You can use the following formats to create a route distinguisher (RD) and configure route targets (RTs):
- AS:nn, where AS is a 16bit autonomous system number (ASN) and nn is a 32bit decimal number
- A.B.C.D:nn, where A.B.C.D is a 32bit IP address and nn is a 16bit decimal number

When you issue the ip vrf name command in global configuration mode, you are placed in VPN routing and forwarding (VRF) configuration mode, where you can configure the VRF.
First, you should create an RD by issuing the rd value command. An RD is a value that is used to create a virtual private network (VPN) prefix to identify the VPN.
You can specify the RD by combining an ASN or IP address with any decimal number.
There are three types of RDs: Type 0, Type 1, and Type 2. The type of RD configuration you create depends on how you issue the value parameter of the rd command and whether you are configuring a multicast VPN environment. Type 0 and Type 1 RDs are used in unicast configurations. A Type 0 RD is configured by issuing the value parameter of the rd command with the 16bit ASN in front of the 32bit decimal number. A Type 1 RD is configured by issuing the value parameter of the rd command with the 32bit decimal number in front of the 16bit ASN. A Type 2 RD is configured similarly to a Type 1 RD but applies to only multicast VPN configurations.
To configure RT extended community attributes for the VRF, you should issue the route-target {import | export | both} value command. Like RDs, RTs are specified by combining an ASN or IP address with any decimal number. The import, export, and both keywords specify whether extended community attributes should be imported, exported, or both.
You should also associate an interface with the VRF by issuing the ip vrf forwarding name command, where name is the name of the VRF as specified in the ip vrf name command. When the ip vrf forwarding command is issued, the IP address is removed from the interface. Therefore, you should reconfigure the IP address on the interface after issuing the ip vrf forwarding command.
The following commands can be used to create a VRF table for a customer and apply it to an interface:
RouterA(config)#ip vrf Customer129 RouterA(config-vrf)#rd 123:6 RouterA(config-vrf)#route-target both 123:6 RouterA(config-vrf)#route-target export 192.168.14.1:77 RouterA(config-vrf)#exit RouterA(config) #interface fa0/1 RouterA(config-if)#ip vrf forwarding Customer129

You would not use the following formats to create RDs and RTs, because the parameters are in the wrong order:
-nn:AS, where nn is a 16bit decimal number and AS is a 16-bit ASN
-nn:A.B.C.D, where nn is a 16bit decimal number and A.B.C.D is a 32-bit IP address

You would not use the following formats to create RDs and RTs, because Media Access Control (MAC) addresses cannot be used to create them:
-nn:MAC, where nn is a 16-bit decimal number and MAC is a 48-bit MAC address
- MAC:nn, where MAC is a 48-bit MAC address and nn is a 16-bit decimal number