Chapter 15: Proxy Caching - Tavve zoneranger User Manual

Chapter 15: Proxy Caching

One of the primary advantages of ZoneRanger is that it is able to act as a proxy for management traffic
on behalf of a wide variety of management applications. As a result, it is possible to have multiple
management applications simultaneously proxying ICMP and SNMP traffic through a common pool of
ZoneRangers to a common set of managed devices. As the number of management applications
increases, and as polling rates increase, managed devices and the networks in which they reside may
become inundated with repeated requests for the same information from different applications.
The ZoneRanger proxy caching feature addresses this issue by saving results of recent ICMP and SNMP
proxy requests in an internal database, and using this cached information to respond to subsequent
requests, as opposed to passing the proxy requests on to the managed devices.
ICMP and SNMP proxy caching are enabled and configured separately, as described in the following
sections.
ICMP Proxy Caching
ICMP proxy caching is configured based on rules associated with specified IP addresses or IP address
ranges. Options associated with each rule include the following:
•
Whether or not a successful ping request to a managed device will be remembered in the cache,
and how long a cached response will be considered to be valid.
•
Whether or not an unsuccessful ping request to a managed device will be remembered in the
cache, and how long a cached response will be considered to be valid.
When an ICMP ping request is received by the ZoneRanger, if ICMP proxy caching is enabled, the
ZoneRanger will attempt to locate a matching caching configuration rule, and a cached result:
•
If a valid cached result is found, based on the applicable configuration rule, the ZoneRanger
will immediately send a positive response back to the Ranger Gateway, if the cached result was
positive, or will discard the request if the cached result was negative.
•
If there is no cached result, or if the cached result is determined to have expired, the request will
be forwarded on to the managed device and will be processed normally.
Whenever an ICMP proxy request is forwarded to a managed device, the cache is refreshed based on the
result. If the managed device responds to the ping, a positive result will be stored in the cache with the
timestamp updated to the current time. If the request times out, a negative result will be stored in the
cache.
SNMP Proxy Caching
SNMP proxy caching is configured based on rules associated with specific SNMP Object Identifiers
(OIDs). Each rule has associated options specifying whether or not caching is enabled for that OID
value, and if so, how long a cached response will be considered to be valid. When an SNMP Get/Set
request is received by the ZoneRanger, if SNMP proxy caching is enabled, the ZoneRanger will inspect
the OIDs specified in the request and attempt to locate matching caching configuration rules, and
associated cached results:
•
If valid cached results are found for all of the specified OIDs, the ZoneRanger will immediately
send a response back to the Ranger Gateway with the cached values.
ZoneRanger 5.5 User's Guide 46