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Configuration Guide - Low Latency Network

CloudEngine 8800, 7800, 6800, and 5800 V200R005C00

This document describes the configurations of Buffer optimization of lossless queues, Fast ECN, Fast CNP, Dynamic ECN threshold of lossless queues, and Dynamic load balancing.
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Licensing Requirements and Limitations for

Licensing Requirements and Limitations for

Involved Network Elements

Other network elements are not required.

Licensing Requirements

Table 3-1 lists the support of and licensing requirements for functions on various switch models. By default, functions are disabled on a new device if these functions are controlled by a license. To use the functions, apply for and purchase the license from the equipment supplier.

Table 3-1 Support of and licensing requirements for functions on various switch models

Switch Model

Buffer Optimization of Lossless Queues

Differentiated Scheduling for Elephant and Mice Flows in Lossless Queues

Fast ECN

Fast CNP

Dynamic ECN Threshold of Lossless Queues

Dynamic Load Balancing

CE8860EI

Supported (not under license control)

Not supported

Supported (not under license control)

Not supported

Not supported

Not supported

CE8861EI

Supported (under license control)

Supported (under license control)

Supported (not under license control)

Supported (under license control)

Supported (under license control)

Supported (not under license control)

CE8868EI

Supported (under license control)

Supported (under license control)

Supported (not under license control)

Supported (under license control)

Supported (under license control)

Supported (not under license control)

CE8850-32CQ-EI

Supported (not under license control)

Not supported

Supported (not under license control)

Not supported

Not supported

Not supported

CE8850-64CQ-EI

Supported (under license control)

Not supported

Supported (not under license control)

Supported (under license control)

Supported (under license control)

Supported (not under license control)

CE6857EI

Not supported

Not supported

Not supported

Not supported

Not supported

Supported (not under license control)

CE6860EI

Supported (not under license control)

Not supported

Supported (not under license control)

Not supported

Not supported

Not supported

CE6865EI

Supported (under license control)

Supported (under license control)

Supported (not under license control)

Supported (under license control)

Supported (under license control)

Supported (not under license control)

CE6870EI

Not supported

Not supported

Supported (not under license control)

Not supported

Not supported

Not supported

CE6875EI

Not supported

Not supported

Supported (not under license control)

Not supported

Not supported

Not supported

Version Requirements

Table 3-2 Products and minimum version supporting the function

Product

Minimum Version Required

CE8860EI

V200R005C00

CE8861EI

V200R005C10

CE8868EI

V200R005C10

CE8850EI

V200R005C00

CE6857EI

V200R005C10

CE6860EI

V200R005C00

CE6865EI

V200R005C00

CE6870EI

V200R005C00

CE6875EI

V200R005C00

Feature Limitations

Limitations on Buffer Optimization of Lossless Queues

  • After manual buffer optimization of lossless queues is enabled, save the configuration and restart the device for the configuration to take effect.
  • After the percentage of the service pool buffer threshold for lossless queues in the chip-level service pool buffer is configured:
    • The chip's capability to forward burst traffic will be lowered, so the inbound and outbound buffer thresholds of each interface need to be adjusted.
    • Ensure that the methods such as priority mapping in the DiffServ domain and the traffic policy containing remark are not used to map a lossy priority to a lossless priority.
    • The burst traffic buffering mode of the device configured by the qos burst-mode command is only valid for the service pool buffer of lossy queues.
Limitations on Differentiated Scheduling for Elephant and Mice Flows in Lossless Queues
  • Differentiated scheduling for elephant and mice flows in lossless queues and the system resource mode large-arp or UFT hybrid mode where ARP entries are specified cannot be both configured.

  • Differentiated scheduling for elephant and mice flows in lossless queues and IOAM are mutually exclusive.
  • Differentiated scheduling for elephant and mice flows is available only to lossless queues 3 to 7.
  • Differentiated scheduling for elephant and mice flows in lossless queues and microsegmentation are mutually exclusive on the CE6865EI, CE8861EI, and CE8868EI.

Limitations on Fast CNP

The destination server sends the CNP to the source server only after receiving the packet tagged with the ECN field.

Limitations on Dynamic ECN Threshold of Lossless Queues

  • If the qos queue ecn command is used to enable the static ECN threshold of lossless queues, the dynamic ECN threshold of all lossless queues cannot be enabled.
  • The static ECN threshold of all queues and the dynamic ECN threshold for lossless queues share chip resources. If chip resources of the device are insufficient during configuration of the services, the device will generate a message indicating that the configuration fails. In this case, you are advised to delete some redundant services such as the static ECN threshold for the lossy queues that are not used.

Limitations on Dynamic Load Balancing

  • Only known unicast traffic can be dynamically load balanced.
  • Only traffic on physical interfaces of the same chip resource can be dynamically load balanced.

    Use the tool for querying relationships between ports and chip resources to query the relationship between ports and chip resources.

  • Dynamic load balancing, path detection, and calculation of the ECMP outbound interface using traffic simulation cannot be applied together.
  • The usage of links that are load balanced is classified into eight ranges in increments of 12.5% of the link bandwidth. If the usage of two links falls into the same range, the two links are thought of as having the same load.

    For example, if the usage of link 1 is 8% and the usage of link 2 is 10%, links 1 and 2 are regarded to have the same load because their usage falls into the same range (0% to 12.5%).

  • For BUM traffic on the VXLAN network, the device replicates packets and prunes packets that support sticky load balancing. The discarded packets affect the dynamic load balancing effect.
  • The dynamic load balancing for an LAG and independent VLAN functions cannot be applied together.
  • The dynamic load balancing for an LAG and elastic load balancing functions cannot be applied together.
  • For dynamic load balancing of an ECMP:
    • The function of preferentially forwarding local traffic needs to be enabled in a stack.
    • The next-hop egress interface of the traffic must be a physical interface, instead of an Eth-Trunk.
    • In scenarios of VXLAN Layer 3 gateways, if the next hop of traffic on both the overlay and underlay networks is an ECMP, only traffic on the underlay network can be load balanced.
    • The ECMP dynamic load balancing and load balancing consistency functions cannot be applied together.
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Updated: 2019-04-20

Document ID: EDOC1100040243

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