The value of tmnxRadProxSrvCacheKeyPktType specifies
the packet type of the RADIUS messages to use to generate the key
for the cache of this RADIUS Proxy server.
In order to generate the key associated with a RADIUS Access-Accept
message, the system uses the attribute of the type
specified by the value of tmnxRadProxSrvCacheKeyAttrType,
within the associated RADIUS message of the type specified by the
value of tmnxRadProxSrvCacheKeyPktType.