As ePMP works like a bridge we need to know how it handles fluctuating packet rates.
How big are the buffers? Does it do Flow Control?
Esp. on transit points between faster and slower interfaces we use FlowControl to avoid packet drops with bursts. We see this happen even on moderately used links as packets arrive at different rates. At ePMP AP we have a transition from Gigabit Ethernet (1000MBit/s) to Wireless (100MBit/s).
@ste wrote:
As ePMP works like a bridge we need to know how it handles fluctuating packet rates.
How big are the buffers? Does it do Flow Control?
Esp. on transit points between faster and slower interfaces we use FlowControl to avoid packet drops with bursts. We see this happen even on moderately used links as packets arrive at different rates. At ePMP AP we have a transition from Gigabit Ethernet (1000MBit/s) to Wireless (100MBit/s).
We have flow control only on Ethernet part of our device.
It means that Ehternet HW will send flow control messages when Ethernet driver can't handle big packet flow .
Ethernet HW can receive flow control messages from link partner and it will pause the transmission if Ethernet driver will try to send a big packet flow.
Hello.
So the official Cambium suggestion is to enable Flow control on the other devide che epmp is connected to?
For example on a switch port or a router port (ex. mikrotik) we should enable flow control or leave to auto?
I have seen problems with Mikrotik but in general it is a good idea.
We see packet drops even on moderately used licensed links which are connected with GigE. Packets arrive at fluctuating rates which fill buffers quite fast.
So you suggest to use flow control on interfaces where the radio is connected... for example on the port on the switch where the EPMP is connected to... or on a router port if the epmp is connected directly to a router port?
thank you
Yes. This is the way to avoid/reduce packet drops between 2 speeds. SAF has a good whitepapers describing what is happening there. Some switches/media converters have no buffers then it makes sense to enable flow control on the next hop.