You are here: Home > Participate > Join a Discussion > Mailman Archives
<<< Chronological >>> Author Index    Subject Index <<< Threads >>>


  • To: RIPE Meeting Attendees < >
  • From: Daniel Karrenberg < >
  • Date: Wed, 23 Sep 92 17:41:22 +0200

Dear RIPErs,

Rob asked me to circulate the following document which we 
received today in preparation of agenda point 

	10. EMPB IP services (PTT Telecom NL)

of the next meeting. 

The document is a technical Annex to the EMPB service contract and
describes (among others) the IP services of the European Multi-Protocol 
Backbone. Because the full document is too long for this wide a 
distribution and some massaging was needed to make it mailable
I have tried to extract the parts about the IP service. The full
table of contents is included. The full document is availabe by
request to ncc@localhost.





              European Multi-Protocol Backbone

                     Service Description


1.  GENERAL                                                 1

2.  SERVICE PRESENCE                                        3

    3.1  Physical Layer                                     4
    3.2  Link and Network Layer Interfaces                  4
         3.2.1 X.25 DCE and DTE Optional User Facilities    5
         3.2.2 Optional CCITT-specified DTE Facilities      5
         3.2.3 X.25 Conformance                             6
         3.2.4 X.75 Utilities                               6
         3.2.5 Future Support of the X.25 and X.75
               Recommendations                              6
         3.2.6 X.25 DTE Gateway                             6
         3.2.7 Charging of X.25 and/or X.75 Calls to
               PSPDN                                        6
    3.3  X.25/X.75 (1980), (1984) and (1988)
         Interworking                                       7

4   IP SERVICE                                              9
    4.1  Introduction                                       9
    4.2  Physical Layer                                     9
    4.3  Link Layer                                         9
    4.4  Network Layer                                     10
    4.5  Routing                                           10
    4.6  Options Supported                                 12
    4.7  Maximum Transfer Unit                             12
    4.8  Access to the IP Service                          12
    4.9  Intra-Network Communication within the EMPB
         Network                                           13
    4.10 Accounting                                        14
    4.11 Implementation of the EMPB IP Service             14

5.  CLNS                                                   15
    5.1  General                                           15
    5.2  Physical Layer                                    15
    5.3  Link Layer                                        15
    5.4  Network Layer                                     15
    5.5  Routing                                           16
    5.6  Options Supported                                 18
    5.7  Maximum Transfer Unit                             18
    5.8  Access to the CLNS Service                        18
    5.9  Intra-Network Communication within the EMPB
         Network                                           19
    5.10 Accounting                                        20
    5.11 Implementation of the EMPB CLNS                   20

6.  ADDRESSING AND ROUTING                                 22
    6.1  General                                           22
    6.2  Addressing Structures                             22
    6.3  X.25 Addressing                                   22
         6.3.1 Access Control Mechanisms                   23
         6.3.2 Address Translation                         25
         6.3.3 Call Request Packet                         27
    6.4  X.25 DTE Gateway                                  27
         6.4.1 Calls from PSPDN to EMPB                    28
         6.4.2 Call Set-up from EMPB to PSPDN:             29
    6.6  Use of NSAP Addresses                             30
         6.6.1 NSAP Address Translation                    31
         6.6.2 SNARE Function                              31
    6.7  IP Addressing                                     31
    6.8  CLNS Addressing                                   32


APPENDIX 1 - Address Ranges Used In The Pilot IXI Service

APPENDIX 2 - Country Codes & Network IDs

Service Description


    The EMPB Service is provided by PTT Telecom on the PTT
    Telecom High Speed Backbone Network. It offers fully
    managed X.25, IP and CLNS communications at data circuit
    capacities up to 2048 kbps with the following main
    technical and/or value adding features:

    - X.25/X.75 interconnections (Interworking between 1980,
      1984 and 1988 CCITT Recommendations)
    - IP - IP and IP - X.25/X.75 interconnections
    - CLNS - CLNS and CLNS - X.25/X75 interconnections
    - Dynamic bandwidth allocation and fully statistical
      sharing between the different services of the intra-
      network data circuit capacity
    - Support of up to 40 digits NSAP addresses
    - Data circuit capacities of Access Ports up to 2048 kbps
    - > 90 % utilisation of the Access Port capacity at
      appropriate packet and window sizes, when the EMPB
      Network is not loaded.
    - End-to-end delay, incl. propagation delay < 100 msec for
      a 128 bytes data packet in 95 % of all cases, when the
      EMPB Network is not loaded.
    - X.25 Address Translation enabling all-to-all communicati-
      on and access authentication of X.25 addresses
    - IP/CLNS network address authentication
    - IP/CLNS policy based routing
    - X.25/X.75/IP/CLNS accounting
    - High quality network management and help desk service
    - Overall Network Service Availability > 99.8% per annum

    The usage of the same backbone network for the provision of
    the X.25 Service, the IP Service and the CLNS yields a
    number of both operational and technical advantages

    - The three services can be operated by the same network
      operations organization. Also, the same network
      management system can be used for all three services.

