Cisco ASA Redistribution example

Redistribution is a process of sharing routing information between different routing protocols. In Cisco ASA, redistribution is used to share information between different routing protocols or between different routing domains. This allows for the integration of various networks and improves overall network efficiency. In this article, we will provide a beginner's guide to redistribution on Cisco ASA, including examples of how to configure redistribution on the device.

Before diving into the configuration process, it's important to understand the different routing protocols that can be used on Cisco ASA. The most common routing protocols used on Cisco ASA are Interior Gateway Routing Protocol (IGRP), Routing Information Protocol (RIP), and Open Shortest Path First (OSPF).

Cisco ASA Redistribution Configuration

The first step in configuring redistribution on Cisco ASA is to determine the routing protocols that will be used. Once the routing protocols have been determined, the next step is to configure redistribution on the Cisco ASA. This can be done using the command-line interface (CLI) or the graphical user interface (GUI).

In the CLI, the command to configure redistribution is "redistribute [protocol] [metric]". The "protocol" parameter specifies the routing protocol that will be redistributed, and the "metric" parameter specifies the metric that will be used for the redistributed routes.

For example, to configure redistribution of IGRP routes into OSPF, the command would be −

redistribute igrp 1 metric 1 1 1 1 1

In this example, the "protocol" parameter is "igrp" and the "metric" parameter is "1 1 1 1 1", which is the default metric for IGRP routes.

It's also possible to configure redistribution using the Cisco ASA GUI. To do this, navigate to the "Configuration" tab and then select "Firewall." Under the "Firewall" menu, select "Routes" and then select "Redistribution." From here, you can configure the routing protocols and metrics that will be used for redistribution.

Cisco ASA Redistribution Example

To provide a concrete example of how redistribution can be used on Cisco ASA, let's consider a network that consists of two separate routing domains: one using OSPF and the other using EIGRP. The goal is to share routing information between the two domains to improve overall network efficiency.

To configure redistribution on Cisco ASA in this scenario, we would first need to determine the routing protocols that will be used. In this case, the routing protocols are OSPF and EIGRP. Next, we would need to configure redistribution on the Cisco ASA using the CLI or the GUI.

Using the CLI, the commands to configure redistribution would be −

router ospf 1
redistribute eigrp 1 metric-type 1

In this example, the "router" command is used to enter OSPF configuration mode, and the "redistribute" command is used to configure redistribution of EIGRP routes into OSPF. The "metric-type" parameter is set to "1" which is the default metric for EIGRP routes.

It's also possible to configure the same redistribution using the Cisco ASA GUI. To do this, navigate to the "Configuration" tab and then select "Firewall." Under the "Firewall" menu, select "Routes" and then select "Redistribution." From here, you can configure the routing protocols and metrics that will be used for redistribution.

Cisco ASA Redistribution - Filtering Redistributed Routes

In some cases, it may be necessary to filter certain routes from being redistributed. This can be done using the "route-map" command. A route map is a set of conditions and actions that are applied to routing updates. The "route-map" command is used to specify which routes should be redistributed and which should be filtered.

For example, to filter routes that have a specific network address from being redistributed, the following command can be used −

route-map mymap permit 10
match ip address 1
set metric 100

In this example, the "route-map" command is used to create a route map called "mymap" with a permit statement. The "match ip address 1" command is used to match routes with a specific network address, and the "set metric 100" command is used to set the metric for the matched routes to 100.

Cisco ASA Redistribution and Summarization

Another important aspect of redistribution on Cisco ASA is summarization. Summarization is the process of combining multiple routes into a single, more general route. This can be useful in large networks where there are many routes to keep track of.

To configure summarization on Cisco ASA, the "summary-address" command can be used. The "summary-address" command is used to specify a summary address and mask for a group of routes.

For example, to summarize routes in the 192.168.0.0/16 network into a single route, the following command can be used −

router ospf 1
summary-address 192.168.0.0 255.255.0.0

In this example, the "router" command is used to enter OSPF configuration mode, and the "summary-address" command is used to specify a summary address of 192.168.0.0 with a mask of 255.255.0.0 for the routes in the 192.168.0.0/16 network.

Redistribution and summarization are important features of Cisco ASA that can be used to improve network efficiency and allow for the integration of various networks. By understanding the basics of redistribution and summarization, network administrators can effectively configure and manage these features on Cisco ASA.

Conclusion

In conclusion, Cisco ASA Redistribution is a powerful feature that allows for the integration of multiple routing protocols and domains. The configuration process can be done via CLI or GUI, filtering and summarization also can be applied to improve the network efficiency. By understanding the basics of redistribution and summarization, network administrators can effectively configure and manage these features on Cisco ASA to improve network functionality and overall network efficiency.