[c-nsp] Layer 3 Core

[Shane Amante]

Paul Stewart wrote:
> Just curious on this topic... searching docs and can't find answer...
> 
> Can you transport VTP over l2tpv3?

Yes, along with CDP and STP, as well.  Take a look at the following:
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/122sx/swcg/l2pt.htm

... which you need to do, in order to not locally process or drop those 
frames at the tunnel ingress & egress routers.

-shane


> Paul
>  
> 
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Shane Amante
> Sent: Thursday, April 05, 2007 2:58 PM
> To: Voll, Scott
> Cc: Stephen Backholm; cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] Layer 3 Core
> 
> Another option to consider is, instead of enabling MPLS forwarding over your
> core, look at encapsulating Ethernet over MPLS inside L2TPv3.  This would
> require you to enable MPLS at the edge(s) of your network, but still run
> native IP forwarding in your core.
> 
> Overall, I would favor MPLS forwarding or L2TPv3/UDP/IP forwarding of EoMPLS
> packets between your locations because you get protection & restoration in
> the core, since that is a natural property of IP or MPLS. 
>   In addition, you gain the benefit of fate-sharing and similar fail-over
> times for Layer-3 & Layer-2 connectivity between the two locations.  One
> downside of L2TPv3, to keep in mind, is it's not ubiquitously available in
> HW on all platforms, (e.g.: 6500/SUP720), whereas native MPLS is more widely
> available.
> 
> I think if you attempt to stand-up a single VLAN over the core, and you lose
> a link in the core, you're out-of-luck.  On the other hand, if you attempt
> to set-up diversely 'routed' VLAN(s) over the core, then you have to
> consider running STP between locations or start looking at other more
> complicated methods to provide protection between both locations.
> 
> -shane
> 
> 
> 
> Voll, Scott wrote:
>> Why add complexity..... I'd just trunk.
>>
>> Scott
>>
>> -----Original Message-----
>> From: cisco-nsp-bounces at puck.nether.net 
>> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Stephen 
>> Backholm
>> Sent: Thursday, April 05, 2007 9:38 AM
>> To: cisco-nsp at puck.nether.net
>> Subject: [c-nsp] Layer 3 Core
>>
>> Currently where I work we run a complete Layer 3 network core. This 
>> decision was made in order to keep Spanning Tree Protocol, ACls, QoS, 
>> and Policing out of the core and at the distribution layer. This has 
>> worked well for us, but we have a need for a few of our server VLANs 
>> to be in opposite geographic ends of campus for redundancy. These 
>> servers run as clusters and require Layer 2 connectivity between them, 
>> so in other words we need Layer 2 connectivity across our Layer 3 core.
>>
>>
>> Here is the question.
>>
>> Would it be better to solve this problem with MPLS or just trunk the 
>> handful of server VLANs across our core?
>>
>>
>> Your thoughts and/or suggestions are appreciated.
>>
>> Regards,
>> Stephen Backholm
>>
>>
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