WAP571 : Link Aggregation Group Question

[matthew1471]

Hi Cisco,

WAP571, running a:

• 5 GHz 40 MHz (so 600 Mbps assuming client supports 3 spatial streams?) and a
• 2.4 GHz 22 MHz (so 144.5 Mbps?)

600 + 144.5 = 744.5 Mbps

The WAP571 supports 2 Ethernet interfaces to be placed in a LAG (Link Aggregation Group).

My question is, does the WAP571 benefit from any performance hand-offs being run in a LAG configuration? Or is it only for where max throughput could exceed 1 Gbps (i.e. 80 MHz width channels)?

I'm wondering if having 2 network interfaces connected means the WAP571 spreads the load internally across the 2 network cards' controllers (the switch is certainly reporting activity on both interfaces) or if the CPU is dual core, is able to make better use of the CPU?

If no performance improvement is there any other advantage to me using the LAG (does the WAP571 retry using a different port if a transmit fails and use the second port for reliability?). I note the WAP571 cannot receive its PoE power from ETH1.

The documentation on the second port is a bit poor in the WAP571 manual (and there's a grammar error in the manual too, "Eth1 will always follows Eth0
configurations" and some strange past-tense English such as the sentence including "always bundled" making it sound like the WAP571 has died and we're speaking about it in posthumous memory), any advice would be welcome as it is one of the selling features of the WAP571 :).

Thank you (as always),
Matthew

[Michiel Beenen · Accepted solution]

Hello Matthew,

From my own experience with the 571, the 2 LAN ports can indeed be used for LAG to balance load between both LAN interfaces. This is especially handy for when clients need speeds that reach 1Gb/s and you ofc also have other clients connected at the same time. 

Im not sure if the CPU load changes because of this, from testing I havent seen much difference except that the load balancing performed well.