Connectivity Guide

load-balance flexhash
Specify the parameters for the Flex Hash mechanism, such as whether IPv4 or IPv6 packets must be subject to Flex Hash
functionality, a unique protocol number, the offset of hash fields from the start of the L4 header to be used for hash calculation,
and a meaningful description to associate the protocol number with the name.
Syntax
load-balance flexhash ipv4/ipv6 ip-proto <protocol number> <description
string> offset1 <offset1 value> [offset2 <offset2 value>]
To disable the Flex hash settings, use the no load-balance flexhash ipv4/ipv6 ip-proto
protocol number command.
Parameters
ipv4 Denotes whether Flex Hash needs to be enabled for IPv4 packets.
ipv6 Denotes whether Flex Hash needs to be enabled for IPv6 packets.
protocol number
Represents the Outer IPv4 protocol field in case of IPv4 packets, and the Outer
IPv6 next header field in case of IPv6 packets.
The ipv4/ipv6 keyword and the IP protocol value are used as keys to identify
if a duplicate flex hash configuration is already present. Duplicate flex hash
configuration is not possible. To change an existing flex hash configuration, you
must delete the existing flex hash attribute and configure the flex attribute afresh.
description
string
A description string is followed by the protocol number to enable you to associate
the protocol number with the protocol name in an easily-identifiable way. For
example, for a protocol number of 254, you can specify the description as RRoCE.
offset1 value Specify the byte offset from the start of the L4 header from which the 2-byte data
is extracted and be used in hash computation. You must enter the offset as an
even number. The offset range is 0 – 30 bytes from start of L4 header.
offset2 value (Optional) Specify the additional 2 bytes that must be extracted from the start of
the L4 header to be used for hash computation. You must enter the offset as an
even number. The offset range is 0 – 30 bytes from start of L4 header.
Default None
Command Modes CONFIGURATION mode
Command
History
Version Description
9.10(0.1) Introduced on the S6010-ON and S4048T-ON.
9.10(0.0) Introduced on the S6100-ON.
9.8(1.0) Introduced on the Z9100–ON.
9.3(0.0) Introduced on the S6000 platform.
9.2(1.0) Introduced on the Z9500.
Usage
Information
With the introduction of various overlay technologies such as network virtualization using generic
routing encapsulation (NVGRE) segments and Routable Remote Direct Memory Access (RRDMA) over
Converged Ethernet (RRoCE), information related to a traffic flow is contained in the L4 header. The
fields in the L2 and L3 headers are not sufficient to distinguish the flows. Therefore, the fields in the L4
header are processed when hashing is performed for packets over LAG and ECMP links. The Flex Hash
functionality enables you to configure a packet search key and matches packets based on the search key.
When a packet matches the search key, two 16-bit hash fields 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 offset of
hash fields from the start of the L4 header, which contains a flow identification field.
You can cause the system to include the fields present at the offsets that you define (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.
Example
DellEMC(conf)# load-balance flexhash ipv4 ip-proto 1 desc offset1 1 offset2
2
Flex Hash and Optimized Boot-Up 571