Re: [multipathtcp] [MPTCP] draft-deng-mptcp-mobile-network-proxy-00

[lingli deng <[e-mail]>]

Hi Sam,

Thanks for your review and comments.
Plz see some initial comments inline:

Lingli


2014-02-25 9:01 GMT+08:00 Xiongchunshan (Sam) <[e-mail]>
:

>  Hello folks,
>
>
>
> Here I have some comments on this document:
>
>
>
> 1)
>
> 5.2  Traffic mediation
>
>    (a) Anchoring of sub-flow traffic: On one hand, it is not always
>
>    possible for a single GW be sitting on the path of every sub-flow
>
>    from a MPTCP session, hence explicit traffic anchoring to enable a
>
>    single point of general control over MPTCP sub-flows should be
>
>    considered.
>
>    (b) Mediation of sub-flow traffic: On the other hand, for fine-
>
>    grained mediation of sub-flow traffic, both static and dynamic
>
>    selection/offloading/pooling policies should be allowed. For
>
>    instance, "always prefer Wi-Fi over 3GPP" could be a static policy
>
>    for bulk data transfer services, while "use 3GPP only for backup
>
>    unless Wi-Fi is congested" could be a dynamic offloading policy for a
>
>    un-prioritized VoIP service.
>
> [xcs]Question for clarification: How does the MPTCP proxy know the binding
> information between the IP and RAT ?  The mobile node knows which IP is
> allocated from which RAT, but it is very hard for the MPTCP Proxy in the
> core network to know these mapping information.
>

*[dll] For 3GPP access networks, the core knows the RAT type as the time of
PDP connection setup. For WLAN, there has been interworking standards via
PDG (packet data gateway) which does the IP binding. So the core network
knows the mapping, and there is a need to integrate MPTCP proxy with
existing architecture to get this information.*


>  One possible solution is the PCRF (defined in the 3GPP) to provide these
> binding information to the MPTCP proxy if the MPTCP proxy performance the
> traffic mediation or let the mobile to do the traffic mediation.
>

*[dll] I agree that interface with PCRF could be a solution to provide
binding information from the network side, as well as acquiring mediation
policy.*

>
>
> Another question is how the rules (e.g. "always prefer Wi-Fi over 3GPP")
> are provided to the MPTCP Proxy or the mobile ? For the MPTCP proxy, it is
> again the PCRF; for the mobile , it is the ANDSF ?
>
>
>

*[dll] Yes, PCRF would be a candidate in the case of proxy mediation and
ANDSF has been proposed to be used by 3GPP for network selection. However,
just for discussion, I personally prefer proxy-based mediation, as it may
not always be proper to rely on the terminal for network-driven policy
enforcement. Therefore, I would suggest we **currently **focuse on
proxy-mediation case. Would you agree?*


>
> 2)
>
> 4.2 Resource pooling for reduced expense
>
>    Due to its low construction and operation expenses, Wi-Fi has been
>
>    adopted by mobile operators as a complementary RAT for their
>
>    traditional 3GPP networks. However, different construction and
>
>    operation expenses of various radio networks result in differences in
>
>    charging rates/policies for different RATs.
>
>    For instance, Wi-Fi access may be charged by the access duration,
>
>    while the 3GPP access may be charged by the consumed data volume.
>
>    Even if using the same policy, Wi-Fi service is expected to be much
>
>    cheaper than 3GPP data service.
>
>    Moreover, different subscription packages may offer various data
>
>    plans for various RATs. For instance, a basic 4G package may contain
>
>    free data volume as well free Wi-Fi access too.
>
>    By enabling MPTCP session between UE and network proxy, via mediating
>
>    sub-flow data traffic based on their Radio access types and the
>
>    user’s subscription package, it is possible to further reduce the
>
>    usage expenses from both sides of the network and user.
>
>
>
> [xcs] it will benefit the user if the user’s expense of data usage is
> reduced, if the WiFi connection is available and charging fee is very low,
> maybe all the traffic from the 4G are moved to the WiFi by the MPTCP proxy,
> and the mobility and QoS of the service maybe aren’t ensured, so it is
> proposed to adding the following sentence to the end of this chapter:
>
> *The QoS/QoE/Service continuity of the current data services are still
> kept when the MPTCP proxy is used to reduce the user’s usage expenses.*
>

*[dll] Good point. I agree.*

>
>
> A assumption for reducing user expense is that the WiFi connection is
> activated beforehand, but sometimes the WiFi connection isn’t activated or
> a wrong WiFi AP is selected by the user( that MPTCP Proxy can’t access the
> WiFi IP flow), that is, one hand, the network need to control the MPTCP
> Proxy to mediate the IP flows, another hand, the network should tell the
> mobile to open which RAT/WiFi to make the MPTCP Proxy work.  i.e. the
> network should provide some information to the UE , to guide the UE to
> select and open another RAT to enable the MPTCP.
>
>
>
*[dll] I agree that it is of great value for mobile terminals to be more
intelligent in enabling multiple interfaces based on network provided
information. But how it is done seems to be out of scope of a MPTCP proxy
discussion.*

>
>
> 3)
>
> 4.1 Dynamic traffic offloading based on network information
>
>    For real-time interactive services with higher QoS requirements it is
>
>    expected that 3GPP network can provide better guarantees on the
>
>    average case. For bulk data transfer who is satisfied with best-
>
>    effort delivery, Wi-Fi would be a great choice. But the vertical
>
>    partition does not fit everywhere for the wireless condition itself
>
>    is quite dynamic and hard to predict. It is important to implement
>
>    adaptive offloading mechanisms in order to achieve higher resource
>
>    utility with ever changing radio environment for a possibly moving
>
>    terminal based on network status, e.g. cell load, AP’s signal
>
>    intensity, user’s subscription type, etc.
>
> [xcs]The same question from 1):  How does the MPTCP Proxy/UE know the
> network status ? The PCRF/ANDSF provides these information to the MPTCP
> Proxy/UE ?
>

 *[dll] Plz refer to the above comments^^*

>
>
> BRs
>
> Chunshan Xiong
>
> Huawei Technologies Co., Ltd.
>
>
>
>
>
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-- 
邓灵莉/Lingli Deng
中国移动通信研究院/China Mobile Research Institute
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