What is lag hashing – Dell POWEREDGE M1000E User Manual

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Configuring Link Aggregation

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loss of link. This provides a more resilient LAG. Best practices suggest using

dynamic link aggregation instead of static link aggregation.When a port is

added to a LAG as a static member, it neither transmits nor receives LACP

PDUs.

What is LAG Hashing?

PowerConnect M6220, M6348, M8024, and M8024-k switches support

configuration of hashing algorithms for each LAG interface. The hashing

algorithm is used to distribute traffic load among the physical ports of the

LAG while preserving the per-flow packet order.
The hashing algorithm uses various packet attributes to determine the

outgoing physical port.
The switch supports the following set of packet attributes to be used for hash

computation:

• Source MAC, VLAN, EtherType, and incoming port.
• Destination MAC, VLAN, EtherType, and incoming port.
• Source IP and Source TCP/UDP port numbers.
• Destination IP and Destination TCP/UDP port numbers.
• Source/Destination MAC, VLAN, EtherType, and incoming port.
• Source/Destination IP and Source/Destination TCP/UDP port numbers.
• Enhanced hashing mode

Enhanced hashing mode has following advantages:

• MODULO-N operation based on the number of ports in the LAG.
• Packet attributes selection based on the packet type. For L2 packets,

Source and Destination MAC address are used for hash computation. For

IP packets, Source IP, Destination IP address, TCP/UDP ports are used.

• Non-Unicast traffic and Unicast traffic is hashed using a common hash

algorithm.

• Excellent load balancing performance.

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