Package SSF.OS.OSPF

Provides classes which together implement a model of the Open Shortest Path First version 2 protocol (limited static version).

See:
Description

Class Summary

BinInt
Debug	Encapsulates and manages some debugging information and methods specific to OSPF.
Dijkstra	Dijkstra's shortest path algorithm.
Interface	An OSPF interface.
LinkInfo	A unit of information describing a link and used in the contents of a link state advertisement.
LSA	An OSPF Link State Advertisement packet.
LSDatabase	An OSPF Link State database.
Options	This class helps OSPF manage run-time options.
Packet	This class implements a generic OSPF packet.
sOSPF	The OSPF interior gateway protocol (IGP).

Package SSF.OS.OSPF Description

Provides classes which together implement a model of the Open Shortest Path First version 2 protocol (limited static version).

The Open Shortest Path First (OSPF) protocol is an IP link-state routing protocol, recommended for distributing routing information among the routers in a single autonomous system (AS), with explicit support for classless inter-domain routing (CIDR) address allocation.

SSF.OS.OSPF is a partial implementation of OSPFv2, based on the Internet Engineering Task Force's Request for Comments number 2328 (RFC 2328), "OSPF Version 2". It is designed to quickly compute the routing tables for arbitrary topologies of OSPF areas in SSFNet network models, and to flood the area with external route announcements from the ASBR routers running the BGP-4 inter-domain routing protocol. The unsupported requirements primarily involve dynamic neighbor discovery and link state updates in response to dynamic topology changes.

This implementation is often referred to as sOSPF (static OSPF). sOSPF is a static version of OSPF which retrieves the adjacency information of all routers in the same AS directly from the underlying network topology database. It then forms the link state databases by retrieving the link properties, and subsequently invokes the shortest path algorithm to compute the routing tables. In this release each router maintains its own link state database. This arrangement permits simulations to be run in parallel (with multiple timelines). However, since all link state databases within an area are essentially identical, for the purpose of saving memory in a simulation it is possible to maintain a single shared link database per area, provided the updates from routers are carefully synchronized to avoid possible errors in a multi-timeline simulation. Such a solution can be provided in a future release.

In sOSPF version 0.1.* only one area per AS is supported. However, sOSPF can accept dynamic AS external route information from inter-AS routing protocols, such as BGP. The routing table computed by an sOSPF ProtocolSession contains the entries for:

• all stub networks in the area,
• all hosts attached directly to sOSPF routers,
• summary networks received from external ASs,
• all point-to-point links attached directly to this router (enough for flooding the external route announcements),

but it does not contain addresses of point-to-point networks between sOSPF routers inside the area that are not directly attached to this router. That does not affect routing of IP packets between hosts.

Further Information See distribution file ssfnet/src/SSF/OS/OSPF/doc/index.html.