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How to discover switch ?

Posted: Tue Apr 12, 2016 12:31 pm
by jjonsson
I have lost contact to a WS-6-MINI switch. If I look at the ARP table on the PtP radio connected, I can see the switch MAC-address and see it's on correct VLAN.
But the switch does for some reason not have an IP-address.

How can I connect to it, without being on-site (It's to far a drive at the moment) ?

Re: How to discover switch ?

Posted: Tue Apr 12, 2016 12:37 pm
by sirhc
jjonsson wrote:I have lost contact to a WS-6-MINI switch. If I look at the ARP table on the PtP radio connected, I can see the switch MAC-address and see it's on correct VLAN.
But the switch does for some reason not have an IP-address.

How can I connect to it, without being on-site (It's to far a drive at the moment) ?


If you have the firmware upgraded to v1.3.9 then UBNT discovery works if you have it enabled then you can run UBNT discovery and find the IP.

It also responds to Cisco Discovery and LLDP if turned on.

That would give you the IP it has assigned

Note, I think it only currently responds to ports in the management/defaul VLAN

Re: How to discover switch ?

Posted: Tue Apr 12, 2016 12:50 pm
by lligetfa
Shall I assume there is a router between you and the MINI so trying a static ARP would be futile? That said, I have not tested static ARP even in the same broadcast domain so not sure it would work. I've also not tried to see if it would reply if I pinged it with the subnet's broadcast IP. Those are tricks I have used in the past with mixed results.

Re: How to discover switch ?

Posted: Tue Apr 12, 2016 2:49 pm
by jjonsson
lligetfa wrote:Shall I assume there is a router between you and the MINI so trying a static ARP would be futile? That said, I have not tested static ARP even in the same broadcast domain so not sure it would work. I've also not tried to see if it would reply if I pinged it with the subnet's broadcast IP. Those are tricks I have used in the past with mixed results.


arp -s 10.0.0.61 EC:13:B2:91:21:2A

gives:
The ARP entry addition failed: Access is denied.

(From a Windows 7 workstation).

I don't think it has an IP-address. When scanning with Advanced IP scanner it doesn't show up (it also shows MAC-address of scanned devices)

Re: How to discover switch ?

Posted: Tue Apr 12, 2016 4:11 pm
by sirhc
Well the IP is only addressable from the Management/Default VLAN.

Meaning if port 2 is not in the Management VLAN a router hooked to port 2 would see a MAC for it (albeit not the MAC on the sticker) the switch would not respond in anyway to that MAC or report the IP.

WHat was the last configuration change you made?

Re: How to discover switch ?

Posted: Tue Apr 12, 2016 5:49 pm
by jjonsson
sirhc wrote:Well the IP is only addressable from the Management/Default VLAN.


I'm pretty sure the VLAN I'm seeing the switch MAC-address on is also the VLAN configured in the switch for Management. Since everything is working (PoE is on, customers working on the different VLAN, I can reach equipment) I'm pretty sure the config of the switch is correct.
I have restarted UBNT router running as DHCP server. So maybe that's the problem....

sirhc wrote:Meaning if port 2 is not in the Management VLAN a router hooked to port 2 would see a MAC for it (albeit not the MAC on the sticker) the switch would not respond in anyway to that MAC or report the IP.


I don't know what port the PowerBeam AC-500 is connected to. But it has the switch MAC-address on the correct management VLAN shown in the bridgetable.

sirhc wrote:WHat was the last configuration change you made?

Don't remember. It has been running a ½ year without any problems....

Again, I guess it must have something to do with me restarting DHCP server on the EdgeRouter (I have all equipment configured for DHCP, mapping those addresses I want to be static...

Re: How to discover switch ?

Posted: Tue Apr 12, 2016 6:14 pm
by sirhc
Man I know some of you guys use DHCP for infrastructure and some create static DHCP leases for the equipment so why not just STATIC ASSIGN them to begin with and eliminate any possible issues like this?

Re: How to discover switch ?

Posted: Tue Apr 12, 2016 7:58 pm
by jjonsson
sirhc wrote:Man I know some of you guys use DHCP for infrastructure and some create static DHCP leases for the equipment so why not just STATIC ASSIGN them to begin with and eliminate any possible issues like this?


I normally configure DHCP + fallback IP to be the same. I might have forgot that here.

Actually it would be much easier if manufacture configured all equipment for DHCP. Then if equipment is reset, you always get the correct IP-address from DHCP server...

But it's so strange. I have found out that I also miss access to an AP on same switch. All other equipment is reachable....