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bp2008
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Failover capabilities with unmanaged switches involved

Thu Aug 22, 2019 7:06 pm

I've been recently working on installing some 10 gigabit networking in my home using two MikroTik switches, and I'm wondering if I can get these to use the pre-existing 1 Gbps Cat5e lines for failover purposes in case the 10 gigabit fiber link goes down.

The original backbone of my home LAN is a series of unmanaged gigabit switches connected with Cat5e. The internet router connects to Unmanaged C. Unmanaged B is where my FreeNAS and unRAID servers are.

Image


My 10 gigabit upgrade consists of:
1) Replacing Unmanaged C with a MikroTik CSS326-24G-2S+RM.
2) Adding a MikroTik CRS305-1G-4S+in to the server closet, with its one RJ45 port connected to Unmanaged B.
3) A new fiber optic cable between the two new MikroTik switches.

Image

Obviously this creates a loop. I am thinking about disabling via the web GUI the port on MikroTik CSS326-24G-2S+RM that connects to Unmanaged A. I can log in remotely to re-enable this port if I notice the 10G fiber connection go down. The question is, can the switch automate this failover process, and enable a specific RJ45 port if one of the SFP+ ports goes down, then bring down the RJ45 port if the SFP+ comes back?
Last edited by bp2008 on Fri Aug 23, 2019 7:49 am, edited 1 time in total.
 
pe1chl
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Re: Failover capabilities with unmanaged switches involved  [SOLVED]

Thu Aug 22, 2019 8:00 pm

Not with unmanaged switches. With managed switches and spanning-tree protocol it would be possible to do auto failover.
 
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sebastia
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Re: Failover capabilities with unmanaged switches involved

Fri Aug 23, 2019 12:36 am

well, there are two in this setup CRS & CSS...
 
pe1chl
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Re: Failover capabilities with unmanaged switches involved

Fri Aug 23, 2019 12:42 am

... but spanning tree does not work over unmanaged switches unless they are very old or very dumb.
 
bp2008
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Re: Failover capabilities with unmanaged switches involved

Fri Aug 23, 2019 7:53 am

Ok, thanks guys. I guess I will just need to handle it manually if the need arises.
 
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sebastia
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Re: Failover capabilities with unmanaged switches involved

Fri Aug 23, 2019 11:57 am

I disagree, an unmanaged switch is essentially invisible on the wire, it just passes packets around and has no own mac.

So the above network boils down to this:
2switches.png
with STP enabled on both ends, on bridge level, auto fail-over will function
# R1
/interface bridge
add name=bridge
/interface bridge port
add bridge=bridge interface=ether1
add bridge=bridge interface=ether2
/ip address
add address=192.168.40.1/24 interface=bridge network=192.168.40.0

# R2
/interface bridge
add name=bridge
/interface bridge port
add bridge=bridge interface=ether1
add bridge=bridge interface=ether2
/ip address
add address=192.168.40.2/24 interface=bridge network=192.168.40.0
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sebastia
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Re: Failover capabilities with unmanaged switches involved

Fri Aug 23, 2019 12:17 pm

And to remove any doubt, this one works just fine too
2+1switches.png
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pe1chl
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Re: Failover capabilities with unmanaged switches involved

Fri Aug 23, 2019 3:13 pm

I disagree, an unmanaged switch is essentially invisible on the wire, it just passes packets around and has no own mac.
I think an unmanaged switch should drop LLDP and STP packets. Unless it is very old or very dumb and does not know about this.
Maybe I am confused and it only drops LLDP not STP. But I would not blindly assume that this will work.
 
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sebastia
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Re: Failover capabilities with unmanaged switches involved

Fri Aug 23, 2019 3:57 pm

unmananged switches don't participate in lldp, as said before they don't even have own mac
even this works just fine in any direction and any link interruption
2+2switches.png
see also web: https://networkengineering.stackexchang ... e-switches
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pe1chl
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Re: Failover capabilities with unmanaged switches involved

Fri Aug 23, 2019 5:11 pm

unmananged switches don't participate in lldp, as said before they don't even have own mac
When you state that, I'm not so sure if you know what is going on...
Even unmanaged switches do drop some traffic and LLDP for sure is one of them!
I'm not sure about spanning tree BPDU, would have to look that up when I have more time.
But the starting point that unmanaged switches forward everything, for sure is wrong.
 
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sebastia
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Re: Failover capabilities with unmanaged switches involved

Fri Aug 23, 2019 7:03 pm

You keep on stating that, but without any references to back up your case.
I on the other hand have proven with above setups that it indeed is the case.

When you state that, I'm not so sure if you know what is going on...
why don't you then explain to us if you're so sure of yourself what is going on, and point to material supporting that???

I say: you are confusing functionalities of un- and managed switches.
 
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Re: Failover capabilities with unmanaged switches involved

Fri Aug 23, 2019 7:37 pm

unmananged switches don't participate in lldp, as said before they don't even have own mac
When you state that, I'm not so sure if you know what is going on...
I'm not sure you do either...
Even unmanaged switches do drop some traffic and LLDP for sure is one of them!
That is a sweeping generalisation and is very easy to prove FALSE.
But the starting point that unmanaged switches forward everything, for sure is wrong.
And your starting point that they all block certain things is also wrong.

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