Is there a preferred setting for Link Layer Encapsulation for Fiber internet connections?
Maybe this will help.
I’m talking about in IPFire->Services->QoS->bandwidthsettings:
There is a dropdown menu where you must pick a setting for various types of internet connection. Which of these would be best for a fiber connection?
There is no difference for Fibre vs Copper. The packets have the same length and overhead depending on the encapsulation your ISP is using.
You might want to choose PPPoE if you have to dial-in. If you are using DHCP you are quite likely using Ethernet with or without VLAN.
2 Likes
For my home connection on standard cable internet I am using the ‘DOCSIS’ setting (my modem is DOCSIS 3.1). But at work we have a business-grade fiber connection. I believe I have it set to ‘Conservative’ because I didn’t know if there was a better option. @ms you’re suggesting that I can also use the ‘DOCSIS’ setting on our business fiber?
DOCSIS is a protocol that is only being used on cable connections. Not on fibre. So that is most likely the wrong option.
If in doubt try Ethernet.
1 Like
I have been using ‘Conservative’ with no issues. I guess I don’t understand fully how this setting affects QoS. I will try ‘Ethernet’ but what difference would I see? Poor performance?
Not poor, but not ideal.
Basically this setting helps QoS to compute any overheard on the wire. Assuming you have a simple Ethernet connection with 1 Gbps, you can transfer 125,000,000 bytes per second. Not more, not less. Exactly that. This is bytes on the physical wire.
QoS deals with IP packets. They don’t have any Ethernet/PPPoE/etc. headers at this point as that is being added later after IPFire has decided to which interface to send the packet. Therefore, if QoS wants to calculate the total bandwidth it cannot account of the overhead. This is done by this setting which simply adds a few bytes for the extra headers for each packet.
So if your line is not saturated, nothing happens. If your line is absolutely saturated to its maximum all of the time and this setting is incorrectly chosen, IPFire will send more data than configured (due to extra overhead) and packets might pile up in the DSL or cable modem as that is not able to send them fast enough. That fills the buffer in the modem and you will have high latency on the link which we call Bufferbloat.
The conservative setting will assume large overheard and if the uplink rate is correctly configured, the queue in the modem will never fill up. Therefore there is no bufferbloat. It will however not utilise the link to 100%. You might only get something like 99.x%.
That is not poor performance, but mathematically worse than 100%.
5 Likes