Still Confused About Switches

[darkarn]

Hi, I read the home network setup guide here (http://www.smallnetbuilder.com/lanwan/lanwan-basics/32065-how-to-improve-network-performance-part-2) and am still unsure why it is ok to connect my devices (laptop, PC, NAS) and APs into one Gigabit switch and then connect the switch into one of my router's LAN ports.

Won't this be as good as all these devices sharing one of the router's LAN ports and thus creating a bottleneck in terms of Internet connectivity?

Thanks!

 

[claykin]

Does your router have Gigabit LAN ports? (many routers still use 10/100 ports) Does your router have enough Gigabit LAN ports for all your devices? If so, just connect all devices to the router.

 

[L&LD]

Unless you have GB WAN (ISP), it shouldn't matter. Same thing happens with each wireless band, for example.

You can, of course, connect the main computer, your NAS and another device to the router's ports so that the connections from any other device to those devices is as fast as possible. The last port will be for the switch and all your secondary devices.

 

[darkarn]

Does your router have Gigabit LAN ports? (many routers still use 10/100 ports) Does your router have enough Gigabit LAN ports for all your devices? If so, just connect all devices to the router.

It does (the new one will have them too), but I don't think 4 will suffice in the really near future.

Unless you have GB WAN (ISP), it shouldn't matter. Same thing happens with each wireless band, for example.

You can, of course, connect the main computer, your NAS and another device to the router's ports so that the connections from any other device to those devices is as fast as possible. The last port will be for the switch and all your secondary devices.

Yep, my ISP will give me 1GBps Internet, hence the concern

 

[L&LD]

With a 1Gbps ISP level, then it is safe to assume that that almost two year old article doesn't apply.


If you have so many devices to connect that the built in ports are an issue, I would connect as I have suggested before or, if needed, put a switch onto each port and spread out the clients that are the most heavily used across the 4 switches.


Keep in mind that while your ISP offers 1Gbps speeds, that doesn't mean that all other internet sites do too. Depending on which specific sites you're using browsing, you may still get the best speeds (without separate switches) from a single switch and all devices plugged into that switch only.

 

[darkarn]

With a 1Gbps ISP level, then it is safe to assume that that almost two year old article doesn't apply.


If you have so many devices to connect that the built in ports are an issue, I would connect as I have suggested before or, if needed, put a switch onto each port and spread out the clients that are the most heavily used across the 4 switches.


Keep in mind that while your ISP offers 1Gbps speeds, that doesn't mean that all other internet sites do too. Depending on which specific sites you're using browsing, you may still get the best speeds (without separate switches) from a single switch and all devices plugged into that switch only.

Ah I see, looks like it will be harder to plan once ISP speeds start to go beyond 1GBps... Anyway, does the rest of the article still applies?

Looks like I will need to use double 5 ports switches then?

 

[L&LD]

When ISP speeds are offered at greater than 1Gbps rates, we should have AC class (with more than 4 antenna) routers that better have 10GBe ports to use those additional streams for more than one client at a time.

Without re-reading that linked article, I'm sure the advice given is still pertinent. With a few adjustments to take into account the fact that the WAN is not the slowest port anymore.

If you really need 8+ ports today, I would be looking at buying a switch for each port as already suggested. 4x 4 port switches will give more overall network performance than 2x 5 port switches can. And may even cost the same or less.

You don't need anything fancy here. Just a switch for each port of your router. And, connecting your devices to these switches in a way that the devices that are usually used online simultaneously are on separate switches. And the devices that interact with each other are on the same switch, if possible too.


For example:

A NAS, a Media Server, an AP and a computer devoted to torrents should be each put on their own switch.

A main computer that uses mostly the NAS should be put on the same switch as the NAS is.

A secondary computer might be best put on the switch with the computer dedicated to torrents.

A printer shared by all devices may be put with the switch that has the AP.

I think you can see that there are more and better possibilities with more switches than with fewer, even if the number of ports used are the same.

Keep in mind too that not all the switches need to be matched (in brand or in number of ports).

