From: Dan (dans@danbsd.a.la)
Date: Tue May 11 2004 - 11:25:28 GMT-3
This draft sound so much like atm LANE? I dont know why the don't just use
LANE and adapt it to ethernet ;)
On Tue, 11 May 2004 10:20:23 -0400, Howard C. Berkowitz <hcb@gettcomm.com>
wrote:
> At 1:00 PM +0530 5/11/04, Sachin Shenoy wrote:
>> Hi,
>>
>> I was wondering if trunking over WAN is possible ...
>> What I mean by that is
>>
>>
>> Serial Link
>> SW1----R1<------------->R2--SW2
>>
>> Is it possible to trunk VLANs from SW1 to SW2 ???
>> (So LAN IP ranges for VLANs on SW1 and SW2 will be the same !)
>
> In certain, restricted, cases, usually requiring gigabit or faster
> transmision media, yes. See such things as Private VLAN Service (more
> the IETF term) and QinQ encapsulation (although the latter is not a WAN
> protocol, but the distinction between LAN and WAN is less and less
> useful). It's also possible using MPLS.
>
> Why do you consider this a good idea? It has potential scalability
> issues, for example, involving both absolute delay greater than expected
> by LAN devices. Another scalability issue is that uncontrolled growth
> at both locations may cause the safe number of devices in a broadcast
> domain to be exceeded.
>
> I've been asked to do this many times, on the basis that "layer 2 is
> simpler." At a certain level of scaling, it is not. In general, in the
> circumstance you describe, I'd route between the sites without
> overwhelming evidence to the contrary. I can even keep VLAN numbers
> consistent at both sites.
>
> Unfortunately, studying for the CCIE lab overempasizes lots of things
> that may be possible, but not a good idea in the real world.
>
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