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DES-7200 Configuration Guide Chapter 4 OSPF
Configuration
4-2
will have the Dijkstra algorithm run again, with a new shortest path tree created.
A group of routers running the OSPF protocol form the autonomous domain
system of the OSPF routing domain. An autonomous domain system consists of
all the routers that are controlled and managed by one organization. Within the
autonomous domain system, only one IGP routing protocol is run. However,
between multiple such systems, the BGP routing protocol is used for route
information exchange. Different autonomous domain systems can use the same
IGP routing protocol. To access the Internet, every autonomous system needs to
request the related organization for the autonomous system number.
When the OSPF routing domain is large, the hierarchical structure is usually used.
In other words, the OSPF routing domain is divided into several areas, which are
connected via a backbone area. Every non-backbone area must be directly
connected with this backbone area.
There are three roles for the routers in the OSPF routing domain according to
their deployment position:
Area Internal Routers, all interface networks of this router are of this area;
ABR (Area Border Router): The interfaced networks of this router belong at
least to two areas, one of which must be the backbone area;
ASBR (Autonomous System Boundary Routers): It is the router between
which the OSPF route domain exchanges the external route domain.
DES-7200 product implements the OSPF by fully complying with the OSPFv2
defined in RFC 2328. The main features of the OSPF are described as below:
Support multiple OSPF processes, up to 64 OSPF processes running at the
same time.
Support VRF. You can run OSPF based on different VRFs.
Support the definition of stubby area.
Support route redistribution with the static route, directly-connected route
and the dynamic route protocol such as RIP, BGP, etc.
Support plain-text or MD5 authentication between neighbors.
Support virtual links.
Support VLSMs.
Support area division
Support NSSA (Not So Stubby Area), as defined in RFC 3101.
Support Graceful Restart, as defined in RFC 3623.