If your network usage makes sense to have more devices on a single switch rather than spread out, because they interact with each other frequently, then that switch can have many more ports for those computers than another switch that might only need to host the AP link and a LAN Printer or two.

Hope this is useful.

 

[darkarn]

When ISP speeds are offered at greater than 1Gbps rates, we should have AC class (with more than 4 antenna) routers that better have 10GBe ports to use those additional streams for more than one client at a time.

Without re-reading that linked article, I'm sure the advice given is still pertinent. With a few adjustments to take into account the fact that the WAN is not the slowest port anymore.

If you really need 8+ ports today, I would be looking at buying a switch for each port as already suggested. 4x 4 port switches will give more overall network performance than 2x 5 port switches can. And may even cost the same or less.

You don't need anything fancy here. Just a switch for each port of your router. And, connecting your devices to these switches in a way that the devices that are usually used online simultaneously are on separate switches. And the devices that interact with each other are on the same switch, if possible too.


For example:

A NAS, a Media Server, an AP and a computer devoted to torrents should be each put on their own switch.

A main computer that uses mostly the NAS should be put on the same switch as the NAS is.

A secondary computer might be best put on the switch with the computer dedicated to torrents.

A printer shared by all devices may be put with the switch that has the AP.

I think you can see that there are more and better possibilities with more switches than with fewer, even if the number of ports used are the same.

Keep in mind too that not all the switches need to be matched (in brand or in number of ports).

If your network usage makes sense to have more devices on a single switch rather than spread out, because they interact with each other frequently, then that switch can have many more ports for those computers than another switch that might only need to host the AP link and a LAN Printer or two.

Hope this is useful.

Thanks, this is indeed useful! Helped greatly in clearing one of the main doubts for this home network do-over

I wonder about the theory behind all these recommendations though, where can I start to learn more aside from Wikipedia?

 

[L&LD]

You're welcome.

The theory is simple.

With the router plus 4 switches topology as outlined above, what we are trying to achieve is to group devices so that they affect other users/devices the least amount, depending on what these devices usually do. While also ensuring that when the network is used at it's fullest, it is operating as fast and efficiently as possible too.

All devices require internet access. The four switches (one for each router port) ensure that we have the most flexibility with this primary requirement by allowing a direct connection to the Router, and therefore the internet, from any switch (and any device on those switch's ports). The four switches also allow any device to access any other device on the network, but the most efficient grouping will try to minimize the times that a device needs to connect to another device by going through the switch, through the router (using two of the router ports) and then to the other switch and finally to the intended device.

It doesn't matter for low or intermittent use of devices, or for when most users are not actively using the network (like a printer, a media server for just a few users, or for backup in the middle of the night, respectively). When the LAN utilization is high though, on a NAS or when many users/devices are active, grouping devices optimally can have a huge effect on the responsiveness of the network for all users and devices.


The best connection is always the most direct connection (all else being equal)! Keep the main usage of the device in mind and also when and how heavily it is used. That will guide you to the best grouping for your devices. Of course, we can't design the perfect network with just four ports on our main router; we still need to make judgment calls on which device should have the priority over another device (or group of devices). However, just thinking about this will improve the network vs. connecting devices randomly to our switch's ports.



A further example:
A customer had two switches (16 port and 24 port) on a 4 port router and had all devices (multiple NAS', computers, AP's and printers) connected to them and with one switch connected to the other.

With an upgrade of the main router (mainly to 10/100/1000 ports) and 4 new switches (newer, quieter, no fan noise), the efficiency of the network as a whole was improved exponentially.

After the upgrade:
1st 8 port switch has the 2 main NAS' and 4 main computers connected.

2nd 16 port switch has 12 workers computers connected along with the 2 secondary NAS'.

3rd 8 port switch has the 4 backup NAS' connected.

4th 16 port switch has 6 printers connected along with 2 AP's (private and guest access) and 2 backup NAS' connected.


In the setup above, internet access was required, but mostly at a low level for any one client device. (This is different than your situation, which is why for you, device grouping is even more important - devices that need to interact with other devices on separate switches will also impact all the devices' using internet (heavily) on those switches too).


