3.1.4 Notes on using flow detection

<Structure of this section>

(1) QoS flow-detection for frames with VLAN Tag

You cannot perform QoS flow detection for frames with three or more VLAN tags by using an Ethernet type for a MAC condition, an IPv4 condition, or an IPv6 condition specified as a flow detection condition.

Either of the following conditions must be satisfied to perform QoS flow detection on the receiving side by an Ethernet type for a MAC condition, an IPv4 condition, or an IPv6 condition specified as the flow detection condition for a frame that has two VLAN tags:

The VLAN tunneling functionality is not active on the Switch.
The VLAN tunneling functionality is active on the Switch but frames were received by a trunk port.

(2) QoS flow-detection for IPv4 fragmented packets

If you perform QoS flow detection by using a TCP/UDP header or ICMP header specified as a flow detection condition for a fragmented IPv4 packet, the second and subsequent fragments cannot be detected because the TCP/UDP header and ICMP header are not in those packets. To perform QoS flow detection for frames that include fragmented packets, specify the MAC header or IP header in the flow detection conditions.

(3) QoS flow-detection for IPv6 packets with extension headers

You cannot perform QoS flow detection for IPv6 packets that have an IPv6 extension header by using a TCP/UDP header or ICMP header as a flow detection condition. To perform QoS flow detection for such packets, specify the MAC header or IPv6 header in the flow detection conditions.

(4) Understanding IPv4 Protocol-Discovery

The protocol name ah or the protocol number 51 cannot be detected as a flow condition.

(5) Operation When Applying QoS Entries

On the Switch, a QoS entry may be applied to an interface*, or other QoS entries may be detected until the specified QoS entry is applied. In this case, statistics for the QoS entries that detected packets are collected.

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When a QoS list containing one or more entries is applied to the interface by using the QoS flow group command
When a QoS flow list is applied by using the QoS flow group command to add an entry
When a QoS entry is applied when the switch is started, the copy operation command is executed, or the restart vlan operation command is executed

(6) Operation when changing QoS entries

If a QoS entry applied to an interface is changed on the Switches, detectable frames cannot be detected until the change has been applied. Consequently, such frames are detected as if they matched another QoS entry.

(7) Simultaneous operation with other functions

Frames are discarded when one of the conditions listed below is satisfied. However, if a frame matches a QoS entry specified for the receiving-side interface, statistics for that QoS entry are collected.

Frames are received from the VLAN port whose data transfer status is Blocking (data transfer stopped).
Frames are received from a port specified by the inter-port relay blocking functionality.
Frames without a VLAN tag are received when the native LAN is not set as the VLAN that uses a trunk port for sending and receiving frames.
Received frames that have a VLAN tag are not set for a VLAN that uses a trunk port for sending and receiving frames.
Frames with a VLAN Tag are received at access, protocol or MAC ports.
Frames that match a filter entry specifying discard (including an implicit discard entry) are received.
Frames are discarded by the MAC address learning functionality.
Frames are discarded by the Layer 2 relay blocking functionality.
Frames are discarded by the Layer 2 authentication functionality.
When a frame is discarded due to an invalid Layer 2 protocol
Frames are discarded by IGMP snooping or MLD snooping.
Frames are discarded by DHCP snooping.
Frames are discarded by storm control.
Packets are discarded by IP layer or IPv6 layer forwarding.