Frame Relay Multipoint Config – Answers Part 2

By certskills January 18, 2013 11:05

#CCNA still makes us think about static Frame Relay mapping. Even when Frame Relay was more popular in real networks, many companies simply didn’t use the frame-relay map command, preferring to instead use the frame-relay interface-dlci command as shown in the previous post. And many people seem to have a mental block about these Frame Relay mappings. Today, the post wraps up this latest config museum piece with a config, and a few comments about the mapping.

Brief Review

Frankly, this post is mostly a continuation of the previous post, just broken into two posts due to the length. So, go back and read the problem statement post, and then answer part 1, before diving in here!

The short version: R1, R2, and R3 use multipoint subinterfaces, a full mesh of PVCs, and IPv4 addresses, .66, and .67, respectively. Figure 1 reviews some of those details. This post looks at the configuration that uses frame-relay map commands.

Figure 1 – Frame Relay Configuration

Full Configuration

Next, Examples 7, 8, and 9 shows the full configuration for Routers R1, R2, and R3 as related to this lab. I repeated the base config from answer part 1 so it’s handy. That is, the configurations shown here fulfill all the requirements for this lab, while using frame-relay map commands.

Example 7: R1 Config


Example 8: R2 Config


Example 9: R3 Config


Breakdown of the frame-relay map Command

Note that the frame-relay map commands sit inside subinterface config mode. This post shows them indented, just under the interface commands that refer to the subinterface. In a real router, you would see a different command prompt that would show the CLI is in subinterface config mode. The point is that the command context tells IOS that this frame-relay map command is about that particular subinterface.

So, back to the two big ideas that the router must somehow connect to each subinterface: which PVCs go with each subinterface, and what is the next-hop router IP address on the other end of those DLCIs.

  • The frame-relay map commands, when configured in a particular subinterface’s configuration mode, tell IOS that the PVC with that DLCI should be connected with, or associated with, that subinterface. Simple enough.
  • The next-hop IP address listed in the frame-relay interface-dlci command lists the IP address of the router on the other end of the PVC. That is, the router on the other side of the cloud.


FR Multipoint Config - Answers
CCENT Practice Question 101: Combining Protocols
By certskills January 18, 2013 11:05
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  1. Wojtek February 27, 16:26

    Is there a mistake in the end of the post or there is something I don’t understand? In the first one, shouldn’t there be a command “frame-relay interface-dlci” instead of “frame-relay map” and “frame-relay map” instead of “frame-relay interface-dlci”?

    “The next-hop IP address listed in the frame-relay interface-dlci command…” – can we map next-hop address with this command?

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  2. certskills Author February 28, 12:26

    Wojtek – look backwards in time, in the blog, and you’ll see the first two posts in this series. The first set up the problem. The second listed a configuration that used frame-relay interface-dlci commands. This post was focused on how to instead configured frame-relay map commands, which then means you don’t need the frame-relay interface-dlci commands. So, short answer, I think you just missed the context of the two prior posts.

    As to your 2nd question, yes, the frame-relay map command maps the next-hop address to the local router’s local DLCI for the PVC connected to the next-hop router.
    Hope this helps!

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