[c-nsp] IPv6 subnets for point-to-point links

[David Barak]

--- Antonio Querubin <tony at aloha.net> wrote:
> On Fri, 13 May 2005, David Barak wrote:
> 
> > one other reason is for monitoring purposes - if
> you
> > use an ICMP-based monitoring solution, it's better
> to
> > ping the remote serial interface address than the
> > customer's router ethernet...
> 
> It's better to ping a loopback address that is
> independent of any physical
> interface.  You can monitor the physical interface
> directly via SNMP traps
> or some syslog detector but neither requires the
> interface to be numbered.

"better" is in the eye of the beholder.  There are
some large ISPs who monitor customers using ICMP
exclusively.  I've run across oodles of customers who
are not interested in having a provider monitor them
via SNMP for a variety of security and process
reasons.

Let me give you a scenario: if a customer is dually
homed, you're pinging their loopback address, and the
link wedges (up/up, no traffic passing).  (I've seen
this plenty of times, unfortunately).  In that case,
no SNMP trap will be generated (unless you're
monitoring BGP state), and pings to the customer's
router will succeed (through the other link).  

I'm not saying that SNMP isn't useful or a good way to
manage a customer, just that it isn't for everyone or
every situation.

-David

David Barak
Need Geek Rock?  Try The Franchise: 
http://www.listentothefranchise.com


		
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