IS-IS reference

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.

This case OSPF do the same thing - generate routes when it started up;
and no doubt it do less mistales then the human person.

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.

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.

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.

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.

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).

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.

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? :slight_smile:

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.

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/.

At least he'll be able to understand what's broke when the network goes down.

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.

--vadim

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).

OSPF (and any other dynamic routing protocol) introduces and removes
routes every time a link or device goes up or down - or perceived

Yes. For the 100-router backbone, it should happen once/day (failed link,
failed router), or once/hour, not more often. Through OSPF route even
dynamil dialup addresses as well - withouth any instability.

to go up and down. A typical scenario can be like: connecting a PC

Hmm, what is PC doing in the CORE backbone built by the L2 switches and
running 100TX or 1,000TX ethernet? And how often does anyone plug in the
broken cards?

No, the myths about the dynamic routing instability is not more than a
myth - until someone don't try to readvertise 60,000 router from BGP to
OSPF or back... I can't understand what all you are flames about - the 2
level schema (IGP for the CORE hosts and networks, IBGP for the
multi-home clients, OSPF-ASE or IGP for the STATIC and DialUP clients)
have not visible disadvantages (except now you can choose IS-IS instead
of OSPF if you use CISCO - can't argue against this).

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.

Yes, but do not mix the customer's and core networks; use OSPF
authentication if you can't avoid this. And even if you mix networks,
plug in broken linux with the wrong configured gated - the worst thing
you can do in the real life is to stole DEFAULT (from the default-less
backbone -:slight_smile: - no one even notify this).

No, we had a lot of problems from the wrong static routes, from the wrong
readvertisements, from the wrong aggregations - and never from the plain
simple OSPF itself...

Boths OSPF and IS-IS have a long history, designed well and realised very
stable (if you don't use something absolutely new and untested). And
there is a very simple ways to prevent the possible sources of
instability (dividing the roiuting to the CORE-IGP and USERS-IBGP is one
of them).

> 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).

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.

Yes, of course; but let's guess what was chosen by your wife?

The OSPF and IS-IS and other MODERN pritocols was designed for the
brain-less usage; if you don't write too many config lines and prevent
some hellish words, you are absolutely safe. The safest config is

router ospf 1
network 0.0.0.0 255.255.255.255 area 0

-:slight_smile:

(you can add 'unnumbered' interfaces to this example as well).

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? :slight_smile:

At least he'll be able to understand what's broke when the network goes down.

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.

Ok, some day I'll ask you to restore normal routing from the heap of
STATIC routes - I did such work twise, and do not want anymore (this was
not in our network, through).

--vadim

Aleksei Roudnev, Network Operations Center, Relcom, Moscow
(+7 095) 194-19-95 (Network Operations Center Hot Line),(+7 095) 230-41-41, N 13729 (pager)
(+7 095) 196-72-12 (Support), (+7 095) 194-33-28 (Fax)