And one more question Amos. Do you mean save in cache by 'go through'? See for example 1st scenario. I know that request goes through proxy 2 and then through parent. But when it comes back, is it saved on proxy 1 AND on proxy 2? 2010/10/19 Amos Jeffries <squid3@xxxxxxxxxxxxx>: > On Mon, 18 Oct 2010 20:50:02 +0200, Konrado Z <konradoz@xxxxxxxxxxxxxxxx> > wrote: >> Hello, >> >> I have to consider four scenarios: >> >> 1) http://img230.imageshack.us/img230/4172/52435275.jpg >> 2) http://img2.imageshack.us/img2/6708/42467335.jpg >> 3) http://img213.imageshack.us/img213/3600/77675899.jpg >> 4) http://img84.imageshack.us/img84/7221/12837089.jpg >> Host is connected only to one proxy (I think it does not matter to >> which one). But proxies servers are connetected to each other. >> >> The question is, on which proxy server the website requested will be >> cached (and why)? >> Unfortunately I do not have RAM memory enough to install two (or three >> in some cases) virtual machines with Squid, so I would much appreciate >> your answers. > > This looks a lot like undergrad homework :P > > Notice that cache storage can be suppressed at any Squid on a wide range > of criteria. So the answer to your question can change dependent on what > you want to configure. The answers below are using the assumption that all > proxies are storing everything cacheable which travels through them. > >> >> My answers: >> 1) >> when 1&2 doesn't have website requested: >> - 1 & 2 cached the website > > Yes. Everything going through #2 also goes through #1. > >> >> 2) >> when 1&2 doesn't have website requested: >> - 1 or 2 /it depends where the host is connected/ requests the website >> and cached it >> >> when 1 has the website requested, but host is connected to 2: >> - 2 requests website from 1, and cached /two servers cached after all/ >> >> when 2 has the website requested, but host is connected to 1: >> - 1 requests website from 2, and cached /two servers cached after all/ >> > > Yes. > > With condition that special request types such as CONNECT (and for some > older squid any dynamic web pages) are not passed to siblings when direct > Internet access is available. These are usually non-cachable anyway so have > little impact on the storage. They require admin config intervention to use > the sibling. > >> 3) >> when 1&2&3 doesn't have website requested: >> - the website is cached 3 and 1 or 3 and 2 /it depends where the host >> is connected/ >> >> when only 3 has the website >> - the website is cached 3 and 1 or 3 and 2 /it is copied from 3/ >> >> when 1 or 2 has the website >> - the website is cached only 1 or only 2 or 1 and 2 or 2 and 1 /it >> depends where the host is connected/ > > No. Simple join of scenarios (1) and (2). > > - proxy #3 caches everything. Because all traffic flows through it. > > - proxy #1 and #2 are exactly the same as scenario (2) with same reasons. > > The fact that proxy #1 and #2 are connected to #3 instead of direct to > internet is not relevant to what gets cached. > >> >> 4) the same situation as in 2 > > Yes. > > Scenario (1) and scenario (2) are the basic units of cache hierarchy > design. Same as with Internet route design. The complexity comes when you > start limiting what requests can go where. Creating big loops, one-way > requests, non-caching, and peering routes. > > Amos >
