Re: [bess] [sfc] [mpls] Progress with draft-farrel-mpls-sfc

<> Mon, 19 March 2018 09:52 UTC

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To: "Henderickx, Wim (Nokia - BE/Antwerp)" <>, Robert Raszuk <>, Adrian Farrel <>
CC: mpls <>, SPRING WG List <>, "" <>, "" <>
Thread-Topic: [sfc] [mpls] Progress with draft-farrel-mpls-sfc
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Date: Mon, 19 Mar 2018 09:52:05 +0000
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Subject: Re: [bess] [sfc] [mpls] Progress with draft-farrel-mpls-sfc
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Hi all,

Wim has a point here.

For all these proposals, a new behavior is needed to be followed by SFC-aware nodes. What differs is the channel used to signal a chain and to supply additional data for SFC purposes.

Leveraging on existing code/capabilities is good for a vendor/implementer, but the risk is that a given solution will need to support all/many of these flavors. Which is not optimal.

The IETF has already a consensus on a transport-agnostic solution. If we open the door for MPLS, we need to open it also for IPv6 EH and so on. Are we OK to go that way? If yes, what is the NEW problem are we trying to solve?



De : sfc [] De la part de Henderickx, Wim (Nokia - BE/Antwerp)
Envoyé : dimanche 18 mars 2018 07:26
À : Robert Raszuk; Adrian Farrel
Cc : mpls; SPRING WG List;;
Objet : Re: [sfc] [mpls] Progress with draft-farrel-mpls-sfc

Indeed, this is exactly my point. If you want an interim solution you want to use what we have and draft-ietf-bess-service-chaining-04 is an example of how you can use the existing data-plane for service chaining. draft-farrel-mpls-sfc requires an implementation change in the data-plane, whether we like it or not and an upgrade is required even in brownfield deployments. So, you better go directly to the final solution defined in IETF SFC WG. If we standardize draft-farrel-mpls-sfc we end up supporting both forever.

From: <<>> on behalf of Robert Raszuk <<>>
Date: Saturday, 17 March 2018 at 19:13
To: Adrian Farrel <<>>
Cc: "Henderickx, Wim (Nokia - BE/Antwerp)" <<>>, mpls <<>>, SPRING WG List <<>>, "<>" <<>>, "<>" <<>>
Subject: Re: [sfc] [mpls] Progress with draft-farrel-mpls-sfc

Hi Adrian,

> That proxy may be a bump in the wire between the SFF and SF

I am not so sure about that ... If this would be just "bump in the wire" you would have zero guarantees that all packets which need to go via given function will actually hit that bump - so this is far from a reliable network service.

There must be associated control plane component attracting traffic to such bump.

That mechanism with basic MPLS (where labels by based MPLS architecture are of local significance) is available with L3VPN extensions as already progressing in BESS (draft-ietf-bess-service-chaining-04) so why not use this for as you state "interim" ?

No one really addressed that question yet and I think it is a critical one to make any further judgement  as to the future of this individual submission.


On Sat, Mar 17, 2018 at 6:46 PM, Adrian Farrel <<>> wrote:
Hi Wim,

Thanks for reading the draft so carefully.

> Adrian, on replacement of NSH. You will have to change the SF with this proposal
> in Non proxy case so this proposal does not solve a brownfield case. Which SF(s)
> support MPLS?

This is not about "replacing" the NSH. As you'll see from point 2, below, this is about providing an interim / migration technology.

Clearly (and I think you agree) in the case where an SF is not SFC-aware, a proxy must be used. That proxy may be a bump in the wire between the SFF and SF, a module of the SFF, or a module of the SF. In the case of PNFs, only the first two options are available. In the case of a VNF, all three options exist.

Now, let us recall where we are starting from. There are PNFs and there are VNFs built to look like PNFs. These SFs do not support MPLS or NSH.

Similarly, there are routers that do not support the NSH.

Now, of course, we would all love to sell major upgrades so that every component of the network is SFC-aware. But we would also like to start deploying SFC into existing network infrastructure.

So your question misses the point. The question to ask is which brownfield routers and SFs support NSH?