Sean M. Doran writes:
...
That is, if I stuffed 9999 into the AS_PATH of an
announcement I generated or learned from elsewhere, AS
9999 would never hear the announcement from anyone who
heard it only from me.
...
This isn't quite correct (though it's peripheral to your main
argument). An EBGP speaker is free to advertise routes containing
9999 to 9999. Furthermore, 9999 is free to accept routes containing
9999. Whether 9999 chooses to do this or not is, as the saying
goes, "purely a local matter." Likewise whether 9999's peers choose
to refrain from sending such routes.
Some BGP implementations, gated for one, may be configured to accept
routes with the router's own AS number in the path. Loop suppression
is still provided by limiting the number of times it may appear.
(Hi, Dennis.)
This is actually useful in some circumstances.
Regards,
--John
"John G. Scudder" <jgs@ieng.com> writes:
Whether 9999 chooses to do this or not is, as the saying
goes, "purely a local matter."
Figures. As with essentially everything in BGP.
Some BGP implementations, gated for one, may be configured to accept
routes with the router's own AS number in the path. Loop suppression
is still provided by limiting the number of times it may appear.
(Hi, Dennis.)
Oh yeah, the AS healing wars.
I didn't realize gated ever implemented this; I do
remember the first time AS path prepending met gated,
though, and a certain Russian and a certain Swede plotting
to build Sprintlink's backbone on top of ANS's using AS
healing. --
This is actually useful in some circumstances.
Oh certainly. I can think of three applications right
now, actually, where that would be the easiest (but
probably also the most dangerous) approach to solving
routing awkwardnesses.
I take it this feature is documented in the usual place?
Sean.
This isn't quite correct (though it's peripheral to your main
argument). An EBGP speaker is free to advertise routes containing
9999 to 9999. Furthermore, 9999 is free to accept routes containing
9999. Whether 9999 chooses to do this or not is, as the saying
goes, "purely a local matter." Likewise whether 9999's peers choose
to refrain from sending such routes.
Some BGP implementations, gated for one, may be configured to accept
routes with the router's own AS number in the path. Loop suppression
is still provided by limiting the number of times it may appear.
(Hi, Dennis.)
This is actually useful in some circumstances.
serious question: what circumstances?
/jws