Re: [L3sm] [l3sm] #17 (draft-ltsd-l3sm-l3vpn-service-model): "same-bearer" Diversity Constraint Augmentation Suggestion

["Landry, Jean-Philippe" <[e-mail]>]

Yes I agree that 5.5.5.3 provides an effective way to implement parallel links from a site to a PE. The context of 5.5.5.3 is one of scaling out bandwidth in cost efficient manner. Now in a broader context, such parallel links are sometimes also implemented to augment diversity or to partition vpn access for mutli-vpn customers. In my comment, I was suggesting that these links could be logical and ride over arbitrary bearers (I provided sub-interface, TDM channels, PVCs, VLANs as examples).



So assuming we have a common definition for what a bearer is, my suggestion was to augment the diversity constraint to allow to control whether multiple parallel logical links ride over common or diverse bearer.



Another way to look at it would be to say that we want the options to control node (PE), line card, and interface diversity. Bearer is really at the interface level.



Practical example: a CE needs to connect to a PE over two 512 kbps T1 TDM channels:



1.  Specifying bearer-diverse constraint would force the implementation of two separate physical T1 circuits (over which the 512 kbps channels would ride separately)

2.  Specifying same-bearer constraint would force the multiplexing of the two 512kbps channels over a single T1 circuit.



With the site-network-access construct, I believe the L3 IPVPN model is really interested in the modeling of the L3 logical links which in the end are receiving the VPN configuration attributes and not so much in the precise modeling of physical links or bearer. Utilizing diversity constraints to influence physical network implementation is a good way to enable high level customer facing requirements without having to absorb all the complexity of physical circuits into the model, in my opinion.



I hope I am making sense for everyone.



Cheers,



JPL

________________________

Jean-Philippe Landry, Senior Technical Architect/Architecte technique principal,

New Technology Introduction, Bell Canada

1 Alexander-Graham-Bell, E2

Verdun, QC, H3E 3B3

téléphone: [phone]

<<mailto:[e-mail]>>

https://session.collaboration.bell.ca/join/krcwz







-----Original Message-----
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Sent: Thursday, September 01, 2016 10:05 AM
To: l3sm issue tracker; [e-mail]; Landry, Jean-Philippe
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Subject: RE: [l3sm] #17 (draft-ltsd-l3sm-l3vpn-service-model): "same-bearer" Diversity Constraint Augmentation Suggestion



Hi,



Having parallel links attached with different bearers to the same PE is achievable using "same-pe" constraint. It is detailed in 5.5.5.3.

Does it fit your requirement ?



Brgds,



Stephane



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From: l3sm issue tracker [mailto:[e-mail]]

Sent: Wednesday, August 31, 2016 22:36

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Subject: [l3sm] #17 (draft-ltsd-l3sm-l3vpn-service-model): "same-bearer" Diversity Constraint Augmentation Suggestion



#17: "same-bearer" Diversity Constraint Augmentation Suggestion



Assuming "same-bearer" diversity constraint is meant for making sure that logical interfaces (such as sub-interfaces, TDM channels, Vlans, PVCs, etc. ) can be consolidated on a common physical (bearer) access (cost saving measure), it would also be logical to allow diverse bearer specification considering these logical access are often meant to be used in Primary/Backup arrangements. Recommending to add bearer-diverse constraint.



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Reporter: [e-mail]<mailto:[e-mail]> | Owner: draft-ltsd-l3sm-l3vpn-

Type: enhancement | [e-mail]<mailto:[e-mail]>

Priority: minor | Status: new

Component: draft-ltsd-l3sm-l3vpn- | Milestone:

service-model | Version:

Severity: - | Keywords:

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Ticket URL: <https://trac.tools.ietf.org/wg/l3sm/trac/ticket/17>

l3sm <https://tools.ietf.org/l3sm/>





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