ANNEX 2 TO THE EMPB SERVICE CONTRACT
- 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.
Daniel
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ANNEX 2 TO THE EMPB SERVICE CONTRACT
EMPB
European Multi-Protocol Backbone
(EMPB)
Service Description
ANNEX 2 TO THE EMPB SERVICE CONTRACT
1. GENERAL 1
2. SERVICE PRESENCE 3
3. X.25 AND X.75 INTERFACE STANDARDS AND CAPACITIES 4
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
APPENDICES
APPENDIX 1 - Address Ranges Used In The Pilot IXI Service
APPENDIX 2 - Country Codes & Network IDs
ANNEX 2 TO THE EMPB SERVICE CONTRACT
Service Description
1. GENERAL
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
including:
- 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.
2. SERVICE PRESENCE
As of the Service Start switching elements of the PTT
Telecom High Speed Backbone Network will be present in the
following countries:
Austria
Belgium
Denmark
France
Germany
Greece
Ireland
Italy
Luxembourg
Netherlands
Portugal
Spain
Sweden
Switzerland
United Kingdom
Slovenia
3. X.25 AND X.75 INTERFACE STANDARDS AND CAPACITIES
+++++ omitted for the purpose of circulation in RIPE +++++
4 IP SERVICE
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
will:
- 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
will:
- 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
datagram.
- 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
memory.
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
Port.
The account information will contain:
- identification of the two networks using the EMPB IP
Service
- 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-
NMC.
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. ADDRESSING AND ROUTING
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
structures:
- 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
destination.
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 +++++