ProLiant BL p-Class GbE2 Interconnect Switch Application Guide

OSPF 120
• Equal Cost Multipath (ECMP)
With equal cost multipath, a router potentially has several available next hops towards any given
destination. ECMP allows separate routes to be calculated for each IP Type of Service. All paths of equal
cost to a given destination are calculated, and the next hops for all equal-cost paths are inserted into the
routing table.
If redundant routes via multiple routing processes (such as OSPF, RIP, BGP, or static routes) exist on your network,
the switch defaults to the OSPF-derived route.
OSPF features not supported in this release
The following OSPF features are not supported in this release:
• Summarizing external routes
• Filtering OSPF routes
• Using OSPF to forward multicast routes
• Configuring OSPF on non-broadcast multi-access networks (such as frame relay, X.25, and ATM)
OSPF configuration examples
A summary of the basic steps for configuring OSPF on the GbE2 Interconnect Switch is listed here. Detailed
instructions for each of the steps is covered in the following sections:
• Configure IP interfaces.
One IP interface is required for each desired network (range of IP addresses) being assigned to an OSPF
area on the switch.
• (Optional) Configure the router ID.
The router ID is required only when configuring virtual links on the switch.
• Enable OSPF on the switch.
• Define the OSPF areas.
• Configure OSPF interface parameters.
IP interfaces are used for attaching networks to the various areas.
• (Optional) Configure route summarization between OSPF areas.
• (Optional) Configure virtual links.
• (Optional) Configure host routes.
Example 1: Simple OSPF domain (CLI example)
In this example, two OSPF areas are defined—one area is the backbone and the other is a stub area. A stub
area does not allow advertisements of external routes, thus reducing the size of the database. Instead, a default
summary route of IP address 0.0.0.0 is automatically inserted into the stub area. Any traffic for IP address
destinations outside the stub area will be forwarded to the stub area’s IP interface, and then into the backbone.
Figure 21 Simple OSPF domain