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mrmut
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How to best connect multiple switches?

Mon Feb 25, 2019 6:15 pm

I have one 3011 router and need to connect it to three switches. How to do it best?

Currently I have connected each switch to the router directly.

Thanks
 
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anav
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Re: How to best connect multiple switches?

Mon Feb 25, 2019 6:56 pm

Without knowing purpose of network or architecture its hard to say.
If you have enough ports separation by port adds more flexibility.
 
kokaKorina
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Re: How to best connect multiple switches?

Mon Feb 25, 2019 6:57 pm

mrmut
It all depends how you want to use them if you want to connect all devices on swithes to be on same subnet then simply take one small switch and connect it to the router and then connect all other switches to the that new switch otherwise you can bridge all ports on router that are connected to the switches but it all depends how you want to design your network and what are your requirements.
 
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mrmut
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Re: How to best connect multiple switches?

Tue Feb 26, 2019 6:03 am

Thanks guys.

If I understand well, generally, if I add more interconnections I get more bandwidth?

I have two site single subnet LAN. The network is bottlenecked by 1gbps interconnection between two routers, and I have 3 switches on each location that are connected directly into the server.

Looking at one router where I use three links to connect three routers, I would get more bandwidth if I connect, say, two links into switch1, then two links from switch1 to switch2 and two links to switch3? I think I can spare that easily, as that is only 2 more links for added 2x speed increase, if I understood the interlinking well.
 
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vecernik87
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Re: How to best connect multiple switches?

Tue Feb 26, 2019 6:26 am

if I add more interconnections I get more bandwidth?
No. Simply said, without proper configuration, connecting more cables between switches will NOT give you more bandwidth. In the best case, switches will notice the loop and disable any excessive ports. In the worst case, your network will collapse due to loops causing packet storms.

Looking at one router where I use three links to connect three routers
Connecting 3 switches into 3 ports on router is typical "star" topology and gives you reasonable bandwidth (dedicated 1 GB line for each switch) without any configuration. Simple, effective.

if I connect, say, two links into switch1, then two links from switch1 to switch2 and two links to switch3?
That would work only if you set all of these ports for bonding (link aggregation). To explain it: every pair of ports, which will be connected to the same device needs to be configured for bonding. That can be done on your RB3011 but I don't know what type of switch you have. If it is unmanaged, you can't obviously do any configuration and therefore bonding will not work. If it is managed, check your specs and/or setting, whether it supports bonding. If you are unsure, feel free to write, what brand and model of switch you got...
 
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mrmut
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Re: How to best connect multiple switches?

Tue Feb 26, 2019 6:45 am

Thanks a lot, I appreciate it!

I have 3011 as a router, and a number of CRS 24p RB switches with RB active. (Cant recall exact model, maybe 326).

As currently is, I am inclined to remain at current config, exactly because it is simple.

Would you mind pointing me to some documentation on the issue?
 
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Re: How to best connect multiple switches?  [SOLVED]

Tue Feb 26, 2019 7:29 am

If you have CRS326, I would definitely recommend to connect them with SFP+. That way, you can get 10Gbit link between them with a single (DAC/Fiber) cable! Although, to get more than 1Gbit link to your router, you will still need to bond few links because RB3011 does not have SFP+ port (don't confuse with SFP which is limited to 1Gbit). It would be worth to think, whether there will be any >1Gbit traffic passing through the router. I assume most common situation for >1Gbit will be devices on lan, communicating one to each other. In such case (unless we talk about inter-VLAN routing), switches might do all the heavy lifting and you wouldn't need any bonding going to your router.

In RouterOS, bonding is represented as a virtual interface which you create and connect to your bridge etc... Then you assign specified Ethernet ports into it as slaves
Complete documentation is here: https://wiki.mikrotik.com/wiki/Manual:Interface/Bonding

If you have CRS3xx running RouterOS, make sure that you don't break HW offload! https://wiki.mikrotik.com/wiki/Manual:C ... es#Bonding
If you are using SwOS in your CRS instead, it will still work: https://wiki.mikrotik.com/wiki/SwOS/CSS326#LAG

In the end, easiest for you is the 802.3ad bonding mode which is also universally compatible with other brands so your server/NAS might like the extra bandwidth. This does not mean you will achieve 2Gbit on any single connection, rather, it allows you to have multiple connection at the same time without being limited by 1Gbit cable.
Example: SW1 is connected with two bonded ethernet cables to SW2. Two devices are connected to SW1 and they try to communicate with another two devices connected to SW2. Both devices should achieve full gigabit speed.
 
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mrmut
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Re: How to best connect multiple switches?

Tue Feb 26, 2019 7:55 am

Thanks!