Protocols And Standards; Ospf Configuration Task List - HP 4800G Series Configuration Manual

forwarding table based on the new routing information received from neighbors and removes the stale
routes.
VPN
OSPF supports multi-instance, which can run in VPN networks.
In BGP MPLS VPN networks, multiple sites in the same VPN can use OSPF as the internal routing
protocol, but they are treated as different ASs. An OSPF route learned by a site will be forwarded to
another site as an external route, which leads to heavy OSPF routing traffic and management issues.
For configuration of this feature, refer to MCE Configuration in the IP Routing Volume.
OSPF sham link
An OSPF sham link is a point-to-point link between two PE routers on the MPLS VPN backbone.
In general, BGP peers exchange routing information on the MPLS VPN backbone using the BGP
extended community attribute. OSPF running on a PE at the other end utilizes this information to
originate a Type-3 summary LSA as an inter-area route between the PE and CE.
If a router connects to a PE router in the same area and establishes an internal route (backdoor route) to
a destination, in this case, since an OSPF intraarea route has a higher priority than a backbone route,
VPN traffic will always travel on the backdoor route rather than the backbone route. To avoid this, an
unnumbered sham link can be configured between PE routers, connecting the router to another PE
router via an intraarea route with a lower cost.

Protocols and Standards

RFC 1765: OSPF Database Overflow
RFC 2328: OSPF Version 2
RFC 3101: OSPF Not-So-Stubby Area (NSSA) Option
RFC 3137: OSPF Stub Router Advertisement
RFC 3630: Traffic Engineering Extensions to OSPF Version 2
RFC 4811: OSPF Out-of-Band LSDB Resynchronization
RFC 4812: OSPF Restart Signaling
RFC 4813: OSPF Link-Local Signaling

OSPF Configuration Task List

An OSPF routing domain has different types of routers, such as intra-area routers, ABR, and ASBR.
OSPF can work normally only after being enabled on a router, regardless of the router's type. On an
OSPF-enabled router, you can use the default values of parameters, such as the transmit interval of
OSPF packets, LSA delay timer, and SPF calculation interval, or configure them as required.
Network planning is needed before OSPF configuration on routers. The configurations for routers in an
area are performed on the area basis. Wrong configurations may cause communication failures, even
routing information block or routing loops between neighboring routers..
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