On Mon, 2009-12-28 at 01:12 -0800, Mike Connors wrote:
> Michael Robinson wrote:
> > I wonder if being a switch it was blocking the dhcp replies? 
> Switches don't block broadcast protocols like DHCP. Routers do and if 
> DHCP traffic
> has to traverse a different network than a DHCP proxy must be configured.
> 
> However, there are a couple of cases where dhcp requests/replies could 
> be inadvertently
> blocked.
> 
> 1. The DHCP client and dhcp server are on different VLANs.
> 
> 2. Spanning Tree port configuration is another. With regular spanning 
> tree (8021.d),
> the switch port could be in blocking mode while the spanning tree is 
> being mapped out and
> therefore any DHCP traffic will not pass thru the port. As best practice 
> we always
> configured the switch ports with rapid spanning tree (802.1w), so that 
> spanning tree convergence
> happened faster and didn't impact dhcp requests.

No VLANS are in use.  I am running DHCP 3 server on CentOS 5.3 listening
on an actual Netgear FA311 network card with an actual Cat5e UTP cable
running 100' into the attic where at this point I go to a 10BaseT hub
and from there I continue on with a Cat5 STP cable outside, underground,
back above ground, and into another building where I terminate at
another FA311 network card in my diskless server.  I tried to replace
the Dlink hub with a Netgear DSS5+ 5 port switch.  I guess my switch is
faulty.  It seems unlikely that the cables themselves didn't handle
100BaseTX transmission okay.  Obviously there was some networking from
the diskless client to the server at 100BaseTX, but somehow the switch
broke DHCP.  Put the slow dumb hub back in, works just fine.  Trouble 
is, I want the higher speed because I'm extending with 802.11g outdoor
access points.  I'm thinking of getting a cable joiner that also acts
as a crossover device and using that instead of a hub or switch.

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