How to confirm slow switches

WildMonkey365 · Aug 30, 2016

Im trying to determine if replacing Switches at a large office (100 PC's and 70 VoIP Phones) will improve Latency issues from Router to every switch in a 5 switch stack. Is doing a speed tests (speedtest.net) on all switches and the Router a good step to take?

gbb0330 · Aug 31, 2016

the fact that you are considering speedtest to diagnose "Latency issues from Router to every switch in a 5 switch stack" makes me wonder, how did you determine that there is a latency issue between the router and the switches?

WildMonkey365 · Aug 31, 2016

gbb0330 :

WildMonkey365 · Aug 31, 2016

I installed a VoIP system (Edgemarc Router and 70 phones that auto negotiates at 1000 Mb Full) the customer had an existing VoIP system and I never looked at the the switch speed rating whether they were 100 Mb or 1000 Mb. The install was successful and the phones worked. The customer, however, complained about lagging call quality and PC speed on most phones and PC's. They had a tech go in and I was told he found a bottle neck in one of the switches and they replaced all 5 switches with 1000 Mb switches and the problem went away. My real question is... How would you confirm that replacing the switches would benefit the situation and how would you find a bottle neck in a switch?

gbb0330 · Aug 31, 2016

those are most likely managed (smart) switches, they have management interface and provide all kinds of statistics.

bill001g · Aug 31, 2016

You would only see a bottleneck in a switched network if you had a poor design. Switches in general run at what is called wirespeed now days. Even the very cheap 4 port switches you can get run that fast. This means every port can run at maximum speed in and out all at the same time. That means a 24 port switch can run 48g of bandwidth with all ports running maximum rate in and out.

You can never bottleneck a single switch.

Now if you have multiple switches connected together if you do not know your traffic patterns you could exceed the ports that run between the switches. Stacked switches eliminate most this problem because they make it appear as a single switch. There is a potential bottleneck in the stacking cables but this is a huge bandwidth that is normally 10g or faster depending on the manufacture.

WildMonkey365 · Aug 31, 2016

gbb0330 :

WildMonkey365 · Aug 31, 2016

What are your thoughts on this... The router I use auto negotiates at 1000/gigabit, the VoIP phones I use auto negotiates at 1000/ gigabit, so the switches used between the router and the phones need to be 1000/gigabit also. Do you think 70 phones+100 PC's (on a seperate subnet/Vlan) Connected to 10/100 switches, would definitely present speed issues on the LAN given that the router and phones auto negotiates at Gigabit?

bill001g · Aug 31, 2016

The phones themselves likely use less than 100kbits/sec each and many times less if you are using a compression codec.

Still if the connection between the router and the switch was only 100m and you had both vlans running over it as a 802.1q trunk then you can easily overload that. You could overload a gig connection if you had enough pc-pc traffic on different vlans.

Now the standard solution is to use layer3 capable switches so the routing between vlans is done in the switch and never goes to the router. A actual router would only be used to get to the internet or maybe a remote office connected via some form of private network.

WildMonkey365 · Aug 31, 2016

Thanks. The Voip and Data are coming from seperate routers into the managed switch. Is there a way to tell if The uplink from router to switch and from switch to switch in a large stack is bottle necking in one particular area or just plain overloaded.

bill001g · Aug 31, 2016

It depends on the switch. Most have the ability to look at current utilization rates but you would have to manually check over a period of time. This is why many companies have network monitoring software. These use SNMP to collect data from the switch on every port and give you nice long term reports. Some of the simpler free ones are mrtg or cacti but there are many more. Their are much more advanced commercial tools..solar winds is one that comes to mind but there are a bunch.

WildMonkey365 · Aug 31, 2016

bill001g :

It depends on the switch. Most have the ability to look at current utilization rates but you would have to manually check over a period of time. This is why many companies have network monitoring software. These use SNMP to collect data from the switch on every port and give you nice long term reports. Some of the simpler free ones are mrtg or cacti but there are many more. Their are much more advanced commercial tools..solar winds is one that comes to mind but there are a bunch.

WildMonkey365 · Aug 31, 2016

are those tools like mrtg or cacti something I can put on my laptop and run/capture while connected to a switch. If so will they confirm over utilization or tell me where a bottle neck is on a particular switch?

bill001g · Aug 31, 2016

Both those are unix based I think. There are some windows based ones and I think solar winds has free and trial based software that will run on windows. To get good results you need to let it run for while so it can actually capture data when the problem occurs. A dedicated device is a much better option but I suppose you could use your laptop.

