[PATCH] Documentation, clarify tuntap IPX example.

From: andrew hendry
Date: Tue Nov 17 2009 - 20:30:50 EST


Can the TUNSETIFF ioctl change a tap's protocol to IPX as the
documentation suggests?
I think tun.c would need IFF_IPX_TAP added for it to work as described?
Otherwise tap can only be ptp or ethernet, and there is no way to
route or use AF_IPX.

Signed-off-by: Andrew Hendry <andrew.hendry@xxxxxxxxx>

--- a/Documentation/networking/tuntap.txt 2009-11-11
14:03:22.676167648 +1100
+++ b/Documentation/networking/tuntap.txt 2009-11-18
11:34:18.106647029 +1100
@@ -127,12 +127,14 @@ Ethernet device, which instead of receiv
media, receives them from user space program and instead of sending
packets via physical media sends them to the user space program.

-Let's say that you configured IPX on the tap0, then whenever
-the kernel sends an IPX packet to tap0, it is passed to the application
-(VTun for example). The application encrypts, compresses and sends it to
-the other side over TCP or UDP. The application on the other side decompresses
-and decrypts the data received and writes the packet to the TAP device,
-the kernel handles the packet like it came from real physical device.
+Let's say for the purpose of example, IPX support was added to tuntap.
+Then whenever the kernel routes an IPX packet to tap0, it is passed to the
+application reading the file descriptor from /dev/net/tun (VTun for example).
+The application encrypts, compresses and sends it to the other side over TCP
+or UDP. The application on the other side decompresses and decrypts the data
+received and writes the packet to the TAP device, the remote kernel handles
+the packet like it came from real physical device. The IPX applications are
+able to communicate as if there was a real IPX network.

4. What is the difference between TUN driver and TAP driver?
TUN works with IP frames. TAP works with Ethernet frames.
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