RG              UP                      CP              AAA
   |               |Establish S-CUSP Channel|               |
   |              1|<---------------------->|               |
   |               |                        |               |
   |               | Report board interface |               |
   |               |      information       |               |
   |              2|------to CP via Ci----->|               |
   |               |                        |               |
   |               |  Update BAS function   |               |
   |              3|    request/response    |               |
   |               |<-----on UP via Ci----->|               |
   |               |                        |               |
   |               | Update network routing |               |
   |               |    request/response    |               |
   |              4|<------- via Ci-------->|               |
   |  Online Req   |                        |               |
5.1|-------------->|                        |               |
   |               | Relay the Online Req   |               |
   |            5.2|-----to CP via Si------>| Authentication|
   |               |                        |    Req/Rep    |
   |               |                     5.3|<------------->|
   |               | Send the Online Rep    |               |
   |            5.4|<----to UP via Si-------|               |
   |               |                        |               |
   |               | Create subscriber      |               |
   |               |    session on UP       |               |
   |            5.5|<--------via Ci-------->|               |
   |  Online Rep   |                        |               |
5.6|<--------------|                        |               |
   |               |                        |  CoA Request  |
   |               |                     6.1|<--------------|
   |               | Update session on UP   |               |
   |            6.2|<--------via Ci-------->|               |
   |               |                        |  CoA Response |
   |  Offline Req  |                     6.3|-------------->|
7.1|-------------->|                        |               |
   |               | Relay the Offline Req  |               |
   |            7.2|------to CP via Si----->|               |
   |               |                        |               |
   |               | Send the Offline Rep   |               |
   |            7.3|<-----to UP via Si------|               |
   |  Offline Rep  |                        |               |
7.4|<--------------|                        |               |
   |               | Delete session on UP   |               |
   |            7.5|<--------via Ci-------->|               |
   |               |                        |               |
   |               |      Event report      |               |
   |              8|---------via Ci-------->|               |
   |               |                        |               |
   |               | Data synchronization   |               |
   |              9|<--------via Ci-------->|               |
   |               |                        |               |
   |               | CGN address allocation |               |
   |             10|<--------via Ci-------->|               |
   |               |                        |               |