tell neighbors:
Cisco_2811_ons (config-router) #network [network] [reverse mask]
It is also necessary to advertise the L3 interface subnets.
Set hello and hold timers (set on the interface and the values on both sides must match):
Cisco_2811_ons (config-if) #ip hello-interval eigrp [autonomous system number] [seconds]
Cisco_2811_ons (config-if) #ip hold-time eigrp [autonomous system number]] [seconds]
Cisco recommends setting hello-time for 1 second and hold-time for 3 seconds.
Install which interfaces EIGRP will use:
Cisco_2811_ons (config-router) # passive-interface default
Cisco_2811_ons (config-router) #no passive-interface [port interface] [slot / number]
This is the minimum teams, after which EIGRP should earn you :)
To view the EIGRP neighbor list:
Cisco_2811_ons # sh ip eigrp neighbors
View routes:
Cisco_2811_ons # sh ip route
Cisco_2811_ons # sh ip route eigrp [autonomous system number]
Debag:
Cisco_2811_ons # debug eigrp [autonomous system number] [what to watch]
Probably everything I wanted to write ... I wanted to be quite brief, because I think that you can find the theory naked yourself :)
If you have any questions - ask, maybe something is missing from your mind while writing :)
PS In a real network, they refused to implement EIGRP due to the presence of stretched VLANs. If the voice VLAN (IP telephony) was still possible to beat and redirect DHCP requests using the ip helper-address command, then with VLANs of different microcontrollers and other things (devices are randomly scattered throughout the territory of the object) + it includes servers It seemed bad, they did not go to him.
So comrades, when designing networks from scratch, think about the future ...;)
ABOUT! I can’t publish in it so far, so it's personal.
I want to talk about the EIGRP protocol: how to configure, where to implement;)
EIGRP is a proprietary cisco-dynamic routing protocol.
In general, routing is the process of determining the route of information in communication networks. (via wikipedia)
The main point is that when using static routing, you need to manually prescribe routes, implement spare links using spanning tree / etherchannel; when using dynamic routing, the devices independently compile the network routing table, choose the shortest path to the point by the specified parameters, balance the load across several channels.
')
Application area
Application area - networks with a large number of routing nodes (on the bsci course, the instructor spoke about dozens of devices). Naturally, if you have one router on the network, there is no talk about the dynamics. Nuance - all devices must be Cisco;) You also need to understand that there should be no stretched VLANs. Each router must have its own unique VLANs.
A stretched VLAN is a VLAN, the devices in which are randomly scattered throughout the network.
We have just such a L2 network (by the way, it was not taken from the head, but actually exists, though they didn’t implement EIGRP, the customer decided, the reasons at the end). Three core switches are connected by a ring, the links between them are Etherchannels. All routing, all main VLAN gateways are raised to Core_SW1.
And after the implementation of EIGRP, we get such a scheme. The three core switches are interconnected by L3 links, the shortest route is dynamically determined by EIGRP, and the traffic is balanced between all links. In general, all connections are used, in contrast to what was where the lines worked, uncutted Spanning Tree.
EIGRP works as follows. A hello-packages are sent to the L3 link (with a specified frequency). After the device receives a response, it establishes "neighbor" relations and begins to exchange information about the networks connected to it. When all devices see each other and establish a neighbor relationship, each of them will have the entire network routing table. It is worth noting the following - if during the hold-timer a hello packet is not received from a neighbor, it is considered dead and its routes are deleted from the routing table.
Customization
You must specify IP addresses for L3 interfaces. By the way, the interfaces on the routers are already L3, on the switches with the routing function they are the same as the default L2 interfaces. To make them L3 and set IP, you need to enter a command on the interface:
no switchport
ip address [IP address] [mask]
After configuring the interfaces, run EIGRP
Cisco_2811_ons (config) #router eigrp [autonomous system number]]
Cisco_2811_ons (config-router) #eigrp router-id [IP-address] / it is possible to set the IP-address by which this device will be identified
We set networks (VLAN'Y) about which we will tell neighbors:
Cisco_2811_ons (config-router) #network [network] [reverse mask]
It is also necessary to advertise the L3 interface subnets.
Set hello and hold timers (set on the interface and the values on both sides must match):
Cisco_2811_ons (config-if) #ip hello-interval eigrp [autonomous system number] [seconds]
Cisco_2811_ons (config-if) #ip hold-time eigrp [autonomous system number]] [seconds]
Cisco recommends setting hello-time for 1 second and hold-time for 3 seconds.
Install which interfaces EIGRP will use:
Cisco_2811_ons (config-router) # passive-interface default
Cisco_2811_ons (config-router) #no passive-interface [port interface] [slot / number]
This is the minimum teams, after which EIGRP should earn you :)
Trabshuting
To view the EIGRP neighbor list:
Cisco_2811_ons # sh ip eigrp neighbors
View routes:
Cisco_2811_ons # sh ip route
Cisco_2811_ons # sh ip route eigrp [autonomous system number]
Debag:
Cisco_2811_ons # debug eigrp [autonomous system number] [what to watch]
Probably everything I wanted to write ... I wanted to be quite brief, because I think that you can find the theory naked yourself :)
If you have any questions - ask, maybe something is missing from your mind while writing :)
PS In a real network, they refused to implement EIGRP due to the presence of stretched VLANs. If the voice VLAN (IP telephony) was still possible to beat and redirect DHCP requests using the ip helper-address command, then with VLANs of different microcontrollers and other things (devices are randomly scattered throughout the territory of the object) + it includes servers It seemed bad, they did not go to him.
So comrades, when designing networks from scratch, think about the future ...;)
Source: https://habr.com/ru/post/64046/
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