On Wed, 19 Oct 2005, Elmar K. Bins wrote:
Tier-2s should be given much more credit than they typically are in write-ups like this. When a customer is single homed to a tier-2 that has multiple tier-1 upstreams, and uses a delegated netblock from the tier-2's aggregations, that means one less ASN and one or more less routes in the global table.
That's the operators' view, but not the customer's. The customer wants redundancy.
That's why SLAs exist.
So we should try to find a way to tell them "Hey, it's mostly Tier-1's (or wannabes) that play such games, stick to a trustworthy Tier-2. And, hey, btw., connect redundantly to them, so you have line failure resiliency and also a competent partner that cares for everything else."
Something like that, but not quite. Whenever one of these reports, which boil down to "everyone must multi-home!", appears, it typically has a stark lack of information on alternatives to *direct* multi-homing. Many customers would rather not multihome directly, and prefer "set it and forget it" connectivity. It's much easier to maintain a multi-pipe connection that consists of one static default route than a pipe to multiple carriers. The former requires simple physical pipe management, which can be left alone for 99% of the time. The latter requires BGP feed, an ASN, and typically much more than 1% of an employee's time to keep running smoothly. Obtaining single-homed connectivity from a Tier-2 mostly "outsources" network support, and small to medium size businesses tend to like that. It's not the only leaf end solution to the problem, but it's a viable one (and can be less costly to the rest of the world in turn). -- -- Todd Vierling <tv@duh.org> <tv@pobox.com> <todd@vierling.name>