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How to set up sFlow on Dell Networking Force10 Switches


This article explains how to set up sFlow on Dell Networking Force10 Switches.


Objectives
  1. Overview
  2. Important Points
  3. Enabling sFlow
  4. Verify sFlow configuration


Overview

The Dell Networking Operating System (OS) supports sFlow version 5.
Dell Networking sFlow is designed so that the hardware sampling rate is per line card port-pipe and is decided based on all the ports in that port-pipe.
If you do not enable sFlow on any port specifically, the global sampling rate is downloaded to that port and is to calculate the port-pipe’s lowest sampling rate. This design supports the possibility that sFlow might be configured on that port in the future. Back-off is triggered based on the port-pipe’s hardware sampling rate.
The default global sampling rate is 32768. The sampling rates are determined as follows:
  • If the interface states are up and the sampling rate is not configured on the port, the default sampling rate is calculated based on the line speed.
  • If the interface states are shut down, the sampling rate is set using the global sampling rate.
  • If the global sampling rate is non-default, for example 256, and if the sampling rate is not configured on the interface, the sampling rate of the interface is the global non-default sampling rate, that is, 256.
To avoid the back-off, either increase the global sampling rate or configure all the line card ports with the desired sampling rate even if some ports have no sFlow configured.


Important Points

  • The Dell Networking OS implementation of the sFlow MIB supports sFlow configuration via snmpset.
  • By default, sFlow collection is supported only on data ports. If you want to enable sFlow collection through management ports, use the management egress-interface-selection and application sflow-collector commands in Configuration and EIS modes respectively.
  • Dell Networking OS exports all sFlow packets to the collector. A small sampling rate can equate to many exported packets. A backoff mechanism is automatically applied to reduce this amount. Some sampled packets may be dropped when the exported packet rate is high and the backoff mechanism is about to or is starting to take effect. The dropEvent counter, in the sFlow packet, is always zero.
  • Community list and local preference fields are not filled in extended gateway element in the sFlow datagram.
  • 802.1P source priority field is not filled in extended switch element in sFlow datagram.
  • Only Destination and Destination Peer AS number are packed in the dst-as-path field in extended gateway element.
  • If the packet being sampled is redirected using policy-based routing (PBR), the sFlow datagram may contain incorrect extended gateway/router information.
  • The source virtual local area network (VLAN) field in the extended switch element is not packed in case of routed packet.
  • The destination VLAN field in the extended switch element is not packed in a Multicast packet.
  • Up to 700 packets can be sampled and processed per second.
Enabling sFlow


Follow the steps below in order to enable sFlow Globally
Command Parameters
FTOS# configuration Enter configuration mode.
FTOS(conf)# sflow enable Enable sFlow globally.
FTOS(conf)# sflow collector <IP ADDR> agent-addr <IP ADDR> Set collector IP address (external device managing sFlow data). Set agent IP address (this or other switching devices that gather data).
FTOS(conf)# sflow max-header-size extended (Optional) By default, the maximum header size of a packet is 128 bytes. When sflow max-header-size extended is enabled, 256 bytes are copied. These bytes are useful for VxLAN, NvGRE, IPv4, and IPv6 tunneled packets.
FTOS(conf)#sflow extended-switch enable Extended sFlow packs additional information in the sFlow datagram depending on the type of sampled packet. 802.1Q VLAN ID and 802.1p priority information.
FTOS(conf)#sflow polling-interval <15-86400> (Optional) Set a specific polling interval to be compatible with the collector
FTOS(conf)#sflow sample-rate <256-8388608> (Optional) Set a specific sample rate to be compatible with the collector. (Only powers of 2. E.g 4096 8192)


Follow these steps below to enable sFlow at the Interface level


Command Parameters
FTOS# Configuration Enter configuration mode.
FTOS(conf)# interface te 0/10 Enter the specific interface.
FTOS(conf-if-te-0/10)# sflow ingress-enable Enable sFlow on the interface.
FTOS(conf-if-te-0/10)#sflow max-header-size extended (Optional) By default, the maximum header size of a packet is 128 bytes. When sflow max-header-size extended is enabled, 256 bytes are copied. These bytes are useful for VxLAN, NvGRE, IPv4, and IPv6 tunneled packets.
FTOS(conf-if-te-0/10)#sflow polling-interval <15-86400> (Optional) Set a specific polling interval to be compatible with the collector
FTOS(conf-if-te-0/10)#sflow sample-rate <256-8388608> (Optional) Set a specific sample rate to be compatible with the collector. (Only powers of 2. E.g 4096 8192)




Verifying sFlow configuration

Verify global configuration details:


FTOS# show sflow
sFlow services are enabled
Global default sampling rate: 32768
Global default counter polling interval: 20
1 collectors configured
Collector IP addr: 133.33.33.53, Agent IP addr: 133.33.33.116, UDP port: 6343
77 UDP packets exported
0 UDP packets dropped
165 sFlow samples collected
69 sFlow samples dropped due to sub-sampling
Verify interface sFlow details:


FTOS# show sflow interface tengigabitethernet 1/1
Te 1/1 sFlow type :Ingress
Configured sampling rate :16384
Actual sampling rate :16384
Counter polling interval :20
Extended max header size :128
Samples rcvd from h/w :0


FTOS# show running-config interface tengigabitethernet 1/16
!interface TenGigabitEthernet 1/16
no ip address
switchport
sflow ingress-enable
sflow sample-rate 8192
no shutdown





Quick Tips content is self-published by the Dell Support Professionals who resolve issues daily. In order to achieve a speedy publication, Quick Tips may represent only partial solutions or work-arounds that are still in development or pending further proof of successfully resolving an issue. As such Quick Tips have not been reviewed, validated or approved by Dell and should be used with appropriate caution. Dell shall not be liable for any loss, including but not limited to loss of data, loss of profit or loss of revenue, which customers may incur by following any procedure or advice set out in the Quick Tips.

文章 ID: HOW11008

上次修改日期: 06/02/2016 10:39 AM


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