[nsp] inbound failover without BGP?

[Tony Tauber]

On Tue, 17 Dec 2002, Furnish, Trever G wrote:

> Is there any way to provide failover routing of INBOUND traffic
> using links from multiple providers, OTHER THAN running BGP with
> those providers?

<snip>

> But wasteful or not, having inbound failover is a requirement for
> most commercial web sites that provide service to paying customers.
> If the link from Provider1 fails, the inbound connections still
> succeed because Provider2 is still announcing to the world that he
> has a path to me.  Is there some other way to do it?
>
> -t.

What failure are you trying to protect against?  From what you say
above ("link ... fails"), the problem is a layer 1, ie. physical,
failure.  Arguably, these failures are indeed the most common and
worthy of attention in resiliency design.

It's certainly also possible that a problem with the ISP router at the
other end of your link could cause outages (eg. card outage or reboot
due to maintenance or failure).

If you were to get physically diverse circuits from one provider that
landed on different routers at their POP (these may be big "if"s), you
would appear to have addressed the problem scenarios I've described.
Are there others you have in mind?

While going to two different providers may get other-end router
diversity it may not get physical diversity out of your building or up
to the telco CO.  Do you have CPE-router diversity on your end to
prevent router problems from causing outages?

Are there other failure scenarios that are of major concern?

Just asking because there seems to be unreasonable FUD in this area.

Tony