[VLAN] Using a switch fabric to emulate multiple NICs

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Alex Zeffertt wrote:
> On Sat, 23 Jul 2005 20:59:11 -0700
> Ben Greear <greearb@xxxxxxxxxxxxxxx> wrote:
> 
> 
>>Alex Zeffertt wrote:
>>
>>
>>>I see your point about leaving the vlan tag in the name but I don't think it is valid in this
>>>particular scenario.  Although each frame sent to the CPU over the MII has a tag, the frame does
>>>not have a tag when it enters the switch via one of the other ports.  Similarly, when the CPU
>>>sends a frame over the MII it is tagged, but the switch removes the tag before sending it out. 
>>>Therefore the tags are used solely on the MII bus as a way of indicating on which port the frame
>>>was received/to which port it should be sent.  This is an implementation detail that I want to
>>>hide and make it look like I've just got 10 NICs.
>>
>>So what happens when the user configures a VLAN on this 'ethernet' port?
>>
> 
> 
> Ben,
> 
> Very good question.  In principle you just get double tagged frames being sent to and fro over the
> MII port, and single tagged frames being sent to and fro over the switch fabric's other ports. 
> However, in reality it's going to be fiddly to get this to work....
> 
> Firstly (and most obviously) you need to choose a switch fabric which can do jumbo frames (i.e. >
> 1522 bytes).
> 
> Secondly you need to be able to make the switch fabric ignore any vlan tags on it's non-MII
> ports, but use the (outer) tag on its MII port.  I'm pretty sure I can do this on the 88e9095 by
> re-configuring the DIX type (used to identify tagged frames on the non-MII ports) from 0x8100 to
> something reserved.  However, I won't know that this will work for sure till I get the eval board.

You may also have to hack on the VLAN code a bit...I'm not sure it completely supports
vlans in vlans, though it should be fairly straight-forward to add such support.

Ben

-- 
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc  http://www.candelatech.com


[Index of Archives]     [Netdev]     [Ethernet Bridging]     [Linux Wireless]     [Kernel Newbies]     [Security]     [Linux for Hams]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux RAID]     [Linux Admin]     [Samba]     [Video 4 Linux]

  Powered by Linux