Minutes

GPRS Infrastructure IP Addressing

Working Party Meeting #1









Meeting date: 19th April 2000

Meeting location: Milton Gate, London UK

Chairman: Kim Fullbrook

Secretariat: Jarnail Malra

Document reference: GPRS_CN\007\0047

Document History
 
Revision Date Changed by Details
Draft A 26 April 2000 Jarnail Malra Initial draft for review
       

Attendees
 
Name Organisation  Responsibility/Representing
Kim Fullbrook BT Cellnet  GPRS Network Technical Architect
Jarnail Malra BT Cellnet GPRS Network Development
Paul Mylotte BT BT Internet Addressing
Adrian Pauling BT BT Internet Engineering
Jyrki Soini Sonera, Finland Network Planning
Peter Gilks Telfort, Netherlands IP Network Design
Clif Campbell SBC Communications, USA GSM Association, GPRS WP Chairman North America
Anders Roos GSM Association GPRS technical advisor/IREG GPRSWP chairman
Mirjam Kuhne RIPE Manager, External Relations
Stephen Burley UUnet Internet Engineering
Nick Hutton UUnet Internet Engineering
Richard Lui UUnet Internet Engineering
Georgio Fioretto TIM, Italy IP Network Design
Keith Mitchell London Internet Exchange Executive Chairman
Etienne Annic France Telecom GPRS Architect

 
 
 

Documentation

The papers/documents listed and attached below were issued and discussed at the meeting.
 
Ref Title/Description Attached
[1] Agenda and Participant list
[2] Meeting presentation slides: "GPRS/Internet IP addressing working party meeting No.1"
[3] Discussion paper: "GPRS - IP address and naming options"
[4] Letter of support from GPRS and Data Services Director, GSM Association: "RIPE Working Party public IP addressing"

 

  1. Introductions


    2. The Chairman welcomed all the members. The agenda [1] was agreed and all attendees introduced themselves to the group.

    A letter [4] from the GPRS and Data Services Director, GSM Association was distributed to the attendees, supporting the work to date on the addressing policy issue and outlining the scope of work that is being undertaken on their behalf.

  2. Meeting objectives
The target objective of the meeting was to determine if Public (registered) IP addresses could be used by the GSM (Mobile Network) operators to address their GPRS network infrastructure in order to support GPRS roaming services.

If Public addressing could be used, then it would be necessary to determine: -

Requirements for the above elements would be identified and defined in an IP addressing policy. This Policy will be submitted to the Regional Internet Registry RIR authorities for their approval and acceptance.

All the GSM operators must then implement this Addressing Policy if they wish to support GPRS roaming services.

Note: IP address requirements for Mobile Terminals was not in the scope of this meeting.

  1. Presentation
The Chairman presented the following subjects to provide the members with an overview of the requirements and stimulate subsequent discussion to determine the best way forward to meet the objectives of the meeting: - The above items are outlined in the presentation slides [2].

The discussion paper [3] provides further details on the topics and issues presented.

  1. Review of GSM operators' current addressing plans
    1. Current address implementation plans


      2. The presentation [2] showed that although the mobile operators are working with the Internet Registry authorities for the approval of an addressing policy, the processes required to define/approve and implement the policy is still expected to take several months. However, some operators are currently in the process of configuring their GPRS networks to support a commercial service by Q2 2000, for which public addresses are required to support roaming services. The only option available to the operators in the given timescales is to use addresses from their existing allocated registered address space to guarantee unique addressing for roaming. These addresses could then be re-aligned if necessary with any subsequently approved addressing policy.

    2. Operator IP address requirements
Attending representatives from the various mobile operators had been requested prior to the meeting to provide an indication of their IP address requirements for their respective networks over the next five-year period. A summary of the information provided at the meeting is given below.
 
Mobile Operator
GPRS equipt supplier
1-5 year network IP address estimates
Comments/Notes
BT Cellnet Motorola 512 (Yr1) - 4000 (Yr5) IP addresses
  • BT Cellnet currently looking at methods to reduce these initial estimates, e.g. more efficient network segregation. Allows parts of the network to be privately addressed and publicly where necessary for roaming
  • One SGSN requires 3 IP addresses.
Telfort (Netherlands) Ericsson 256 addresses by year 5, but could be reduced to 128 as equipment becomes more efficient in the future Relatively small network (market share 8 times smaller compared with BT Cellnet).

Ericsson equipment implementation makes use of 'virtual' IP addresses, i.e. a single IP address can be used to address a number of GPRS nodes/interfaces
TIM (Italy) Ericsson Estimates not available at time meeting as network requirements not yet defined. 

Principally less than BT Cellnet's estimates

  
Sonera (Finland) Nokia Estimates not available at time meeting 'Virtual' IP addressing as for Ericsson equipment not believed to be supported by Nokia equipment. A GPRS node could typically support 120K subscribers, with 16 interfaces, with each interface believed to require a separate IP address.
France Telecom Not declared Estimates not available at time meeting  
SBC Communications, USA Not yet selected.  Estimates not available at time meeting, but expect a large number of IP addresses (possibly 10 times lager than BT Cellnet) required due to a large national coverage footprint
  • Could implement a multi-vendor equipment solution, giving rise to a potentially complex address implementation/management situation.
  • Considering allocating dedicated GGSNs to specific customer sites; this will significantly increase the address requirements, e.g. 1000 customers will require 1000 GGSNs and corresponding IP addresses (plus wastage due to subnetting)

 

Number of IP address requirements per operator dependent upon number of key factors, such as: -

  1. Notes on general discussions to meet requirements
    1. General


      2. There are expected to be approximately 20-25 operators supporting or in the process of supporting GPRS by the end of this year, and increasing in the following years. However, most of these operators may not yet be aware that a potential issue exists when it comes down to addressing their networks to support roaming.

