Description:

If a different instance of the LANCOM Management Cloud (LMC) is used instead of the public LMC (for instance, a private cloud), this must be communicated to the LANCOM devices so that they contact the correct LMC instance. To avoid having to store this manually on every device, one way is to distribute the LMC domain to the devices by means of the DHCP option 43.

This article describes the procedure for distributing the LMC domain to LANCOM devices via the LMC option 43.


Distributing the DHCP domain with the DHCP server integrated in LCOS:

When using the DHCP server integrated in LCOS, the LMC domain is entered using the menu LMC parameters. The device automatically converts the parameters into the format required by DHCP option 43 and distributes the LMC domain.

In order for local configuration changes to be adopted in the LMC, the Project Specifications option Apply to the LMC must be enabled.


1) Configuration by LANconfig:

1.1) In LANconfig, open the configuration for the router that acts as the DHCP server and go to the menu item IPv4 → DHCPv4 → LMC parameter.

1.2) Change the following parameters:

  • Network name : From the drop-down menu, select the network that is to use the LMC domain.
  • LMC domain : Enter the LMC domain which is to be distributed to the devices (in this example lmc.company.de ).

You can optionally specify the Rollout project ID and the Rollout location ID so that the devices are directly assigned to the correct project and site.

1.3) This concludes the configuration of the LMC domain. You can now write the configuration back to the device.


2) Configuration via the LANCOM Management Cloud:

2.1) Connect to the LMC, go to the Devices menu, and click on the Name of the router that acts as the DHCP server.

2.2) Go to the Detail configuration tab and then to the menu IPv4 → DHCPv4 → LMC parameter.

2.3) Click on New entry to enter an LMC domain.

2.4) Modify the following parameters and then click Save entry:

  • Network name : Select the network that is to use the LMC domain.
  • LMC domain : Enter the LMC domain which is to be distributed to the devices (in this example lmc.company.de ).

You can optionally specify the Rollout project ID and the Rollout location ID so that the devices are directly assigned to the correct project and site.

2.5) Click Save to accept the change.

2.6) In the Devices menu, select the router that acts as DHCP server and click the “dots” icon in the top right-hand corner.

2.7) Click on Configuration roll out. This concludes the configuration of the LMC domain.



Distributing the LMC domain with a separate DHCP server:

When operating a separate DHCP server, the LMC domain is specified via the DHCP option 43 as a TLV (Type Length Value) in hexadecimal notation.

Structure of the LMC domain:

The LMC domain is communicated in the following format:

<Sub-option number of the LMC domain> <Length of the LMC domain> <LMC domain>

  • The LMC domain sub-option number is 18. In hexadecimal notation this is 12.
  • The length of the LMC domain is the number of characters. In our example, the LMC domain lmc.company.de has 14 characters. In hexadecimal notation this is e.
  • In hexadecimal notation, the LMC domain lmc.company.de results in the value 6c 6d 63 2e 63 6f 6d 70 61 6e 79 2e 64 65.


In our example, the domain lmc.company.de must therefore be transmitted as follows:

Since each entry must have two characters, the e of the LMC domain length is prefixed with a leading 0, resulting in 0e.

12 0e 6c 6d 63 2e 63 6f 6d 70 61 6e 79 2e 64 65