"routing table slots" and the real problem

Mr. Dana Hudes dhudes at graphnet.com
Mon Mar 3 15:13:15 UTC 1997

I hear you but the problem in 'open systems' is not memory or cpu speed:
it's the backplane.
I worked on the end of the NSFnet NSS project and with it forward to
where we had later versions
of software (including gated) and new cards intended for the 6611 but
with software rewritten
by clever people and fixes to the AIX kernal by a very smart programmer.
We had port density
-- 8 sync ports on a card, 2 sync + LAN (ether or tokenring your choice)
-- and we had high
end cards (FDDI and T3 from the NSFnet days, ATM over T3 and over TAXI
at the very end).
But an Rs/6000 is not a gigabit router. The theoretical max on the
backplane was 622Mbit and that
includes IP forwarding and disk I/O. I assure we did not hit 620Mbit
even going T3 <->T3.
Then there is the small point that an RS/6K is not exactly cheap like a

I have no idea whatsoever of the throughput capacity of PCI bus on a PC
but everyone in the
gigabit game is using switched backplanes rather than a shared bus. The
nature of the switch
is different in different vendors of course (Netstar is a 16way
crosspoint switch, for example,
while I heard someone was building a router with an ATM OC3 backplane).

The issue is not only whether open systems can take full routing and do
the route computations
because I'm sure they can (the Route Arbiter does). The question is
whether they can do that AND forward packets in today's (multi)gigabit
core on a normal shared bus architecture.
Noone I know is selling ATM backplanes for PC's .....

Joseph T. Klein wrote:

  Warning -- I feel a diatribe emerging. ;-)

  Afordability is primarily a question of how large your existing
  base of legacy routers is and your cash flow.

  You can build a box using a free versionof Unix (FreeBSD, NetBSD,
  Linux, or whatever your religion of the day), off the shelf
  hardware, and gated to route a full backbone routing table
  (memory and CPU are cheap) for less than $3K. This is less
  than the cost of a single interface card for a Cisco 7xxx!

  Kids; do not try this at your gateway without adult supervision.

  We are re-designing the Internet to make up for the fact the
  largest manufacturers of routers has been slow to develop and
  deploy systems that can keep up with the growth curve. A lot of
  this comes down to size of the memory bus on low cost systems.

  If port density was not so poor on general purpose hardware, we
  would have been far better off deploying "open systems" for routers
  rather than what exists today.

  I have always liked my Ciscos, but I truly love routing with my Unix

  systems running gated. ... now If I could find some cheap
  DS-3 cards for a DEC AlphaStation 500. ;-)

  I may be talking out of my hat here, but I suspect a DEC
  500 with 256M of RAM ranks pretty well against a 75xx.

  Somebody, dig up the stats for me ...

  If router manufacturers worked on hardware and all used an open
  software standard ... such as gated ... we would all be better off.
  Open standards allow all of us to benefit from the work of others.
  The old Unix Guru's mantra is 'build on the works of others.'

  Let us not make the mistakes of the 1890s and associate domination
  of the market by oligopolies as good capitalism. Big corporations,
  like big government, tend to move slowly.

  Open markets NOT dominated by a single large player is GOOD
  capitalism. It increases the pace of innovation and prevents
  price fixing. It makes for a healthy, dynamic, marketplace.

  This holds true for routers, backbone providers, toasters
  and operating systems (sorry Bill)

  open standards = open markets

  Open standards prevent the failures of a single market
  player from inhibiting the growth of the industry.

  Open standards lower the cost to upgrade large installed

  Reductions in the federal budget are squeezing R&D expenditures in
  the US to an all time low. Large corporate downsizing and corporate
  mergers have done the same for most large corporations. The bulk
  of innovation in the US will come from small companies and
  development consortiums.

  It is from these that the next generations of routers will
  come. Open standards make the rapid utilization of new
  technologies possible and fuel the growth of small companies.

  The Internet is a great place for consorting on standards.
  This is what is cool about the IETF!

  Standards do not keep the big boys from playing ...
  Cisco and Bay could easily join in an open standard
  for router software. It would not be hard to have interoperability
  between the IP portions of IOS and gated.

  IOS is the PL-1 of routers. Bay's management reminds me of CICS. ;-)

  Back to the subject ...

  You CAN also use the RA (where available) to reduce your routing
  overhead, save memory and reduce CPU usage. (The RA runs a hacked
  version of gated that calculates large routing tables quite well.)

  Hmm ...

  router $100,000 amortized over 3 years =  2,800/month
  going DS-3 price at a NAP with line    =  7,000/month
  engineer $70,000 per year min.         =  5,900/month
  overhead for a small company           = 20,000/month

  $50+/month/mile for OC-3 lines ... don't even talk about
  local loop costs!

  Routers connect customers.
  customers = cash flow.

  The highest cost of running a national network is not buying
  it is bandwidth, staff, and administrative overhead.

  Router cost is primarily a factor for smaller networks with limited
  cash flow.

  I contend ...

  It is the ISPs who try to be dual homed with 'routing tricks' rather

  than using edge routers that can process a core routing table, who
  contribute most to routing instability.

  Boardwatch stated that 14% of ISPs are dual homed. I would bet
  that 70% of those do not use routers capable of processing a core
  routing table.

  Anybody have any stats?

  We need cheap routers that run BGP4 and can eat a core routing
  2501s just don't hack it in dual homed configurations ... and most
  small guys just don't wish to blow $50,000 on putting 7505s at the
  edges of their networks.

  --- On Sun, 02 Mar 1997 13:48:46 -0500  Paul Ferguson
  <pferguso at cisco.com> wrote:
  > At 01:39 PM 3/2/97 -0500, Perry E. Metzger wrote:
  > >
  > >True enough. Of course, this doesn't mean that we can't have
  > >table growth, as we will have processor capacity growth, but it
  > >mean that the growth of the routing tables must be kept in line
  > >what the router processors can do.
  > >
  > True enough. However, it might also be novel to keep the cost
  > down to a level that people can actually afford.
  > - paul

  ---------------End of Original Message-----------------

  From:   Joseph T. Klein, Titania Corporation http://www.titania.net
  E-mail: jtk at titania.net  Sent:   13:25:09 CST/CDT 03/02/97

  "They that can give up essential liberty to obtain a little
  safety deserve neither liberty nor safety."
                  -- Benjamin Franklin, 1759

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