HP (Hewlett-Packard) HP-UX 11i v2 Manuale Utente
Configuring gated
Configuring the OSPF Protocol
Chapter 3
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it is not required that an AS boundary router be a backbone router. An
AS boundary router learns about routes other than its attached AS
through exchanges with other routing protocols or through configuration
information. Each AS boundary router calculates paths to destinations
outside of its attached AS. It then advertises these paths to all routers in
its AS.
AS boundary router learns about routes other than its attached AS
through exchanges with other routing protocols or through configuration
information. Each AS boundary router calculates paths to destinations
outside of its attached AS. It then advertises these paths to all routers in
its AS.
Following are the two levels of routing in an AS:
•
Intra-area routing, where the source and destination of a packet
both reside in the same area. Routing is handled by internal routers.
both reside in the same area. Routing is handled by internal routers.
•
Inter-area routing, where the source and destination of a packet
reside in different areas. Packets travel through an intra-area route
from the source to an area border router, then travel an inter-area
route on a backbone path between areas. Finally, they travel another
intra-area route to the destination.
reside in different areas. Packets travel through an intra-area route
from the source to an area border router, then travel an inter-area
route on a backbone path between areas. Finally, they travel another
intra-area route to the destination.
Planning Your OSPF Configuration
Following is a suggested sequence of steps in planning the OSPF routing
in your autonomous system:
in your autonomous system:
1. If your AS exchanges routing information with other autonomous
systems, you need to obtain a unique AS number from the Internet
Assigned Numbers Authority.
Assigned Numbers Authority.
2. Partition the AS into areas. You can partition any interconnected
networks into lists of address ranges, with each address range
represented as an address-mask pair. The area border routers
summarize the area content for each address range and distribute
the summaries to the backbone. See “The networks Statement” on
page 66 for more information on specifying address ranges.
represented as an address-mask pair. The area border routers
summarize the area content for each address range and distribute
the summaries to the backbone. See “The networks Statement” on
page 66 for more information on specifying address ranges.
3. Identify the internal routers for each area. An internal router
configuration contains only one area definition.
4. Identify the area border routers and the areas to which they
interface. The configuration for each area border router contains
multiple area definitions.
multiple area definitions.
5. For each router, determine the interface type for each area. Router
interfaces can be multicast, non-broadcast multi-access (NBMA), or
point-to-point. See “The interface Statement” on page 67 for more
information on router interfaces.
point-to-point. See “The interface Statement” on page 67 for more
information on router interfaces.