Ever since I got my MacbookPro a few weeks ago, I’ve had all kinds of network problems with it. The network performance seemed like I was on a dialup line – when it worked. I wish I looked here first :(
An excerpt from that page sums it up all:
Allan Webb
RE: Vince Smith’s post about his confusion over Cisco’s voice vlan and 802.1q.
Vince is (self-admittedly) confused. Yes, the problem is with 802.1q tagged packets. But you would usually never see this issue, since 802.1q packets normally wouldn’t be seen anywhere but on a vlan trunk port (ie, your Mac would never see them).
The important point here is Cisco’s VOIP implementation actually treats a single physical network port as having two vlans on it: the regular data vlan (for your computer), and the voice vlan (for the voip phone). Your phone plugs into the network port and your computer plugs into the phone; the phone essentially acts as a 2 port hub.
However, since the devices sit on two different vlans, there are 802.1q packets on that physical wire and your Mac will see them. Hence the problem. Apple will need to fix the NIC driver to resolve this.
Here is an example of the switchport configuration that defines both the data and voice vlans on a single physical port:
interface FastEthernet1/0/6
switchport access vlan 2
switchport mode access
switchport voice vlan 3
spanning-tree portfast
