Re: [cso] Some thoughts from the CSO Bar BOF...
"Kathy McEwen" <k.mcewen@verizon.net> Fri, 03 December 2010 17:11 UTC
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From: Kathy McEwen <k.mcewen@verizon.net>
To: 'Mirja Kühlewind' <mirja.kuehlewind@ikr.uni-stuttgart.de>, cso@ietf.org
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Date: Fri, 03 Dec 2010 11:12:32 -0600
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Subject: Re: [cso] Some thoughts from the CSO Bar BOF...
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Interesting thoughts, I have some additional comments inserted below... -----Original Message----- From: cso-bounces@ietf.org [mailto:cso-bounces@ietf.org] On Behalf Of Mirja Kühlewind Sent: Friday, December 03, 2010 8:37 AM To: cso@ietf.org Subject: Re: [cso] Some thoughts from the CSO Bar BOF... Hi, I participated in both Bar BoFs and I believe that in the area of Cross-Layer Optimization is still a lot of space to do thing better but I don't believe in a generic approach. I would like to response to the points below and also give some feedback to the charter. First the points below: (a) If you would have the global system view which has all the information about the application and the network state, I'm sure its possible to optimize the system such that all players will benefit. But we are talking here about a distributed system where every player tries to maximize its own benefit. KCM:: First of all, this is possible, we have built a system that is taking both a global cross network view and implemented to be distributed across networks and nodes. The protocols (Layers 2, 3/4, and 7) we have defined do not attempt to "maximize" to the individual nodes benefit, rather to enable a cross-network cooperation in negotiating resources and managing delivery end-to-end. I am also aware of at least 2 or 3 other disruptive start up competitors that are looking at doing something uncomfortably similar, as well as numerous Tier 1 network equipment providers exploring ways to deliver exactly this functionality. I would say even if you provide the needed information you can't be sure that automatically everybody will benefit. Moreover, you would have to give for every player the right incentives to actually make a decision that will optimize the whole system and not only the benefit of one single player. KCM:: Agreed, which is why Layer 7 protocols are needed, to enable the network to share in intelligence about the "application" or "data" being communicated or delivered. In the case of any professional media (music, video, news, entertainment, pictures, ...) there are strict "digital rights" management that must be respected. There is also the need for monetization, and the same content that is protected, generally has an owner that expects to be paid or has been paid for such content to be delivered/provided. Today there are "caches" created by Content Delivery Network (CDN) companies, such as Akamai, Level 3, Limelight, ..., that are fully aware of these "digital rights", and in many cases may participate in the subscription/authentication portion of the exchange as they take over the roles of caching entire websites. More and more, network providers and content providers are moving in a direction of pushing content closer and closer to the edges of networks. In the case of the internet, this traditionally has landed at broadband access providers peering points, and is not really anywhere near the actual consumer edge. Many network providers are now looking at how to extend the CDN inside these broadband ISP network borders, take a look at announcements from Verizon, Telefonica, AT&T, DT, BT, etc.. CDNs interoperate with each other, acting as their own overlay islands in the networks, clearly benefiting them as one single player. Todays CDN and IP/MPLS protocols do not cooperate to extend services in a managed way across multiple network domains. So, yes some monetization is needed for these providers to agree to cooperate as well, again this is something very well done in Layer 7, with subscription, billing, and admission control methods, without impacting the packet flows at layer 1/2-3. By standardizing and agreeing on some protocols here perhaps this can enable many, many players, multiple network providers, media providers and CDN providers, as well as application providers and consumers to benefit. Moreover, if you have several entities/different point in different layers which make decisions based on the same information, you have to be very careful that those decisions will not be counterproductive. E.g. an application changes the coding to lower bitrate and the network reserves more capacity at the same time. KCM:: Agreed, which is the motivation to have clear APIs and standards to enable communication of key information between layers 2/3, 7 and into the application itself. If a connection is created source to destination, enabling a massive transfer of data at a very high bit rate, then the application decides to adapt the codec rate, and doesnt inform the network, then the only way for the network to know the rate has changed is to monitor the flows. Take video for example, one can do some level of deep packet inspection to monitor the video control protocols (RTSP, RTMP, RTMP-WM, etc ) for adaptive rate change messages coming up from the clients (as this is how they all work today). But this is costly relative to a server actually sending a message in real time to notify the network that a rate change is going to take place just before they start sending the modified rate. This application message can then be shared with the lower layer 2/3 sub network systems to notify them to modify the capacity as well. One only needs to take a look at the example posted to NANOG recently by BBC of what is yet to come on the networks (Hot topic: Level 3 Communications Issues Statement Concerning Comcast's Actions) extracted from post: Whatever marketing feel like, there is no absolute High Definition, it's really Higher Definition where the reference is undefined. When access speeds get to 1Gbit/s they'll no doubt be unhappy that we may stream something like this - http://www.bbc.co.uk/news/technology-11436939 http://www.bbc.co.uk/blogs/researchanddevelopment/2010/10/super-hi-vision-tr ials It's basically impossible to show the stability of such a complex system. It's already hard to make any stability investigations about multi-protocol networks. KCM:: Disagree, todays SS7 voice networks deliver voice globally, across