Subject: Re: [NSIS] WG Last Call on draft-ietf-nsis-req-06.txt

From: Kuntal Chowdhury <[email-masked]>
Date: Mon, 27 Jan 2003 16:47:09 -0600

Hi all,
Here is an attempt to generalize the scope of NSIS in 3G wireless networks. The 
following is the suggested update/re-write of section 10.2 and 10.3.

Issue Name: 7
Submitter name: Louis-Nicolas Hamer and Kuntal Chowdhury
Submitter email address: [email-masked]
Date first submitted: 22/01/2003
Reference: none
Document: draft-ietf-nsis-req-06.txt
Comment type: T
Priority:  2
Section: 10.2 & 10.3

Proposed text:

10.2 3G Wireless Networks

    In this scenario, the user is using the packet services of a 3rd
    generation wireless system (e.g. 3GPP/UMTS, 3GPP2/cdma2000). The
    region between the End Host and the Edge Node (Edge Router)
    connecting the wireless network to another QoS domain is considered
    to be a single QoS domain.

    The issues in such an environment regarding QoS include:

    1) 3G wireless networks provide their own QoS technology with
    specialized parameters to co-ordinate the QoS provided by both the
    radio access and wired access networks. Provisioning of QoS
    technologies within a 3G wireless network can be described mainly
    in terms of calling bearer classes, service options and service
    instances. These QoS technologies need to be invoked with suitable
    parameters when higher layers trigger a request for QoS. Therefore
    these involve mapping of the requested higher layer QoS parameters
    onto specific bearer classes or service instances. The request for
    allocation of resources might be triggered by signaling at the IP
    level that passes across the wireless system, and possibly other
    QoS domains. Typically, wireless network specific messages are
    invoked to setup the underlying bearer classes or service instances
    in parallel with the IP layer QoS negotiation, to allocate resources
    within the radio access network.

    2) The IP signaling messages are initiated by the NSIS initiator and
    interpreted by the NSIS Forwarder. The most efficient placement of the
    NSIS Initiator and NSIS Forwarder has not been determined in 3G wireless
    networks, but a few potential scenarios can be envisioned. The NSIS
    Initiator could be located at the End Host e.g. UE or MS (triggered by
    applications), the Access Gateway or at a node that is not directly on
    the data path, such as a policy server. The Access Gateway could act as
    a proxy NSIS Initiator on behalf of the UE/MS or an End Host. The Policy
    Server that manages per-flow/aggregate resources within its QoS domain
    (e.g. the 3G wireless network) may act as a proxy NSIS Initiator for the
    UE/MS or the Access Gateway. Depending on the placement of the NSIS
    Initiator, the NSIS Forwarder may be located at an appropriate
    point in the 3G wireless network.

    3) The need for re-negotation of the resource needs in a new 3G wireless
    domain due to UE/MS mobility. In this case the NSIS Initiators and the
    NSIS Forwarders will have to detect mobility events and trigger
    re-negotiation of resources autonomously.

10.3 An example scenario for a 3G wireless network

    The 3G wireless access scenario is shown in Figure 1. The Proxy-Call
    State Control Function (P-CSCF) is the outbound SIP proxy (only used
    in IMS). The Access Gateway is the egress router of the 3G wireless
    domain and it connects the radio access network to the Edge Router
    (ER) of the backbone IP network. The Policy Server is the entity
    responsible for managing the resource allocations/de-allocations in
    the 3G wireless domain. It is also responsible for the policy-based
    control of the end-user service. The Policy Server also controls the
    Access Gateway to open and close the gates and to configure per-flow
    policies, i.e. to authorize or forbid user traffic. The P-CSCF (only
    used in IMS) and the Access Gateway communicate with the Policy Server,
    for network resource allocation/de-allocation decisions. The User
    Equipment (UE) or the Mobile Station (MS) consists of a Mobile Terminal
    (MT) and Terminal Equipment (TE), e.g. a laptop.

