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Author Topic: Advice on network topography - congestion  (Read 10963 times)

Chunkers

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Advice on network topography - congestion
« on: November 16, 2016, 08:10:54 PM »

My network has grown randomly and with no thought given to its structure, plus I don't know anything about how to properly organise a network.  If I log into my router now there will be at least 35 devices with IP addresses and I am not even sure what they all are.......

Here is my networking strategy :

1. Buy new network device
2. Find spare network port on nearby device
3. Plug device in

Lately I have been having some trouble with buffering between my HTPC server and client devices, now my kids are older the demand on the network has grown considerably, particularly streaming video which is what everyone seems to want to do. 

Its a bit of a surprise, as I guess I thought that with Gigabit everywhere I would never have a problem.  I don't think its the server, which has plenty of power and memory.

I have drawn a lovely picture of my network in its current configuration and where I think the bottleneck is, if anyone who understands networking has a chance to have a look any comments appreciated..

Is there a tool I can use to see if there are / where are the bottlenecks?

I reckon LAN5 is the pinch point, presumably with the current configuration each HD video stream has to go in both directions to the router.  I guess it is better to have your servers at the top of the network hierarchy, perhaps I should move my HTPC server onto the main router ?  I think I will try that tomorrow :



Cool beans!  :cool:

Chunks
« Last Edit: November 16, 2016, 08:13:20 PM by Chunkers »
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d2d4j

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Re: Advice on network topography - congestion
« Reply #1 on: November 16, 2016, 08:34:49 PM »

Hi chunkers

Others may disagree but you have a small network, and it does not look bad from your pic

I would not move your htpc yet, rather I would look at what devices are having the issue streaming e.g. Are the devices on wifi - which I'm thinking they are

You may have a mismatch between 100/1000 on the wap devices

Do you use vlans

Is your htpc capable of nic bonding, but you need to check your switch as well, or you could end up with a storm

Is your switch a managed switch - if so, what level switch - I guess level 2

Have you run any speed tests on network

If wifi devices are having the issue - which wap are they mainly connected too - if power plug wap - hardwire it

Are all devices on same node or have you separated them

On your loadbalancer, have you set any QoS, and are your settings correct for bonding/loadbalance/DNS etc

Can you reproduce the slowness

I hope that helps a little but there is more, just run out of time sorry

Many thanks

John
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Chunkers

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Re: Advice on network topography - congestion
« Reply #2 on: November 16, 2016, 09:27:53 PM »

Hi chunkers

Others may disagree but you have a small network, and it does not look bad from your pic

I would not move your htpc yet, rather I would look at what devices are having the issue streaming e.g. Are the devices on wifi - which I'm thinking they are


Thanks for your reply, great to get some advice and glad it looks OK.  I assumed the problem was network related because I see the buffering on both wireless and wired clients, I have some suspicions about my switch which is an unmanaged TP-Link TL-SG1008D (mine is version 1, version 7 now on sale) - it is a gigabit switch and does appear to be working correctly.  Regarding your questions

Do you use vlans

No

Is your htpc capable of nic bonding, but you need to check your switch as well, or you could end up with a storm

The server is running MediaPortal on Windows 10 and currently has a single NIC (motherboard), I could obviously install more NIC's

Is your switch a managed switch - if so, what level switch - I guess level 2

It's one of these TP-Link TL=SG1008D switches, unmanaged (Version 1)

Have you run any speed tests on network

No, but I could easily do this, I am getting green lights on my main router which suggests it sees a Gigabit connection but I don't have any data for downstream

If wifi devices are having the issue - which wap are they mainly connected too - if power plug wap - hardwire it
Not consistent really, all three, the reason I have three WAP's is to get coverage in all parts of the house

Are all devices on same node or have you separated them
Not really sure what this means

On your loadbalancer, have you set any QoS, and are your settings correct for bonding/loadbalance/DNS etc
My loadbalancer is only managing WAN loads as far as I can see.  My router has lots of diagnostics, I just found this, not sure if its any help :



Can you reproduce the slowness
Its not really consistent to be honest but I only really notice it when I am watching TV on a client, very occasionally I will get buffering - which seems weird because its all local to my network.

