Automatic Exiting Of Stub Router Mode; Ospf Ecmp (Equal Cost Multipath) - Fujitsu PSWITCH 2048T User Manual

User's Guide
a stub router. You can also configure OSPF to start up in stub router mode that
advertises only regular metrics after a configurable startup period.
 OSPF passive interface and point-to-point operation via Ethernet. You can set a
static cost to the area range. LSA transmission pacing can be set, reducing the
possibility that the receive buffer of the adjacent node will overrun. The LSA
pacing group spreads self-generated LSAs at refresh intervals to avoid periodic
flooding spikes. Disabling LSA flooding on a specific interface can reduce
flooding on the meshed network. OSPF supports ECMP, and the maximum
number of next hops can be set. The delay and hold timers can be set so that
the shortest path algorithm is executed frequently and OSPF does not consume
too much CPU time.
 OSPF can redistribute connected, static, and BGP routes. Distribution lists can be
configured to filter redistributed routes. Routers can be configured to generate
default routes. Default generation can be conditional on the non-OSPF default
route being present in the unicast routing table.
 Standard OSPF MIB specified in RFC 1850, and its own MIB variables.
 RFC 6860 to hide OSPF passing-through networks. A transit-only network is
defined as a network connecting only routers. Hiding the transit-only network
speeds up the convergence of the network and reduces the vulnerability to
remote attacks against routers in the transit-only network.

3.1.9.15.2. Automatic Exiting of Stub Router Mode

OSPF goes into stub router mode and notifies other routers not to use the router as
a transit point. This is accomplished by setting the metric of the transit link of the
router LSA to maximum and re-sending the router LSA specified in RFC 3137. The
stub router mode can be started automatically when resources run out, or it can be
started by configuration. The stub router mode can be set to always be enabled, or
it can be enabled only for a set period after it is started. OSPF automatically
attempts to exit stub router mode when stub router mode is started because of low
resources. OSPF checks various resource constraints once every 60 seconds and if
sufficient resources are available (if all the necessary resources are below the
constraint threshold), it will exit stub router mode by regenerating the router LSA
with appropriate metric value on the transit link.

3.1.9.15.3. OSPF ECMP (Equal Cost Multipath)

IP routing protocol A device that runs OSPF manages multiple equal cost routes for
all destinations. These multiple routes have the same type (intra-area, inter-area,
type 1 external or type 2 external), cost, and the same associated area. However,
each route is defined by a separate advertising router and next hop.
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