    - An X.25 Access Port may simultaneously be used for normal
      X.25 traffic, for encapsulated IP traffic and for
      encapsulated CLNS traffic.

    - The intranet forwarding of datagrams within the EMPB
      Network supporting the X.25 Service, the IP Service and
      the CLNS will make use of the same internal datagram,
      thereby sharing in a fully statistical manner the same
      bandwidth.    - The handling of the routing of X.25 packets, IP datagrams
      and CLNS packets requires a number of addressing
      functions. These will be based on the same address
      administration system.

    - These addressing functions will also be used for
      provision of access control functions as required.

    As of the Service Start switching elements of the PTT
    Telecom High Speed Backbone Network will be present in the
    following countries:

      United Kingdom


+++++ omitted for the purpose of circulation in RIPE +++++


4.1   Introduction

      The overall purpose of the EMPB IP Service is to allow
      Autonomous Systems (ASs) running an IP protocol to
      communicate with each other via the EMPB Service. The EMPB
      Network constitutes itself a single Autonomous System (AS).

      The EMPB IP Service will be implemented in accordance with
      the time schedule described in Section 4.11 below.

      Following the Service Start an IP Pilot will be carried out
      in accordance with Annex 5 to the Contract. During this
      pilot the actual dimensioning and configuration will be
      determined and an agreement will be made on the access
      authentication, accounting and reporting.

      The EMPB IP Service will be provided through an IP Access
      Port which may be configured with the following
      specifications for the Physical Layer, the Link Layer and
      the Network Layer:

4.2   Physical Layer

      An Access Port may be configured with the appropriate
      interface module for the support of any data circuit
      capacity up to 2048 kbps. At 64, 1920, 1984 and 2048 kbps
      G.703 may be used. In addition V.36 and X.21 may be used
      for all data circuit capacities up to 2048 kbps, V.35 up to
      72 kbps and V.24/V.28 up to 20 kbps.

      Furthermore the Layer 1 interface may be a Local Area
      Network in accordance with ISO 8802-3 (Ethernet).

4.3   Link Layer

      The access protocols supported on an Access Port may be one
      of the following:

      -  HDLC (LAPB)
      -  PPP (RFC 1171 and 1172)
      -  X.25 (IP encapsulated in X.25 using RFC 877)
      -  Frame Relay (Core Aspects of CCITT Q.922, Annex A, PVC)
      -  LAN (ISO 8802-3)

4.4   Network Layer

      Supported Service Protocol:

      -  DARPA IP (RFC 791)

      Supported routing protocols:

      - EGP (RFC 904)
      - BGP (RFC 1267)

4.5   Routing

      The EMPB IP Service supports Class A, B and C addresses.

      The EMPB IP Service is built up by a number of IP Routers
      and IP Gateways. The IP Routers are distributed in the EMPB
      Network to the sites where IP Access Ports are located, and
      they communicate with each other and with the external
      gateways about net-reachability information. They manage
      the routing tables for one or more IP Gateways. An IP
      Gateway receives and transmits IP datagrams from/to
      external gateways and based on the routing table received
      from the IP Router routes the IP datagrams to the next
      external gateway possibly through another IP Gateway.

      The EMPB IP Routers use either static routing where the
      routing tables are updated from the EMPB-NMC, or dynamic
      routing, where the routing tables are updated by exchanging
      net-reachability information with the external gateways or
      between the EMPB IP Routers - for EGP on a regular basis,
      and for BGP whenever an update message has been received
      from an external gateway or from the EMPB-NMC, or whenever
      a change has occurred in the connections to the external
      gateways or to the other EMPB IP Routers. The dynamic
      routing information may be overlayed with information from
      the EMPB NMC defining routing policies, e.g. defining that
      networks cannot intercommunicate via the EMPB Service, when
      they are connected to Access Ports in the same country.

      When an EMPB IP Router is informed about a new network, it
      will use the address administration system to check that
      the address designates a registered EMPB IP network and to
      get a potential group number for collective accounting.

      Each IP Access Port is controlled by an IP Gateway residing
      at the port. The IP Gateways communicate with each other
      via the Datagram Service of the EMPB Network, and they

      -  based on information received from the EMPB IP Router
         maintain a routing table with the networks, that are
         authorized to use the EMPB IP Service.
      -  obtain information from the EMPB IP Router about the best
         route to each of the different networks.

