When creating a VLAN, what does the priority setting actually do?
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Can anyone explain how the priority setting when creating a VLAN in pfSense affects traffic? Would it function any different than if I setup a PRIQ traffic shaping rule on a VLAN interface after I created it?
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802.1p values.
https://en.wikipedia.org/wiki/IEEE_P802.1p
If I set vlan 5 to proirity 5 I see the following:-
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So from what I'm reading its QoS applied at the Layer 2 level. Maybe this is a dumb question but does that mean this is only really useful if I'm saturating my switch capacity?
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More saturating the output to a single port. There's a problem with switches often called "funneling" where a port is overwhelmed with traffic from multiple ports. Beyond that, these days, it takes some effort to saturate a switch. If you're worried about end to end priority, you have to look at diffserv at the IP level.
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I could see that being a possibility on a trunk port but its never been a problem that I have witnessed. I don't personally have any traffic flow problems but I read a guide about setting up VLANs in pfSense for VoIP and they said it was absolutely critical to set the priority when creating the VLAN. I was just curious whether it provided much benefit or not.
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Well, you have to understand the traffic on the LAN to say it's critical. With Gb LANs, it's not likely to be an issue, unless you have a lot of traffic. A lot of this sort of thing was developed back in the 10 Mb days, when it was easier to saturate a LAN.
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That wikipedia article suggests that the default should be 1, not 0. The pfsense docs say of VLAN Priority: "Leave at the default value, blank". But blank isn't the default in the web UI, 0 is.
So I'm wondering if there's a UI bug here, and the default should really be 1...
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default is best effort.. Which is what it will be when you leave it at 0
In the article you linked to - look at the pcp value.
It just shows that 0 in the gui, because you haven't set a value. ie its blank ;) and zero is the default. Notice how the 0 is grey.. and its not really there if you try and edit it.
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Wow that grey is subtle, but I see it now.
Looking at the wiki article again, I see the confusion: look how the first column has 0 and 1 reversed, unlike the second column.
So what wiki refers to as "priority" (second column) is not what pfsense means by "priority". In fact, pfsense wants the raw PCP value, it seems.
Thanks!