Open Shortest Path First (Ospf) - Fujitsu Siemens Computers PRIMERGY BX Description

Features of the Switch
static routes, 150 for
255 and are independent of route metrics. Most routing protocols use a route metric to
determine the shortest path known to the protocol, independent of any other protocol.
The best route to a destination is selected by using the route with the lowest preference
value. When there are multiple routes to a destination, the preference values are used to
determine the preferred route. If there is still a tie, the route with the best route metric will be
chosen. To avoid problems with mismatched metrics (i.e. RIP and OSPF metrics are not
directly comparable) you must configure different preference values for each of the protocols.
The reference configure value is below
•
Static - The static route preference value in the router. The default value is 1. The range is 1 to
255.
•
OSPF Intra - The OSPF intra route preference value in the router. The default value is 8. The
range is 1 to 255. The OSPF specification (RFC 2328) requires that preferences must be given
to the routes learned via OSPF in the following order: intra < inter < type-1 < type-2.
•
OSPF Inter - The OSPF inter route preference value in the router. The default value is 10. The
range is 1 to 255. The OSPF specification (RFC 2328) requires that preferences must be given
to the routes learned via OSPF in the following order: intra < inter < type-1 < type-2.
•
OSPF Type-1 - The OSPF type-1 route preference value in the router. The default value is 13.
The range is 1 to 255. The OSPF specification (RFC 2328) requires that preferences must be
given to the routes learned via OSPF in the following order: intra < inter < type-1 < type-2.
•
OSPF Type-2 - The OSPF type-2 route preference value in the router. The default value is 150.
The range is 1 to 255. The OSPF specification (RFC 2328) requires that preferences must be
given to the routes learned via OSPF in the following order: intra < inter < type-1 < type-2.
•
RIP - The RIP route preference value in the router. The default value is 15. The range is 1 to
255.

Open Shortest Path First (OSPF)

The Open Shortest Path First (OSPF) protocol uses within larger autonomous networks in
preference to RIP. OSPF is a link-state protocol that multicasts table updates only when a
change has taken place and transmits only the changed portion of the table. To give
preferences to certain routes, OSPF uses both administratively assigned costs for a given
router and link-states as metrics. In addition, OSPF supports variable-length subnet masks.
OSPF can operate within a hierarchy. The largest entity within the hierarchy is the
autonomous system (AS), a collection of networks under a common administration sharing a
common routing strategy. This is sometimes called a
a number of areas or groups of contiguous networks and attached hosts. Routers within the
same area share the same information, so they have identical topological databases.
Information is sent in the form of link-state advertisements (LSAs) to all other routers within the
same hierarchical area. An area's topology is not visible to routers outside the area.
Two different types of OSPF routing occur as a result of area partitioning: Intra-area and
Interarea. Intra-area routing occurs if a source and destination are in the same area. Inter-area
routing occurs when a source and destination are in different areas. An OSPF backbone
distributes information between areas.
PRIMERGY BX600 supports OSPF version 2 in accordance with RFC 2328. PRIMERGY
BX600 also provides a compatibility mode for the RFC 1583 OSPF specification, which allows
interoperability with OSPF version 2 routers using the older implementation.
26
). These values are arbitrary values in the range of 1 to
OSPF Type-2
. An AS can be divided into
routing domain
Lan Switch and Router Blade
Introduction