This is a series of packet dumps of a ping exchange through a Wireless link composed of a Netgear MR814 Access Point and a Linksys WET-11 operating in infastructure mode. There are two PC's, a Desktop running Win 2k (IP: 192.168.101.103), and a laptop running Win 98 (IP: 192.168.101.102). The Desktop is located on an Ethernet segment connected to the MR814 Access Point. The Laptop is connected via it's docking station Ethernet port to the Ethernet port of the WET-11. The packet exchange was recorded twice, once from the AP end and once from the WET-11 end. In both cases the Laptop initiated the ping. Because the packet dumps were recorded at two different times, sequence numbers will differ in packets shown from the AP end and the WET-11 end. The intent is to show what happens to the hardware addresses in the Ethernet header. There was enough delay between the test runs so that the Laptop ARP Cache was empty. This way the ARP request/response could also be observed.
The packets were recorded using a Power Mac 6500/225, Mac OS 9.1, Etherpeek 3.5. The names near the Ethernet and IP addresses are from Etherpeek's name table, which allows a more human readable packet display. Other annotations are built-into the packet display.
The Netgear MR814 Firmware Version is 4.09, Aug 23 2002
The Linksys WET-11 Firmware Version is 1.32
The first packet out of the Laptop is an ARP request. Note the hardware source address of the Laptop in the Ethernet Header.
The WET-11 transmitted the packet to the AP. On the AP side it was also an ARP request. Note the hardware source address in the Ethernet Header is now that of the WET-11.
The Desktop received the above packet. It then generated an ARP response. Note the destination address in the Ethernet Header is that of the WET-11.
The Access Point transmitted the packet to the WET-11 where it emerged as an ARP response. Note the destination address in the Ethernet Header is that of the Laptop.
The Laptop next sent the Echo Request. Again, note the source and destination addresses in the Ethernet header. Source is Laptop, destination is Desktop.
When the Echo Request emerges from the AP, it now contains the WET-11 hardware address in the Ethernet header source address.
The desktop now responds by sending an Echo Reply. Shown here at the AP end.
The Echo Reply as sent to the Laptop.
The WET-11 uses an address substitution technique on the Ethernet packet header that is similar to IP based Network Address Translation (NAT), but at the Ethernet level.
B. Matson, May 28, 2003, Sebastopol, CA.