Alcatel-Lucent 7750 SR OS Service Manual page 1094

VPRN Service Configuration Commands
Context config>service>vprn>ospf
Description
This command enables limits on the number of non-default AS-external-LSA entries that can be
stored in the LSDB and specifies a wait timer before processing these after the limit is exceeded.
The limit value specifies the maximum number of non-default AS-external-LSA entries that can be
stored in the link-state database (LSDB). Placing a limit on the non-default AS-external-LSAs in the
LSDB protects the router from receiving an excessive number of external routes that consume
excessive memory or CPU resources. If the number of routes reach or exceed the limit, the table is in
an overflow state. When in an overflow state, the router will not originate any new AS-external-
LSAs. In fact, it withdraws all the self-originated non-default external LSAs.
The interval specifies the amount of time to wait after an overflow state before regenerating and
processing non-default AS-external-LSAs. The waiting period acts like a dampening period
preventing the router from continuously running Shortest Path First (SPF) calculations caused by the
excessive number of non-default AS-external LSAs.
The external-db-overflow must be set identically on all routers attached to any regular OSPF area.
OSPF stub areas and not-so-stubby areas (NSSAs) are excluded.
The no form of the command disables limiting the number of non-default AS-external-LSA entries.
Default
no external-db-overflow — No limit on non-default AS-external-LSA entries.
Parameters
limit — The maximum number of non-default AS-external-LSA entries that can be stored in the
interval — The number of seconds after entering an overflow state before attempting to process non-
external-preference
Syntax external-preference preference
no external-preference
Context config>service>vprn>ospf
Description
This command configures the preference for OSPF external routes.
A route can be learned by the router from different protocols in which case the costs are not
comparable; when this occurs the preference is used to decide which route will be used.
Different protocols should not be configured with the same preference, if this occurs the tiebreaker is
per the default preference table as defined in the Table 6, "Route Preference Defaults by Route Type,"
on page 1095. If multiple routes are learned with an identical preference using the same protocol, the
lowest cost route is used.
If multiple routes are learned with an identical preference using the same protocol and the costs
(metrics) are equal, then the decision of what route to use is determined by the configuration of the
ecmp in the config>router context.
The no form of the command reverts to the default value.
Default
external-preference 150 — OSPF external routes have a default preference of 150.
Page 1094
LSDB before going into an overflow state expressed as a decimal integer.
Values
0 — 2147483674
default AS-external-LSAs expressed as a decimal integer.
Values
0 — 2147483674
7750 SR OS Services Guide