WildMonkey365 · Sep 1, 2016

bill001g :

You would only see a bottleneck in a switched network if you had a poor design. Switches in general run at what is called wirespeed now days. Even the very cheap 4 port switches you can get run that fast. This means every port can run at maximum speed in and out all at the same time. That means a 24 port switch can run 48g of bandwidth with all ports running maximum rate in and out.

You can never bottleneck a single switch.

Now if you have multiple switches connected together if you do not know your traffic patterns you could exceed the ports that run between the switches. Stacked switches eliminate most this problem because they make it appear as a single switch. There is a potential bottleneck in the stacking cables but this is a huge bandwidth that is normally 10g or faster depending on the manufacture.

WildMonkey365 · Sep 1, 2016

can you explain how a 24 port switch can run 48g of bandwidth? thats twice what I would assume. I would think a 24 port gigabit switch could run 24g of bandwidth being that there is 24 ports each 1000meg...

bill001g · Sep 1, 2016

Ehternet is full duplex it can transmit and receive 1g of data at the same time.

WildMonkey365 · Sep 1, 2016

bill001g :

You would only see a bottleneck in a switched network if you had a poor design. Switches in general run at what is called wirespeed now days. Even the very cheap 4 port switches you can get run that fast. This means every port can run at maximum speed in and out all at the same time. That means a 24 port switch can run 48g of bandwidth with all ports running maximum rate in and out.

You can never bottleneck a single switch.

Now if you have multiple switches connected together if you do not know your traffic patterns you could exceed the ports that run between the switches. Stacked switches eliminate most this problem because they make it appear as a single switch. There is a potential bottleneck in the stacking cables but this is a huge bandwidth that is normally 10g or faster depending on the manufacture.

WildMonkey365 · Sep 1, 2016

bill001g :

WildMonkey365 · Sep 1, 2016

My company Uses Dlink DGS 1210-28 model switches. All ports are gigabit/poe. the max throughput is 56g according to Dlink. How can I know if the switch and to be more specific, how can know if an uplink port between switches are being over utilized?

bill001g · Sep 1, 2016

Can't say I use mostly cisco,HP, juniper switches and those are pretty obvious. Didn't find a manual when I went looking but I did find their expensive monitor software for those switches. There has to be a menu someplace that will display the port utilization. Hard to say since it is mostly a GUI based system. Those you search and search for the page you want which is why I prefer command line switches where you can just search the manual for the command. There are suppose to have a command line also but it is hard to say if they include all the support. Devices that are designed to be web configured tend to have limited command support.

WildMonkey365 · Sep 3, 2016

bill001g :

The phones themselves likely use less than 100kbits/sec each and many times less if you are using a compression codec.

Still if the connection between the router and the switch was only 100m and you had both vlans running over it as a 802.1q trunk then you can easily overload that. You could overload a gig connection if you had enough pc-pc traffic on different vlans.

Now the standard solution is to use layer3 capable switches so the routing between vlans is done in the switch and never goes to the router. A actual router would only be used to get to the internet or maybe a remote office connected via some form of private network.

WildMonkey365 · Sep 3, 2016

bill001g :

The phones themselves likely use less than 100kbits/sec each and many times less if you are using a compression codec.

Still if the connection between the router and the switch was only 100m and you had both vlans running over it as a 802.1q trunk then you can easily overload that. You could overload a gig connection if you had enough pc-pc traffic on different vlans.

Now the standard solution is to use layer3 capable switches so the routing between vlans is done in the switch and never goes to the router. A actual router would only be used to get to the internet or maybe a remote office connected via some form of private network.

WildMonkey365 · Sep 3, 2016

My company just sold a 200 phone Voip hosted system. I can only assume there is also 200+ PC's on the new customers existing LAN. Do you think we could get away with using Standard Layer 2 Managed Switches (All Gigabit) connecting from Switch to Switch, if the Data Vlan and Voip Vlan are going into seperate Uplink/Connection Ports on the Main Switch? The connection from the Voip Router to Main Switch will Auto Negotiate at 1000Mb on both sides.

bill001g · Sep 4, 2016

If you have separate uplinks for the 2 vlans then it would be close to impossible to exceed 1g of bandwidth with just voip phones.

You are lucky to be able to install that way. Most VoIP installation I have done lately want to save money and use soft client phones on the pc. Even some user complain that they don't want a phone on the desk and want to just click on the person email in outlook and be able to make phone calls to them.

How to confirm slow switches

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