Dell FCX624-S Laptop User Manual


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956 PowerConnect B-Series FCX Configuration Guide
53-1002266-01
Configuring OSPF
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PowerConnect->R4
PowerConnect->R5
PowerConnect->R6
Normally, the Dell PowerConnect switch will choose the path to the R1 with the lower metric. For
example, if R3 metric is 1400 and R4 metric is 600, the Dell PowerConnect switch will always
choose R4.
However, suppose the metric is the same for all four routers in this example. If the costs are the
same, the switch now has four equal-cost paths to R1. To allow the switch to load share among the
equal cost routes, enable IP load sharing. The software supports four equal-cost OSPF paths by
default when you enable load sharing. You can specify from 2 to 6 paths.
NOTE
The Dell PowerConnect switch is not source routing in these examples. The switch is concerned only
with the paths to the next-hop routers, not the entire paths to the destination hosts.
OSPF load sharing is enabled by default when IP load sharing is enabled. To configure IP load
sharing parameters, refer to “Configuring IP load sharing” on page 829.
Configuring external route summarization
When the Layer 3 Switch is an OSPF Autonomous System Boundary Router (ASBR), you can
configure it to advertise one external route as an aggregate for all redistributed routes that are
covered by a specified address range.
When you configure an address range, the range takes effect immediately. All the imported routes
are summarized according to the configured address range. Imported routes that have already
been advertised and that fall within the range are flushed out of the AS and a single route
corresponding to the range is advertised.
If a route that falls within a configured address range is imported by the Layer 3 Switch, no action is
taken if the Layer 3 Switch has already advertised the aggregate route; otherwise the Layer 3
Switch advertises the aggregate route. If an imported route that falls with in a configured address
range is removed by the Layer 3 Switch, no action is taken if there are other imported routes that
fall with in the same address range; otherwise the aggregate route is flushed.
You can configure up to 32 address ranges. The Layer 3 Switch sets the forwarding address of the
aggregate route to zero and sets the tag to zero.
If you delete an address range, the advertised aggregate route is flushed and all imported routes
that fall within the range are advertised individually.
If an external LSDB overflow condition occurs, all aggregate routes are flushed out of the AS, along
with other external routes. When the Layer 3 Switch exits the external LSDB overflow condition, all
the imported routes are summarized according to the configured address ranges.
NOTE
If you use redistribution filters in addition to address ranges, the Layer 3 Switch applies the
redistribution filters to routes first, then applies them to the address ranges.
NOTE
If you disable redistribution, all the aggregate routes are flushed, along with other imported routes.
To configure a summary address for OSPF routes, enter commands such as the following.