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Chapter 4
Transparent Proxy Caching
A Traffic Server cluster with virtual IP failover adds reliability; if one node fails, another node can take up its
transparency requests. See
Virtual IP failover‚ on page 47
.
Figure 4-3. Using a router to filter HTTP requests
Interception bypass
A very small number of clients and servers do not interoperate correctly with web proxies. Some of the causes
of interoperability problems include:
•
Client software bugs (homegrown, non-commercial browsers)
•
Server software bugs
•
Applications which send non-HTTP traffic over HTTP ports as a way of defeating security restrictions
•
Server IP authentication (the origin server limits access to a few client IP addresses, but the Traffic Server
IP address is different, so it cannot get access). This is not in frequent use because many ISPs dynamically
allocate client IP dial-up addresses, and more secure cryptographic protocols are now more often used.
Web proxies are common in corporate and Internet use, so interoperability problems are extremely rare.
However, in those rare cases, Traffic Server contains an adaptive learning module that recognizes
interoperability problems caused by transparent proxying and automatically bypasses the traffic around
Traffic Server without operator intervention.
Traffic Server follows two types of bypass rules:
•
Dynamic (also called adaptive) bypass rules are generated dynamically if you configure Traffic Server to
bypass the cache when it detects non-HTTP traffic on port 80, or when it encounters certain HTTP errors.
See “Dynamic bypass rules,” below.
•
Static bypass rules must be manually configured in the bypass configuration file (
bypass.config
). See
Static bypass rules‚ on page 32
.
end users
Traffic Server
world wide web
router
non port:80 traffic
non80
80
all
port:80 traffic
