Not sure where the problem is...

[Phal]

Thursday night / Friday morning last week we had a little Thunder storm etc. Friday morning my internet was crap :/ lots of packet loss and large chunks of complete loss varying from 10 seconds to 5 minutes.

Later that day I called Virgin support and went through their basic stuff and nothing seemed to make it any better so an engineer visit was organised.

Over the weekend it got better, the packet loss was slowly getting better and the large chunks of complete loss were less frequent.

Yesterday there was still a fair amount of loss when I was testing it using Pingplotter but it was useable at least.

This morning I was supposed to have an engineer visit but I later found out this was cancelled because they thought theyd fixed the damn problem... just forgot to tell me! So I wasted a morning but thats another story...



Now Ive got a Sonicwall TZ190W firewall/route which is plugged into the standard modem they give you.

No problems pinging the router or the modem at all but if I removed the Sonicwall then a lot of the packet loss now disappears. I already tested without the Sonicwall over the weekend and it was still fubared then so I assumed it wasnt the Sonicwall but now this has started to make me think it could be that.

The thing that confuses me is that I can use my Sonicwall with my housemates ADSL connection fine... no packet loss there and thats routed over 2 Netgear ethernet over powerline adapters :/ so that should be more prone to loss.

The Sonicwall is also dual WAN so Ive tried both WAN interfaces with my Cable modem and they both suffer from loss :\

Virgin told me this morning they were investigating slow internet speed around the Brighton area but I dont believe anything they say anymore since they just seem to lie.

Gonna see if I can borrow another TZ190 from work to test ;/ but I dont think its the problem. I even tried different MTU sizes but that made no differences and 1500 seems to be the usual MTU for cable internet.

Any thoughts? lol :|

 

[Skidilliplop]

The second WAN interface is disabled is it not? if it's got a route out of both WAN ports, possibly by accidentally connecting the modem to a different one at some point, then it might well try and load balance between the WAN interfaces. Any packets routed to the interface with no modem on it will be lost and will result in partial and sometimes sporadic packet loss. Make sure the only default route points out the active interface and any manually configurable load balancing settings are disabled. Normally directly attached routes will be deleted when the interface goes down but default routes are not usually treated as directly attached and can remain poining to a downed interface.

Another thing to check is the Duplex setting on the two devices and ensure the cable between them is correct in accordance with the MDI/MDIX settings and not damaged.

There are some other possible causes but these would be the ones i would investigate first.

 

[Phal]

Yeah, the two interfaces are set in Failover mode so traffic is always routed over just 1 interface.

The second interface was plugged into my friends ADSL router and that seemed to work fine with no packet loss which was weird.

As for the duplex settings on the interface, its jus set to auto negotiation? Unless theres other duplex settings somewhere else :| but I just seem to get the usual duplex choices of auto negotiation or 100mbit/10mbit full or half duplex.

 

[Skidilliplop]

sometimes auto netgotiation doesn't work properly. Try forcing them to 100 full and double check the routing table to ensure there is only the one default route.

did you check the cable?

 

[Phal]

Yeah I thought about that but didnt try it :/ guess ill have a play when I get home again.

Its just annoying cos it was working fine before and now it doesnt lol

 

[Skidilliplop]

That is why i would think it's a dynamically controlled thing like speed/duplex negotiation or dynamically learned routes, if no config wiring method has been changed at all.

Metal Fatigue and cable failures are also plausible.

 

[Phal]

Possibly :/ the cable Im using to link the WAN interface to the VM Cable modem is the freebie patch cable they give you with the modem. Its not very old but I doubt its particularly high quality.