[c-nsp] ATOM Basic Question

Oliver Boehmer (oboehmer) oboehmer at cisco.com
Mon Oct 11 09:18:57 EDT 2004

>   You said " Replacing a legacy Frame-relay L2 service by ATOM ". What
> advantages for the provider/customer to use ATOM versus the legacy
> Frame-Relay L2 service? 

well, in general it reduces the number of networks to be built/managed..
So it is often more a $$$ than a technical/feature decision..

>   I keep wondering about this because sometimes I think that
> keep providing isolated L2 services like Frame-Relay is more 
> secure and reliable than offering it via MPLS. 

The security argument is weak, and a reliable MPLS network is also able
to provide reliable L2 services.. Of course you can argue that two
separate networks are more reliable than a single one, but this comes at
a price...

> Your thoughts about practical implementations/advantages are highly
> appreciated. 

I'd like to defer this question to the alias as I haven't really worked
with many customers on AToM, but the lack of full PNNI integration
(we're working on this) has been an issue with some deployments I'm
aware of..
On the other hand I'm seeing some customers moving to ATM over MPLS due
to a rather expensive bw upgrade path in their ATM core.. YMMV


> -----Original Message-----
> From: Oliver Boehmer (oboehmer) [mailto:oboehmer at cisco.com]
> Sent: Monday, October 11, 2004 2:44 PM
> To: Yasser Aly; cisco-nsp at puck.nether.net
> Subject: RE: [c-nsp] ATOM Basic Question
>>   With MPLS-VPN the provider is involved in the customer routing.
>> That's to say the CE next hop is the PE router of the provider.
>>    Now, if I am having a customer where he is having Frame-Relay L2
>> service. The provider role here is on L2 level only and L3 is done
>> between customer router only. Now if I am interested to offer ATOM
>> such that the customer is still getting from me Frame-Relay service
>> and it is carried over the MPLS backbone. What will be the next-hop
>> for the customer? Will it be the provider PE router - like the case
>> of MPLS-VPN -, or the Provider routers will be totally transparent
>> for the customer and the customer next-hop will be his other branch ?
> With ATOM, the MPLS network is (more or less) transparent, 100%
> transparent from a Layer3 perspective.. I say "more or less" because
> some 
> some L2 stuff
> like OAM for ATM is performed on the PE.. for example you can
> basically replace a legacy Frame-relay L2 service by ATOM..
> 	oli

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