Chapter 10 Routing Protocols

 

 

 

 

Table 73 Configuration > Network > Routing Protocol > RIP (continued)

 

LABEL

DESCRIPTION

 

Redistribute

 

 

 

 

 

Active OSPF

Select this to use RIP to advertise routes that were learned through OSPF.

 

 

 

 

Metric

Type the cost for routes provided by OSPF. The metric represents the “cost” of

 

 

transmission for routing purposes. RIP routing uses hop count as the measurement

 

 

of cost, with 1 usually used for directly connected networks. The number does not

 

 

have to be precise, but it must be between 0 and 16. In practice, 2 or 3 is usually

 

 

used.

 

 

 

 

Active Static Route

Select this to use RIP to advertise routes that were learned through the static route

 

 

configuration.

 

 

 

 

Metric

Type the cost for routes provided by the static route configuration. The metric

 

 

represents the “cost” of transmission for routing purposes. RIP routing uses hop

 

 

count as the measurement of cost, with 1 usually used for directly connected

 

 

networks. The number does not have to be precise, but it must be between 0 and 16.

 

 

In practice, 2 or 3 is usually used.

 

 

 

 

Apply

Click this button to save your changes to the ZyWALL.

 

 

 

 

Reset

Click this button to return the screen to its last-saved settings.

 

 

 

10.3 The OSPF Screen

OSPF (Open Shortest Path First, RFC 2328) is a link-state protocol designed to distribute routing information within a group of networks, called an Autonomous System (AS). OSPF offers some advantages over vector-space routing protocols like RIP.

•OSPF supports variable-length subnet masks, which can be set up to use available IP addresses more efficiently.

•OSPF filters and summarizes routing information, which reduces the size of routing tables throughout the network.

•OSPF responds to changes in the network, such as the loss of a router, more quickly.

•OSPF considers several factors, including bandwidth, hop count, throughput, round trip time, and reliability, when it calculates the shortest path.

•OSPF converges more quickly than RIP.

Naturally, OSPF is also more complicated than RIP, so OSPF is usually more suitable for large networks.

OSPF uses IP protocol 89.

OSPF Areas

An OSPF Autonomous System (AS) is divided into one or more areas. Each area represents a group of adjacent networks and is identified by a 32-bit ID. In OSPF, this number may be expressed as an integer or as an IP address.

There are several types of areas.

•The backbone is the transit area that routes packets between other areas. All other areas are connected to the backbone.

 

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ZyWALL 110/310/1100 Series User’s Guide