Added mcast demo
.,
diff --git a/Demo/sockets/README b/Demo/sockets/README
index 0c68190..11dc7cb 100644
--- a/Demo/sockets/README
+++ b/Demo/sockets/README
@@ -8,3 +8,10 @@
throughput.py Client and server to measure TCP throughput.
udpecho.py Client and server for the UDP echo protocol.
radio.py Receive time broadcasts from broadcast.py.
+
+The following two files are only relevant on SGI machines (or other
+systems that support multicast):
+
+mcast.py A Python translation of
+ /usr/people/4Dgifts/examples/network/mcast.c
+IN.py Needed by mcast.py -- translation of <netinet/in.h>