Moog Components Group
201750-xxx MM2/Mini4 10/100
Feb 24, 2009
Ethernet Daughterboard Manual, Rev B
Page 3 of 8
1
MM2/Mini4 10/100 Ethernet Daughterboard, P/N: 201750-xxx
The Prizm MM2/Mini4 10/100 Ethernet daughterboard combines the functionality of a four-
port 10/100 Ethernet switch and a high speed synchronous Ethernet to serial bridge to
provide an end-to-end Ethernet link over a fiber multiplexer. This board must be stacked
onto a MM2 or a Mini4 motherboard set.
The board contains no user-modifiable jumper selections for this board. All functions are
handled automatically.
1.1
10/100 Ethernet Interface:
The 10/100 Ethernet daughterboard automatically supports both 10 and 100Mbps Ethernet
on each of the 4 switch ports. Mixed port-to-port Ethernet rates are supported and rate
adaptation is handled automatically. The 5
th
port on the switch connects to the synchronous
Ethernet to serial bridge chip. This chip buffers the Ethernet packets and flows the packets
serially through the MM2/Mini4 daughterboard connector at a synchronous data rated
defined by the MM2 (16Mbps) or Mini4 (25Mbps).
The 100Mbps Ethernet data rate is approximately 4 times the daughterboard throughput
capacity of the MM2 and Mini4. Therefore there will be some degradation to the Ethernet
traffic throughput over the MM2 or Mini4. At the 10Mbps Ethernet rate there should be
little throughput degradation.
Testing by Prizm has determined the following end-to-end throughput rates:
MM2 or Mini4
Ethernet Rate
Throughput
MM2
10Mbps
8Mbps
MM2
100Mbps
15Mbps
Mini4
10Mbps
20Mbps
Mini4
100Mbps
25Mbps
Ethernet throughput is typically defined as the number of bits in a ping packet divided by the
round-trip time that a ping packet takes to get from the originating PC to the target PC and
back again. As this is a round-trip measurement, the ping packet bit size is doubled for this
computation.
For example from table above:
1.
Size of ping packet = 15766 bytes * 8 = 126,128 bits per packet
2.
Round-trip time = 17.05 milliseconds
Throughput = Size of ping packet * 2 / Round-trip time
= (126,128 * 2) / 0.01705
= 14,795,073 bps
= 14.79Mbps
