RG              UP                       CP             AAA
     | DHCP Discovery|                        |               |
    1|-------------->|                        |               |
     |               |Relay the DHCP Discovery|               |
     |              2|-----to CP via Si------>|      AAA      |
     |               |                        |    Req/Rep    |
     |               |                       3|<------------->|
     |               |  Send the DHCP Offer   |               |
     |              4|<----to UP via Si-------|               |
     |  DHCP Offer   |                        |               |
    5|<--------------|                        |               |
     |  DHCP Request |                        |               |
    6|-------------->|                        |               |
     |               | Relay the DHCP Request |               |
     |              7|-----to CP via Si------>|               |
     |               |                        |               |
     |               |  Create Subscriber     |               |
     |               |   Session Request      |               |
     |              8|<--------via Ci---------|               |
     |               |  Create Subscriber     |               |
     |               |   Session Response     |               |
     |              9|---------via Ci-------->|               |
     |               |                        |   Accounting  |
     |               |                      10|<------------->|
     |               |  Send DHCP ACK         |               |
     |             11|<----to UP via Si-------|               |
     |               |                        |               |
     |  DHCP ACK     |                        |               |
   12|<--------------|                        |               |
     |               |                        |               |