On Wed, Jul 07, 2004 at 04:21:39PM +1000, Darren Reed wrote: > IP 1.1.1.1.1701 > 2.2.2.2.1701: l2tp:[TLS](24460/3222)Ns=23239,Nr=647 > *MSGTYPE(ICCN) *TX_CONN_SPEED(156000) *FRAMING_TYPE(A) > *VENDOR0c7f:ATTR0066(00000000000000000000000000) RX_CONN_SPEED(156000)
I'm not sure what the "framing type" in an L2TP session signifies - does it signify what framing is used for the PPP traffic once it leaves the L2TP tunnel, or does it (for some not-entirely obvious reason) signify what framing is used *inside* the tunnel? RFC 2661 says Once tunnel establishment is complete, PPP frames from the remote system are received at the LAC, stripped of CRC, link framing, and transparency bytes, encapsulated in L2TP, and forwarded over the appropriate tunnel. The LNS receives the L2TP packet, and processes the encapsulated PPP frame as if it were received on a local PPP interface. which sounds as if you're *not* supposed to send PPP frames over the wire in RFC 1662 byte-stuffed form. However, I found some mail on the Ethereal list about packets with RFC 1662 byte-stuffing inside L2TP - and the packets might have been involved in some 3GPP2 stuff - so perhaps the CDMA2000 folks didn't bother reading section 5.3 of RFC 2661 carefully, and decided to send byte-stuffed crud in L2TP packets. Or perhaps this is some wacky vendor-specific stuff, where they decided to send extra framing and escaping octets over the network for some reason; a Google for l2tp site:3gpp2.org didn't find anything. > But all of the real CDMA/1xRTT stuff is ITU defined (= $$ to obtain.) What about http://www.3gpp2.org/Public_html/specs/index.cfm - This is the tcpdump-workers list. Visit https://lists.sandelman.ca/ to unsubscribe.