nanog mailing list archives
Re: PPP Question
From: "William Allen Simpson" <wsimpson () greendragon com>
Date: Tue, 16 Dec 97 20:07:12 GMT
Catching up on NANOG after returning from IETF, I found this incongruous message, and would like to correct the misinformation. The PPP Maximum Receive Unit is negotiated, but this is a "maximum", not a "fixed" size. Smaller packets can be sent. While it would be perfectly legal to fill the remainder of the packet with padding, I know of no vendor that does it. This would seriously waste bandwidth. The padding feature is available for old chipsets that require 16-bit and 32-bit output data alignment. Further questions about PPP should be sent to the ietf-ppp () merit edu mailing list, as designated in RFC1661.... Yes, NANOG is also hosted by Merit, but the lists have different purposes. Really. As usual, joining a list requires a message to <list>-request. I was amazed at the number of messages arising from nanog list members complaining that pppsdh () greendragon com did not allow sending a "join", "request", "subscribe" or other subject to the mailing list directly. (heavy sigh)
From: "Chris MacFarlane" <cjm () ican net> More to the point is that the frame size is negotiated while handshaking. Once two devices agree on the size it is fixed for the duration of the session. -----Original Message----- From: George Janosik <gjanosik () torrentnet com>Is a PPP frame size static or elastic? RFC 1661 states: ... But, it also says the the Information field "MAY" be padded up to the MRU. I have hard time believing that a PPP frame would be static.
WSimpson () UMich edu Key fingerprint = 17 40 5E 67 15 6F 31 26 DD 0D B9 9B 6A 15 2C 32
Current thread:
- PPP Question George Janosik (Dec 10)
- <Possible follow-ups>
- PPP Question George Janosik (Dec 10)
- Re: PPP Question Chris MacFarlane (Dec 10)
- Re: PPP Question William Allen Simpson (Dec 16)