20.1.4 sFlow statistical operation of the Switch

<Structure of this section>

(1) sFlow Statistics-Collected Ports

The Switch can sample sFlow stats for Ethernet interfaces. In addition, you can select either reception (ingress) or transmission (egress) as the sampling attribute on a per-device basis.

(2) Target packet of the flow sample

All packets processed by the Switch are subject to flow samples.

Depending on the sampling attribute, the following packets are not treated as sampling targets:

Packets that are not treated as sampling targets in the reception specification

Packets discarded by the Ethernet interface

Packets that are not treated as sampling targets in the transmission specification

Packets sent from port mirroring and policy-based mirroring mirror ports

(3) Discarded Packet Flow Sample Operation

Even if packets are discarded by the Switch, the flow sample of the Switch may send sFlow packets as if they were forwarded to collectors. Check and operate the conditions under which packets are discarded by other functions. The following table shows the flow sample operation for discarded packets by other functions.

Table 20-15: Sample flow of discarded packets by another facility
Ability to discard		Receive order	Specify transmission
Filter (receiver)		Do not collect	Do not collect
Filter (sender)	Applies to Ethernet interface	Be collected	Be collected
Filter (sender)	Applies to VLAN interfaces	Be collected	Do not collect
QoS (bandwidth monitoring)		Do not collect	Do not collect
QoS (discard control)		Be collected	Do not collect
Storm Control		Do not collect	Do not collect
Inter-port relay blocking		Be collected	Do not collect
Layer 2 function*1		Do not collect	Do not collect
Layer 3 function*2		Do not collect	Do not collect

#1

The following types of discard frames are used by Layer 2:

.Discarded by MAC address-learning function

.Discarded because it cannot be relayed by VLAN

.Discarded in Layer 2 Blocking

.Disposal by Layer 2 authentication

.Disposal by IGMP snooping,MLD snooping,DHCP snooping

.Discard When Layer 2 Protocol Is Disabled

#2

Layer 3 discarded packets are listed below.

.Discarding Error Packets by IP Layer

(4) Notes on the sampling position of the flow sample contents

The following table describes the flow sampling contents of the Switch. The same applies when a packet discarded by the Switch is subject to flow sample processing.

Table 20-16: Flow sampling contents
Sampling attribute	Flow sampling content
Receive order	Contents of reception
Specify transmission	Contents of transmission

(5) Notes on flow sample contents when using other functions together

The flow sample information collected by the Switch varies depending on the functionality used by the sampling target port and the forwarding conditions for sampling packets. The following table shows the flow sample collection contents (header type data) when other functions are used and the relay conditions are used.

Table 20-17: Contents of flow sample collection when another facility is used and when forwarding conditions are used
Combination function and relay condition	Receive order	Specify transmission
VLAN (TPID setting of VLAN Tag)	Received TPID *1	TPID when sending*1
VLAN tunneling (tunneling port reception)	Information before adding Tag for tunneling*2	Information after adding Tag for tunneling13
VLAN tunneling (tunneling port transmission)	Information before deleting Tag for tunneling23	Information after deleting Tag for tunneling*1
VLAN Tag transformation (Tag Translation Port Receive)	Tag data before conversion*2	Converted Tag info*1
QoS bandwidth monitoring (penalty DSCP rewrite)	DSCP value before rewriting*4	DSCP after rewriting*4
QoS markers (DSCP rewrite)	DSCP value before rewriting*4	DSCP after rewriting*4
QoS markers (User priority rewrite)	User priority before rewriting*2	User priority after rewriting*1

#1: Header type frame information.
#2: Header-type frame information and switch-type received packet VLAN information.
#3: If VLAN Tag is two or more stages, IPv4 type, IPv6 type, user type, and URL type are not collected.
#4: Header-type frame information, IPv4 type TOS information, and IPv6 type priority information.

(6) Packets subject to counter sample collection

The counter sample on the Switch counts all packets sent and received on the port regardless of whether they are sent or received.

(7) Functions that cannot be used with flow statistics

Do not use the following together on the same port.

Using sFlow statistic send (egress) specification with the port mirroring monitor port for transmission frames.
Using sFlow statistic send (egress) specification with a mirror port that uses 802.1Q Tag grant facility.