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I'm trying to rebuild the network from my work and I was thinking what is the best way to connect three switches and a router.

The router has 4 ports so I thought to connect 2 switches to the router (each switch connected with 2 cables to the router) and then connect the third switch to one of the others with two cables. So is like this, two cables from switch one to the router, two cables from switch two to the router and two cables from switch 3 to switch 1 or 2.

So my questions are:

Is it better to connect the router to each switch with a cable or the more cables you have the better?

If I connect the switch 3 to switch 1 or 2 is it better to connect it with a cable or you get better performance with more cables.

If I'm wrong and there is a better or more efficient way to connect them please let me know.

The router is a Netgear RP114 (I'll upgrade it to a Sonicwall NSA 240), switch 1 is a Netgear GS748T, switch 2 is a Cisco Catalyst 2924-XL and switch 3 is a D-link DGS-1024D.

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I have 4 servers (file, email, terminal services and "erp"), 20 printers and 50 pc, so I want to conect the servers and the printers to swith 1 and the other things to switches 2 and 3. Thanks for your help –  Carlos Morales Jun 10 '10 at 14:22

6 Answers 6

up vote 3 down vote accepted

From a basic resiliency standpoint and lowest used ports & cables I'd consider the following, if the devices support spanning tree:

Switch A Port 1 -> Router Port 1
Switch B Port 1 -> Router Port 2
Switch C Port 1 -> Switch A Port 2
Switch C Port 2 -> Switch B Port 2

Set spanning tree on for those ports only. This way you'd be fine when(not if) any one of the devices/ports/links fails.

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Hi, I have a doub, if I connect them like that I'll have a loop and that will not affect the network? Thank you –  Carlos Morales Jun 10 '10 at 14:55
1  
That's where my stipulation of using Spanning Tree Protocol(STP) is critical. STP prevents loops. –  Jeff Hengesbach Jun 10 '10 at 15:04
    
Ok, thanks for your help, I will connect them that way, but I'm not sure if there will be a problem with switch 3 (D-Link DGS-1024D), because it is unmanaged and I can not configure STP on it. Will be enough with STP on switch 1 and 2? –  Carlos Morales Jun 10 '10 at 15:41
    
No, you must have STP on all switches in the network for STP to be effective. Otherwise you will get bridging loops. –  Vatine Jun 11 '10 at 11:43
    
@Vatine: If you have a switch that does not support spanning tree, make sure it only hooks up to a single upstream switch. And configure bpduguard on its port. –  MikeyB Aug 31 '11 at 19:56

Option 1: Connect all three switched directly to the router, if your router have enough Ethernet ports and then enable Dot1Q encapsulation to enable inter VLAN routing (if your switches are not L3; couple of switches give you both the features). In this case your all layer 2 traffic will go through layer 3 and I don't think that someone need that in his or her network.

or

Option 2: Connect your main switch directly to the router and then connect remaining 2 switches to your main switch. Change the mode of main switch from STP client to STP server, and change the mode of reaming switched from server to client. Do not connect client switch with each other - it will cause switching loops. If you need a redundant link between all switched then you must enable STP and other loop avoidance protocols too.

Personally I suggest to use the second method.

Right now I am also working on the same, I have a Cisco 1941/k9 router and three cisco SF300-24 port switches (L2/L3).

Regards,

Sandeep Kumar Sharma

MCP, MCSA, MCSA:M, MCSE, CCENT, CCNA

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Use cables.

Just kidding. First of all, I think we might need some more information such as what you will be connecting to these switches. If you have a couple servers, and then a bunch of workstations, you might want to use 2 cables to 1 switch with all the important stuff on it, and then connect each of the 2 other switches using just 1 and put your workstations on those.

I think having the 2 cable setup only protects against the actual cables failing, and as far as speed goes it depends how much traffic will go across it. I'll edit my answer if you supply some more information if you want, just leave a comment.

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Note that using more than one cable to connect two network devices only gives you something if the devices both support interface bonding (usually called "bonding" or "etherchannel"). Otherwise, the two cables are effectively only resilience.

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And, as said above, only if the devices all support STP. If they don't, extra cables get you L2 loops which will kill your network. –  mfinni Jun 11 '10 at 12:49

I made you a diagram to explain this (difficult to explain verbally). One option is with using Spanning Tree protocol and the other without it. Be careful, if you use the spanning tree topology without enabling spanning tree first, you will have massive looping and broadcast issues.

http://i.imgur.com/8zK6k.png

The router should only connect to one port on one switch. Most routers do not do STP.

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STP - Spanning tree protocol

  1. enables multiple cable connections.
  2. blocks all but one cable route to stop layer 2 loops.
  3. auto switches to an alternative cable route should the active one die.

I.e. you will only be using one cable for traffic anyway. You aren't using aggregation so just stick to one cable from switch to router. Make sure you do not make a circuit e.g. S1 > S2 > R1 > S1 or simliar.

To be honest you need to minimize the switches unless essential as all you are doing is adding hops = latency ;)

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