Figure 16 Addressing Of Ip Packets - WaveRider LMS4000 User Manual

3 Detailed Description
Addressing of IP Packets
Figure 16 shows how the source and destination MAC and IP addresses are sent in IP
packets travelling between the end-user's PC and the Internet network servers.
Destination IP
Address
Source IP
Address
CCU Radio MAC
Destination
MAC Address
End-user PC MAC
Source MAC
Address
End-user PC
Destination IP
Address
Source IP
Address
End-user PC MAC
Destination
MAC Address
CCU Radio MAC
Source MAC
Address
As shown in Figure
destination IP addresses are maintained throughout the route between the end-user PC and
network servers. The source and destination MAC addresses, however, change whenever the
packet is passed through a router. This change of MAC addresses also takes place in the
CCU router application.
Internet to End-user Computer Data Transmission
1. Internet traffic comes through the gateway router, and possibly through backhaul and
Ethernet switches, to the CCU Ethernet port.
2. The CCU receives an IP 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
3. The CCU reads the destination IP address. If the destination IP address is the same
as either the CCU Radio or Ethernet IP address, the packet is sent to the CCU
application.
4. The CCU checks the Routing Table, described in
page 184. 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.
26
End-user PC to Network Server
Network Server IP Address
End-user PC IP Address
NAP Router MAC
Address
CCU Ethernet MAC Address
Address
EUM CCU Switch
End-user PC IP Address
Network Server IP Address
CCU Ethernet MAC Address
Address
NAP Router MAC
Address
Network Server to End-user PC
Figure 16 Addressing of IP Packets
16, if NAT is not enabled in the NAP Router, then the source and
Port Filter Table (CCU and EUM)
Internet Router
Address
A MAC
NAP Router
MAC
A
Backhaul NAP Router
Backhaul
(no NAT)
NAP Router
MAC
Internet Router
Address
A MAC
on page 183, the packet is discarded.
Routing Table (CCU and EUM)
Destination IP
Address
Source IP
Address
Network
Destination
Server MAC
Address MAC Address
A Address
Internet
Source MAC
Router MAC
Address B Address
B Address
B A B
Internet Router
(several)
Network Server
Destination IP
Address
Source IP
Address
Internet
Destination
Router MAC
Address B
MAC Address
B Address
Network
Source MAC
Server MAC
Address
Address
A Address
APCD-LM043-4.0
on