ubiquiti and spanning tree

[browolf]

In the summer we had our network upgraded to unifi 10GB. We got 2x Xg + 10x 48p-500w connected with fibre. (one for each building)

 

We discovered dhcp wasn't working for new leases and it was the fault of (rapid) spanning tree protocol.

 

we turned off spanning tree protocol on all the switches

 

we discovered we couldn't turn it off on all the switches. (one building kills the network)

 

We leaned that spanning tree only needs to be enabled on uplinks and not all the ports.

 

We realized that we could just enable spanning tree on the XGs

 

We realized there's a problem because some buildings are connected to other buildings and then the XG.

 

There doesn't seem to be any way to control which ports spanning tree is enabled on. Maybe we need more XGs for the other junction points?

[TechMonkey]

Have you used the CLI interface?

 

I've not used Ubiquiti but I had a quick search and it looks like it is similar to HP switches. The UI allows you to turn on and off Port spanning, but to edit ports you have to do it via CLI.

https://dl.ubnt.com/guides/edgemax/EdgeSwitch_CLI_Command_Reference_UG.pdf Page 208 gives you the command. From somewhere else it looks like you need to SSH onto the switch and from the switch telnet back on to the switch to use the config commands.

 

If you've not used the CLI before, or you are not used to programming Spanning Tree I would be very careful and maybe contact the installers and ask them to configure it properly. You could kill your network if you do something incorrect!

[FN-GM]

We leaned that spanning tree only needs to be enabled on uplinks and not all the ports.

 

This is 100% wrong. It is needed on all ports especially the ones facing the clients. Without this if you have a cable plugged into 2 data points (users like to do this when moving desks to they are not trailing on the floor) it will bring down your entire network fairly quickly. It will be a nightmare to find out where this is.

 

The feature you're looking for to get DHCP working is Portfast. This is applied to ports that your clients connect to (import not to enable on uplinks). What is happening is the spanning tree process is taking a little time to put the port into forward and the DHCP is timing out. Portfast puts the port into forwarding right away and does the spanning tree process in the background.

Edited September 10, 2018 by FN-GM

[browolf]

This is 100% wrong. It is needed on all ports especially the ones facing the clients. Without this if you have a cable plugged into 2 data points (users like to do this when moving desks to they are not trailing on the floor) it will bring down your entire network fairly quickly. It will be a nightmare to find out where this is.

 

The feature you're looking for to get DHCP working is Portfast. This is applied to ports that your clients connect to (import not to enable on uplinks). What is happening is the spanning tree process is taking a little time to put the port into forward and the DHCP is timing out. Portfast puts the port into forwarding right away and does the spanning tree process in the background.

 

 

I thought if it was on the uplink it would disable a switch but not the whole network?

 

Now you mentioned "forwarding" I found this in the manual book

 

"spanning-tree edgeport

This command specifies that an interface (or range of interfaces) is an Edge Port within the common and internal

spanning tree. This allows this port to transition to Forwarding State without delay"

 

Guess this is the equivalent to portfast..

[chazzy2501]

Spanning tree should be enabled on every port, and if possible (rapid) RSTP should be set for clients or they likely will time out looking for dhcp. RSTP is the default for every switch (on my XGs I've put it in STP mode as no clients connect, only switches)

[FN-GM]

I thought if it was on the uplink it would disable a switch but not the whole network?

 

Now you mentioned "forwarding" I found this in the manual book

 

"spanning-tree edgeport

This command specifies that an interface (or range of interfaces) is an Edge Port within the common and internal

spanning tree. This allows this port to transition to Forwarding State without delay"

 

Guess this is the equivalent to portfast..

 

That sounds like the equivalent.

[chazzy2501]

Thinking on this!!! I had a similar problem during my initial install! I also have an undesirable extended star topology as well. Set the root switches (the XG switches) to plain STP. Place all other switches to RSTP. (give them 5 minutes to settle)

[browolf]

Thinking on this!!! I had a similar problem during my initial install! I also have an undesirable extended star topology as well. Set the root switches (the XG switches) to plain STP. Place all other switches to RSTP. (give them 5 minutes to settle)

 

rstp was on by default - that was causing all the problems!

[FN-GM]

How did you get on with what was said in post 4?

[browolf]

How did you get on with what was said in post 4?

 

Haven't got round to it yet. Who knows if we even have the correct console cable... 90 jobs on the helpdesk - keeping stuff working is more important than making it work properly! :-)

[browolf]

Have you used the CLI interface?

 

I've not used Ubiquiti but I had a quick search and it looks like it is similar to HP switches. The UI allows you to turn on and off Port spanning, but to edit ports you have to do it via CLI.

https://dl.ubnt.com/guides/edgemax/EdgeSwitch_CLI_Command_Reference_UG.pdf Page 208 gives you the command. From somewhere else it looks like you need to SSH onto the switch and from the switch telnet back on to the switch to use the config commands.

 

If you've not used the CLI before, or you are not used to programming Spanning Tree I would be very careful and maybe contact the installers and ask them to configure it properly. You could kill your network if you do something incorrect!

 

Apparently that manual is for edgeswitches but not unfi switches. The cli for unifi has hardly any options

 

[ATTACH=CONFIG]50224[/ATTACH]

[TechMonkey]

Apparently that manual is for edgeswitches but not unfi switches. The cli for unifi has hardly any options

 

[ATTACH=CONFIG]50224[/ATTACH]

I don't use Unifi so just going on stuff I've read, but is that lack of options after SSH and then Telnetting?

[browolf]

I don't use Unifi so just going on stuff I've read, but is that lack of options after SSH and then Telnetting?

 

 

Yep! it's that limited.

[Primus]

Yep! it's that limited.

 

What? No it's not that limited at all - Unifi has full CLI support!

 

For example.

[TechMonkey]

What? No it's not that limited at all - Unifi has full CLI support!

 

For example.

That looks like what I was reading about. SSH onto the switch and then telnet back onto the same switch.

[browolf]

That looks like what I was reading about. SSH onto the switch and then telnet back onto the same switch.

 

 

That doesn't work, or I'm doing it wrong...?

 

[ATTACH=CONFIG]50238[/ATTACH]

[browolf]

I didn't explicitly say how the problem with DHCP got solved.

 

There's a bug in the unifi switches that whereby when DHCP guard is off, there's some part of it that is still on and that part is still checking dhcp packets and randomly dropping them.

 

So turning DHCP guard on and specifying our dhcp servers magically fixed the problem.