Cheers!

Chunks
« Last Edit: November 16, 2016, 09:35:55 PM by Chunkers »
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sevenlayermuddle

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Re: Advice on network topography - congestion
« Reply #3 on: November 16, 2016, 10:21:04 PM »

One can theorise about the benefits/drawbacks of multiple switches vs density of cabling.   But in practice I've found you can get away with an awful lot,  I've only ever identified two factors that ever caused real symptoms...

1) wireless..  It has I improved a lot, with amazingly good theoretical performance, that will sometimes even be seen in real world performance.    But in demanding or hostile environment, it never come close to being a substitute for wired lan.

2) hardware failure... I don't know whether your switches would be classified as 'consumer grade' but if they are, they are likely stuffed full of aluminium electrolytic capacitors with a design life of a few months to a year or two.   Failure mode often manifests in high error counts, with retransmissions that impact performance of connected equipment.

Just my opinion, based on personal experience that may or may not be typical.  :)
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Chrysalis

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Re: Advice on network topography - congestion
« Reply #4 on: November 16, 2016, 10:23:22 PM »

QoS I suspect can solve this.

Also yeah 5ghz wireless AC exceeds 100mbit ethernet comfortably even with its inconsistent performance it tends to bottom out over 100mbit.
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d2d4j

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Re: Advice on network topography - congestion
« Reply #5 on: November 16, 2016, 10:58:20 PM »

Hi

I hope you don't mind, but my last question was more pertinent as to issue

There is a big lack of information so guess work took over, and I mentioned 100/1000 primary because of wap points (based on it's residential not commercial equipment)

I am not familiar with tp link switches, albeit it's a dumb hub, not switch as we always use HP procurve but I also am not sure what pause is on the pic supplied, but on tapatalk, when trying to view large on pic, it keeps reverting back so is hard to see. I suspect this pause maybe part of the issue perhaps

However, as I first started, if it's not replicateable, then this may suggest it may be a mix of hardware, network etc, and not just 1 failure point

I stress though, there is not enough information to fully determine

Many thanks

John
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Chunkers

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Re: Advice on network topography - congestion
« Reply #6 on: November 17, 2016, 09:31:42 AM »

Thanks for the thoughts, I think I will focus on replacing the old switch first and then start looking at my server - what would people recommend as an 8 port Gigabit switch suitable for home use?

I found this review on Tomshardware which suggests that the Netgear's GS308 is a good choice - its also super cheap on Amazon.

Is there any benefit (for me) in getting a managed switch like this Netgear GS108?  Any reason why I would need a managed switch?

Cheers

Chunks

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Chunkers

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Re: Advice on network topography - congestion
« Reply #7 on: November 17, 2016, 09:43:33 AM »

Hi

I hope you don't mind, but my last question was more pertinent as to issue

There is a big lack of information so guess work took over, and I mentioned 100/1000 primary because of wap points (based on it's residential not commercial equipment)

I am not familiar with tp link switches, albeit it's a dumb hub, not switch as we always use HP procurve but I also am not sure what pause is on the pic supplied, but on tapatalk, when trying to view large on pic, it keeps reverting back so is hard to see. I suspect this pause maybe part of the issue perhaps

However, as I first started, if it's not replicateable, then this may suggest it may be a mix of hardware, network etc, and not just 1 failure point

I stress though, there is not enough information to fully determine

Many thanks

John

Thanks for the advice, here is the description of the data shown in the table :

Unicast:
Displays the number of normal unicast packets received or transmitted on the port.
Broadcast:
Displays the number of normal broadcast packets received or transmitted on the port.
Pause:
Displays the number of flow control frames received or transmitted on the port.

