I have a 46 mile link in the 5900 MHz ham band crossing over the majority of the San Francisco peninsula... pretty challenging run. 3 foot dishes and NetMetal 5 units at each end.

The link is running very reliably, usually around 86 Mbps each way, occasionally higher, sometimes down lower.

But for my application, I really don't need anywhere near that much bandwidth - but I am transporting some VoIP traffic - so I'd really like to avoid the long retransmit times that happen when the radio needs to downshift, often several steps.

So...
Can I lock in a lower set of AC rates?
Would I be better off switching to N and can I lock in a set of lower N rates with this hardware?
If not, is there some hardware that comes in as nice a box (or that I can swap into the NetMetal 5 box) that will allow locking in a subset of lower N rates?
Will we be getting the ability to narrow the channel (giving me a bit more margin as well) with this hardware?


I really like the ability to easily tune into the ham band, and the link is really much better than I imagined it would be, but the jitter caused by the retransmits is killing me here...

64 bytes from xxx: icmp_seq=71 ttl=62 time=4.65 ms
64 bytes from xxx: icmp_seq=72 ttl=62 time=5.70 ms
64 bytes from xxx: icmp_seq=73 ttl=62 time=17.9 ms
64 bytes from xxx: icmp_seq=74 ttl=62 time=9.86 ms
64 bytes from xxx: icmp_seq=75 ttl=62 time=3.69 ms
64 bytes from xxx: icmp_seq=76 ttl=62 time=3.60 ms
64 bytes from xxx: icmp_seq=77 ttl=62 time=5.59 ms
64 bytes from xxx: icmp_seq=78 ttl=62 time=15.5 ms
64 bytes from xxx: icmp_seq=79 ttl=62 time=4.74 ms
64 bytes from xxx: icmp_seq=80 ttl=62 time=4.34 ms
64 bytes from xxx: icmp_seq=81 ttl=62 time=11.8 ms
64 bytes from xxx: icmp_seq=82 ttl=62 time=845 ms
64 bytes from xxx: icmp_seq=83 ttl=62 time=5.99 ms
64 bytes from xxx: icmp_seq=84 ttl=62 time=15.5 ms
64 bytes from xxx: icmp_seq=85 ttl=62 time=5.10 ms
64 bytes from xxx: icmp_seq=86 ttl=62 time=4.37 ms
64 bytes from xxx: icmp_seq=87 ttl=62 time=3.78 ms
64 bytes from xxx: icmp_seq=88 ttl=62 time=11.1 ms
64 bytes from xxx: icmp_seq=89 ttl=62 time=1356 ms
64 bytes from xxx: icmp_seq=90 ttl=62 time=360 ms
64 bytes from xxx: icmp_seq=91 ttl=62 time=6.63 ms
64 bytes from xxx: icmp_seq=92 ttl=62 time=10.7 ms

rtt min/avg/max/mdev = 3.198/50.085/1359.801/203.294 ms,

Turning off the higher MCS values on the AP-side can help as the system doesn't try to move up to higher modulations. You can also turn off the A/G rates to keep control packets in higher modulations.

Running with narrower bandwidth can also help as the smaller your channel, the lower the probability of getting hit with interference.

i was told there is nothing in the AC spec for tuning data rates. Mikrotik support told me that.

Please try out the newest RouterOS Release Canditate version as there are improvements for 11ac when you use 802.11 wireless protocol.
Also it is possible to limit the max data-rates for the AC You can limit the VHT data rates so they would not use MCS9 or MCS8.

Have you tried using Nstreme?

Some people have troubles with it, but we're running it on some link without issues.

Bandwidth is much lower, but ping and jitter are low and stable