Date: Tue, 25 Jul 1995 11:20:24 -0700 From: Darryl Okahata <darrylo@hpnmhjw.sr.hp.com> To: Ron Steele <rjs@clark.net> Cc: question freebsd <freebsd-questions@freefall.cdrom.com> Subject: Re: ping times using ppp Message-ID: <199507251820.AA003476425@hpnmhjw.sr.hp.com> In-Reply-To: Your message of "Mon, 24 Jul 1995 20:47:16 -0000." <Pine.3.87.9507242016.A1847-0100000@localhost>
next in thread | previous in thread | raw e-mail | index | archive | help
> When trying to do interactive work over a ppp link, I find the latency
> time very annoying. Ping generally reports round trip times of about
> a quarter second. I use hardware handshaking and v.34 modem on
> 16550 compatable serial card. Currenty 2.0R, soon to be upgrading.
>
> Does this time seem about right? Any ideas on how to improve these times?
As Mike said, this isn't unusual. With my PPI V.FC (not V.34)
modems, I see ping times around 160-180ms. To do error correction and
data compression, modems "packetize" data; basically, when sending data,
the modem tries to gather a packet of data (256 bytes, I think) before
sending. However, this doesn't work well with interactive use, and so
there's a timeout; when the timeout occurs, the partial packet is sent.
This timeout is the cause of the long latencies (and note that two
timeouts probably occur with ping -- one for each direction).
-- Darryl Okahata
Internet: darrylo@sr.hp.com
DISCLAIMER: this message is the author's personal opinion and does not
constitute the support, opinion or policy of Hewlett-Packard or of the
little green men that have been following him all day.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199507251820.AA003476425>