ip and routing subtleties

[David Bandel]

On 2/4/07, Bill Campbell <linux-sxs at celestial.com> wrote:
> On Sun, Feb 04, 2007, David Bandel wrote:
> >Folks,
> >
> >Anyone need to actually understand the ip utility?  While I've used ip
> >for ipv6 and other related things, I had forgotten just how poor the
> >ip documentation was until I had to brush up this week.
> >
> >I bought another 2Mb frame relay (wish we had fiber available here)
> >and stuck a Sangoma Wanpipe card (ugh) in beside my Cyclades PC300
> >then had to write the routing tables, etc., for the two distinct
> >routes.  Since I'm not assigned an AS, dynamic routing is out.  So,
> >with three public IP blocks and a dozen different private IP blocks in
> >use, I wrote the necessary scripts to handle it.
>
> I refuse to use Cyclades since they thoroughly screwed me by selling me a
> card that wouldn't work with the version of Linux I specifically said I
> would be using, then charging a 15% ``restocking'' fee when it wouldn't
> work.  I've had excellent results and support from Sangoma, even having
> them replace a card nuked by a lightning strike.

Yeah, I know, you've said before.  But the PC300 is now an official
kernel module.  With Sangoma, OTOH, I just went through many hours of
d/l build, build crash, rinse, repeat, until you find by trial and
error the particular software version you need (no easy reference
chart included).  The software also talks about GCC3 which hasn't been
on my system in months.  And the wancfg utility just flat doesn't
work, it's a POS. So if I had my choice, I buy a dozen PC300s.

>
> >The exercise made me realize that some folks who might need to
> >understand this won't.  OTOH, I may be one of the few unhappy saps
> >without an AS but with numerous inbound and outbound routes.
> >
> >If there's interest, let me know while it's still fresh in my feeble old mind.
>
> I would be interested.  So far the only thing I've figured out how to do
> with the ``ip'' command is to temporarily add/delete IP addresses to an
> interface while configuring systems on our LAN that will be used on a
> different network.

The ip command is great for that.  And it removes that nonsensical
notion of eth#:#.  No aliasing, just an IP assigned to an interface.
You know if you down the main eth0 IP, you loose the _entire_
interface, aliases and all.  That's just DUMB.  Not so with ip.

OK, will start on an SXS.  It may only be of value to you and me (and
any other ISPs on the list), but I think this documentation needs
doing anyway.

Ciao,

David A. Bandel
-- 
Focus on the dream, not the competition.
            - Nemesis Air Racing Team motto