CoS rewrite rules: Rewrite of the first three bits of IPv6 DSCP value

Rewrite rules that rewrite only the first three bits of the IPv6 DSCP value. Junos OS provides a new rewrite rule option, inet6-precedence, at the [edit class-of-service rewrite-rules] hierarchy level that allows you to set a 3-bit code point for a particular forwarding class and loss priority for IPv6 traffic. This new rewrite rule option can also be applied to packets entering an MPLS LSP.