Dell BigIron RX Series, Configuration Manual

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BigIron RX Series Configuration Guide 713
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Configuring OSPF
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Configure OSPF group Link State Advertisement pacing
The BigIron RX paces LSA refreshes by delaying the refreshes for a specified time interval instead
of performing a refresh each time an individual LSA’s refresh timer expires. The accumulated LSAs
constitute a group, which the BigIron RX refreshes and sends out together in one or more packets.
The pacing interval, which is the interval at which the device refreshes an accumulated group of
LSAs, is configurable to a range from 10 – 1800 seconds (30 minutes). The default is 240 seconds
(four minutes). Thus, every four minutes, the device refreshes the group of accumulated LSAs and
sends the group together in the same packets.
Usage guidelines
The pacing interval is inversely proportional to the number of LSAs the device is refreshing and
aging. For example, if you have approximately 10,000 LSAs, decreasing the pacing interval
enhances performance. If you have a very small database (40 – 100 LSAs), increasing the pacing
interval to 10 – 20 minutes might enhance performance slightly.
Changing the LSA pacing interval
To change the LSA pacing interval, use the following CLI method.
To change the LSA pacing interval to two minutes (120 seconds), enter the following command.
BigIron RX(config-ospf-router)# timers lsa-group-pacing 120
Syntax: [no] timers lsa-group-pacing <secs>
The <secs> parameter specifies the number of seconds and can be from 10 – 1800 (30 minutes).
The default is 240 seconds (four minutes).
To restore the pacing interval to its default value, enter the following command.
BigIron RX(config-ospf-router)# no timers lsa-group-pacing
OSPF ABR type 3 LSA filtering
OSPF ABR Type 3 LSA filtering increases the ability of an ABR that is running the OSPF protocol to
filter type 3 link-state advertisements (LSAs) that are sent between different OSPF areas. Only
packets with specified prefixes will be sent from one area to another area and prohibits all packets
with other prefixes.
Type 3 LSAs refer to summary links and are sent by ABRs to advertise destinations outside the
area. OSPF ABR Type 3 LSA filtering gives the administrator improved control of route distribution
between OSPF areas.
Usage and configuration guidelines
•
The “area prefix-list” command is only applicable to the ABRs. If the router is not an ABR
the configuration is accepted however it will start working only after router is made ABR.
•
With this feature enabled in the “in” direction, all type 3 LSAs originated by the ABR to this
area, based on information from all other areas, are filtered by the prefix list. Type 3 LSAs
that were originated as a result of the area range command in another area are treated
like any other type 3 LSA that was originated individually. Any prefix that does not match an
entry in the prefix list is implicitly denied.