many network domain owners, fixed and wireless, out to endpoints that are both digital and analog, across fiber (PON), coax/cable (DOCSYS, DS3), copper (DSL, ADSL, VDSL, T1/EI, ) and the air (GSM, CDMA, AMPS, UMTS, WiFi, WiMAX, soon LTE), satellite links, and in many different container formats. Codecs are managed end to end, and negotiated in the mobile domain to allow for end to end transcoding free connections, as well as dynamically beginning a transcoding as needed if a user makes a handover to a different system. The network nodes are all running Layer 7 protocols to achieve the end to end cooperation, cut billing records (enabling monetization), verify subscription/roaming rights (enabling monetization between providers), negotiate admission with reservation that is totally aware of codec/bandwidth/L1/L2/L3 (including a large variety of TDM, IP, ATM and MPLS protocols) and working in tight cooperation with those layers to achieve the end to end globally connected Quality with stability that is in most cases regulated to provide availability to 5 9s (99.999% of the time the system is up and stably running = 5.26 minutes per year). Contrast this with your average internet system availability, then perhaps you may be right. (b) I still don't get your point here. As you say 'best effort' means that you always try to get the maximum but you never know what the maximum is/what you get. This doesn't go in-line for me with any kind of services guarantees. If you want guarantees you can use e.g. resource reservation. But than you know exactly what you get and you don't need any further cross-layer state information. KCM:: Networks, even IP/MPLS are not just best effort today, they have DiffServ (TOS), ATM PVC, MPLS-TE/RSVP, etc. The data network providers offer private network connections with everything from very strict service level agreements (SLA) to very loose or none. Unfortunately, today these tight SLA agreements cannot easily be extended to applications demanding the connections in real time. Is there any network provider that is offering on-demand 2-3 Mbps connections source to destination within milliseconds, or even seconds? Or even 1 Gbps connections? NTT, in the first CSO Bar BoF in Europe did show that they have demonstrated it can be done with optical layer components given a request from applications. I wonder if they used this to enable the BBC demo referenced above from London to Tokyo?? Wouldnt this be a cool thing to enable a very high definition broadcast of a real time event at the London Summer 2012 Olympics across the net? Coordinated, in cooperation with multiple network and media providers across UK, Canada, USA, Japan and the rest of the world. Conversely today, consumers and media providers alike depend on satellites, dedicated access links from their edit/origination points to distribution points then out to closed network Satellite, Broadcast, and Cable/IPTV. Consumers may not understand SLA and services guarantees but they do understand quality, they do pay for it, and they do change providers when they are dissatisfied with the quality of the service they are experiencing. Application and media providers understand SLA very well, and they often go to great lengths to ensure their consumers get the very best experience they can from their web sites. Unfortunately, for consumers and these providers, today they cannot extend that guarantee through the ISP down to the consumer. (c) You say: '... definition of a "data center" as something like "a location within the network where application resources maybe aggregated". What? Is 'the network' in your case the Internet? I would say a data center is not in the Internet. It maybe is at the border of the Internet but its a completely separated network were one entity has the control over all the physical devices within this network. That makes it easier to solve certain problems in a data center than in the Internet. But I don't see how it help to define the problem of CSO any better. KCM:: If you ignore the data center, you will be ignoring the requirements of the end-to-end solution. The data center is the source on the web, and the source can come from your PC (if you have your own web server on one), a server at an enterprise, a server in a big data center, a CDN cache server, or a network cache server. The location where the application resides could be on a mobile device, connecting to a server in the mobile network or outside the mobile network. Understanding where the source and destination points are, what they are capable of, and what protocols they are capable of communicating or not, and how those applications and devices will interwork with the network. Our solution (products and protocols), have incorporated these requirements into a network solution that is capable of adapting to the dynamic changing needs of the devices, access and the applications. Without an understanding of these it would be very difficult to define what the Layer 7 protocols need (subscription, billing, service enablement) and what they need to interwork with the Layer 2/3 protocols for an end-to-end service delivery. (d) Can you provide the pointers to all this material? But for me this examples look already so different that I wouldn't wanne try to find one generic solution for all of them. We just wrote an project proposal where the original idea was to do something about cross-layer optimization. But as we couldn't define the problem clearly, we thought it might make more sense to look at specific problems (one certain application in one network scenario) and find a solution for those problems in such a that it is generic enough to be used by other applications as well. (I have to say I'm working on transport protocols, so we were mainly focusing on solutions in the transport layer with application layer information/for one specific application type). KCM:: We have focused first on a specific application too, that being video delivery from web sites to consumers. Some remarks about the charter: - I still don't see which information you want to exchange. Whenever I asked this question, I got the same two examples like delay and bandwidth. But I don't believe that any application developer does understand what to do with these information. Btw. you can ask your socket interface for the congestion window and the RTT. These information are basically similar but completely useless for the application. You could maybe use these information aggregated over a certain time. This