This article provides information on how to setup the class-of-service on a SRX device, which is configured in the transparent (Bridge) mode.
Take an example of BGP packets. The goal is to honor BGP control packets, as they come marked with high priority; that is the Network Control queue in DSCP. SRX should place them in the NC queue, so that they get high priority.
The following output is taken from a chassis cluster; but it is valid for a standalone device as well. The packets are coming in from the
reth0 interface and going out of the
reth1 interface. The following output is before the configuration change:
SRX# run show class-of-service rewrite-rule
Rewrite rule: dscp-default, Code point type: dscp, Index: 31
Forwarding class Loss priority Code point
best-effort low 000000
best-effort high 000000
expedited-forwarding low 101110
expedited-forwarding high 101110
assured-forwarding low 001010
assured-forwarding high 001100
network-control low 110000
network-control high 111000
Rewrite rule: dscp-ipv6-default, Code point type: dscp-ipv6, Index: 32
Forwarding class Loss priority Code point
best-effort low 000000
best-effort high 000000
expedited-forwarding low 101110
expedited-forwarding high 101110
assured-forwarding low 001010
assured-forwarding high 001100
network-control low 110000
network-control high 111000
SRX# run show interfaces reth0 extensive | match "Queue|3 network"
Egress queues: 8 supported, 4 in use
Queue counters: Queued packets Transmitted packets Dropped packets
3 network-cont 0 0 0 < packets not shown
Queue number: Mapped forwarding classes
SRX# run show interfaces xe-1/0/0 extensive | match "Q
CoS queues : 8 supported, 4 maximum usable queues
Egress queues: 8 supported, 4 in use
Queue counters: Queued packets Transmitted packets Dropped packets
3 network-cont 0 0 0 < packets not shown
Queue number: Mapped forwarding classes
CoS transmit queue Bandwidth Buffer Priority Limit
3 network-control 5 500000000 5 0 low none
SRX# run show interfaces reth1 extensive | match "Queue|3 network"
Egress queues: 8 supported, 4 in use
Queue counters: Queued packets Transmitted packets Dropped packets
3 network-cont 0 0 0 < packets not shown
Queue number: Mapped forwarding classes
SRX# run show interfaces xe-1/0/1 extensive | match "Queue|3 network"
CoS queues : 8 supported, 4 maximum usable queues
Egress queues: 8 supported, 4 in use
Queue counters: Queued packets Transmitted packets Dropped packets
3 network-cont 0 0 0 < packets not shown
Queue number: Mapped forwarding classes
CoS transmit queue Bandwidth Buffer Priority Limit
3 network-control 5 500000000 5 0 low none
After making the following configuration change, you can see that the packets are marked in the correct queue.
SRX3400# show class-of-service
interfaces {
reth0 {
unit 0 {
classifiers {
ieee-802.1 default; < Apply classifier to interface
}
rewrite-rules {
dscp default; < Apply the default dscp rewrite rule
}
}
}
reth1 {
unit 0 {
classifiers {
ieee-802.1 default;
}
rewrite-rules {
dscp default;
}
}
}
}
SRX# ...s reth0 extensive | match "Queue counter|3 net
Queue counters: Queued packets Transmitted packets Dropped packets
3 network-cont 758 758 0 < packets queued correctly
SRX# ...ow interfaces reth1 extensive | match "Queue c
Queue counters: Queued packets Transmitted packets Dropped packets
3 network-cont 394 394 0 < packets queued correctly
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Devices operating in Layer 2 transparent mode support the following Class-of-Service (CoS) functions:
=====================================================================================================
IEEE 802.1p behavior aggregate (BA) classifiers to determine the forwarding treatment for packets entering the device.
Note that only IEEE 802.1p BA classifier types are supported on devices operating in transparent mode.
Rewrite rules to redefine IEEE 802.1 CoS values in outgoing packets.
Note that rewrite rules that redefine IP precedence CoS values and Differentiated Services Code Point (DSCP) CoS values are not supported on devices operating in transparent mode.
-Shapers to apply rate limiting to an interface.
-Schedulers that define the properties of an output queue.
For more information about CoS components and configuring CoS on SRX Series devices, see "Junos OS Class of Service Configuration Guide" for Security Devices. Here is the link;
http://www.juniper.net/techpubs/en_US/junos12.1/information-products/topic-collections/security/software-all/class-of-service/index.html?book-junos-security-swconfig-cos.html
You configure BA classifiers and rewrite rules on transparent mode devices in the same way as on devices operating in Layer 3 mode.
For transparent mode devices, however, you apply BA classifiers and rewrite rules only to logical interfaces configured with the family bridge configuration statement.
For more information about configuring Layer 2 logical interfaces, see Configuring Layer 2 Logical Interfaces.
http://www.juniper.net/techpubs/software/junos-security/junos-security10.2/junos-security-swconfig-interfaces-and-routing/transparent-mode-cos-overview-section.html