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Network connection dropping for PC's but not for IP phones on a VLAN`
We recently had a new building added to our site. In that building we have a 3x Netgear GS748TPS switches which are stacked. 2 out of 3 of those stacked switches have fibre connections which are in a LAG uplink back to our core switch.
In this new building we have our PC's etc on the default LAN, but we have our VoIP system on a VLAN.
The connection to the PC's keeps dropping at random times for short periods. The connection to the IP phones on the VLAN does not drop and is consistently up.
If you look at the attached image, this shows me pinging a PC (left) and Phone (right) at the same time. The PC and phone are on the same desk and connected into the same switch. They are not daisy chained and they are in separate sockets (the socket which has the phone is tagged).
Something seems to be causing the default LAN connection to repeatedly drop. Seeing as the VLAN seems to be performing well I am sure it is not anything physical and is probably something that needs configuring on the Netgear switch.
What might be causing this? We currently only have one person working in this building and it is now causing problems. Very soon we will have a team moving in so we need to get it sorted as soon as possible.
Any help appreciated.
In this new building we have our PC's etc on the default LAN, but we have our VoIP system on a VLAN.
The connection to the PC's keeps dropping at random times for short periods. The connection to the IP phones on the VLAN does not drop and is consistently up.
If you look at the attached image, this shows me pinging a PC (left) and Phone (right) at the same time. The PC and phone are on the same desk and connected into the same switch. They are not daisy chained and they are in separate sockets (the socket which has the phone is tagged).
Something seems to be causing the default LAN connection to repeatedly drop. Seeing as the VLAN seems to be performing well I am sure it is not anything physical and is probably something that needs configuring on the Netgear switch.
What might be causing this? We currently only have one person working in this building and it is now causing problems. Very soon we will have a team moving in so we need to get it sorted as soon as possible.
Any help appreciated.
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Do you have more than one PC up and running at the same time?
Do they drop at the same time?
If they do, does it matter on which switch of the stack you are connected or not?
If you run taskmanager at the same time, do you see the CPU go up while the pings fail?
How is the stack attached to the core switch?
Do they drop at the same time?
If they do, does it matter on which switch of the stack you are connected or not?
If you run taskmanager at the same time, do you see the CPU go up while the pings fail?
How is the stack attached to the core switch?
I have 2 PC's currently setup in the building. If I ping them both at the same time, the connections do NOT seem to drop at the same time.
The PC's are in different switches in the stack.
The stack is connected to the core switch via 2x fibre connections. One of these fibre connections in in switch 1 the second is in switch 2. These are members of an Uplink LAG back to the core switch to provide redundancy.
I have kept an eye on task manager and have not noticed the CPU going up during these drop outs.
The PC's are in different switches in the stack.
The stack is connected to the core switch via 2x fibre connections. One of these fibre connections in in switch 1 the second is in switch 2. These are members of an Uplink LAG back to the core switch to provide redundancy.
I have kept an eye on task manager and have not noticed the CPU going up during these drop outs.
This may or may not be related but while testing I have noticed something which is quite interesting.
While rdp'ing to the pc just now to monitor task manager, the connection was barely dropping at all. After I logged off and ended the rdp session the dropped packets got a lot worse.
Almost like the connection drop outs are worse if there is not a constant stream of traffic to/from the PC (like a semi-sleep mode).
Like I say though, that could be coincidence as the drop outs are so random
While rdp'ing to the pc just now to monitor task manager, the connection was barely dropping at all. After I logged off and ended the rdp session the dropped packets got a lot worse.
Almost like the connection drop outs are worse if there is not a constant stream of traffic to/from the PC (like a semi-sleep mode).
Like I say though, that could be coincidence as the drop outs are so random
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What type of network cards do you have in the PC? Are they at the latest driver level?
Have you checked the duplex on the port?
Yes, set as "Full"
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Have updated the NIC driver (its an onboard intel driver). I still get the same result
Which subnet are you pinging from?
Have you checked the links on the LAG, are there any errors on the ports? Are they both set to Full Duplex also?
What happens when you try using one uplink instead of two in a LAG?
Have you checked the links on the LAG, are there any errors on the ports? Are they both set to Full Duplex also?
