Classifying and prioritizing OOB traffic using DSCP marking
When two SteelHeads see each other for the first time, either through autodiscovery or a fixed target rule, they set up an Out-of-Band (OOB) splice. This is a control TCP session between the two SteelHeads that the system uses to test the connectivity between the two appliances.
After the setup of the OOB splice, the two SteelHeads exchange information about each other such as the hostname, licensing information, RiOS versions, capabilities, and so on. This information is included in the Riverbed control channel traffic.
By default, the control channel traffic is not marked with a DSCP value. By marking the control channel traffic with a DSCP or ToS IP value, you can prevent dropped packets and other undesired effects on a lossy or congested network link.
In RiOS 9.0 and earlier, a CLI command enables the global DSCP setting to tag inner channel setup packets or OOB packets with a DSCP value. RiOS 9.1 provides a way to separate the inner channel setup packets from the OOB packets and mark the OOB control channel traffic with a unique DSCP value.
Before marking OOB traffic with a DSCP value, ensure that the global DSCP setting is not in use. Global DSCP marking includes both inner channel setup packets and OOB control channel traffic. This procedure separates the OOB traffic from the inner channel setup traffic. For details on disabling global DSCP marking, see the [no] qos dscp-marking enable command in the Riverbed Command-Line Interface Reference Manual.
To classify OOB traffic with a DSCP marking
1. Choose Networking > Network Services: Quality of Service to display the Quality of Service page.
2. Under QoS Profiles, click Edit next to the profile name to display the QoS Profile Details page.
3. Under QoS Rules, select Add a Rule.
4. From the Application or Application Group drop-down list, select Riverbed Control Traffic (Client) if the SteelHead being configured is a client-side SteelHead. Select Riverbed Control Traffic (Server) if a the SteelHead being configured is a server-side SteelHead.
OOB packets are marked on the server-side SteelHead based on the value configured on client-side SteelHead if a rule is not explicitly configured on the server-side SteelHead.
5. Under Outbound DSCP, select a DSCP marking value or a ToS IP value from the drop-down list.
6. Click Save to save your settings permanently.
The new QoS rule appears in the QoS Rules table.