      -  maintain an account table based on source and destination
         networks or groups of such networks for collective
         accounting, and generate account records from time to
         time or on demand.

      When an IP datagram is received at an IP Access Port from
      an external gateway, the IP Gateway residing at that port

      -  check the authorization of the source and destination
         networks. If either of these are not known, the IP
         datagram will be discarded.

      -  fragment the IP datagram, if the receiving external
         gateway cannot handle datagrams of its size.

      -  determine the Access Port, through which the destination
         network may best be reached, and forward the IP datagram
         to the external gateway connected to that Access Port via
         the IP Gateway residing at it. This latter IP Gateway
         will normally only pass the IP datagram on to the
         external gateway. Only in case of source routing and time
         stamping will it read/modify the datagram header.

      -  verify the checksum of the IP datagram and recompute it,
         after it has been updated.

      -  update the Time to Live field and discard the IP
         datagram, if this field will become -1, before the IP
         datagram has reached the next external gateway.

      -  make source routing, if the IP datagram contains the
         optional field Source Route.

      -  add its own internet address and the internet address of
         the IP Gateway at the exit Access Port, in case the
         optional field Record Route is contained in the IP

      -  insert the time in the IP datagram, if the optional field
         Timestamp is contained in the IP datagram.

      -  generate an error report when an IP datagram is
         discarded. This action is also performed by the IP
         Gateway at the exit Access Port if it cannot deliver an
         IP datagram.
      The routing principle used for the IP traffic over the EMPB
      Network will ensure that only two EMPB IP Gateways are
      involved in the communication via the EMPB Network ('one-
      hop') and that the shortest path between them is chosen,
      thereby keeping the load on the EMPB to a minimum, and as
      long as two outages in the EMPB Network do not exist at the
      same time that the IP datagrams are delivered to the EMPB
      Access Port closest to the receiving network, i.e. a
      shortest path selection.

      Policy based routing will be possible in order, for
      instance, to prevent networks connected to Access Ports in
      the same country to intercommunicate and prevent otherwise
      authorized networks to send traffic via the EMPB Service,
      when entering the EMPB Service by transitting certain
      connecting networks.

      Each IP Access Port has available 1 Mbyte of Random Access
      Memory (RAM) in a basic configuration for routing and ac-
      counting. If needed the memory may be expanded with 2
      Mbytes RAM. If it is assumed that each IP network that may
      use the EMPB Service has two paths in average, it occupies
      66 bytes in the router table. With e.g. 5000 networks
      supported the routing table will occupy 330 kbytes of main

4.6   Options Supported

      The following optional functions are supported:

      -  Loose Source Routing
      -  Strict Source Routing
      -  Record Route
      -  Time Stamp

4.7   Maximum Transfer Unit

      The EMPB IP Service supports Maximum Transfer Units (MTUs)
      of up to 64 kbytes.

4.8   Access to the IP Service

      The EMPB IP Service can be accessed using either HDLC, PPP,
      X.25, Frame Relay or LAN.

      When using HDLC access to an IP Access Port, mapping of the
      IP datagrams onto the HDLC service is done in accordance
      with ISO 8880-3.

      For HDLC access the access line is connected directly to
      the EMPB Network node at which the IP Access Port software
      is running.

      The EMPB IP Service can also be accessed using X.25. This
      means that all IP Gateways (or stations on LANs) connected
      to an X.25 network, which in turn has a connection to the
      EMPB Service, can use the EMPB IP Service. It also means
      that an EMPB X.25 access line can be used for both normal
      X.25 traffic and IP traffic simultaneously.

      The EMPB Service will provide a network internal IP/X.25
      Gateway function, which may be located in any of the nodes
      in the EMPB Network and therefore also may be distributed
      at all the Access Ports, if needed.

      When an external gateway wants to access the IP/X.25
      Gateway via X.25, it will use the EMPB address of the
      IP/X.25 Gateway. This EMPB address will be the same
      irrespective of the entry Access Port. The EMPB Service
      will determine that the called address specifies the
      IP/X.25 Gateway, and the gateway module closest to the X.25
      Access Port at which the call came in, will be pointed out
      as the termination point of the X.25 call.

      The IP/X.25 Gateway will perform the encapsulation and
      decapsulation of the IP datagrams into and from X.25 in
      accordance with RFC 877.

      If fragmentation has to be made for outgoing traffic on
      X.25, because the IP datagrams are larger than the X.25
      packets, then the IP datagrams will be sent as complete
      packet sequences using the M-bit.

