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Author Topic: Weird latency issues with Dual WAN and Netgear SRX5308  (Read 1926 times)


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Weird latency issues with Dual WAN and Netgear SRX5308
« on: August 24, 2015, 03:23:33 PM »


I'm going to share my experience of an issue I've been having with my Dual FTTC WAN and my SRX5308. Hopefully someone might have some insight into what's causing it.

I got the SRX5308 in January this year and it worked ok until a couple of months ago when I started to see weird latency spikes on my thinkbroadband ping monitor graphs, the latest which looks like this

The errors all occur between 9am and 10:30pm. My domestic, 3 years old, boiler operates between 5.30am and 10pm. It doesn't generate a massive noise and there are no funny bursts of noise I've been able to detect. Each loss is between 4 and 60 seconds long.

So I've done a lot of troubleshooting:

Firstly my LAN. It's composed of three VLANs (default, VLAN ID 5 and 6). 5 and 6 are used to give access to IGMP IP-TV from BT, without saturating my LAN. The LAN seems to work really nicely.

The VDSL lines are performing at a pretty normal rate for the length of the circuit. They have some CRC errors, about 40 per hour, and operate without interleave.

The first WAN uses an HG612 and PPPoE the second WAN is connected to a BT HH5 which provides DHCP to the SRX. Testing the HH5 directly I can bypass the loss of WAN completely. So I initially though it must be a problem with the SRX, and the support agent at Netgear agreed and replaced it. The new SRX has the same issue.

I've taken the original config and then factory wiped it and set it up with single WAN and it appears to work OK. When I add the second WAN it starts failing again.

To be honest I've lost faith in the SRX5308 and am probably going to replace it with a PC hardware device running pfSense. But I wondered if I'm missing something obvious to someone with more skill and understanding than me.

I've taken out some data from the stats from the VDSL modem. At the point this excerpt was taken, the line had been  up for about 3 or 4 days. I restarted it after installing a UPS to see if there was a power supply issue!

adslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   0
Last initialization procedure status:   0
Max:   Upstream rate = 25404 Kbps, Downstream rate = 70388 Kbps
Bearer:   0, Upstream rate = 20000 Kbps, Downstream rate = 71102 Kbps

Link Power State:   L0
Mode:         VDSL2 Annex B
VDSL2 Profile:      Profile 17a
TPS-TC:         PTM Mode(0x0)
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    6.1       9.2
Attn(dB):    13.0       0.0
Pwr(dBm):    13.5       1.6
         VDSL2 framing
         Bearer 0
MSGc:      18      150
B:      239      236
M:      1      1
T:      22      5
R:      0      16
S:      0.1074      0.3771
L:      17872      5410
ES:      792      33
SES:      0      0
UAS:      26      26
AS:      257593


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Re: Weird latency issues with Dual WAN and Netgear SRX5308
« Reply #1 on: September 14, 2015, 11:27:12 AM »

Just as an update to this issue...

I dumped the srx5308 and now have a pfsense box doing the job... It's stopped the weird latency issues.

pfsense is so much better.



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Re: Weird latency issues with Dual WAN and Netgear SRX5308
« Reply #2 on: September 14, 2015, 03:39:57 PM »

Sometimes things just have to go this way. Pleased that you're doing better.