[25103] in North American Network Operators' Group
Re: IS-IS reference
daemon@ATHENA.MIT.EDU (Dana Hudes)
Mon Sep 13 17:41:30 1999
From: "Dana Hudes" <dhudes@panix.com>
To: "Vadim Antonov" <avg@kotovnik.com>, <alex@Relcom.EU.net>
Cc: <nanog@merit.edu>
Date: Mon, 13 Sep 1999 17:40:00 -0400
Errors-To: owner-nanog-outgoing@merit.edu
OSPF has passwords. While it has to be the same on all links, it still =
locks out the wise guys with old version of GateD.
As for folks who understand this stuff deeply, while we may be rare it =
is sometimes difficult to get the word out when oneself is available for =
a project. Furthermore, I've had ridiculously low offers ($70k from =
UUNET).=20
----- Original Message -----=20
From: Vadim Antonov <avg@kotovnik.com>
To: <alex@Relcom.EU.net>
Cc: <nanog@merit.edu>
Sent: Monday, September 13, 1999 4:37 PM
Subject: Re: IS-IS reference
>=20
> Alex P. Rudnev <alex@Relcom.EU.net> wrote:
>=20
> >> The real answer - do static routing whereever you have only a =
single
> >> path for packets to go thru. To eliminate mistakes, generate
> >> configuration automatically from master maps kept at network =
engineering
> >> computers.
>=20
> >This case OSPF do the same thing - generate routes when it started =
up;
> >and no doubt it do less mistales then the human person.
>=20
> No, it doesn't do the same thing - the difference is about the same
> as the difference between compile-time and run-time type checking.
>=20
> OSPF (and any other dynamic routing protocol) introduces and removes
> routes every time a link or device goes up or down - or perceived
> to go up and down. A typical scenario can be like: connecting a PC
> with a broken NIC card to an Ethernet segment can easily cause massive
> packet loss, causing rapid route flap which basically infects the
> entire backbone. If that backbone carries even a fraction of full
> exterior routing table, this would cause loss of coherence between
> routing tables and persistent routing loops.
>=20
> Additionally _no_ exising IGP has anything resembling protection
> from malfunctioning routing software _or_ malicious or negligient
> operators of host-based rotuing software. I had to track down people
> who enable gated on their linux boxes just for the fun of it, and
> screw the entire network up in the process, more times than i care
> to count.
>=20
> In other words, dynamic routing is very brittle, and requires quite
> a lot of care to make sure it works right, and that a single-point
> failure won't affect the significant portion of the network. If
> you would claim that you ever did an analysis like that for any real
> network i'd have to ask you to enlighten all of us about the obviously
> break-through novel network design technique you're using.
>=20
> > No, the comparation between OSPF and STATIC looks like the =
comparation
> > between the old (from 1950 year) and modern (Mersedess-600) cars - =
the
> > first is very simple implemented and difficult to drive; the second =
is
> > very complex implemented but very simple to drive (but if you are to =
be
> > starving on the unhabitant ireland with the good roads, you'll =
choose the
> > first car; but it seemd for me you just choose something more =
complex in
> > the real life).
>=20
> Did you notice that it takes a highly trained specialist with =
appropriate
> (and rather expensive) equipment to diagnose and fix a problem in a =
Mercedes?
> A hammer and few expletitives usually suffice for a Packard.
>=20
> That's the real difference. People who understand routing protocols
> and how they interact with level-2 transport are still extremely rare
> and rather expensive. Even the major ISPs here in US have serious =
staffing
> problems. An average corporate MIS department is best characterized =
as
> clueless (what other explanation is here for the Microsoft dominance? =
:)
>=20
> In other words, you're advising kids who don't yet know how to hold a
> hammer to start using chain saw. In a situation like that i would
> expect a lot of cut-off bodily parts.
>=20
> > PS. And if someone use STATIC widely, a few years ago some other =
person
> > should be sitting for a few days and flame the first one digging =
through
> > a heaps of the static routes /it's real example from my life/.
>=20
> At least he'll be able to understand what's broke when the network =
goes down.
>=20
> BTW, dealing with heaps of statics is very simple: do a numbering plan =
first,
> so the routes are aggregable. That is helpful for dynamic routing, =
too.
>=20
> --vadim
>=20
>=20
