Signamax
™
065-7840C-WS 24-Port 10/100/1000BaseT/TX WebSmart Switch
Publication date: June, 2011
Revision 1.0
43
3-6. Link Aggregation
Basically, Link Aggregation is used to aggregate the bandwidth of more than
one port to an assigned logical link. This highly increases total bandwidth to the
targeted device. There is more than one Link Aggregation technology in many
vendors’ switch products already, which may cause the problem of interoperability.
This is the reason why now we have IEEE 802.3ad Link Aggregation Control
Protocol (LACP).
Why 802.3ad (LACP)?
Network is varying. For example, if a port malfunctioned or unplugged
accidentally in a static trunk port, administrator has to reconfigure it, or the network
will get trouble. Therefore, offering a tool with automatic recovery capability is
necessary for an administrator. LACP is a protocol that allows a switch able to know
whether its partner has the capability to co-setup a trunk between them.
Usually, if administrator wishes to increase the bandwidth of a specific link,
he may:
1.
Buy new network equipment with higher throughput, or
2. Aggregate the bandwidth of more than one port to a logical link.
If the item 1 is the case, the cost of that choice may be beyond your budget,
and the solution caused by the limitation of hardware performance may not be
scalable.
If the item 2 is the case, now there is not much more extra cost and the
solution can be flexible according to the demand of bandwidth, because all required
equipment is there already. Moreover, there is no worry about the interoperability
issue. By applying LACP in your network, you will not only gain the benefits shown
below to improve the performance of your network, but you also have the
investment capital usable for future new products:
1. Public standardized specification
2. No interoperability issue
3. No change to IEEE 802.3 frame format, no change in software and
management.
4. Increased bandwidth and availability
5. Load sharing and redundancy
6. Automatic
configuration
7. Rapid
configuration and reconfiguration
8. Deterministic
behavior
9. Low risk of duplication or mis-ordering
10. Support existing IEEE 802.3 MAC Clients
11. Backwards compatibility with aggregation-unaware devices
There are also some constraints when applying LACP.
1. LACP does not support inter-switch bandwidth aggregation.
2. The ports aggregated must operate in full-duplex mode.
3. The ports in the same Link Aggregation Group must have the same
speed, for example, all with 100 Mbps or all 1000 Mbps. You cannot
aggregate a 1000 Mbps and two 100 Mbps for a 1.2Gbps trunk port.
Summary of Contents for 065-7940C-WS
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