USG Flex 100H and GS1920-24HPv2 VLAN and LAG Internet speed issue

snekbaev · October 4

Hi,

USG fw: V1.35(ABXF.2)
Switch fw: V5.00(ABMI.1)

I've configured everything needed: separate zones (not using existing LAN zone), VLANs, policies, configured LAG (LACP) on 3 ports and connected to switch. Everything seems to be fine, however, after that I decided to test Internet speed using services like speedtest.net and fast.com, the former showed 1/3 of our 1 Gb/s WAN, sometimes it's half, occasionally climbs to 7xx-8xx Mb/s, but generally seems to stay 1/3 or 1/2-ish, while fast.com shows around 100 Mb/s, usually a bit lower, with rare spikes to 150 Mb/s, but consistently close to 100 Mb/s over multiple tests. I tested by connecting the PC to the modem - close to max, plugged it to USG directly into LAN zone (reserved some ports for troubleshooting), lower, but still closer to the max, however, via switch - as described above. Tried mingling with cables, unplugged 2 out of 3 LAG ports, changed LAG to be 2 port only, moved switch LAG ports from 26, 27, 28 into 1-24 range (22, 23, 24) - same thing. Tried changing LAG hashing algorithm to src-dst-mac, same on the switch, doesn't seem to make much difference from what my config of src-dst-ip-mac and src-dst-ip on the switch was. In the end, to rule out LAG-related issue I removed port 22 from LAG on the switch and port 6 from the USG. Then in the "Interfaces" on USG for all VLANs changed the member from LAG interface to p6. And then when tested speeds were like as if I'm plugged into USG directly - near max. Changed VLANs back to use existing LAG the issue came back, changed to p6 - all good.

What am I missing from the configuration? Or is there a problem with the software given, afair, this USG model just recently got VLAN support for LAG interfaces?

Thank you!

Follow up questions:

for LAG (LACP) do I need to have odd or even number of ports for the best utilization?
on GS1920 there are extra combo ports, for the best performance, should I keep the switch LAG ports in the 1-24 range or can I move them back to 25-28 combo port range?

Thanks again!

PeterUK · October 4

So in short testing without a LAG to the USG speed is fine but not with a LAG?

This might be a performance issue not known?

So why you need a LAG? as the USG FLEX 100H only has 1Gb a LAG would not seem to help here? I could understand if you had two LAG groups per subnet to have LAN traffic between subnets go fast or if you had the FLEX 200H with 2.5Gb as WAN and LAG 1Gb ports to even out the bandwidth.

so some tests you can do are get a Download Manager like FDM 3.9.7

Free Download Manager for Windows | Download

Find a test download or ISO and start with one thread and see how fast that downloads (after Preparing files on the disk should pick up speed) then add threads + to see if download speed scales.

snekbaev · October 4

Hi,

in my (limited networking) understanding idea is to create a somewhat single channel/pathway with several 1 Gb/s lanes, so that traffic from/to VLANs between (depending on policies) and outgoing to WAN will utilize the same pipe but will be sorted depending on their ip/mac values, felt simpler, at least. And yes, I'm interested why LAG (even with one cable connected) behaves the way it does

Thank you!

PeterUK · October 4

So yes do the download I said you could also check the CPU of the Flex as you download

snekbaev · October 4

will check next week when in the office, but earlier looked at CPU while doing speedtest.net, if not mistaken it stayed under 15%-20%. However, won't be surprised if speed will be good, as mentioned in the original post: occasionally speedtest.net did go close to ~800 MB/s, but not as stable (and higher) when just port was used. The fast.com test, on the other hand, immediately indicates an issue ~1/10 speed vs when going through port.

snekbaev · 7:19AM

ah, forgot to ask earlier: at home I have GS1900 and after the LAG interface was created I've assigned my VLANs to that interface, not ports. But in GS1920 UI I don't see the LAG interface in VLAN configuration, only ports, so I assigned VLANs to ports that are in the LAG group. AFAIR, I tried clicking around but didn't see an option to actually use LAG (as I have at home). Is this the way it is done in case of GS1920? Wasn't 1900's approach more logical or? Thank you!

PeterUK · 10:29AM

I don't think currently the FLEX H had VLAN LAG support

As for the GS1900 LAG I'm not sure about that one I'm thinking what you might be seeing in the LAG Management that list available with ports and VLAN? The GS1920 and other models to add VLAN to a LAG you don't do it at the LAG section but VLAN section after setup of the LAG.

snekbaev · 11:46AM

before posting I read:

https://community.zyxel.com/en/discussion/29502/vlan-over-lag-is-not-currently-supported-wtf
https://support.zyxel.eu/hc/en-us/articles/27011543473298--FAQE-USG-FLEX-H-Series-VLAN-Assignment-to-LAG-Interface-uOS-1-32-Why-does-the-new-UI-approach-allow-configuration-of-unsupported-features

given I'm on 1.35 assumed I'm good, I didn't see any "beta" notice.

In GS1900: "Configuration → VLAN → VLAN Port" there for each VLAN I select from the dropdown I can see all my ports and then LAG1 to LAG8 listed. And I have configured LAGx for VLANs I need, not the ports in these LAG groups. Similarly, if I go to "Configuration → VLAN → Port" it also lists all the ports and LAG1-LAG8 separately. In GS1920 when configuring LAG interfaces it shows predefined names like T1 to T14, ok, but then when I need to configure VLAN (different view) I only see ports, not a single Tx interface. Thus I assumed I actually need to configure ports instead of Tx interfaces which made less sense to me unlike with GS1900. So either I've missed something in the UI or there's a bug in the firmware and LAG interfaces are not listed or this is how you configure GS1920 when it comes to LAG and VLAN which is, as mentioned, less intuitive.

USG Flex 100H and GS1920-24HPv2 VLAN and LAG Internet speed issue

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