D-Link xStack DGS-3420 Series Reference Manual page 227

xStack® DGS-3420 Series Layer 2 Managed Stackable Gigabit Switch Web UI Reference Guide
trTCM – Two Rate Three Color Marker. This, along with the srTCM, are two methods available on the switch for
metering and marking packet flow. The trTCM meters and IP flow and marks it as a color based on the flow's
surpassing of two rates, the CIR and the PIR.
CIR – Committed Information Rate. Common to both the trTCM and the srTCM, the CIR is measured in bytes of IP
packets. IP packet bytes are measured by taking the size of the IP header but not the link specific headers. For the
trTCM, the packet flow is marked green if it doesn't exceed the CIR and yellow if it does. The configured rate of the
CIR must not exceed that of the PIR. The CIR can also be configured for unexpected packet bursts using the CBS
and PBS fields.
CBS – Committed Burst Size. Measured in bytes, the CBS is associated with the CIR and is used to identify
packets that exceed the normal boundaries of packet size. The CBS should be configured to accept the biggest IP
packet that is expected in the IP flow.
PIR – Peak Information Rate. This rate is measured in bytes of IP packets. IP packet bytes are measured by taking
the size of the IP header but not the link specific headers. If the packet flow exceeds the PIR, that packet flow is
marked red. The PIR must be configured to be equal or more than that of the CIR.
PBS – Peak Burst Size. Measured in bytes, the PBS is associated with the PIR and is used to identify packets that
exceed the normal boundaries of packet size. The PBS should be configured to accept the biggest IP packet that is
expected in the IP flow.
srTCM – Single Rate Three Color Marker. This, along with the trTCM, are two methods available on the switch for
metering and marking packet flow. The srTCM marks its IP packet flow based on the configured CBS and EBS. A
packet flow that does not reach the CBS is marked green, if it exceeds the CBS but not the EBS its marked yellow,
and if it exceeds the EBS its marked red.
CBS – Committed Burst Size. Measured in bytes, the CBS is associated with the CIR and is used to identify
packets that exceed the normal boundaries of packet size. The CBS should be configured to accept the biggest IP
packet that is expected in the IP flow.
EBS – Excess Burst Size. Measured in bytes, the EBS is associated with the CIR and is used to identify packets
that exceed the boundaries of the CBS packet size. The EBS is to be configured for an equal or larger rate than the
CBS.
DSCP – Differentiated Services Code Point. The part of the packet header where the color will be added. Users
may change the DSCP field of incoming packets.
The ACL Flow Meter function will allow users to color code IP packet flows based on the rate of incoming packets.
Users have two types of Flow metering to choose from, trTCM and srTCM, as explained previously. When a packet
flow is placed in a color code, the user can choose what to do with packets that have exceeded that color-coded
rate.
Green – When an IP flow is in the green mode, its configurable parameters can be set in the Conform field, where
the packets can have their DSCP field changed. This is an acceptable flow rate for the ACL Flow Meter function.
Yellow – When an IP flow is in the yellow mode, its configurable parameters can be set in the Exceed field. Users
may choose to either Permit or Drop exceeded packets. Users may also choose to change the DSCP field of the
packets.
Red – When an IP flow is in the red mode, its configurable parameters can be set in the Violate field. Users may
choose to either Permit or Drop exceeded packets. Users may also choose to change the DSCP field of the
packets.
Users may also choose to count exceeded packets by clicking the Counter check box. If the counter is enabled, the
counter setting in the access profile will be disabled. Users may only enable two counters for one flow meter at any
given time.
To view this window, click ACL > ACL Flow Meter, as shown below:
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