The 1st switch allowed the main computers direct access to the 2 main NAS units and without interfering with other network users. (This change alone kept the heaviest LAN traffic isolated to a single switch which benefitted all network users).


The 2nd switch allows the secondary computers direct access to their most used data on the secondary NAS and without interfering with other network users. (Again, this change for these workers kept their network traffic isolated from the other users and vice versa and made a huge change to the responsiveness of their immediate tasks).


The 3rd switch allows for the staggered NAS backup functions from the NAS units on the 1st switch. Each main NAS is backed up to each backup NAS on a rotating schedule (they have up to 1 month, 1 week and 3 days worth of backup data for each main NAS). (By using separate switch and router ports for the backup NAS', the backups can run at maximum speed without affecting other network users (router port 1 & router port 3 can communicate at full speeds without affecting router port 2 & router port 4 at all)).


The 4th switch allows for all users to print as needed, allows the AP's a direct connection to the internet as required and hosts the 2 backup NAS' for the 2 secondary NAS's on the 2nd switch. (Again, the backup units are on separate switches from the NAS' that are backed up to allow for the fastest speeds possible. Also, both NAS backups can happen at full speeds; between router ports 1&3 and between router ports 2&4).


Sorry for the wall of text, but I hope that with these added details, it becomes clearer what we want to achieve by 'grouping' devices to certain switches.

Like I said, the theory is simple. Writing it out just makes it seem more complicated.

 

[darkarn]

You're welcome.

The theory is simple.

With the router plus 4 switches topology as outlined above, what we are trying to achieve is to group devices so that they affect other users/devices the least amount, depending on what these devices usually do. While also ensuring that when the network is used at it's fullest, it is operating as fast and efficiently as possible too.

All devices require internet access. The four switches (one for each router port) ensure that we have the most flexibility with this primary requirement by allowing a direct connection to the Router, and therefore the internet, from any switch (and any device on those switch's ports). The four switches also allow any device to access any other device on the network, but the most efficient grouping will try to minimize the times that a device needs to connect to another device by going through the switch, through the router (using two of the router ports) and then to the other switch and finally to the intended device.

It doesn't matter for low or intermittent use of devices, or for when most users are not actively using the network (like a printer, a media server for just a few users, or for backup in the middle of the night, respectively). When the LAN utilization is high though, on a NAS or when many users/devices are active, grouping devices optimally can have a huge effect on the responsiveness of the network for all users and devices.


The best connection is always the most direct connection (all else being equal)! Keep the main usage of the device in mind and also when and how heavily it is used. That will guide you to the best grouping for your devices. Of course, we can't design the perfect network with just four ports on our main router; we still need to make judgment calls on which device should have the priority over another device (or group of devices). However, just thinking about this will improve the network vs. connecting devices randomly to our switch's ports.



A further example:
A customer had two switches (16 port and 24 port) on a 4 port router and had all devices (multiple NAS', computers, AP's and printers) connected to them and with one switch connected to the other.

With an upgrade of the main router (mainly to 10/100/1000 ports) and 4 new switches (newer, quieter, no fan noise), the efficiency of the network as a whole was improved exponentially.

After the upgrade:
1st 8 port switch has the 2 main NAS' and 4 main computers connected.

2nd 16 port switch has 12 workers computers connected along with the 2 secondary NAS'.

3rd 8 port switch has the 4 backup NAS' connected.

4th 16 port switch has 6 printers connected along with 2 AP's (private and guest access) and 2 backup NAS' connected.


In the setup above, internet access was required, but mostly at a low level for any one client device. (This is different than your situation, which is why for you, device grouping is even more important - devices that need to interact with other devices on separate switches will also impact all the devices' using internet (heavily) on those switches too).


The 1st switch allowed the main computers direct access to the 2 main NAS units and without interfering with other network users. (This change alone kept the heaviest LAN traffic isolated to a single switch which benefitted all network users).


