NEED HELP: Throughput halved over VLAN

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Goobie

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Hello.

I'm tinkering with my home network and I noticed that when I run Iperf between 2 PCs connected to the same switch but on different VLANs the throughput is halved. Is this because the switch is old or is this a configuration problem?

The setup:
PC1 (VLAN1) ---> Netgear GS716T Gigabit managed switch ---> PC2 (VLAN1) = 900Mb/s
PC1 (VLAN1) ---> Netgear GS716T Gigabit managed switch ---> PC2 (VLAN2) = 580 Mb/s

Apart from this speed issue the VLANs work as they should. In case anybody was wondering; VLAN2 is for my CCTV cameras

Thank you
 
How you getting from vlan1 to vlan2? Something must be acting as the router between the 2 vlans, I'd look at that device as the culprit.
 
On the firewall is vlan1 and vlan2 on the same physical network card ?

If so might be worth testing if you move the vlan's to seperate cards.
 
warwickw said:
On the firewall is vlan1 and vlan2 on the same physical network card ?

If so might be worth testing if you move the vlan's to seperate cards.
Click to expand...

On the router? Yes it is

it look something like this

PC1 (VLAN1)
|
Netgear GS716T---PFSENSE---WAN
|
PC2(VLAN2)
 
What router hardware is it ? Can you add another NIC attached to the switch on vlan2
 
warwickw said:
What router hardware is it ? Can you add another NIC attached to the switch on vlan2
Click to expand...

It is one of those small form factor PCs from China (almost like a NUC) but with 2 NICs

Intel(R) Celeron(R) CPU J1800 @ 2.41GHz
Current: 2407 MHz, Max: 2408 MHz
2 CPUs: 1 package(s) x 2 core(s)

so cannot add another NIC
 
What happens if you move the PC in to Vlan2, do you get gig speeds?

Where is the routing done between vlan 1 and 2?

Looking your diagram from vlan1 to 2, it doesn't go through the firewall?

What's the CPU doing on the router? When you move traffic across vlans it has to be routed so if CPU is under strain it will have a performance impact.

Traffic with in the same vlan will be switched
 
gregmcc said:
What happens if you move the PC in to Vlan2, do you get gig speeds?
Click to expand...

If I move PC1 also to VLAN2 then yes I get gig speeds

gregmcc said:
Where is the routing done between vlan 1 and 2?
Click to expand...

Must be in the pfsense router...I don't know

gregmcc said:
Looking your diagram from vlan1 to 2, it doesn't go through the firewall?
Click to expand...

correct

gregmcc said:
What's the CPU doing on the router? When you move traffic across vlans it has to be routed so if CPU is under strain it will have a performance impact.
Click to expand...

when on the same VLAN then CPU is at 6%
when on different VLANs then the CPU shoots up to 90/97%
 
Last edited:
Just to summarise, default gateway in both vlan's is the pfsense router.
pfsense router spikes to 90% when crossing the vlan.

Bottleneck here looks to be the pfsense router.
 
Goobie said:
If I move PC1 also to VLAN2 then yes I get gig speeds



Must be in the pfsense router...I don't know



correct



when on the same VLAN then CPU is at 6%
when on different VLANs then the CPU shoots up to 90/97%
Click to expand...
There's your problem. Your firewall is not beefy enough to work at wire speed.
 
Sinbad said:
Why do you need gigabit between your cameras and the rest of the lan?
Click to expand...

Oh damnit I guess you are right! I have 4 VLANs and being able to move big files around at full speed would be nice, but then the few times that this happens I probably can wait a few minutes longer for the transfer to complete.
 
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