Service Manual

15
Flex Hash and Optimized Boot-Up
This chapter describes the Flex Hash and fast-boot enhancements.
Flex Hash Capability Overview
This functionality is supported on the platform.
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
This feature is supported on the platform.
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. In Dell Networking OS Release 9.3(0.0), 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
S6000-109-FTOS(conf)# load-balance ingress-port enable
When load balancing RRoCE packets using ex hash is enabled, the show ip flow command is disabled. Similarly, when the
show ip flow command is in use (ingress port-based load balancing is disabled), the hashing of RRoCE packets is disabled.
Flex hash APIs do not mask out unwanted byte values after extraction of the data from the Layer 4 headers for the oset value.
2. Use the load-balance flexhash command to specify whether IPv4 or IPv6 packets must be subjected to the ex hash
functionality, a unique protocol number, the oset of hash elds 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.
Flex Hash and Optimized Boot-Up
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