July 10, 2009 at 15:21Implement and configure EIGRP
Hello, something very rarely replenishes the Cisco blog, it is necessary to fix it.
ABOUT! I can’t publish in it yet, so in personal.
I would like 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 register routes, implement spare links using the spanning tree / etherchannel; when using dynamic routing - devices independently compile a network routing table, choose the shortest path to the point according to the specified parameters, balance the load on several channels.
Scope - networks with a large number of routing nodes (on the bsci course, the instructor talked about dozens of devices). Naturally, if you have one router in your network, there is no talk about dynamics. Nuance - all devices must be Cisco;) You also need to understand that there should not be stretched VLANs. Each router must have its own unique VLANs.
A stretched VLAN is a VLAN, devices in which are randomly scattered throughout the network.
We have such an L2 network (by the way, it wasn’t taken from the head, but really exists, though they didn’t introduce EIGRP, the customer decided so, about the reasons at the end). Three core switches are connected by a ring, the links between them are Etherchannels. All routing, all the main VLAN gateways are raised on Core_SW1.
And after the implementation of EIGRP we get such a scheme. Three core switches are interconnected by L3 links, using EIGRP the shortest route is dynamically determined, traffic is balanced between all links. In general, all connections are used, unlike what it was, where the lines worked, unkilled Spanning Tree.
EIGRP works as follows. Hello packets are sent via the L3 link (with a specified frequency). After the device receives a response, it establishes a "neighborly" relationship and begins to exchange information about the networks connected to it. When all devices see each other and establish neighbor relations, each of them will have the entire network routing table. It is worth noting the following - if a hello packet is not received from a neighbor during the hold timer, it is considered dead and its routes are deleted from the routing table.
You must specify IP addresses for L3 interfaces. By the way, on routers L3 interfaces, and so on switches with a routing function, are L2 default 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 the
networks (VLANs) that we will tell neighbors about:
Cisco_2811_ons (config-router) #network [network] [ reverse mask]
It is also necessary to announce the subnets of L3 interfaces.
Set the hello and hold timers (set on the interface and must match on both sides):
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 to 1 second, and hold-time to 3 seconds.
Set 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 number of commands after which EIGRP should work for you :)
To see the list of EIGRP neighbors:
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]
Debug:
Cisco_2811_ons # debug eigrp [autonomous system number] [what to see]
Probably all that I wanted to write ... I wanted to be brief enough, because I think that you can find a bare theory yourself :)
If you have questions, ask, maybe I overlooked something while writing :)
PS In the real network, they refused to implement EIGRP due to the presence of extended VLANs. If the voice VLAN (IP-telephony) could still be beat and redirect DHCP requests using the ip helper-address command, then with VLAN'om of different microcontrollers and other things (devices are randomly scattered throughout the territory of the object) + servers enter it, the breakdown was poorly presented, they did not go to it.
So comrades, when designing networks from scratch, think about the future ...;)
ABOUT! I can’t publish in it yet, so in personal.
I would like 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 register routes, implement spare links using the spanning tree / etherchannel; when using dynamic routing - devices independently compile a network routing table, choose the shortest path to the point according to the specified parameters, balance the load on several channels.
Application area
Scope - networks with a large number of routing nodes (on the bsci course, the instructor talked about dozens of devices). Naturally, if you have one router in your network, there is no talk about dynamics. Nuance - all devices must be Cisco;) You also need to understand that there should not be stretched VLANs. Each router must have its own unique VLANs.
A stretched VLAN is a VLAN, devices in which are randomly scattered throughout the network.
We have such an L2 network (by the way, it wasn’t taken from the head, but really exists, though they didn’t introduce EIGRP, the customer decided so, about the reasons at the end). Three core switches are connected by a ring, the links between them are Etherchannels. All routing, all the main VLAN gateways are raised on Core_SW1.
And after the implementation of EIGRP we get such a scheme. Three core switches are interconnected by L3 links, using EIGRP the shortest route is dynamically determined, traffic is balanced between all links. In general, all connections are used, unlike what it was, where the lines worked, unkilled Spanning Tree.
EIGRP works as follows. Hello packets are sent via the L3 link (with a specified frequency). After the device receives a response, it establishes a "neighborly" relationship and begins to exchange information about the networks connected to it. When all devices see each other and establish neighbor relations, each of them will have the entire network routing table. It is worth noting the following - if a hello packet is not received from a neighbor during the hold timer, 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, on routers L3 interfaces, and so on switches with a routing function, are L2 default 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 the
networks (VLANs) that we will tell neighbors about:
Cisco_2811_ons (config-router) #network [network] [ reverse mask]
It is also necessary to announce the subnets of L3 interfaces.
Set the hello and hold timers (set on the interface and must match on both sides):
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 to 1 second, and hold-time to 3 seconds.
Set 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 number of commands after which EIGRP should work for you :)
Troubleshooting
To see the list of EIGRP neighbors:
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]
Debug:
Cisco_2811_ons # debug eigrp [autonomous system number] [what to see]
Probably all that I wanted to write ... I wanted to be brief enough, because I think that you can find a bare theory yourself :)
If you have questions, ask, maybe I overlooked something while writing :)
PS In the real network, they refused to implement EIGRP due to the presence of extended VLANs. If the voice VLAN (IP-telephony) could still be beat and redirect DHCP requests using the ip helper-address command, then with VLAN'om of different microcontrollers and other things (devices are randomly scattered throughout the territory of the object) + servers enter it, the breakdown was poorly presented, they did not go to it.
So comrades, when designing networks from scratch, think about the future ...;)