Westermo RedFox Series - Manual (Page 363)

Westermo OS Management Guide
Version 4.17.0-0
17.1.1 Introduction to Link Aggregation
Link aggregation enables physical links to be bundled together to form a single
logical link, an aggregated link, see
fig. 17.1 . Upper layer protocols will treat the
aggregate as a single MAC entity, i.e., as one Ethernet port with its own label, a
MAC address assigned, and so on. In WeOS, aggregates are named ”a0”, ”a1”,
etc., and inherit their MAC address from one of their member ports.
Switch Switch
Member link Aggregated link
Physical view
Switch Switch
Aggregated link
Logical view
Figure 17.1: Example of link aggregation with four member links
All member ports in an aggregate are able to forward data. However, the IEEE802.1AX
standard[
13 ] mandates the aggregate to deliver packets in order per data flow
to avoid problems for upper layer protocols. This means the switch will send all
traffic of an individual data flow through the same member link. Other flows may
be sent through other member links. The effectiveness of this load balancing
depends on several factors:
❼ The granularity by which the switch can distinguish between different traffic
flows: WeOS units determine packet flow based on the combination of the
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