Foundry Configuration Guide for the FESX, FSX, and FWSX
20 - 30
© Foundry Networks, Inc.
December 2005
Normally, the Foundry router will choose the path to the R1 with the lower metric. For example, if R3’s metric is
1400 and R4’s metric is 600, the Foundry router 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 router
now has four equal-cost paths to R1. To allow the router 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 – 6 paths.
NOTE:
The Foundry router is not source routing in these examples. The router 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, see “Configuring IP Load Sharing” on page 16-41.
Configure 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 route(s) 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.
NOTE:
This option affects only imported, type 5 external routes. A single type 5 LSA is generated and flooded
throughout the AS for multiple external routes. Type 7-route redistribution is not affected by this feature. All type 7
routes will be imported (if redistribution is enabled). To summarize type 7 LSAs or exported routes, use NSSA
address range summarization.
To configure a summary address for OSPF routes, enter commands such as the following:
FESX424 Router(config-ospf-router)# summary-address 10.1.0.0 255.255.0.0
The command in this example configures summary address 10.1.0.0, which includes addresses 10.1.1.0,
10.1.2.0, 10.1.3.0, and so on. For all of these networks, only the address 10.1.0.0 is advertised in external LSAs.
Syntax:
summary-address <ip-addr> <ip-mask>
The <ip-addr> parameter specifies the network address.
Содержание FastIron Edge Switch X424
Страница 36: ...Foundry Configuration Guide for the FESX FSX and FWSX 2 12 Foundry Networks Inc December 2005...
Страница 56: ...Foundry Configuration Guide for the FESX FSX and FWSX 3 20 Foundry Networks Inc December 2005...
Страница 70: ...Foundry Configuration Guide for the FESX FSX and FWSX 4 14 Foundry Networks Inc December 2005...
Страница 198: ...Foundry Configuration Guide for the FESX FSX and FWSX 8 38 Foundry Networks Inc December 2005...
Страница 316: ...Foundry Configuration Guide for the FESX FSX and FWSX 12 26 Foundry Networks Inc December 2005...
Страница 334: ...Foundry Configuration Guide for the FESX FSX and FWSX 13 18 Foundry Networks Inc December 22 2005...
Страница 350: ...Foundry Configuration Guide for the FESX FSX and FWSX 15 12 Foundry Networks Inc December 2005...
Страница 458: ...Foundry Configuration Guide for the FESX FSX and FWSX 18 18 Foundry Networks Inc December 2005...
Страница 712: ...Foundry Configuration Guide for the FESX FSX and FWSX 22 32 Foundry Networks Inc December 2005...
Страница 760: ...Foundry Configuration Guide for the FESX FSX and FWSX A 34 Foundry Networks Inc December 2005...
Страница 796: ...Foundry Configuration Guide for the FESX FSX and FWSX C 18 Foundry Networks Inc December 2005...
Страница 820: ...Foundry Configuration Guide for the FESX FSX and FWSX E 10 Foundry Networks Inc December 2005...