[nsp] ip load-sharing per-packet - cef accelerated ?

sthaug at nethelp.no sthaug at nethelp.no
Tue Mar 11 10:05:27 EST 2003

> > Every reference I have indicates cisco HDLC is simpler than PPP and thus 
> > has less overhead. cisco HDLC has no LCP for example.
> Link setup negotiation is much more complex in PPP, this is true (as HDLC
> has no negotiation).
> Data transfer overhead and CPU load is very similar.

Yup. So once the link is up, there is no reason to believe that PPP
has more overhead.

We still run Cisco HDLC on most links here, but we may at some point
in the future switch to PPP. Mostly because there are more features
available, and all the development seems to be in the PPP area. See
the message from Aaron Leonard included below.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no
From: Aaron at Cisco.COM (Aaron Leonard)
Subject: Re: HDLC drops connection after 20 secs?
Date: Tue, 13 Feb 2001 21:24:27 GMT
Message-ID: <3a89a235.2320000073 at usenet.cisco.com>

~ |   This has been a chronic problem in recent IOS - in general,
~ |   HDLC keepalives often don't work.  We have been fixing this
~ |   in a piecemeal fashion but unfortunately not comprehensively.
~ |   Some applicable DDTSes: CSCds27672, CSCds29905, CSCds50407.
~ |   I would recommend that you either disable keepalives or switch
~ |   to PPP.  (There's no advantage to running HDLC vs. PPP and plenty
~ |   of disadvantages.)
~ For those of us who have been running HDLC for many years - and still
~ configure new links with HDLC: What are the disadvantages of HDLC?

Well, there's no authentication in HDLC - which I should think
would be of significance to someone using dial up links
such as the original poster.  PPP has (as I'm sure you know), many
other features that HDLC lacks: multilink, interleave,
address (/DNS/WINS) negotiation, link-layer idle timeouts, etc.

In general, all the active development for the last many years
has gone into PPP.  HDLC has generally been ignored.  Which is not
necessarily a BAD thing, until something changes which causes
HDLC to break, and then we might be slow to fix it.

But ... if you are happy with HDLC over leased lines, and you
don't need any fancy features ... then there's nothing wrong
with you keeping on doing it.



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