Users Guide

Flex Hash and Optimized Boot-Up

This chapter describes the Flex Hash and fast-boot enhancements.

Topics:

• Flex Hash Capability Overview

• Conguring the Flex Hash Mechanism

• LACP Fast Switchover

• Conguring LACP Fast Switchover

• LACP

• RDMA Over Converged Ethernet (RoCE) Overview

• Sample Congurations

• Preserving 802.1Q VLAN Tag Value for Lite Subinterfaces

Flex Hash Capability Overview

The ex hash functionality enables you to congure a packet search key and matches packets based on the search key. When a packet

matches the search key, two 16-bit hash elds are extracted from the start of the L4 header and provided as inputs (bins 2 and 3) for

RTAG7 hash computation. You must specify the oset of hash elds from the start of the L4 header, which contains a ow identication

eld.

You can congure the system to include the elds present at the osets that you dene (from the start of the L4 header) as a part of LAG

and ECMP computation. Also, you can specify whether the IPv4 or IPv6 packets must be operated with the Flex Hash mechanism.

Keep the following points in mind when you congure the ex hash capability:

• A maximum of eight ex hash entries is supported.

• A maximum of 4 bytes can be extracted from the start of the L4 header.

• The oset range is 0 – 30 bytes from the start of the L4 header.

• Flex hash uses the RTAG7 bins 2 and 3 (overlay bins). These bins must be enabled for ex hash to be congured.

• If you congure ex hash by using the load-balance ingress-port enable and the load-balance flexhash

commands, the show ip flow and show port-channel-flow commands are not operational. Flex hash settings and these

show commands are mutually exclusive; only one of these capabilities can be functional at a time.

Conguring the Flex Hash Mechanism

The ex hash functionality enables you to congure a packet search key and matches packets based on the search key. When a packet

matches the search key, two 16-bit hash elds are extracted from the start of the L4 header and provided as inputs (bins 2 and 3) for

RTAG7 hash computation. You must specify the oset of hash elds from the start of the L4 header, which contains a ow identication

eld.

1 You can enable bins 2 and 3 by using the load-balance ingress-port enable command in Global Conguration mode. To

congure the ex hash functionality, you must enable these bins.

CONFIGURATION mode

Dell(conf)# load-balance ingress-port enable

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