could give you an impression about the link state but still doesn't give you any guaranteed information for the future as the link state changes permanently. It's a really complicated task to define an interface in such a that not only the right information can be exchanged but they are also represented in the right what. It's not only what but also how. - From the Bar BoF I had the impression that the problem is more about which information should be exchanged but the charter is talking about a whole protocol. I would say to exchange information in one point between the layers you don't need a protocol but an inferface. I don't believe that you can find a generic interface here that will address all problems (and will be implemented by all kind of applications). I would assume that you have to change/extend the interface for every problem separately. If you want a protocol to expose certain information within the same layer, this is completely different problem. This also goes in the direction of measuring and monitoring network state. There are tons of proposal for measuring all different kind of thing. And again I would say the solution differ a lot depending on what information you are aiming for. - One more general comment: Whenever you talk about CSO I have the feeling that you basically want to provide more information for the application. Why not providing more information for the lower layers about the traffic characteristics, requirements and maybe even user preferences of the application? Should the information actually go in both directions or will this increase the possibility of counterproductive decision? KCM:: We would be happy to interwork with other network equipment to share some of our protocols and application information that could be shared across the layers, to enable the lower layers to work cooperatively with the applications. We would very much like to see some movement within IETF, particularly around the layers in MPLS and optical that they do own the protocols for. We have some very innovative ways of handling video packets, including for multicast/broadcast, that could easily be extending to work cooperatively with other network platforms. On the Layer 7, application side, we have used much of the protocols defined in 3GPP, as our solution is intended for both the fixed and mobile markets, and 3GPP has already worked out all the mobility/roaming subscription/billing tricks in their protocols. We plan to take what we have modified in the 3GPP protocols back to them to see if they will extend their standards to incorporate these modifications too. Just my thoughts. I would like to start this discussion on the list, as I think this is an intresting topic but your proposal it not concrete enough for me to see the action points in the IETF. I'm an academic and do research on this topic up to now. Mirja On Tuesday 09 November 2010 21:28:20 Greg Bernstein wrote: > Hi folks interested in cross stratum optimization (CSO) a few thoughts > on some of the interesting points raised at the Bar BOF and to > possibly stimulate further discussion: > > (a) Who benefits from CSO? The application provider or the carrier? It > seems to be viable CSO should benefit both. The network operator > (carrier, ISP, IT department, etc...) should benefit from more > effective utilization of network resources (links, switches, routers, > etc...) and gain more flexibility in dealing with fault conditions. > The application provider benefits from being able to offer either > higher quality services or better assurances on service quality. > Essentially the network operator gets to influence the placement of > load on the network while the application provider gets information > that allows them to optimize their resources along with their customers experience. > > (b) Isn't the Internet "best effort"? How can you talk of providing a > better "network experience" to applications? > First CSO isn't strictly aimed at the "Internet" in general, but would > start with various network domains (LAN, OSPF area, AS, etc...). Also > "best effort" is a somewhat misleading term since it doesn't take into > account overall statistical quality measures that are very important > to user experiences. For example 2000 sessions sharing a link on a > first come first serve basis are considered "best effort" whether the > link is a T1 or an OC-192 but will generally experience greatly > different "average" QoS ;-) . Depending on the network context and > technology various service level guarantees may be explicit or implicit. > > (c) What's a "data center" and do we include "hosts"? Folks interested > in CSO come from a number application and network areas. The essence > is that guidance from the network provider to the application provider > concerning network state and capability provides benefits to both. In > one of the drafts we tried a definition of a "data center" as > something like "a location within the network where application > resources maybe aggregated". > I'd say a "host" (or my laptop) would qualify. Other ideas? > > (d) Examples? During some of the background work for the CSO drafts we > looked at a number of examples that we published in the original draft. > We've also looked at "pre-CSO" type mechanisms that are being used to > try and optimize applications. These include "old school" and "new > school" CDN approaches, load balancing within and between data > centers (local versus global), various papers dealing with local and > wide area VM migration, and High Performance Computing applications > (radio astronomy being an interest of mine). Would it be useful to > organize these in some way? We had some of these in the original CLO > draft but the overall length was getting to long. For our WSON work > we set up web pages to keep track not just editors copies of our > drafts (for all to work with) but supplemental material (some of which > was later published in IEEE/OSA journals). > > Just some thoughts from a jet lagged Californian ;-) > > Greg B. _______________________________________________ cso mailing list <mailto:cso@ietf.org> cso@ietf.org <https://www.ietf.org/mailman/listinfo/cso> https://www.ietf.org/mailman/listinfo/cso
- [cso] Some thoughts from the CSO Bar BOF... Greg Bernstein
- Re: [cso] Some thoughts from the CSO Bar BOF... Mirja Kühlewind
- Re: [cso] Some thoughts from the CSO Bar BOF... Kathy McEwen
- Re: [cso] Some thoughts from the CSO Bar BOF... Greg Bernstein
- Re: [cso] Some thoughts from the CSO Bar BOF... Young Lee