This article demonstrates how to prioritize traffic generated by the host or the Routing Engine (RE), assign them to their respective outbound queues, and re-mark them. 

User wants to prioritize traffic originating from the device over other data traffic.

If you want to classify some host protocols into a high priority queue and others to a best effort queue, you need to configure a specific firewall filter and apply it on the loopback interface in the output direction to complete this selective per-protocol queue assignment.

A sample firewall filter configuration is given as follows:

+  interfaces {
+      lo0 {
+          unit 0 {
+              family inet {
+                  filter {
+                      output RE-EGRESS-REMARK;
+                  }
+                  address 192.168.1.1/32;
+              }
+          }
+      }
+  }
+  firewall {
+      family inet {
+          filter RE-EGRESS-REMARK {
+              term ALLOW-BGP {
+                  from {
+                      protocol tcp;
+                      port bgp;
+                  }
+                  then {
+                      forwarding-class FC3;
+                      dscp cs6;
+                  }
+              }
+              term ALLOW-TELNET-SSH {
+                  from {
+                      protocol tcp;
+                      port [ telnet ssh ];
+                  }
+                  then {
+                      forwarding-class FC1;
+                      dscp af42;
+                  }
+              }
+              term ACCEPT-ALL {
+                  then accept;
+              }
+          }
+      }
+  }

In this example, only the BGP and SSH/Telnet protocols are re-assigned to specific queues. This reclassification is also performed by the RE kernel. For other protocols that only match the last “term,” the RE uses the default queue assignment rules.