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authorGuy Harris <guy@alum.mit.edu>2001-06-15 20:23:41 +0000
committerGuy Harris <guy@alum.mit.edu>2001-06-15 20:23:41 +0000
commit4a5b324abb476e0ada0cebfafde8769be9bfc2aa (patch)
treec49d051e4e66f815732d787a915b68aa89f8636c /packet-ethertype.c
parent738fe781f90b0eeb2553d17c13cf39a0fe8a9f17 (diff)
Explain why we have to be ready to handle Ethernet frames with
protocol type values that are PPP protocol types. svn path=/trunk/; revision=3554
Diffstat (limited to 'packet-ethertype.c')
-rw-r--r--packet-ethertype.c18
1 files changed, 14 insertions, 4 deletions
diff --git a/packet-ethertype.c b/packet-ethertype.c
index b4d7b3ea7b..0a0adeb8cf 100644
--- a/packet-ethertype.c
+++ b/packet-ethertype.c
@@ -1,7 +1,7 @@
/* ethertype.c
* Routines for calling the right protocol for the ethertype.
*
- * $Id: packet-ethertype.c,v 1.16 2001/06/14 20:37:07 guy Exp $
+ * $Id: packet-ethertype.c,v 1.17 2001/06/15 20:23:41 guy Exp $
*
* Gilbert Ramirez <gram@xiexie.org>
*
@@ -75,9 +75,19 @@ const value_string etype_vals[] = {
{ETHERTYPE_ETHBRIDGE, "Transparent Ethernet bridging" },
/*
- * XXX - is there a standard for running PPP protocols atop
- * Ethernet, using the PPP protocol type value as the
- * Ethernet protocol type value?
+ * NDISWAN on Windows translates Ethernet frames from higher-level
+ * protocols into PPP frames to hand to the PPP driver, and translates
+ * PPP frames from the PPP driver to hand to the higher-level protocols.
+ *
+ * Apparently the PPP driver, on at least some versions of Windows,
+ * passes frames for internal-to-PPP protocols up through NDISWAN;
+ * the protocol type field appears to be passed through unchanged
+ * (unlike what's done with, for example, the protocol type field
+ * for IP, which is mapped from its PPP value to its Ethernet value).
+ *
+ * This means that we may see, on Ethernet captures, frames for
+ * protocols internal to PPP, so we list as "Ethernet" protocol
+ * types the PPP protocol types we've seen.
*/
{PPP_IPCP, "PPP IP Control Protocol" },
{PPP_LCP, "PPP Link Control Protocol" },