This post is about terminating PPPoE sessions dynamicly on a Juniper MX. Recently i’ve setup dynamic PPPoE termination succesfully on a MX series, the goal was to migrate PPPoE termination functionality from a Cisco 7206 VXR towards one of our Juniper MX’s.

There is documentation from juniper that describes how to set this up:

I stumbled upon several weird things while testing with PPPoE that i thought may be worth sharing.

There are several ways to setup PPPoE termination on a MX:

  • Static subscriber management
  • Dynamic subscriber management

When configuring static subscriber management you need to provision a logical interface for each subscriber, this will not scale when you hit more subscribers.

Dynamic subscriber management is the way i wanted to go, because of the amount of subscribers we have.

JunOS version 13.3R9 experiences

I started testing on JunOS 13.3R9, some things:

  • Documentation was not clear on whether you needed to set the access-profile at the vlan-profile or global.
  • Noticed that the command set available was not very useful for some serious troubleshooting
  • The dynamic ppp profile needs to end with -profile in the name, if you think of using a different name it will not work, it’s probably documented somewhere internally at Juniper.
  • IPCP DNS configuration for clients was not configurable and supported in this release.
  • test aaa commands cannot be used on a MX, you can give the command but it won’t do a thing. This command is apparently only valid on a Juniper EX?

After this experience a new recommended JTAC version was released so i continued with testing on JunOS 15.1R6.7.

JunOS version 15.1R6.7 experiences

Right after the upgrade from JunOS 13.3R9 towards 15.1R6.7, the PPPoE configuration that was previously working stopped completely.

After doing some packetcaptures i could see the PADI coming in from clients, but the MX was dead silent. “show pppoe statistics” were all at 0 confirming the MX was dead silent.

After some debugging i found the following message from auto-configuration:

The reason of this message is that dynamic subscriber management apparently only works on JunOS 15.x and onwards when you run the chassis in enhanced ip mode. I couldn’t find a reference of this in the release notes, but ok… :-)

After setting the configuration as described here PPPoE started working again! So what is this PPPoE configuration about?

The Cisco 7206VXR configuration for PPPoE that I was trying to convert was basicly the following config:

Configuration of dynamic subscriber management

Here is the configuration that i have used to setup dynamic subscriber management using dynamic vlans and dynamic PPP interfaces. The result of this configuration is that end-users can plug-and-play and the only thing you need to do is have a radius account for the happy enduser.

AAA configuration

System configuration

Before applying any dynamic-profile related stuff, I’ve enabled versioning on the MX, this allows a dynamic-profile to be adjusted while subscribers are online.

Dynamic vlan profile configuration

Dynamic ppp profile configuration

Interface configuration

Although it looks easy, it took a while before getting things working and to know how the demux interface works (or not ;-)).

I hope this helps other people setting up PPPoE termination on the MX platform, feel free to comment.