[c-nsp] ARP strangeness

[Frank Bulk - iName.com]

Gert, you couldn't be more insightful: I did a software upgrade of the 7609
a few weeks ago, which led our helpdesk to raise this issue to me.

Frank

-----Original Message-----
From: Gert Doering [mailto:gert at greenie.muc.de]
Sent: Wednesday, January 19, 2011 3:54 AM
To: Frank Bulk - iName.com
Cc: 'Keegan Holley'; rodunn at cisco.com; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] ARP strangeness

Hi,

On Wed, Jan 19, 2011 at 01:47:20AM -0600, Frank Bulk - iName.com wrote:
> You're correct - without broadcast support, re-population initiated from
the
> 7609 is impossible.  Once it's expired, the FTTH access gear's design,
which
> blocks broadcast traffic, makes it impossible for the CPE to respond to
the
> broadcast ARP.  The FTTH access gear never allows broadcast traffic to
> ingress from the 7609.  So the only thing that can re-populate the 7609's
> ARP cache is an ARP request by the CPE, *but* the CPE only does that after
a
> DHCP exchange after power on, never again, even after a full DHCP
exchange.

This sounds like a very very stupid design in the FTTH gear.

Imagine what happens if the 7609 needs to be rebooted - *all* customers
having to powercycle their CPEs?

(Also, the whole idea of "blocking broadcasts from the ISP side" is
bogus to start with - broadcasts from the CPE side are what needs to
be well-controlled and only distributed to the ISP PE...)

gert
--
USENET is *not* the non-clickable part of WWW!

//www.muc.de/~gert/
Gert Doering - Munich, Germany
gert at greenie.muc.de
fax: +49-89-35655025
gert at net.informatik.tu-muenchen.de