- From: Luigi Rizzo <luigi@labinfo.iet.unipi.it>
- Date: Sun, 17 Dec 1995 12:00:43 +0100 (MET)
- To: Duane Wessels <wessels@colorado.edu>
- Cc: mogul@pa.dec.com, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
> First, I apologize for jumping into the middle of this thread. I'd like > to make a couple of comments about how TTL and Forwarded are relevant > to the Harvest cache. > > A TTL header would not help Harvest to eliminate loops. When the > loop is completed and the cache gets a second request for the same URL, > this second client-side request becomes "attached" to the first request > (on the server-side). The caches will deadlock until one of them times > out. The forwarded header would solve this problem quite easily > (except for the hassle of parsing it). At first I thougt that deadlocks would only occur when a node in the loop finishes it resources (be them connections, processes, whatever). I thought that there were *many* of them, so a suitable TTL would avoid deadlocks. This looks like the same problem, except that there is exactly *one* resource on each node. > I totally agree that a HTTP-traceroute will be very useful. However, I > don't think we need TTL to do it. If I understand correctly, > traceroute uses increasing TTLs because the IP LSRR option is/was not > always implemented, and the fixed IP header size limit only allowed > something like nine addresses to be recorded. Since HTTP doesn't > suffer from either of those problems, wouldn't it be better to just > have the Forwarded lines included in the response header? Then you > only need to make one request. Convincing arguments! Luigi ==================================================================== Luigi Rizzo Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it Universita' di Pisa tel: +39-50-568533 via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 http://www.iet.unipi.it/~luigi/ ====================================================================
Received on Sunday, 17 December 1995 03:12:45 UTC