What happens when you try using one uplink instead of two in a LAG?
I am pinging from the same subnet as the computers.
Do you know how I can check the links on the LAG for errors?
The LAG is set to 'FULL' duplex mode.
To test your last suggestion regarding using one uplink, should I just physically remove one of the uplinks? Or should I do this in the switch firmware?
Do you know how I can check the links on the LAG for errors?
The LAG is set to 'FULL' duplex mode.
To test your last suggestion regarding using one uplink, should I just physically remove one of the uplinks? Or should I do this in the switch firmware?
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I do not know the config of your switches but is there a duplex setting of auto? If so, please set it to auto and see what the negotiation results are. If duplex then you should be ok, if half-duplex you may have found one possible error.
sb1mpo - thank you, i will hopefully find a suitable opportunity to try that today and will post the results.
mat1458 - the switch has only has the option of FULL or HALF duplex mode. All live ports are set as FULL.
mat1458 - the switch has only has the option of FULL or HALF duplex mode. All live ports are set as FULL.
I have not had a chance to physically remove one of the uplinks but had a weird issue just now.
One of the PC's totally dropped off the network for over 5 mins (the other was behaving as per usual). My colleague was in the building so asked him to look at all the connections. They were all fine and the activity light was flashing in the back of the PC.
He unplugged the cable from the PC and plugged it back in. This then got things going again.
One of the other symptoms that has been reported is that every morning the computer needs to be restarted to establish a network connection. It almost acts as if the NIC goes to sleep. However, i have an identically imaged PC which I have in our office and that Pings perfectly and does not appear to drop a beat.
One of the PC's totally dropped off the network for over 5 mins (the other was behaving as per usual). My colleague was in the building so asked him to look at all the connections. They were all fine and the activity light was flashing in the back of the PC.
He unplugged the cable from the PC and plugged it back in. This then got things going again.
One of the other symptoms that has been reported is that every morning the computer needs to be restarted to establish a network connection. It almost acts as if the NIC goes to sleep. However, i have an identically imaged PC which I have in our office and that Pings perfectly and does not appear to drop a beat.
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It is looking like the LAG is the issue.
As suggested by sb1mpo I have disconnected one of the two fibre connections in the LAG. I have been pinging the PC's for a few minutes now and I have not seen a drop yet.
I will monitor it for the next hour or so, but can anyone suggest what I have done incorrectly with the LAG configuration? Is there a good guide for configuring a LAG for Netgear switches?
As suggested by sb1mpo I have disconnected one of the two fibre connections in the LAG. I have been pinging the PC's for a few minutes now and I have not seen a drop yet.
I will monitor it for the next hour or so, but can anyone suggest what I have done incorrectly with the LAG configuration? Is there a good guide for configuring a LAG for Netgear switches?
Can you first check the other link of the LAG? If the errors reappear one of the ports might be broken, otherwise the LAG config could be faulty.
The interface statistics (including errors) should be visible through RMON (see http://documentation.netgear.com/gs700tp/enu/202-10393-01/GS700TP_UG-09-10.html#wp137796).
For the LAG configuration I'd choose a LACP config. When the LAG is set up dynamically eventual errors would bring the LAG down automatically. With a static configuration you can create black holes (see http://documentation.netgear.com/gs700tp/enu/202-10393-01/GS700TP_UG-06-06.html).
The interface statistics (including errors) should be visible through RMON (see http://documentation.netgear.com/gs700tp/enu/202-10393-01/GS700TP_UG-09-10.html#wp137796).
For the LAG configuration I'd choose a LACP config. When the LAG is set up dynamically eventual errors would bring the LAG down automatically. With a static configuration you can create black holes (see http://documentation.netgear.com/gs700tp/enu/202-10393-01/GS700TP_UG-06-06.html).
I would first start by checking interface errors on the LAG ports on either side of the link. If you see any then either the config is wrong or the cable is bad, but I would go with the second one and replace the cable.
Simon
Simon
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The Windows operating systems have distinct methodologies for designing and implementing networks, and have specific systems to accomplish various networking processes, such as Exchange for email, Sharepoint for shared files and programs, and IIS for delivery of web pages. Microsoft also produces server technologies for networked database use, security and virtualization.