Service SAP QoS Policy Command Reference
292 Quality of Service Guide
port-redirect-group — This parameter is used to mark a given forwarding class queue for
redirection to an egress port queue group. This is only used when the specific queue group
instance is assigned at the time the qos policy is applied to the SAP. This redirection model
is known as SAP based redirection.
packet-byte-offset
Syntax packet-byte-offset {add add-bytes | subtract sub-bytes}
no packet-byte-offset
Context config>qos>sap-egress>hsmda-queues
Description This command adds or subtracts the specified number of bytes to the accounting function for each
packet handled by the HSMDA queue. Normally, the accounting and leaky bucket functions are based
on the 14-byte Ethernet DLC header, 4-byte or 8-byte VLAN tag (optional), 20-byte IP header, IP
payload and the 4-byte CRC (everything except the preamble and inter-frame gap). For example, the
packet-byte-offset command can be used to add the frame encapsulation overhead (20 bytes) to the
queues accounting functions.
The accounting functions affected include:
• Offered High Priority / In-Profile Octet Counter
• Offered Low Priority / Out-of-Profile Octet Counter
• Discarded High Priority / In-Profile Octet Counter
• Discarded Low Priority / Out-of-Profile Octet Counter
• Forwarded In-Profile Octet Counter
• Forwarded Out-of-Profile Octet Counter
• Peak Information Rate (PIR) Leaky Bucket Updates
• Committed Information Rate (CIR) Leaky Bucket Updates
• Queue Group Aggregate Rate Limit Leaky Bucket Updates
The secondary shaper leaky bucket, scheduler priority level leaky bucket and the port maximum rate
updates are not affected by the configured packet-byte-offset. Each of these accounting functions are
frame based and always include the preamble, DLC header, payload and the CRC regardless of the
configured byte offset.
The packet-byte-offset command accepts either add or subtract as valid keywords which define
whether bytes are being added or removed from each packet traversing the queue. Up to 20 bytes may
be added to the packet and up to 43 bytes may be removed from the packet. An example use case for
subtracting bytes from each packet is an IP based accounting function. Given a Dot1Q encapsulation,
the command packet-byte-offset subtract 14 would remove the DLC header and the Dot1Q header
from the size of each packet for accounting functions only. The 14 bytes are not actually removed from
the packet, only the accounting size of the packet is affected.
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