Frame Relay Interface-dlci

Coolhandluke

Can someone clarify or simply tell me if there is a mistake in the ROUTE OCG. In the EIGRP section (pg 6 it gives an example of calculating the bandwidth allocation (which is all fine) but then gives the code below:

interface Serial0/0/0.20 multipoint
ip address 172.16.1.1 255.255.255.240
frame-relay interface-dlci 201
frame-relay interface-dlci 202
frame-relay interface-dlci 203

I was under the impression that Interface-dlci was used with point-to-point sub-interfaces to assign DLCI to a specific interface and that multipoint interfaces used map statements.

Can anyone clear this up for me ?

Thanks

7of9

I think they may just be trying to simplify the configuration rather than go into frame-relay any deeper?

Usage GuidelinesThis command is typically used for subinterfaces; however, it can also be used on main interfaces. Using the frame-relay interface-dlcicommand on main interfaces will enable the use of routing protocols on interfaces that use Inverse ARP. The frame-relay interface-dlcicommand on a main interface is also valuable for assigning a specific class to a single PVC where special characteristics are desired. Subinterfaces are logical interfaces associated with a physical interface. You must specify the interface and subinterface before you can use this command to assign any DLCIs and any encapsulation or broadcast options. See the "Examples" section for the sequence of commands.This command is required for all point-to-point subinterfaces; it is also required for multipoint subinterfaces for which dynamic address resolution is enabled. It is not required for multipoint subinterfaces configured with static address mappings.

In contrast, the usage guidelines for frame relay map are...

By requiring selection of a designated router, OSPF treats a nonbroadcast, multiaccess network such as Frame Relay in much the same way as it treats a broadcast network. In previous releases, this required manual assignment in the OSPF configuration using the neighbor interface router command. When the frame-relay map command is included in the configuration with the broadcast keyword, and the ip ospf network command (with the broadcast keyword) is configured, there is no need to configure any neighbors manually. OSPF will now automatically run over the Frame Relay network as a broadcast network. (See the ip ospf network interface command for more detail.)

So, they may be trying to trick you here since, without the map command and broadcast specified in the OP's example, you'll need to configure your neighbors manually.

Zartanasaurus

You can use the frame-relay interface-dlci command wherever you want. It's not a requirement that they only be used on PTP subinterfaces. The only problem with that config is that you're going to have to do map statements anyway since it's a mpoint subinterface, so it's not necessary to do the interface-dlci unless you're assigning map-classes to a specific DLCI.