The set of IP protocol ids to apply the classification to.
Example: If this set has protocols(bits) 1 and 5 set to a
'1', and the classification is 'multicastData', this will
force IGMP to treat received frames with IP protocol ids of
1 and 5 as 'multicast data', and forward those frames to
IGMP joined clients. Similarly if ids 1 and 5 were set to
'routing protocol' then IGMP would treat received frames with
these ids as routing protocols, etc.