Cisco Catalyst 3550

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Catalyst 3550 Multilayer Switch Command Reference
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Chapter 2 Catalyst 3550 Switch Cisco IOS Commands
ip vrf (global configuration)
• rd: specify Route Distinguisher as either an autonomous system-relative composed of an
autonomous system (AS) number and an arbitrary number, or as an IP-address-relative composed
of an IP address and an arbitrary number.
– 16-bit AS number: 32-bit number (for example, 101:3)
– 32-bit IP address: 16-bit number (for example, 192.168.122.15:1.)
• route-target {import | export | both} route-target-ext-community: specify Target VPN Extended
Communities. You can specify the Target for export, import, or both.
To return to global configuration mode, use the exit command. To return to privileged EXEC mode, use
the end command.
Use an import route map when an application requires finer control over the routes imported into a VRF
than that provided by the import and export extended communities configured for the importing and
exporting VRF. The import map command associates a route map with the specified VRF. You can
filter routes that are eligible for import into a VRF, based on the route target extended community
attributes of the route, by using a route map. The route map might deny access to selected routes from a
community that is on the import list.
If you set a maximum routes threshold, the switch rejects routes when the threshold limit is reached. If
you enter warn-only, the switch creates a syslog error message when the maximum number of VRF
routes exceeds the allowed limit, but additional routes are still allowed
A route distinguisher (RD) creates routing and forwarding tables and specifies the default route
distinguisher for a VPN. A route distinguisher must be configured for a VRF to be functional. The RD
is added to the beginning of the customer's IPv4 prefixes to change them into globally unique VPN-IPv4
prefixes.
The route target specifies a target VPN extended community. Like a route-distinguisher, an extended
community is composed of either an autonomous system number and an arbitrary number or an IP
address and an arbitrary number.
The ip vrf vrf-name command creates a VRF routing table and a Cisco Express Forwarding (CEF)
forwarding table, both named vrf-name. Associated with these tables is the default route distinguisher
value route-distinguisher.
Examples This example shows how to create the VRF named vpn1, enter VRF configuration mode, and import a
route map to the VRF:
Switch(config)# ip vrf vpn1
Switch(config-vrf)# rd 100:2
Switch(config-vrf)# route-target both 100:2
Switch(config-vrf)# route-target import 100:1
Related Commands Command Description
ip vrf (interface configuration) Associate a VRF routing table or a route map with an interface.