The 2nd switch allows the secondary computers direct access to their most used data on the secondary NAS and without interfering with other network users. (Again, this change for these workers kept their network traffic isolated from the other users and vice versa and made a huge change to the responsiveness of their immediate tasks).


The 3rd switch allows for the staggered NAS backup functions from the NAS units on the 1st switch. Each main NAS is backed up to each backup NAS on a rotating schedule (they have up to 1 month, 1 week and 3 days worth of backup data for each main NAS). (By using separate switch and router ports for the backup NAS', the backups can run at maximum speed without affecting other network users (router port 1 & router port 3 can communicate at full speeds without affecting router port 2 & router port 4 at all)).


The 4th switch allows for all users to print as needed, allows the AP's a direct connection to the internet as required and hosts the 2 backup NAS' for the 2 secondary NAS's on the 2nd switch. (Again, the backup units are on separate switches from the NAS' that are backed up to allow for the fastest speeds possible. Also, both NAS backups can happen at full speeds; between router ports 1&3 and between router ports 2&4).


Sorry for the wall of text, but I hope that with these added details, it becomes clearer what we want to achieve by 'grouping' devices to certain switches.

Like I said, the theory is simple. Writing it out just makes it seem more complicated.

No worries, thanks for taking the time to write this, now I see what's going on with this strategy! It's a bit like minimising the amount of switching work on the router's side right?

 

[L&LD]

No worries, thanks for taking the time to write this, now I see what's going on with this strategy! It's a bit like minimising the amount of switching work on the router's side right?

To be clear: the router isn't burdened with switching work. No good switch is. And the switch on a router is effectively separate from the routing functions.

What we are minimizing is the bottlenecks in the physical topology as dictated by the limited number of ports the router has (and, we'd still be complaining if it had 8 ports or more).

Get a cup of your favorite beverage, get comfortable and read my posts again a few times. It will sink in.


What we are minimizing is the 100% utilization of the network for it's normal workload. Not between devices on the same switch (there are no penalties there), but rather between the devices on separate switches when other devices on those same switches also need to communicate with the internet or themselves with other devices on other switches.

The issue is the single 'road' that multiple devices need to use (the 4 ports of our router) in those situations.

Fortunately, most network devices do not need full network performance 24/7.

That is why we have a chance to organize users / devices in a more efficient topology than simply randomly connecting any device to any port on a router or switch.


Almost all current devices we have today can fully saturate the 1GBe LAN connections we have. And now, your ISP has the possibility to offer that level of performance too to your devices. It's because of this that we have to consider an optimal grouping of users / devices.

Even with 10GBe ports on all our routers and switches, that same limitation would surface again at 10 devices or less when they were forced to go through a 10GBe port pair.


So, it's not just about minimizing what our 'port poor' router is switching. It is more about balancing the devices in such a way that the most important destination (internet, or other internal network devices, or both - depending on how, when and how often it is required be each device) is serviced at the highest level possible.


With only four ports, we have a good chance of achieving that even with fairly high expectations and even with larger home and even some business networks too.

 

[darkarn]

To be clear: the router isn't burdened with switching work. No good switch is. And the switch on a router is effectively separate from the routing functions.

What we are minimizing is the bottlenecks in the physical topology as dictated by the limited number of ports the router has (and, we'd still be complaining if it had 8 ports or more).

Get a cup of your favorite beverage, get comfortable and read my posts again a few times. It will sink in.


What we are minimizing is the 100% utilization of the network for it's normal workload. Not between devices on the same switch (there are no penalties there), but rather between the devices on separate switches when other devices on those same switches also need to communicate with the internet or themselves with other devices on other switches.

The issue is the single 'road' that multiple devices need to use (the 4 ports of our router) in those situations.

Fortunately, most network devices do not need full network performance 24/7.

That is why we have a chance to organize users / devices in a more efficient topology than simply randomly connecting any device to any port on a router or switch.


Almost all current devices we have today can fully saturate the 1GBe LAN connections we have. And now, your ISP has the possibility to offer that level of performance too to your devices. It's because of this that we have to consider an optimal grouping of users / devices.

