LinuxSA Mailing list archives

  From: John Edwards <isplist@pinnacle.net.au>
  To  : Mark Newton <newton@atdot.dotat.org>
  Date: Thu, 07 Dec 2000 11:25:34 +1030

Re: "Host based" routers and BGP

Mark Newton wrote:

> Ok, here's why you'd use a dedicated router in a routing role:
> 
>   1.  PC hardware sucks arse.  You have no idea about exactly how badly
>       it sucks arse until you're an ISP with tens of thousands of customers
>       who can't use the Internet because a crappy Taiwanese power supply
>       has borked itself *again*.  A truly excellent reason to run a dedicated
>       router is because it's not a PC, and that reason is serious enough to
>       be all the convincing you should need even if you can't find any other
>       reasons.

Some Cisco hardware is made in Taiwan, and Mexico, and about 40 other
locations. Country has nothing to do with it. You can buy PC hardware
surpassing Cisco quality standards from people like HP and Compaq, but
then the Cisco starts to look like a bargain. Integrated Circuits and
other chips used to have gradings from 1 to 5 depending on how well they
passed their initial tests, and the military got all the number 1 rated
stuff, I think you can find the number 2 gear in Cisco and good quality
servers. This is the sort of thing that makes genuine Cisco ram cost an
astronomical amount, you're paying for a piece of ram that's statisticly
better than average.
 
>   2.  General purpose operating systems aren't good at routing.  If you
>       asked a 2nd-year computer science student to come up with the most

PC's make up for it with grunt. While a purpose built router might have
an efficient RISC cpu, the PC will have a cheaper x86 thing running
around 5 to 10x faster. That more than makes up for any inefficiency,
although extra ram and bus accesses may cause more latency.

>   3.  Scalability.  The PCI bus is simply not scaleable enough to handle
>       a large ISP's core.  End of story.  There is no argument on this.  If
>       you're serious about network performance, you can't use a PC as a
>       router.

The Cisco 7000 series routers often found at an ISP's core use a PCI bus
[1] :)
The Ericsson/ACC boxes use a more scalable TDM backplane ;)

>   4.  Features.  Want a single box to run OSPF, BGP and legacy RIP?  Simple;
>       Give it a few configuration commands and you're away.  Want to add

Havn't you ever wanted to be able to run perl on your Cisco? This would
probably be a very bad idea, but there are still times when I want stuff
to be more dynamic than a static configuration file. Say I want to be
able to have automatically adjusting local prefs using a BGP community
between 1 and 100 [2], on the Cisco I'd need 100 route-map entries. On
an Open-source PC-based system I could hack in something to
automatically handle that. 

There are also times when I'd rather configuration changes done by
external monitoring and rsh/expect could be done all on the one box
instead.
 
>   5.  Support.  Usually the open-source model wins out big time here, because

The main thing that's lacking due to network effects more than anything.
An open source router that really works would help in this area.

I still use Cisco, and find them to be the best for routing but they're
not perfect. I also feel that too many people have put the Cisco
Blinkers [3] on and are letting that hurt their objectivity.

John Edwards


[1] Just that it's not limited to 132Mb/s.
[2] Fortunately I have no foreseeable need to do this.
[3] No Tatoos though, you can't claim total brand loyalty until people
indeliably mark their bodies with your product's logo, ala Harley
Davidson.

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