Netapp VIFs loadbalancing

NetApp loadbalancing algorithm for determining ethernet load balancing (vifs) differs from Cisco, so it’s normal to see unbalanced traffic in Netapp vifs.

The Cisco method for determining load balancing is : http://www.cisco.com/warp/public/473/4.html

 
The NetApp method is described as:

((source_address XOR destination_address) % number_of_links)  —  where source and destination take the last byte of the IP or MAC address to perform the calculation.

Example :

Filer IP is 10.128.60.1
clients are 10.128.60.[3-6]

(1 xor 3) % 3 == 2 % 3 == link#2 (e0d)
(1 xor 4) % 3 == 5 % 3 == link#2 (e0d)
(1 xor 5) % 3 == 4 % 3 == link#1 (e0c)
(1 xor 6) % 3 == 7 % 3 == link#1 (e0c)
 
If a client used 10.128.60.2 or 10.128.60.9, then we would see outgoing traffic on e0b.  MAC address hashing calculation it would be more imbalanced than the IP address method:

(0xB6 xor 0x4E) % 3 == 0xF8 % 3 == 248 % 3 == link#2 (e0d)
(0xB6 xor 0xD8) % 3 == 0x6E % 3 == 110 % 3 == link#2 (e0d)
(0xB6 xor 0x56) % 3 == 0xE0 % 3 == 224 % 3 == link#2 (e0d)
(0xB6 xor 0x80) % 3 == 0x36 % 3 == 54 % 3 == link#0 (e0b)

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