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Flex Hash and Optimized Boot-Up
This chapter describes the Flex Hash and fast-boot enhancements.
Topics:
• Flex Hash Capability Overview
• Conguring the Flex Hash Mechanism
• LACP Fast Switchover
• Conguring LACP Fast Switchover
• LACP
• RDMA Over Converged Ethernet (RoCE) Overview
• Sample Congurations
• Preserving 802.1Q VLAN Tag Value for Lite Subinterfaces
Flex Hash Capability Overview
The ex hash functionality enables you to congure 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 oset of hash elds from the start of the L4 header, which contains a ow identication
eld.
You can congure the system to include the elds present at the osets that you dene (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 congure 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 oset 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 congured.
• If you congure 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.
Conguring the Flex Hash Mechanism
The ex hash functionality enables you to congure 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 oset of hash elds from the start of the L4 header, which contains a ow identication
eld.
1 You can enable bins 2 and 3 by using the load-balance ingress-port enable command in Global Conguration mode. To
congure the ex hash functionality, you must enable these bins.
CONFIGURATION mode
Dell(conf)# load-balance ingress-port enable
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