                            +--------+
                 +--------->| P-CSCF |-------> SIP signaling
                /           +--------+
               / SIP            |
              |             +--------+
              |             | Policy |         +----------------+
              |             | Server |<------->| NSIS Forwarder |<--->
              |             +--------+         +----------------+
              |                 |                  ^
              |                 |COPS              |
              |                 |                  |
          +------+          +---------+            |
          | UE/MS|----------| Access  |<-----------+         +----+
          +------+          | Gateway |----------------------| ER |
                            +---------+                      +----+

                   Figure 1: 3G wireless access scenario

    The Policy Server has all the required QoS information for per-flow
    or aggregate admission control in 3G wireless networks. It receives
    resource allocation/de-allocation requests from the P-CSCF and/or
    Access Gateway etc. and responds with policy decisions. Hence the
    Policy Server may be a candidate entity to host the functionality
    of the NSIS Initiator, initiating the "NSIS" QoS signaling towards the
    core IP network. On the other hand, the UE/MS may act as the NSIS
    Initiator or the Access Gateway may act as a Proxy NSIS Initiator
    on behalf of the UE/MS. In the former case, the P-CSCF/Policy Server
    has to do the mapping from codec types and media descriptors (derived
    from SIP/SDP signaling) to IP traffic descriptor. In the latter
    case, the UE/MS may use any appropriate QoS signaling mechanism as the
    NSIS Initiator. If the Access Gateway is acting as the Proxy
    NSIS initiator on behalf of the UE/MS, then it may have to do the
    mapping of parameters from radio access specific QoS to IP QoS
    traffic parameters before forwarding the request to the NSIS Forwarder.

    The NSIS Forwarder is currently not part of the standard 3G wireless
    architecture. However, to achieve end-to-end QoS a NSIS Forwarder is
    needed such that the NSIS Initiators can request a QoS connection to
    the IP network. As in the previous example, the NSIS Forwarder
    could manage a set of pre-provisioned resources in the IP network,
    i.e. bandwidth pipes, and the NSIS Forwarder performs per-flow admission
    control into these pipes. In this way, a connection can be made between
    two 3G wireless access networks, and hence, end-to-end QoS can be
    achieved. In this case the NSIS Initiator and NSIS Forwarder are
    clearly two separate logical entities. The Access Gateway or/and the
    Edge Router in Fig.1 may contain the NSIS Forwarder functionality,
    depending upon the placement of the NSIS Initiator as discussed in
    scenario 2 in section 10.2. This use case clearly illustrates the need
    for an "NSIS" QoS signaling protocol between NSIS Initiator and NSIS
    Forwarder. An important application of such a protocol may be its use
    in the end-to-end establishment of a connection with specific QoS
    characteristics between a mobile host and another party (e.g. end host
    or content server).

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---

From: Brian Williams <[email-masked]>
Date: Wed, 29 Jan 2003 14:13:45 +1100

Hi Kuntal.
I would suggest some small tweaking in the wording as follows (the 
changes are in the parts between the <>):

2) The IP signaling messages are initiated by the NSIS initiator and 
interpreted by the NSIS Forwarder. The most efficient placement of the 
NSIS Initiator and NSIS Forwarder has not been determined in 3G wireless 
networks, but a few potential scenarios can be envisioned. The NSIS 
Initiator could be located at the End Host e.g. UE or MS (triggered by 
applications), the Access Gateway or at a node that is not directly on 
the data path, such as a policy server. The Access Gateway could act as 
a proxy NSIS Initiator on behalf of the UE/MS or an End Host. The Policy 
<Decision Function that controls> per-flow/aggregate resources <with 
respect to the session> within its QoS domain (e.g. the 3G wireless 
network) may act as a proxy NSIS Initiator for the UE/MS or the Access 
Gateway. Depending on the placement of the NSIS Initiator, the NSIS 
Forwarder may be located at an appropriate point in the 3G wireless 
network.

The 3G wireless access scenario is shown in Figure 1. The Proxy-Call 
State Control Function (P-CSCF) is the outbound SIP proxy (only used in 
IMS). The Access Gateway is the egress router of the 3G wireless domain 
and it connects the radio access network to the Edge Router (ER) of the 
backbone IP network. <The Policy Decision Function is an entity 
responsible for controlling bearer level resource 
allocations/de-allocations in relation to session level services eg SIP. 
The Policy Decision Function may also control the Access Gateway to open 
and close the gates and to configure per-flow policies, i.e. to 
authorize or forbid user traffic.>
/brian

Kuntal Chowdhury wrote:

> Hi all,
> Here is an attempt to generalize the scope of NSIS in 3G wireless 
> networks. The following is the suggested update/re-write of section 
> 10.2 and 10.3.
>
> Issue Name: 7

---

From: Kuntal Chowdhury <[email-masked]>
Date: Wed, 29 Jan 2003 14:19:27 -0600

Hello Brian,
Yes, I agree with your updates. I will revise the proposed text with your comments.

