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Configuring frame-relay involves the following steps:
• Changing the encapsulation for frame-relay
• Configuring the LMI type (optional for IOS 11.2 or higher)
• Configuring the frame-relay map (optional unless you are using subinterfaces)
• Configuring subinterfaces (optional)
• If using a point-to-point subinterface, configuring your DLCI
To begin, select the frame-relay encapsulation on the interface. There are two types of frame-relay encapsulations: Cisco and IETF. Cisco is the default. The syntax to set your encapsulation is encapsulation frame-relay [ietf]
Next, you can configure the LMI type. The three LMI types are Cisco, Ansi, and Q933a. For IOS 11.2 and higher, the LMI type is automatically detected. For earlier IOS versions, enter the following command under the interface: frame-relay lmi-type [cisco | ansi | q933a]
The third option, configuring a static frame-relay map, is optional unless you are using subinterfaces. The frame-relay map will map a Layer 3 address to a local DLCI. This step is optional because inverse-arp will automatically perform this map for you. The syntax for a frame-relay map is as follows: frame-relay map protocol address dlci[broadcast] [cisco | ietf]
Parameter Description
Protocol Layer 3 protocol such as IP or IPX.
Address The Layer 3 address of the remote router (such as an IP address or IPX address).
DLCI Your local DLCI defining your PVC to the remote router.
Broadcast Optional, this allows for broadcasts and multicasts to traverse your Nonbroadcast Multiaccess (NBMA) frame-relay network.
Cisco | IETF Optional, this allows you to change your frame-relay encapsulation per DLCI.
For example, if you were connected to another router using DLCI 100 and the router had the IP address of 10.0.0.2, your frame-relay map statement would be Router(config-if)#frame-relay map ip 10.0.0.2 100
If you want to use a routing protocol across your Frame Relay network, you will need to add the keyword broadcast to the end of this command. Routing protocols use broadcasts and multicasts by default, and Frame Relay does not enable broadcasts and multicasts without the use of the broadcast keyword. If you are using inverse-arp to create your maps for you, inverse-arp assumes that you want to use routing protocols and adds the broadcast feature for you.
If you are using a routing protocol in a hub-and-spoke topology, you will probably want to use subinterfaces to avoid the split horizon problem. To configure a subinterface, remove the IP address off the main interface and put it under the subinterface. Configuring a subinterface involves assigning it a number and specifying the type. The following command creates point-to-point subinterface serial0/0.1: Router(config)#interface serial0/0.1 point-to-point
To create a multipoint subinterface, enter multipoint instead: Router(config)#interface serial0/0.1 multipoint
After entering one of these commands you will be taken to the subinterface configuration mode where you can enter your IP address: Router(config-subif)#ip address 10.0.0.2 255.0.0.0
If you are using a multipoint subinterface, you will need to configure Frame Relay maps and you cannot rely on inverse-arp.
If you are using a point-to-point subinterface, you will need to assign a DLCI to the subinterface. This is only for point-to-point subinterfaces; this is not needed on the main interface or on multipoint subinterfaces. To assign a DLCI to a point-to-point subinterface, enter the following command under the subinterface: frame-relay interface-dlci dlci
Now let's put the entire configuration together. The following configuration will configure frame-relay for the Sleepy router using a point-to-point subinterface to connect to the Bashful router and a multipoint subinterface to connect to the Grumpy router.
interface serial 0/0
encapsulation frame-relay
!
! Take the IP address off the main interface:
no ip address
!
! Configure the connection to the Bashful router
interface serial 0/0.1 point-to-point
ip address 10.0.0.1 255.0.0.0
frame-relay interface-dlci 100
!
! Configure the connection to the Grumpy router
interface serial 0/0.2 multipoint
ip address 14.0.0.2 255.0.0.0
frame-relay map ip 14.0.0.3 200 broadcast
Posted by campbell123
www.cisco.com/en/US/tech/tk713/tk237/technologies_tech_note09186a008014f8a7.shtml
Posted by crouse
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