Hello, Folks can correct me if I'm wrong but I'll take a shot at this.
By default Junos assigns traffic generated by the RE to different queues based on the traffic type: http://www.juniper.net/techpubs/en_US/junos10.0/information-products/topic-collections/config-guide-cos/id-10346810.html#id-10346810 It's not very clear on that page but traffic generated in Queue 3 will get proper ToS markings applied. Here's an OSPF packet capture: me@blah> monitor traffic interface xe-0/0/0 no-resolve size 1500 detail Address resolution is OFF. Listening on xe-0/0/0, capture size 1500 bytes 16:04:41.745098 Out IP (tos 0xc0, ttl 1, id 21968, offset 0, flags [none], proto: OSPF (89), length: 84) 10.1.1.1 > 224.0.0.5: OSPFv2, Hello, length 48 Note the ToS value is 0xC0 = 1100 0000 -> The ToS field = 110 = 6. There are default IP classifiers applied to all L3 interfaces. For example, here are the defaults for an MPLS interface: me@blah> show class-of-service interface xe-0/0/0 Physical interface: xe-0/0/0, Index: 154 Queues supported: 8, Queues in use: 8 Scheduler map: <default>, Index: 2 Congestion-notification: Disabled Logical interface: xe-0/0/0.0, Index: 2684275768 Object Name Type Index Rewrite exp-default exp (mpls-any) 33 Classifier exp-default exp 10 Classifier ipprec-compatibility ip 13 The default IP classifier: me@blah> show class-of-service classifier type inet-precedence name ipprec-compatibility Classifier: ipprec-compatibility, Code point type: inet-precedence, Index: 13 Code point Forwarding class Loss priority 000 best-effort low 001 best-effort high 010 best-effort low 011 best-effort high 100 best-effort low 101 best-effort high 110 network-control low 111 network-control high As you can see pbit 6 traffic goes to the NC queue. The default schedulers applies to the interface: me@blah> show class-of-service scheduler-map Scheduler map: <default>, Index: 2 Scheduler: <default-be>, Forwarding class: best-effort, Index: 21 Transmit rate: 95 percent, Rate Limit: none, Buffer size: 95 percent, Buffer Limit: none, Priority: low Excess Priority: low Drop profiles: Loss priority Protocol Index Name Low any 1 <default-drop-profile> Medium low any 1 <default-drop-profile> Medium high any 1 <default-drop-profile> High any 1 <default-drop-profile> Scheduler: <default-nc>, Forwarding class: network-control, Index: 23 Transmit rate: 5 percent, Rate Limit: none, Buffer size: 5 percent, Buffer Limit: none, Priority: low Excess Priority: low Drop profiles: Loss priority Protocol Index Name Low any 1 <default-drop-profile> Medium low any 1 <default-drop-profile> Medium high any 1 <default-drop-profile> High any 1 <default-drop-profile> Note that 5% is assigned to NC making sure that RE traffic always has a minimum BW %. I'm note sure why you'd want to change this. You obviously want to add other Queues and assign BW % as required. Just make sure you always leave pbit 6 mapped to NC FC (queue 3) and leave some BW assigned to it. I wouldn't re-map RE traffic from Queue 3 to some other queue. In Junos (the MX anyway) the queue number as no meaning so there's no reason to move NC from queue 3 to some other queue. I hope this helps. Serge ________________________________ From: MOHAMED EDREES - JNT <[email protected]> To: "[email protected]" <[email protected]> Sent: Monday, March 12, 2012 10:28:50 AM Subject: [j-nsp] QOS (Network Control traffic Queue) Dear Experts As known in juniper routers the network control traffic by default will be queued in the default queue # 3 which by default called network-control, my questions are How this forwarding will be forwarded to the queue without applying and classifier on the control plane or even in interface fxp1? Another question which will depend on the answer of the first one If we modified the queues to carry different code points as shown below, will the control traffic such as BGP messages will follow these changes or it will go to the default queue # 3 without consideration for the code-points value assigned to that queue. The default Queues Configuration [edit class-of-service] forwarding-classes { queue 0 best-effort; queue 1 expedited-forwarding; queue 2 assured-forwarding; queue 3 network-control; The Modified configuration for example forwarding-classes { queue 7 nc; queue 4 af41; queue 3 af31; queue 2 af21; queue 0 be; Best Regards, Mohamed Edrees This message (including any attachments) is intended only for the use of the individual or entity to which it is addressed and may contain information that is non-public, proprietary, privileged, confidential, and exempt from disclosure under applicable law or may constitute as attorney work product. 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