The ultimate bandwidth management solution
英文
What is Web Cache
A cache is a device, running software, which sits between a set of users who are browsing the Internet and the Internet itself. When a user requests an object from the Internet the cache will fetch that object on behalf of the user. So instead of the user request being sent it becomes a request from the cache device itself. This is called Proxying. All caches are also proxies but not all proxies are caches. The difference is that a cache will not only fetch the object on behalf of the user it will also store the object locally so that the next time a user requests the same object it will not have to be fetched from the Internet at all but simply served at wire speed from the local cache thereby increasing user response time enormously and at the same time saving expensive bandwidth.
Actually, it is a little more complex but that is the essence. Obviously the cache also needs to store some parameters about the object in order to ensure that it does not serve a local object to the user when it has changed at the original site. The key parameter is when it expires. Most sites today have an expires header in each page and this is obviously the best method for our software to use to determine whether an object has expired or not but failing that we have various other methods of establishing a reasonable expires parameter. In addition our software has the ability to ask the remote server if an object has changed prior to asking for the object itself. This is part of the HTTP1.1 standard and if the remote server is compliant (most are today) then, if we have an object in cache but the freshness is in doubt, we can request the object only 鈥渋f modified since鈥�. If not modified then the remote server only needs to send us a very small 鈥渘ot modified鈥� response rather than the entire page or object. This once again allows us to save bandwidth and improve response times.
Why we need Web Cache
ROI
Bandwidth savings are typically between 20 and 45% on an SunGate cache depending on what sites are typically accessed. This can easily be converted to real cash savings and used to calculate a very short return on investment.
User satisfaction
It is unfortunately true to say that today鈥檚 Internet can be a little frustrating and sometimes slow. Caching provably enhances user response times and thereby user satisfaction. SunGate鈥檚 cache will serve even an old expired object for the user if the Internet times out for some reason so you will at least get something even if it may be a little out of date.
Each time a User requests an object, a server (called a DNS server) has to go out to the Internet to look up the IP Address of the site that was requested. This often makes the request appear to hesitate for a while before the download starts and often is a big bottleneck. SunGate鈥檚 cache engine has a built-in DNS cache which significantly reduces the number of lookups needed (typically 85 to 90% DNS cache hits) and starts downloads much faster which makes users very much happier.
SunGate Built-in Cache
If you don't already have a cache and you dont have a large-scale cache requirement, using an integrated cache solution of SunGate is very cost effective and integrated very well. With an integrated cache of SunGate, HTTP traffic from end user enters the SunGate (towards the internet) as normal traffic. The SunGate passes the traffic to the internal cache server, which either returns the traffic as "cached" traffic, or retrieves the pages and passes the packets for the transaction through as non-cached traffic.
SunGate Integrated With External Cache
it is quite common for us to find that an organization already has a firewall and/or proxy in place and we have made sure that SunGate will work quite happily with all of them. We are comfortable being in front, behind or even next to any other firewall and will maintain your system integrity and even enhance it for you. This includes being able to transparently cache.