uBSID is an End.B6.Insert with NEXT-C-SID Flavor SID, and the 
corresponding segment-list is <fc00:2024:uSID20::,fc00:2024:uSID21>.
case1,  uBSID is the non-last SID of the container:
        Node N receives a packet:
        IPv6：SA = 2024::1, DA=FC00:2024:uBSID:uSID2:uSID3
                               :uSID4::uSID5:uSID6::
        SRH1:(FC00:2024:uSID7:uSID8::,FC00:2024:uBSID:uSID2
             :uSID3:uSID4:uSID5:uSID6::;SL=1)
        After the End.B6.Insert with NEXT-C-SID Flavor behavior, 
        the packet looks like:
        IPv6：SA = 2024::1, DA=FC00:2024:uSID20:uSID21::
        SRH2:(FC00:2024:uSID2:uSID3:uSID4::uSID5:uSID6::,
             FC00:2024:uSID20:uSID21::;SL=1)
        SRH1:(FC00:2024:uSID7:uSID8::,
             FC00:2024:uBSID:uSID2:uSID3:uSID4:uSID5:uSID6::;SL=1)

case2, uBSID is the last SID of the C-SID container:
       Node N receives a packet:
       IPv6：SA = 2024::1, DA=FC00:2024:uBSID::
       SRH1:(FC00:2024:uSID7:uSID8::,
            FC00:2024:uSID2:uSID3:uSID4:uSID5:uSID6:uBSID::;SL=1)
       After the End.B6.Insert with NEXT-C-SID Flavor behavior, 
       the packet looks like:
       IPv6：SA = 2024::1, DA=FC00:2024:uSID20:uSID21::
       SRH2:(FC00:2024:uSID20:uSID21::;SL=0);SRH2 may be omit
       SRH1:(FC00:2024:uSID7:uSID8::,
             FC00:2024:uSID2:uSID3:uSID4:uSID5:uSID6:uBSID::;SL=1)

case3, uBSID is in the last of the C-SID container of the SRH:
       Node N receives a packet:
       IPv6：SA = 2024::1, DA=FC00:2024:uBSID:uSID7:uSID8::
       SRH1:(FC00:2024:uBSID:uSID7:uSID8::,
             FC00:2024:uSID1:uSID2:uSID3:uSID4:uSID5:uSID6::;SL=0)
       After the End.B6.Insert with NEXT-C-SID Flavor behavior, 
       the packet looks like:
       IPv6：SA = 2024::1, DA=FC00:2024:uSID20:uSID21::
       SRH2:(FC00:2024:uSID7:uSID8::,FC00:2024:uSID20:uSID21::;SL=1)
       SRH1:(FC00:2024:uBSID:uSID7:uSID8::,
            FC00:2024:uSID1:uSID2:uSID3:uSID4:uSID5:uSID6::;SL=0)