The value of tmnxCcIpv6FltrSourceIpMask specifies the IP Mask value
for this policy IPv6 Filter entry. The mask is ANDed with the received
source IP address to match the tmnxCcIpv6FltrSourceIpAddr.
The default value of 0 disables matching on the Source IP address.
This field can only be set if the value of tmnxCcIpv6FltrDirection is set
to egress.