Regards,
Kuntal

---

From: Kuntal Chowdhury <[email-masked]>
Date: Wed, 29 Jan 2003 16:12:20 -0600

Hi all,
Here is the updated text for issue# 7. I incorporated the comments from Maarten 
and Brian.

------------------------------------------------------------------------------

    2) The IP signaling messages are initiated by the NSIS initiator and
    interpreted by the NSIS Forwarder. The most efficient placement of
    the NSIS Initiator and NSIS Forwarder has not been determined in 3G
    wireless networks, but a few potential scenarios can be envisioned.
    The NSIS Initiator could be located at the End Host e.g. UE or MS
    (triggered by applications), the Access Gateway or at a node that is
    not directly on the data path, such as a Policy Decision Function.
    The Access Gateway could act as a proxy NSIS Initiator on behalf of
    the UE/MS or an End Host. The Policy Decision Function that controls
    per-flow/aggregate resources with respect to the session within its
    QoS domain (e.g. the 3G wireless network) may act as a proxy NSIS
    Initiator for the UE/MS or the Access Gateway. Depending on the
    placement of the NSIS Initiator, the NSIS Forwarder may be located at
    an appropriate point in the 3G wireless network.

    3) The need for re-negotiation of resources in a new 3G wireless
    domain due to UE/MS mobility. In this case the NSIS Initiator and the
    NSIS Forwarder should detect mobility events and autonomously trigger
    re-negotiation of resources.

10.3 An example scenario for 3G wireless networks

     The 3G wireless access scenario is shown in Figure 1. The Proxy-Call
     State Control Function (P-CSCF) is the outbound SIP proxy (only used
     in IMS). The Access Gateway is the egress router of the 3G wireless
     domain and it connects the radio access network to the Edge Router
     (ER) of the backbone IP network. The Policy Decision Function (PDF)is
     an entity responsible for controlling bearer level resource allocations/
     de-allocations in relation to session level services e.g. SIP. The
     Policy Decision Function may also control the Access Gateway to open
     and close the gates and to configure per-flow policies, i.e. to
     authorize or forbid user traffic. The P-CSCF (only used in IMS) and
     the Access Gateway communicate with the Policy Decision Function, for
     network resource allocation/de-allocation decisions. The User Equipment
     (UE) or the Mobile Station (MS) consists of a Mobile Terminal (MT) and
     Terminal Equipment (TE), e.g. a laptop.

                            +--------+
                 +--------->| P-CSCF |---------> SIP signaling
                /           +--------+
               / SIP            |
              |                 |
              |              +-----+            +----------------+
              |              | PDF |<---------->| NSIS Forwarder |<--->
              |              +-----+            +----------------+
              |                 |                  ^
              |                 |                  |
              |                 |                  |
              |                 |COPS              |
              |                 |                  |
          +------+          +---------+            |
          | UE/MS|----------| Access  |<-----------+     +----+
          +------+          | Gateway |------------------| ER |
                            +---------+                  +----+

    The PDF has all the required QoS information for per-flow or aggregate
    admission control in 3G wireless networks. It receives resource
    allocation/de-allocation requests from the P-CSCF and/or
    Access Gateway etc. and responds with policy decisions. Hence the PDF
    may be a candidate entity to host the functionality of the NSIS
    Initiator, initiating the "NSIS" QoS signaling towards the backbone IP
    network. On the other hand, the UE/MS may act as the NSIS Initiator or
    the Access Gateway may act as a Proxy NSIS Initiator on behalf of the
    UE/MS. In the former case, the P-CSCF/PDF has to do the mapping from
    codec types and media descriptors (derived from SIP/SDP signaling) to
    IP traffic descriptor. In the latter case, the UE/MS may use any
    appropriate QoS signaling mechanism as the NSIS Initiator. If the Access
    Gateway is acting as the Proxy NSIS initiator on behalf of the UE/MS,
    then it may have to do the mapping of parameters from radio access
    specific QoS to IP QoS traffic parameters before forwarding the request
    to the NSIS Forwarder.

---------------------------------------------------------------------------------

-Kuntal