User's Manual Part 1

26 APCD-LM043-8.0 (DRAFT C)
3: Detailed Description
3.3.2 Internet to End-user Computer Data Transmission using Routed
Mode
1. Internet traffic comes through the gateway router, and possibly through backhaul and
Ethernet switches, to the CCU Ethernet port.
2. The CCU receives a packet through the CCU Ethernet port and checks the TCP or
UDP port number. If the port number appears in the CCU Port Filter Table, described
in Port Filter Table (CCU and EUM) on page 231, the packet is discarded.
3. The CCU reads the destination MAC address. If the destination MAC address is the
same as either the CCU Radio or Ethernet MAC address, the packet is sent to the
CCU application.
4. The CCU checks the Routing Table, described in Routing Table (CCU and EUM) on
page 232. If the route to the destination is through the CCU Ethernet port, then the
packet is discarded, since it is not destined for a host in the CCU’s radio subnet.
5. If the route to the destination is through the CCU Radio Port, then the CCU obtains the
destination Ethernet MAC address from the ARP Table, described in ARP Table (CCU
and EUM) on page 236. If the destination is not listed in the ARP Table, the CCU
obtains its MAC address by issuing an ARP query. Once it gets the MAC address, it
adds the entry to the ARP Table.
6. Using the destination Ethernet MAC address, the CCU obtains the EUM ID from the
Address Translation Table, described in Address Translation Table (CCU only) on
page 238.
7. Using the EUM ID, the CCU obtains the EUM grade of service from the Registration
Table, described in Registration Table (CCU only) on page 240.
8. The packet is then transmitted through the Polling MAC and radio interface to the
EUM.
9. The EUM receives the packet through the EUM radio port and checks the port
number. If the port number appears in the EUM Port Filter Table, the packet is
discarded.
10. If the port number does not appear in the EUM Port Filter Table, the EUM checks the
destination MAC address. If the MAC address is the EUM MAC address, then the
packet is forwarded to the EUM application; otherwise, the packet is sent out through
the Ethernet port to the end user’s equipment.
3.3.3 End-user Computer to Internet Data Transmission using Routed
Mode
1. The EUM receives packets from the end-user’s equipment through the Ethernet port.
2. The EUM checks the port number. If the port is listed in the EUM Port Filter Table, the
packet is discarded.
3. If it is not already in the list, the EUM adds the source Ethernet address to the Bridge
Table, described in Bridge Table (EUM or CCU in Switched Ethernet or Through Only
Mode) on page 242. The EUM determines whether or not the source is entitled to air
access, based on the Bridge Table.
4. If the source is not entitled to air access, the packet is discarded.