      For LAN access the IP Access Port is connected directly to
      the LAN network via a LAN controller of the IP Access Port
      equipment. The IP Access Port acts in the role of an IP
      Gateway, communicating directly with the stations on the
      LAN. Alternatively a LAN bridge can be used to connect the
      LAN and the IP Access Port.

4.9   Intra-Network Communication within the EMPB Network

      The internal transfer of IP datagrams within the EMPB
      Network is considered as a "one-hop" communication between
      two IP Gateways on the same network, i.e the IP datagrams
      will be forwarded directly by the network internal Datagram
      Service to the IP/X.25 Gateway at the exit Access Port
      without passing other IP Gateways.

4.10  Accounting

      Accounting information may be collected at each IP Access

      The account information will contain:

      -  identification of the two networks using the EMPB IP
      -  the number of bytes sent in one direction
      -  the number of bytes sent in the other direction
      -  the number of datagrams sent in one direction
      -  the number of datagrams sent in the other direction
      -  time of starting the accounting
      -  time of generating the account record

      In order to reduce the number of account records generated
      by an IP Access Port it will be possible to collect account
      information from a group of networks in one account record.

      The grouping of networks will be administered by the EMPB-

      Each entry in the account table takes up 35 bytes. Each IP
      Access Port has available 1 Mbyte of Random Access Memory
      (RAM) in a basic configuration for routing and accounting.
      With 500 kbytes to be used for accounting, approximately
      15,000 entries can exist at the same time. Before memory
      runs out, a sufficient number of account records will be
      generated to release table entries. If needed the memory
      may be expanded with 2 Mbytes RAM. In addition account
      records may be stored on a disk attached to the switching
      elements when the main memory is not sufficient to hold the
      accounting tables. Disks with capacities from 20 Mbytes to
      1 Gbytes are supported.

4.11  Implementation of the EMPB IP Service

      The implementation of the EMPB IP Service offering will be
      carried out in a number of phases.

      The first version is scheduled for availability for pilot
      test trials in October, 1992. It will be able to provide a
      DARPA IP interface using the EGP (Exterior Gateway Proto-
      col) over lines which may be configured to run HDLC, PPP or
      X.25 (IP encapsulated in X.25).

      The second version is scheduled for January, 1993 at which
      time routing information may be exchanged between IP
      Gateways by using BGP (Border Gateway Protocol), and Frame
      Relay may be used to access the EMPB IP Service.

      The third version is scheduled for July, 1993 at which time
      also direct LAN connections will be offered.

5.    CLNS

+++++ omitted for the purpose of circulation in RIPE +++++


6.1   General

      This Chapter details the addressing mechanisms available
      within the EMPB Service and their use, particularly:

      -  the various addressing structures supported,
      -  the structure of the X.25 address,
      -  the address translation and control mechanisms,
      -  transition issues related to X.25 access control,
      -  the use of NSAPs for X.25 call set-up and
      -  addressing for IP and CLNS communication.

6.2   Addressing Structures

      The EMPB Service will support the following addressing

      -  X.121 addresses for the X.25 service,
      -  NSAP addresses (as per ISO 8348/Add.2) for the X.25 and
         CLNS services,
      -  IP addresses for the IP service.

6.3 - 6.6 +++++ omitted for the purpose of circulation in RIPE +++++

6.7   IP Addressing

      An IP address consists of a 4-byte integer. The address
      is built up as a network address and the address of the
      entity within the network that may be used as source or

      The information needed to perform authentication and
      routing decisions based on policies or static routing
      principles will be transferred by representatives of the
      subscribing organization to PTT Telecom, who will
      register the information in the Address Database of the
      EMPB Network. Such information must contain the addresses
      of the networks that are allowed to use the EMPB Network,
      for static routing also the paths or distances to the
      networks, and optionally certain Access Port paths which
      are barred from use with the Access Port.

      Whenever an IP Gateway external to the EMPB Network
      transmits to it a routing table update with a new network
      address, this address will be checked against the Address
      Database for authentication of the network and for
      control of specific routing policies concerned with the
      network, before the routing table update is performed.

      When an IP datagram enters the first IP Gateway within
      the EMPB Network the source and destination network
      addresses will be checked for authentication and against
      the routing policies. If either of the two addresses is
      not known by the EMPB Network or the combination of the
      two violates a routing policy, the datagram will be
      discarded at the first IP Gateway.

6.8   CLNS Addressing

+++++ omitted for the purpose of circulation in RIPE +++++

  • Post To The List:
<<< Chronological >>> Author    Subject <<< Threads >>>