Administrator Guide

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
Dell(conf)# load-balance flexhash ipv4 ip-proto 1 desc offset1 1 offset2 2
load-balance ingress-port enable
Enable the Flex hash functionality. This utility is supported on the C9000 platform.
Syntax
load-balance ingress-port enable
To disable the Flex hash capability, use the no version of this command.
Default None
Command Modes CONFIGURATION mode
Command History
This guide is platform-specific. For command information about other platforms, refer to the relevant Dell
Networking OS Command Reference Guide.
The following is a list of the Dell Networking OS version history for this command.
Version Description
9.9.(0.0) Introduced on the C9010.
9.3(0.0) Introduced on the S6000 platform.
Usage Information Flex hash uses the RTAG7 bins 2 and 3 (overlay bins). These bins must be enabled for Flex hash to be configured.
These bins contain the source module and source port information. These bins are disabled by default in releases
of Dell Networking OS earlier than Release 9.3.0.0. The default behavior of disabling of these bins occurs because
of incorrect egress port information that would otherwise be displayed in the output of the diagnostic show
command of show ip flow.
As a result, when load balancing of RRoCE packets using Flex hash is enabled, the show ip flow command is
not functional. Similarly, when show ip flow command operates (ingress port based load balancing is disabled)
the hashing of RRoCE packets is not operational.
Flex hash APIs do not mask out unwanted byte values after extraction of the data from the Layer 4 headers for
the offset value.
Example
Dell#load-balance ingress-port enable
Flex Hash and Optimized Boot-Up 639