Question about VLAN tagging for packets
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Posted by on March 21, 2007, 2:43 pm
Please log in for more thread options Hi, Does anyone know how to resolve the following situation: I have a VLAN switch that has three ports: port 1 is connected to network uplink, port 2 is connected to a server, port 3 is connected to a desktop. I'd like to make the following scenario to work: In preboot environment (EFI), I need to use an application from the desktop to send packets to the server (port 2) and use another application to send packets to network uplink (port 1). In OS environment, all packets should send packets to network uplink (port 1). To support this scenario, what should the switch be configured? Can using PVID resolve this problem, for example we set PVID port 1="1", PVID port 2="2", and PVID port 3="1" or "2", so packets arrived at port 3 will be tagged with its PVID number (either "1" or "2") by the switch and forwarded to port which has the same PVID number (but this won't work since port 3 need to be able to forward packets to port 1 and port 2 depending on the application. Thanks so much for the help. | |||||||||||||||||||
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Posted by Albert Manfredi on March 21, 2007, 5:53 pm
Please log in for more thread options Why is there any need for VLANs in what you describe? Why not simply forget about using VLANs? In both of your conditions, I don't see where VLANs are needed. Also, if you do want to add VLANs, best not to use VID of 1, since some switches use VID 1 for non-VLAN traffic. Bert | |||||||||||||||||||
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Posted by glen herrmannsfeldt on March 21, 2007, 8:05 pm
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mohamad.ridha@intel.com wrote: (snip) > To support this scenario, what should the switch be configured?
> Can using PVID resolve this problem, for example we set PVID port > 1="1", PVID port 2="2", and PVID port 3="1" or "2", so packets > arrived at port 3 will be tagged with its PVID number (either "1" or > "2") by the switch and forwarded to port which has the same PVID > number (but this won't work since port 3 need to be able to forward > packets to port 1 and port 2 depending on the application. I would consider what might happen with non-virtual LANs. VLANs should each be like a separate physical net, for IP that usually means a different (sub)net. That would usually mean two physical ports for host 3, though if it is VLAN aware it might be able to do two logical ports on one physical port. That is, the host should tag the ports based on routing table destination. -- glen | |||||||||||||||||||
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Posted by on March 23, 2007, 8:25 am
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> mohamad.ri...@intel.com wrote:
> > (snip) > > > To support this scenario, what should the switch be configured?
> > Can using PVID resolve this problem, for example we set PVID port > > 1="1", PVID port 2="2", and PVID port 3="1" or "2", so packets > > arrived at port 3 will be tagged with its PVID number (either "1" or > > "2") by the switch and forwarded to port which has the same PVID > > number (but this won't work since port 3 need to be able to forward > > packets to port 1 and port 2 depending on the application. >
> I would consider what might happen with non-virtual LANs. > > VLANs should each be like a separate physical net, for IP that > usually means a different (sub)net. That would usually mean two > physical ports for host 3, though if it is VLAN aware it might > be able to do two logical ports on one physical port. That is, > the host should tag the ports based on routing table destination. > > -- glen If you have a Layer 2 switch it should already take care of your issue. A layer 2switch will know what port the server is on. Unless I'm missing something I also don't see what the vlan is doing for you in this example. | |||||||||||||||||||
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Posted by BernieM on March 24, 2007, 11:11 pm
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> Hi,
> > Does anyone know how to resolve the following situation: > > I have a VLAN switch that has three ports: port 1 is connected to > network uplink, port 2 is connected to a server, port 3 is connected > to a desktop. > I'd like to make the following scenario to work: > > In preboot environment (EFI), I need to use an application from the > desktop to send packets to the server (port 2) and use another > application to send packets to network uplink (port 1). > In OS environment, all packets should send packets to network uplink > (port 1). > To support this scenario, what should the switch be configured? > Can using PVID resolve this problem, for example we set PVID port > 1="1", PVID port 2="2", and PVID port 3="1" or "2", so packets > arrived at port 3 will be tagged with its PVID number (either "1" or > "2") by the switch and forwarded to port which has the same PVID > number (but this won't work since port 3 need to be able to forward > packets to port 1 and port 2 depending on the application. > > Thanks so much for the help. > Unless it's a layer-3 switch aka router, hosts in different vlans cannot contact each other. One solution is to have a trunk link to the server and have the server in both the network uplink vlan and the pc vlan. Then the pc can communicate with the server and the server can communicate with the network uplink. if you want the pc to communicate with whatever's at the other end of the network uplink then configure routing on the server and configure the pc to use it as it's default gateway. BernieM | |||||||||||||||||||
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> network uplink, port 2 is connected to a server, port 3 is connected
> to a desktop.
> I'd like to make the following scenario to work:
>
> In preboot environment (EFI), I need to use an application from the
> desktop to send packets to the server (port 2) and use another
> application to send packets to network uplink (port 1).
> In OS environment, all packets should send packets to network uplink
> (port 1).
> To support this scenario, what should the switch be configured?
> Can using PVID resolve this problem, for example we set PVID port
> 1="1", PVID port 2="2", and PVID port 3="1" or "2", so packets
> arrived at port 3 will be tagged with its PVID number (either "1" or
> "2") by the switch and forwarded to port which has the same PVID
> number (but this won't work since port 3 need to be able to forward
> packets to port 1 and port 2 depending on the application.