Disable the Control Word for Layer 2 VPNs

The emulated VC encapsulation for Layer 2 VPNs is accomplished by adding a 4-byte control word between the Layer 2 protocol data unit (PDU) being transported and the VC label that is used for demultiplexing. Various networking formats (ATM, Frame Relay, Ethernet, and so on) use the control word in a variety of ways.

The JUNOS software does not support the control word for any networking format, meaning that it is not fully compliant with the Internet draft in cases where the control word is mandatory. To be minimally compliant with the Internet draft, JUNOS supports a null control word (a control word of all zeros). This null control word is configured by default. If JUNOS receives a packet with a control word attached, the control word is discarded before the packet is forwarded to its destination.

On networks with equipment that does not support the control word, you can disable it by including the no-control-word statement. For a list of hierarchy levels at which you can configure this statement, see the statement summary section for this statement.

no-control-word;