Re: [squid-users] Four squid scenarios

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_at_treenet.co.nz>:
> On Mon, 18 Oct 2010 20:50:02 +0200, Konrado Z <konradoz_at_partyinfo.com.pl>
> 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
>
Received on Tue Oct 19 2010 - 20:06:09 MDT