Thanks Duane, This makes more sense. I'll discuss this further with my network services collegues to grasp the routing issues for our case. Ton. ==> From: Duane Wessels | Ton Verschuren writes: | | >I know. Still, for a cache to fill it has to fetch docs and thus act as | >a parent. If the NLANR cache acts as a parent for all MW connected | >ISP's than *all* misses from those ISP's get routed through the NLANR | >cache and for the transatlantic traffic the lines of NLANR's ISP will | >fill up. No? | | In order for the cache to fill, yes some MW customers will need to call | the cache a parent. Some could call the cache a sibling. | | However, it isn't so black-and-white as that. Squid can be configured | to measure RTTs to origin servers. Squid's ICP replies will include | the RTT estimations, and the child cache can compare these values to | its own measurements, or those made by other (parent) caches. | | Additionally, for the MW cache, we have modified Squid to return an | ICP_MISS_NOFETCH reply for requests origin servers which appear to be | unreachable (presumably due to incomplete routing info). Upon | receiving this reply, the child cache will not forward the request to | us. | | Thus, a child cache can use our MW cache as a parent only for origin | servers which are reachable by us, and which our cache is "closer" to. | If the child cache is closer, then it will forward the request | directly. | | A potential problem is that the RTT measurement feature is not compiled | in by default. It requires building Squid with a macro defined, and | installing the ICMP sending/receiving program with root privs. | | A few more details can be found at | http://squid.nlanr.net/Squid/FAQ/FAQ-7.html#ss7.6 | | Duane W. | -- | wessels@nlanr.net Think Globally, Cache Locally.