Control word for BGP VPLS

For hash calculation, transit routers must determine the payload. While parsing an MPLS encapsulated packet for hashing, a transit router can incorrectly calculate an Ethernet payload as an IPv4 or IPv6 payload if the first nibble of the DA MAC is 0x4 or 0x6, respectively. This false positive can cause out-of-order packet delivery over a pseudowire.This issue can be avoided by configuring a BGP VPLS PE router to request that other BGP VPLS PE routers insert a control word between the label stack and the MPLS payload.