EVPN-VPWS: Control word

Junos OS supports the insertion of a control word between the label stack and the MPLS payload in a network with EVPN-VPWS service. When you enable the control word feature on a PE device, the PE device advertises support for a control word. If all the PE devices in an EVI on the EVPN-VPWS serviced network support control word, then the PE device inserts a control word between the label stack and the L2 header in the packet thus preventing the packet from being misidentified by transit devices. This feature prevents a transit device from delivering out-of-order packets as a result of the device's load-balancing hashing algorithm.