Date: Thu, 18 Sep 2003 13:47:01 -0400 From: Keptin Komrade Dr. BobWrench III esq.
And, I might add, in the case of a highly complex anycast application, you will need to check not only for correctness, but for timeliness.
In a realtime system, something that is late is considered incorrect. A DNS response that arrives after three seconds is unsat, and (from a RT perspective) incorrect. I should have been more clear in my wording.
And, again, in the case of a highly complex app such as an anycast DNS, you need to check several behind the scenes apps, such as maybe a db, the responsivness of your high avail partner server, the dns daemon, connectivity through two or more network paths, connectivity to master update servers, BGP on whatever boxes are providing BGP, etc, the list goes on.
Yes on all counts, except perhaps connectivity... BGP handles that. If you mean killing the link in case of saturation, I'd argue that's a bad idea -- that just means the large traffic quantity will go elsewhere.
But again, that's just my opinion, I could be wrong. ;-)
That's why one uses a daemon with main loop including something like: success = 0 ; for ( i = checklist ; i->callback != NULL ; i++ ) success &= i->callback(foo) ; if ( success ) send_keepalive(via_some_ipc_mechanism) ; The BGP mechanism listens for keepalives via the IPC mechanism. Eddy -- Brotsman & Dreger, Inc. - EverQuick Internet Division Bandwidth, consulting, e-commerce, hosting, and network building Phone: +1 785 865 5885 Lawrence and [inter]national Phone: +1 316 794 8922 Wichita _________________________________________________________________ DO NOT send mail to the following addresses : blacklist@brics.com -or- alfra@intc.net -or- curbjmp@intc.net Sending mail to spambait addresses is a great way to get blocked.