Example 1: Premium Services Class Web Server
policy videoservice_p1 { uses videoselect
res 45% max 100% dscp 10
}
policy other_v4_p { uses other_v4 res 1M
}
adapter lan0 {
uses premwebservice_p1, videoservice_p1, other_v4_p
}
#
#This file can be replicated on all premium services servers.
####
In this example, the res and max attributes are specified as percentages rather than absolutes, to facilitate replicating this configuration file on several servers. The dscp attribute is not relevant to the example, but is included for illustrative purposes.
This example defines three classes of traffic. The Web service traffic class is for Web service traffic only, so only srcport is assigned to http/tcp. This does not include Web browsers, because any http traffic they initiate has the dstport set. This traffic class is assured 45% of the adapters’ bandwidth. If it needs that much bandwidth it will get it, subject to the caveat: it is “promised” (reserved) but not completely “guaranteed”. If it needs more than 45%, it is allowed to send up to 100% of the adapter’s bandwidth, assuming there is available bandwidth not being used by the res rate of any other policy.
The second policy is for video service traffic. The use of videosrv in filter videoselect is only allowed if videosrv can be found in /etc/services and converted to a port number. This class of traffic is assured 45% of the adapter’s bandwidth and is also allowed to send up to 100% of the bandwidth.
This example also provides a policy for all other IPv4 traffic. This policy assures all other IPv4 traffic at least 1Mbps of the adapter’s bandwidth. If this policy had not been specified, the implicit default policy applied would have assured 80Kbps.
If all three traffic classes have more traffic than their reserved rates, they can send faster. The three share the excess bandwidth roughly equally.
120 | Appendix B |