(Supporting ADX v03.1.00) Owner manual

12 Brocade Virtual ADX Server Load Balancing Guide

53-1003247-01

Overview

Connection assignments with enhanced weighted predictor for enhanced weighted load-balancing

In enhanced weighted load-balancing, the traffic is distributed in the same proportions as in

weighted load-balancing, but the order of distribution is different. With enhanced weighted

load-balancing, the real server with the greatest weight is allocated a connection first, but then the

next connection is allocated to the real server with the next greatest weight, and then to the server

with the next greatest weight on-down-the-line, until all servers have received their first connection.

The process repeats with each real server getting a connection in sequence until each real server

has connections equal to its assigned weight.

Table 5 shows the distribution pattern for Enhanced Weighted Load-Balancing in an example

configuration with three real servers, A, B, and C. Real Server A has a weight of 1, Real Server B has

a weight of 2, and Real Server C has a weight of 3. The numbers in bold indicate which server

receives the new connection. When the weighted predictor is configured, connections are assigned

as shown in Table 5.

Weighted and Enhanced Weighted predictors can be enabled as described in: “Changing the

Load-Balancing Predictor Method” on page 21.

TABLE 5 SLB with the enhanced weighted predictor

Real Server A Real Server B Real Server C

weight = 1 weight = 2 weight = 3

Connections Server load

a. For the enhanced weighted predictor, the server load is calculated as connections x [combined weights /

server weight] = server load. Fractional remainders are rounded down. If there is a tie, the server with the highest

weight receives the connection.

Connections Server load Connections Server load

0 0 x 6 / 1 = 0 0 0 x 6 / 2 = 0 0 0 x 6 / 3 = 0

0 0 x 6 / 1 = 0 0 0 x 6 / 2 = 0 1 1 x 6 / 3 = 2

0 0 x 6 / 1 = 0 1 1 x 6 / 2 = 3 1 1 x 6 / 3 = 2

1 1 x 6 / 1 = 6 1 1 x 6 / 2 = 3 1 1 x 6 / 3 = 2

1 1 x 6 / 1 = 6 1 1 x 6 / 2 = 3 2 2 x 6 / 3 = 4

1 1 x 6 / 1 = 6 2 2 x 6 / 2 = 6 2 2 x 6 / 3 = 4

1 1 x 6 / 1 = 6 2 2 x 6 / 2 = 6 3 3 x 6 / 3 = 6

1 1 x 6 / 1 = 6 2 2 x 6 / 2 = 6 4 4 x 6 / 3 = 8

1 1 x 6 / 1 = 6 3 3 x 6 / 2 = 9 4 4 x 6 / 3 = 8

2 2 x 6 / 1 = 12 3 3 x 6 / 2 = 9 4 4 x 6 / 3 = 8

2 2 x 6 / 1 = 12 3 3 x 6 / 2 = 9 5 5 x 6 / 3 = 10

2 2 x 6 / 1 = 12 4 4 x 6 / 2 = 12 5 5 x 6 / 3 = 10

2 2 x 6 / 1 = 12 4 4 x 6 / 2 = 12 6 6 x 6 / 3 = 12

2 2 x 6 / 1 = 12 4 4 x 6 / 2 = 12 7 7 x 6 / 3 = 14

2 2 x 6 / 1 = 12 5 5 x 6 / 2 = 15 7 7 x 6 / 3 = 14