Even with 10GBe ports on all our routers and switches, that same limitation would surface again at 10 devices or less when they were forced to go through a 10GBe port pair.


So, it's not just about minimizing what our 'port poor' router is switching. It is more about balancing the devices in such a way that the most important destination (internet, or other internal network devices, or both - depending on how, when and how often it is required be each device) is serviced at the highest level possible.


With only four ports, we have a good chance of achieving that even with fairly high expectations and even with larger home and even some business networks too.

Ah I see, so in other words, it's a matter of "if no need use the main route (i.e. the router's ports) and can just use the side routes (i.e. the switch's ports), just do it"? I hope I am getting it right this time

 

[azazel1024]

More or less.

The fewer hops the better in general. So prioritize those hops to the devices that need the fewest.

Along with that, each hop has a maximum width, you want devices that need the most width on the same switch.

A gigabit switch port has 1Gbps up and 1Gbps down as its maximum width. HOWEVER, almost all halfway decent switches WITHIN the switch, have a switching fabric, that is 2Gbps times the number of ports.

So if you have an 8 port switch, its fabric is 16Gbps. Any one port is still limited to its rate of 1Gbps up and 1Gbps down though. This can come in to play if you have a bunch of devices that want to talk to a bunch of difference devices ACROSS switches. One switch, no worries, each device is just limited to its port speed. However, if you, say, had a desktop and a laptop connected on one switch and the desktop was trying to hit a server on another switch and the laptop was trying to get out to the internet, also hung off the second switch, you'd be limited to the port speed of the link between switches.

If all 4 "devices" were on the same switch, they would only be limited to their own port speed, because the switching fabric can handle all ports at full speed at once.

One other way to mitigate this inter-switch bottleneck, is to have switches that can do LAG (link aggregation grouping). So you can connect multiple ports between switches. If you figure the maximum bandwidth you'd ever need between switches, because of the device mix you have, is 2Gbps, then you can group two ports on each switch and connect them between switches (both switches have to have LAG, its a managed switch feature).

No matter what though, the more jumps you have, the more latency you have. Latency is in the MICROsecond range when it comes to LAN traffic, but there are some applications which are run off the network where that can matter (and latency increases a factor of 10 for every speed change, so 100Mbps connections have 10x the latency of 1Gbps and 10Mbps connections have 10x the latency of 100Mbps connections, this is because almost all switches are store and foreward, which means they are looking to get a full TCP packet before they'll forward it on to its destination port, which takes packet size divided by transmit/receive rate to get a full packet. Slower speeds, takes longer to get that entire packet before it gets forwarded).

Me personally, my internet connection is way slower than my LAN speeds, so I have a core switch that everything is connected off of and my router stands alone (with just the one LAN port connected back to my switch). Connecting things to my router potentially slows stuff down with the router LAN port being a bottleneck. Of course I have some things where they will NEVER generate anything like 1Gbps of traffic, so they COULD live off a router port. Though, for convenience, location and management sake, I have a second 16 port GbE semi-managed switch that those devices typically hang off of, with that connected back to my core switch with two port/2Gbps uplink between the switches (just in case).

My really high traffic/speed devices, my server (2Gbps/2 ports), my desktop (2Gbps/2 ports), some of my LAN drops that might see my laptop (1Gbps/1 port) hard wired too, as well as my router and all of my access points live off my core switch and "slow" devices, such as my MoCA bridge, network printer and a couple of very secondary LAN drops live off the secondary switch.

 

[Sonicmojo]

Me personally, my internet connection is way slower than my LAN speeds, so I have a core switch that everything is connected off of and my router stands alone (with just the one LAN port connected back to my switch). Connecting things to my router potentially slows stuff down with the router LAN port being a bottleneck.

I have read and re-read this post over this past week - leading up to a "re-connect" of my LAN based on your recommendations.

Oddly after doing what you said to do "Never connect one switch to another" - I now have a very clear "slowdown in access" to my server.

