In the referenced message, Austin Schutz said:
On Mon, May 13, 2002 at 06:57:19AM -0400, PS wrote:
Multiple ASNs wouldn't solve anything in this case. What was wanted was under normal circumstances both A and B only announce a /20, and when the link between A and B breaks announce more specifics. Multiple ASN = inconsistent AS.. no no.
Not necessarily. If 'A' originates the aggregate route it can still be transited via 'B', though with an additional AS hop. Not a perfect solution, but then neither is running a gre tunnel.
Austin
The only perfect solution is having multiple internal paths which are resilient to simultaneous outage. Failing that, I've never had a problem with GRE. Back in 1994-1997 or so, I used them a lot for disconnected sites, much as someone else mentioned, across sprint. Worked great and was certainly cheaper than interlata circuits.