      This is where a common addressing policy would help. The policy can be used by all the operators and will give them visibility of any issues and requirements associated with addressing their network. The policy should identify how unique and extensible address space can be requested and assigned to the operator for use in the GPRS infrastructure.

    2. Mobile Terminals


      3. IP address requirements for mobile terminals were outside the scope of this meeting.

      Although these terminals would require a large volume of addresses, the addresses will be provided from the address range of their host Corporate networks or their ISP, e.g. Freeserve, UUnet. The mobile network operator will not supply these addresses.

      The addresses being sought for this meeting were solely of the mobile operator's internal network infrastructure to allow network elements to be addressed by network elements of other GPRS operators to support roaming services, i.e. SGNS, GGSN and DNS.

    3. 3G/UMTS Networks


      4. Third Generation (3G) networks were considered out of scope of this meeting. However, it was pointed out that these networks will also require a significant chunk of IPv4 address for their infrastructure and should thus be also be factored into the GPRS requirements. But the details for 3G are still largely yet unknown, the standard have not been finalised, hence no basis currently exists to determine the address requirements for these networks.

    4. DNS name space
Clarification was requested as to why the GPRS infrastructure will use DNS servers that exist independently from the Internet DNS servers.

The following attributes are associated with the GPRS DNS servers: -

In summary, the GPRS DNS servers will only be used to address the elements within GPRS infrastructure of the operator's own network, or another operator's GPRS network during roaming. The DNS server and the addresses it uses to address the GPRS elements will never be directly visible to the Internet. Hence, there was no requirement to utilise the Internet DNS servers. The current arrangement also adds to the security of the GPRS networks.
    1. 'Roaming' access via the Internet


      2. It was clarified that provided a roaming mobile user can access the Internet locally, it should be possible for that user to access their corporate network using the Internet as the backbone instead of the roaming backbone provided between the user's home network and the network he is currently roaming in. However, the user would then be subjected to the quality of service offered by the Internet at that point in time.

    2. GSM Association routing registry


      3. It was proposed that the GSM Association maintains a routing registry, containing routing details associated with each operator, e.g. IP address range allocated, IP addresses for their DNS, SGSNs and GGSNs, AS number, APNs, etc.

    3. Routing protocol


      4. Routing protocol BGP4 will be used for routing IP traffic between the mobile network operators.

    4. Autonomous System (AS) numbers
It was undecided whether a 'Private' or 'Public' AS number should be assigned to the network of each operator. Each scheme has its individual merits.

The network on which the GPRS elements reside can be essentially considered as a Private network. Hence, a Private AS number could be used, provided it is never be presented to the Internet.

Each operator could be allocated either a Private or Public AS number, i.e. no necessity for all operator networks to be addressed by a common scheme. If say a Private scheme was initially selected by an operator, it should still be possible to re-engineer their network to support a Public scheme in the future if necessary.

  1. Way forward
    1. General summary
The following is a general summary of the discussions on the way forward.
  1. It was agreed by all the meeting members that Registered IPv4 addresses should be used for the GPRS infrastructure. Each GPRS operator can use existing request processes to obtain addresses from their Local Internet Registries (LIR). A proposal to this effect will be submitted to the Regional Internet Registry authorities for approval.
  2. GPRS operators can apply to become an LIR, or alternatively it was suggested that the GPRS Inter-PLMN Backbone network providers such as Concert and Global One offer the LIR service to GPRS operators.
  3. Autonomous System numbers are considered to be provisionally assigned as Private. However, the operators will be given the opportunity to discuss and express their opinion on this matter within the GSM Association's IREG membership.
  4. Re-use of any Inter-NIC allocated address space already assigned to an operator is recommended where possible for their GPRS infrastructure. The host-master at relevant Internet Registry should be notified of this re-use to ensure their database records are accordingly updated.
  5. The GSM Association should maintain a routing registry to keep track of the routing details associated with each network operator.
    1. Actions arising
  1. Jarnail Malra to produce minutes and circulate to attendees and GSM Association/IREG
  2. Adrian Pauling to circulate details of the meeting to the LIR Working Party
  3. Kim Fullbrook to circulate meeting details to UMTS Naming Forum
  4. Mirjam Kuhne to update other RIRs on the outcome of this meeting
  5. Kim Fullbrook to attend the next RIPE meeting on 16/17 May 2000 to present the proposals resulting from this meeting and steer it through to adoption.
  6. BT Cellnet to arrange to update the GSM Association's IREG roaming guideline document (IR.33) to correspond with the proposed addressing policy.
  7. Anders Roos to present the issue of AS numbers for discussion/agreement at the next IREG WP meeting.
  8. Adrian Pauling and Paul Mylotte to produce a justification document summarising the use of Public addressing in the GPRS infrastructure.
[END]