RE: [Nolug] Any VLAN experts out there?

From: Dennis Bourn <>
Date: Wed, 4 May 2011 18:56:38 -0500
Message-ID: <551D1BAD04875842B7B8BBF3F2ACD627011F12@venus.tomba.local>

I used to use Ubiquiti NanoStations to connect a wired device to a wireless network. I always had trouble with DHCP accross that link. But Static IPs would work fine.

-----Original Message-----
From: on behalf of Chris Jones
Sent: Wed 5/4/2011 5:32 PM
Subject: RE: [Nolug] Any VLAN experts out there?
Yes, vlan10 even works. I can ping the cable modem with a laptop on the
other switch. The one weird thing I'm seeing is dhcp takes a few minutes to
give out an ip.
On May 4, 2011 5:24 PM, "Dennis Bourn" <> wrote:
> Are any other VLANs part of that trunk (and working?)? That will answer
the question as to if you should look closer at the wireless link.
> -----Original Message-----
> From: on behalf of Chris Jones
> Sent: Wed 5/4/2011 5:12 PM
> To:
> Subject: Re: [Nolug] Any VLAN experts out there?
> I did notice that one of the switches you can actually set a port as being
> "trunk" and on the other one you don't. It has access ports and a few
> types, but for a trunk you apparently just tag whatever vlan's go on it.
> Come to think of it, I have the modem going into one VLAN10 port, but
> is a 2nd VLAN10 port next to that one to give us a spare. I plugged into
> that with my laptop and I was able to get out. Well, if you two are
> thinking that it's something to do with the trunk, I might add that the
> trunk link between the two switches is going over a Ubiquiti Nanobridge
> On Wed, May 4, 2011 at 4:48 PM, Jeremy <> wrote:
>> I will attest to the fact that trunk configuration on the Dell
>> switches is a bit stupid and easy to goof up. I'll echo what Dennis said
>> - that would be where I would check first.
>> Another troubleshooting option is to eliminate the trunk. First,
>> disconnect the router from the second switch and reboot the cable modem.
>> On the first switch, where the modem is attached, setup an untagged port
>> VLAN 10, connect a laptop and verify that you can access the internet
>> through just one switch. If that works, then the trunk ports are probably
>> your problem.
>> J
>> On 5/4/2011 3:25 PM, Dennis Bourn wrote:
>>> The modem will be trying to communicate directly with the router. The
>>> stuff is "hidden" from both of those devices if they are configured as
>>> described, with their respective ports being untagged.
>>> The problem will likely be the trunk port between the switches. Are both
>>> using .1Q trunking? If you assign an IP address to vlan10 on the
>>> can you ping them from the sonicwall or vice versa. If no ping command
>>> present, plug a laptop into the Untagged VLAN10 port and ping from
>>> Dennis Bourn
>>> -----Original Message-----
>>> From: on behalf of Chris Jones
>>> Sent: Wed 5/4/2011 3:08 PM
>>> To:
>>> Subject: Re: [Nolug] Any VLAN experts out there?
>>> is a dell 2848 and the other is a "cisco small business"
>>> switch, router is sonicwall. Only the router and modem are on that vlan.
>>> As far as I can tell I've done everything by the book, all I can think
>>> is
>>> the modem is trying to communicate directly with the router and it
>>> support "hops".
>>> On May 4, 2011 2:37 PM, "Jeremy"<> wrote:
>>>> On 5/4/2011 2:13 PM, Chris Jones wrote:
>>>>> I'm running into an odd issue at one of my sites. We're trying to set
>>>>> them up with cable modem internet through charter, but we have some
>>>>> serious physical limitations to their network, which basically result
>>>>> in us having to set this up in a fairly complicated manner.
>>>>> We have 2 managed VLAN switches. One goes in each of 2 locations, and
>>>>> they will be linked together via uplink/stacking ports. Here's how
>>>>> the signal flow works:
>>>>> - Charter goes into a port untagged for VLAN10 on Switch A
>>>>> - Charter goes out thru the trunk port of Switch A that is tagged for
>>>>> all relevant VLAN's
>>>>> - Charter goes into the trunk port of Switch B
>>>>> - Charter goes out of an untagged port on Switch B and into the router
>>>>> Problem is, this is not working. It seems like the managed switches
>>>>> are doing something to the packets that the Charter modem does not
>>>>> like, screwing with MAC addresses or something. Does anyone know
>>>>> anything that may help me out here? Is there something I need to turn
>>>>> on in the switches to keep them from interfering with this traffic?
>>>> Are the cable modem and router the only devices in VLAN 10? Do you
>>>> have ANY other devices - PCs, servers, printers - in that VLAN?
>>>> What type of switches and router are in the setup?
>>>> J
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