Back in this post:

http://forums.smallnetbuilder.com/showthread.php?p=152775#post152775

You recommend the following layout:

1. Connect Switch 1 (16 Port Dlink) directly to Port 1 on the RT-AC66U
2. Connect Switch 2 (8 Port DLink) directly to Port 2 on the RT AC66U
3. Connect DIR-655 (as AP) directly to Port 3 on the RT-AC66U
4. Connect link from my server to Port 4 on the RT-AC66U?

But as soon as I did this - the transfer speed between my workstation (On Switch 1) to my Server (on Switch 2) has now really taken a hit.

Seems that this route:

Switch 1->RT-AC66U->Switch 2

Is slower and more labor intensive than

Switch 1-> Switch 2 -> RT-AC66U

If I could put the server on Switch 1 - I would - but that's not possible right now. So I may have to go back to the "Switch 2 to Switch 1" connection - effectively make my layout like yours - with just a single LAN port on the router being used (coming off Switch Two)

Thoughts on why this is slow. Logic suggests it should be OK. But I suspect withe router inbetween the switches now - that is acting as a choke point?

Appreciate an update.

Cheers!

Sonic.

 

[Cloud200]

I am not sure where some of this information is coming from but the fastest networks 99% of the time are the flattest.

the less layers you have the less hops you get.
the less hops you get the lower the chance of collisions (which STILL occur with switches when you connect them) and the lower the latency.

The optimal way to set up a network with a gigabit WAN connection:

Internet
|
WAN port of Router
|
Gigabit port/LAG Group/10Gbe port of router
|
Gigabit port/LAG Group/10Gbe port of CORE switch
|
Wireless access points, Servers, Uplinks to other Switches, Client devices if you have enough ports.

just remember.
1x 48 port switch will give you a faster network than 2x 24 port switches, a significantly faster network than 3x 16 port switches and for G_D's sake please don't make a 6x 8 port or (Shudders) 12x 4 port network.

 

[L&LD]

Switch 1 to Switch 2 is less 'hops' than Switch 1 to Router to Switch 2, I can see why it may be faster with a normally suboptimal Switch 1 connected to Switch 2 configuration.

It may also have something to do with the quality (or interaction) of the DLink switches (with the Router) too and also consider the LAN traffic that is running between the router's two ports and it's other ports and the other switches at the same time.

Can you physically move / switch the servers between the Routers ports 2 and 4 to test?

That may be the best compromise given the cable layout and your network usage requirements?


Of course, jumping between two threads to answer and understand your problem is a little hard.

Can you give a quick drawing of your layout with the router and switches shown?

 

[Sonicmojo]

Can you give a quick drawing of your layout with the router and switches shown?

Sure - will try and get something up tomorrow.

Sonic.

 

[azazel1024]

Switch 1 to Switch 2 is less 'hops' than Switch 1 to Router to Switch 2, I can see why it may be faster with a normally suboptimal Switch 1 connected to Switch 2 configuration.

It may also have something to do with the quality (or interaction) of the DLink switches (with the Router) too and also consider the LAN traffic that is running between the router's two ports and it's other ports and the other switches at the same time.

Can you physically move / switch the servers between the Routers ports 2 and 4 to test?

That may be the best compromise given the cable layout and your network usage requirements?


Of course, jumping between two threads to answer and understand your problem is a little hard.

Can you give a quick drawing of your layout with the router and switches shown?

This.

Also, I've heard that sometimes Asus (admittedly I have heard bad things about others on occasion) have squiffy things going on with their switch ports sometimes. Sometimes 1 of the ports just seems to have problems with switching or has problems with specific devices connected to it. I did have a Netgear 3500L that had a similar issue. It would take FOREVER to autonegotiate GbE from 100Mbps initial connected speed. Occasionally it would just refuse to negotiate GbE on the one port. It only happened with a couple of different devices. My 8 port GbE switch it immediately negotiated GbE. My laptop it would almost patently refuse to do GbE (didn't matter the cable I used), my desktop the same (because I wanted to test it). My server, immediate GbE. Forced GbE from the end device and it would freak out and fail completely (not even fast ethernet speeds).