Mikrotik DHCP servers and 'offering lease.. without success'

[billbuchan]

I have a small but incredibly irritating issue with a handful of UBNT devices now refusing to accept DHCP. They're all VLAN'd, and in my test machines case, going through four Netonix switches, all upgraded to 1.3.2. These devices used to quite happily accept DHCP - hence my frustration.

The Mikrotik router (I've tried 6.26, 6.20) all report:

'<dhcp server> offering lease <ip address> for <mac address> without success'.

I can't see any spurious ARP entries on that VLAN, if that helps.

Any pointers gratefully received,

---* Bill

[mike99]

WDS enabled on AP ?
viewtopic.php?f=17&t=971&hilit=mikrotik+dhcp

[sirhc]

I do not think it is us but if you can figure out that it is Eric will get right on it.

We are going to push v1.3.3 Final tomorrow since v1.3.3rc5 seems very stable, you could try v1.3.3rc5 who know right!

[billbuchan]

Yes, WDS is enabled on all access points. It does get really squirrely when it's not enabled, doesn't it?

I may try 1.3.3r5 - but since this vlan route comes through our core switch - I may chicken out..

---* Bill

[sirhc]

Eric is going to release v1.3.3 FINAL tonight or tomorrow so at some time you will have to upgrade at a time when you are ready then if that does not fix it then put together a LAB for eric to try and see what he can from your LAB.

We do not think it is us we are willing to LAB it if you put together a known LAB that will show the issue.

[billbuchan]

Thats fantastic, thanks!

I'm fairly sure its the shonky Mikrotik 6.26 code. I think everything 6.27-6.32 is somewhat 'cursed' in terms of Mangle rules - I wouldn't be at all surprised if DHCP is broken in 6.26.

---* Bill

[billbuchan]

I have a solution, but you're not going to like it.

We have a Mikrotik router [2011 running 6.26] going through a WISP 6 switch (1.33), then a UBNT AC link (7.14), then a WISP-12 switch (1.33) and then fanning out to various devices (NS's running 5.5.10, Mimosa's running 1.2.2, etc).

With the Port setting DS Snoop switched ON, DHCP doesn't work.

Switch it off, and DHCP bursts into life.

We're testing this against more of our infrastructure.

This has caused us about 14 days of misery - at its peak, we had 180 devices offline and 'lost', and whilst still passing traffic, two links went down that we couldn't manage.

I wouldn't recommend that position to anyone - it's been a miserable two weeks.

Whilst I LOVE the DS Snoop feature - it's saved our bacon quite a few times and is a remarkable feature - it's got to stay off till you've had a chance to examine this.

Hope this helps,

---* Bill

[billbuchan]

Quick update. Just done the rest of the infrastructure. Even Mikrotk CCR 6.32 (seriously dodgy crap) and FOUR sequential hops through switches) - all worked with DS Snoop turned off.

Thats around 180 devices (Mimosa, UBNT M, UBNT AC), 20 switches (all on 1.33), four routers (Mikrotik 2011/6.26 and CCR/6.32).

I'm guessing thats a smoking gun?

Minimal test case is Mikrotik 6.2x device with DHCP, single switch, UBNT Nanostation Loco with DHCP enabled.

Hope this helps, (and I hope no other poor sod has to go through this ;) )

---* Bill