[Bridge] VLAN translation + PVST+

[Bridge] VLAN translation + PVST+

[Ian Schwimmer]

Hello, I am creating a configuration where a Redhat server running 
bridge-tools 0.9.5 will be bridging between different VLANs on the same 
physical interface (for example: a bridge consisting of eth1.100 and 
eth1.110). This physical interface is being connected to modern Cisco 
switches running PVST+.

The Cisco switch does not like this configuration as the tags on its 
BPDUs are being changed but the contents of the BPDUs are left unchanged.

I need to be running PVST+ because there will be multiple Linux servers 
performing this VLAN translation/remapping (so there are going to be 
some loops that I will need blocked).

Has anyone succeeded in getting VLAN translation/remapping (bridging 
between two different VLAN tags) working with Cisco PVST+? (not simply 
disabling spanning tree). Thank you!

Ian Schwimmer
310-897-9001
ian@us.checkpoint.com

Re: [Bridge] VLAN translation + PVST+

[Gergely Madarasz]

On Wed, May 17, 2006 at 06:09:37PM -0700, Ian Schwimmer wrote:
> Hello, I am creating a configuration where a Redhat server running 
> bridge-tools 0.9.5 will be bridging between different VLANs on the same 
> physical interface (for example: a bridge consisting of eth1.100 and 
> eth1.110). This physical interface is being connected to modern Cisco 
> switches running PVST+.
> 
> The Cisco switch does not like this configuration as the tags on its 
> BPDUs are being changed but the contents of the BPDUs are left unchanged.
> 
> I need to be running PVST+ because there will be multiple Linux servers 
> performing this VLAN translation/remapping (so there are going to be 
> some loops that I will need blocked).
> 
> Has anyone succeeded in getting VLAN translation/remapping (bridging 
> between two different VLAN tags) working with Cisco PVST+? (not simply 
> disabling spanning tree). Thank you!

Actually I have just written a patch for 2.6.16 the other day which
supports PVST+ packet format. It adds a pvst_vlan attribute to each port
in a bridge, which, if not 0, causes the bpdu's sent on that port to use
the pvst+ llc header and add the vlan tlv at the end of the packet. 

For example you can bridge two vlan interfaces like eth0.4 and eth1.7,
with setting pvst_vlan to 4 on eth0.4 and to 7 on eth1.7 (no automatic
voodoo). Your example can be done too, briding two vlans on the same
trunk.

Should I send the patch to the list or just in private?

-- 
Madarasz Gergely        gorgo@broadband.hu         gorgo@linux.rulez.org
    It's practically impossible to look at a penguin and feel angry.
        Egy pingvinre gyakorlatilag lehetetlen haragosan nezni.

Re: [Bridge] VLAN translation + PVST+

[John W. Linville]

On Wed, May 17, 2006 at 06:09:37PM -0700, Ian Schwimmer wrote:
> Hello, I am creating a configuration where a Redhat server running 
> bridge-tools 0.9.5 will be bridging between different VLANs on the same 
> physical interface (for example: a bridge consisting of eth1.100 and 
> eth1.110). This physical interface is being connected to modern Cisco 
> switches running PVST+.

I'm curious as to how this is useful?  What is the point of having
two VLANs on the same segment if you are just going to bridge them
together?  Is this useful for something beyond some sort of migration?

Curious,

John
-- 
John W. Linville
linville@tuxdriver.com

Re: [Bridge] VLAN translation + PVST+

[Ian Schwimmer]

It is useful if the server doing the bridging is also doing something 
else, such as firewall policy enforcement.

Then, you may move hosts in and out of the "protected" VLAN simply by 
changing their port VLAN assignment. No messing with cabling, no IP 
address changes.

-Ian

John W. Linville wrote:
> On Wed, May 17, 2006 at 06:09:37PM -0700, Ian Schwimmer wrote:
>   
>> Hello, I am creating a configuration where a Redhat server running 
>> bridge-tools 0.9.5 will be bridging between different VLANs on the same 
>> physical interface (for example: a bridge consisting of eth1.100 and 
>> eth1.110). This physical interface is being connected to modern Cisco 
>> switches running PVST+.
>>     
>
> I'm curious as to how this is useful?  What is the point of having
> two VLANs on the same segment if you are just going to bridge them
> together?  Is this useful for something beyond some sort of migration?
>
> Curious,
>
> John
>   

Re: [Bridge] VLAN translation + PVST+

[Vivek Kuncham]

I have no idea how I got on this list.  Would someone mind taking me 
off?  I'm not sure how to do it.

Thanks,
Vivek

On 5/18/2006 11:02 AM, Ian Schwimmer wrote:

> It is useful if the server doing the bridging is also doing something 
> else, such as firewall policy enforcement.
>
> Then, you may move hosts in and out of the "protected" VLAN simply by 
> changing their port VLAN assignment. No messing with cabling, no IP 
> address changes.
>
> -Ian
>
> John W. Linville wrote:
>
>> On Wed, May 17, 2006 at 06:09:37PM -0700, Ian Schwimmer wrote:
>>  
>>
>>> Hello, I am creating a configuration where a Redhat server running 
>>> bridge-tools 0.9.5 will be bridging between different VLANs on the 
>>> same physical interface (for example: a bridge consisting of 
>>> eth1.100 and eth1.110). This physical interface is being connected 
>>> to modern Cisco switches running PVST+.
>>>     
>>
>>
>> I'm curious as to how this is useful?  What is the point of having
>> two VLANs on the same segment if you are just going to bridge them
>> together?  Is this useful for something beyond some sort of migration?
>>
>> Curious,
>>
>> John
>>   
>
>
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[Bridge] getting off list

[Stephen Hemminger]

On Thu, 18 May 2006 11:35:56 -0400
Vivek Kuncham <vkuncham@fas.harvard.edu> wrote:

> I have no idea how I got on this list.  Would someone mind taking me 
> off?  I'm not sure how to do it.
> 
> Thanks,
> Vivek

Every posting on this list has a footer with the web site of the mailing list.
Go there, enter your email address, hit unsubsribe
Then respond to the confirmation email.

Re: [Bridge] VLAN translation + PVST+

[Ben Greear]

John W. Linville wrote:
> On Wed, May 17, 2006 at 06:09:37PM -0700, Ian Schwimmer wrote:
> 
>>Hello, I am creating a configuration where a Redhat server running 
>>bridge-tools 0.9.5 will be bridging between different VLANs on the same 
>>physical interface (for example: a bridge consisting of eth1.100 and 
>>eth1.110). This physical interface is being connected to modern Cisco 
>>switches running PVST+.
> 
> 
> I'm curious as to how this is useful?  What is the point of having
> two VLANs on the same segment if you are just going to bridge them
> together?  Is this useful for something beyond some sort of migration?

You can add a bridge group for 10 vlans, and route them to another bridge
group of 10 VLANs.  You can also enforce firewall rules on particular
VLANs (ie, could put each customer on individual VLAN, and backhaul them
all to one linux box to bridge/firewall/bill/etc them...)

Ben

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