Multicast:
Displays the number of normal multicast packets received or transmitted on the port.
Undersize:
Displays the number of the received frames (including error frames) that are less than 64 bytes long.
Normal:
Displays the number of the received packets (including error frames) that are between 64 bytes and the maximum frame length. The maximum untagged frame this router can support is 1518 bytes long and the maximum tagged frame is 1522 bytes long.
Oversize:
Displays the number of the received packets (including error frames) that are longer than the maximum frame.
Total (Bytes):
Displays the total number of the received or transmitted packets (including error frames).

Not sure if it helps.

Chunks
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Ronski

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Re: Advice on network topography - congestion
« Reply #8 on: November 17, 2016, 10:18:27 AM »

I'm currently using a netgear GS116 and would also be interested in the benefits of a managed switch.

Chunkers, I wonder if it's your HTPC that's struggling, have you looked at disc through put, cpu usage etc?
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d2d4j

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Re: Advice on network topography - congestion
« Reply #9 on: November 17, 2016, 10:32:49 AM »

Hi

In very simple terms, I stress very simple, a switch directs packets to the correct port and not all ports of the switch. A managed switch allows more control over packets at switch level device

A dumb hub outputs all packets to all ports

Also, as sevenlayer states, cheap devices are not built the same, so deprecation is expected.

@xhunkers, on your tplink device you took screen capture from, what is on port 4, where the pause value is high

Many thanks

John

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Chunkers

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Re: Advice on network topography - congestion
« Reply #10 on: November 17, 2016, 10:37:34 AM »

I'm currently using a netgear GS116 and would also be interested in the benefits of a managed switch.

Chunkers, I wonder if it's your HTPC that's struggling, have you looked at disc through put, cpu usage etc?

Good question, yes I have looked at it and I think you are right to be suspicious.  I don't see anything obvious other than I notice that since the Windows 10 upgrade a new LAN driver has been issued which I have now installed.

It is an i5-2500 PC, 8Gb RAM running Windows 10 and with a quad tuner DVB-T2 card installed.  Typically it runs at less than 5% CPU occasionally spiking up to 20%, memory use is usually around 25%.
I have been running it for a couple of years and when I originally put it together I tested it recording 8 simultaneous streams and it coped easily.

I know whats going to happen, I am going to change a whole bunch of stuff and trhe problem will go away without me ever knowing what it was, lol

o7

Chunks
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Ronski

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Re: Advice on network topography - congestion
« Reply #11 on: November 17, 2016, 01:26:07 PM »

It could be disk I/O that's the problem, what kind of setup do you have there? Do you have antivirus or anything else the could be using the disk heavily?

You can go into the resource monitor and view the disk i/o.
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Ronski

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Re: Advice on network topography - congestion
« Reply #12 on: November 17, 2016, 02:04:36 PM »

In very simple terms......

Thanks John, for a more in depth explanation Chunkers might find this useful.
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aesmith

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Re: Advice on network topography - congestion
« Reply #13 on: November 18, 2016, 12:37:03 PM »

Just looking at the drawing, if lengths permit then I'd move LAN 3 and LAN 4 from the router onto the switch.  Keep the switch as the centre of your network.   

Can you make any sort of estimate of the loads that your video streaming puts on the network?  For example is six streams each of 20meg (megabits/sec)?
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Chunkers

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Re: Advice on network topography - congestion
« Reply #14 on: November 18, 2016, 01:45:46 PM »

Just looking at the drawing, if lengths permit then I'd move LAN 3 and LAN 4 from the router onto the switch.  Keep the switch as the centre of your network.   

Can you make any sort of estimate of the loads that your video streaming puts on the network?  For example is six streams each of 20meg (megabits/sec)?

I will have a look at what diagnostics my router has to show data rates as I think it would be useful to see how much the HD streams use.

One question :  Does all data get routed through the main router on a network like mine?

I always assumed that all traffic goes via the router which is why I thought it would be better to have the server on the main router (not the switch) to avoid having the link between the router and the switch (LAN 5) having to cope with double the data rate for each stream i.e. up to the router and then back to the client each time ...... is this wrong?

I replaced the old switch with this new one which arrived from Amazon, was only £20 so figured it was an easy thing to try :



o7

Chunks


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