ETSI TR 102 353 V1.2.1 (2015-12)

ETSI TR 102 353 V1.2.1 (2015-12)






TECHNICAL REPORT
Satellite Earth Stations and Systems (SES);
Broadband Satellite Multimedia (BSM);
Guidelines for the Satellite Independent
Service Access Point (SI-SAP)

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2 ETSI TR 102 353 V1.2.1 (2015-12)



Reference
RTR/SES-00352
Keywords
broadband, interface, satellite, service
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3 ETSI TR 102 353 V1.2.1 (2015-12)
Contents
Intellectual Property Rights . 4
Foreword . 4
Modal verbs terminology . 4
1 Scope . 5
2 References . 5
2.1 Normative references . 5
2.2 Informative references . 5
3 Definitions and abbreviations . 5
3.1 Definitions . 5
3.2 Abbreviations . 6
4 SI-SAP architecture . 6
4.1 BSM functional architecture. 6
4.2 Client-Server model . 8
4.3 SI-SAP model . 8
4.4 Protocols for the CSF-3 interface . 9
5 SI-SAP addresses and identifiers . 11
5.1 General . 11
5.2 SI-SAP addressing . 11
5.2.0 Overview . 11
5.2.1 BSM_IDentity (BSM_ID) . 11
5.2.2 Unicast and group BSM_IDs . 12
5.2.3 IP unicast addressing . 12
5.2.4 IPv4 multicast addressing . 13
5.3 Queue IDentifiers (QIDs) . 14
6 SI-SAP functions . 14
6.1 General . 14
6.1.0 Overview of functional planes and groups . 14
6.1.1 U-plane functions . 15
6.1.2 C-plane functions . 15
6.1.3 M-plane functions . 15
6.2 SI-SAP data transfer . 15
6.3 SI-SAP address resolution . 16
6.3.1 General . 16
6.3.2 Static vs. dynamic address resolution . 17
6.3.3 Unicast address resolution . 17
6.3.4 Multicast address resolution . 17
6.4 Resource reservation . 18
6.4.1 General . 18
6.4.2 Resource reservation . 18
6.4.3 Quality of Service . 19
6.5 Group receive . 19
6.5.1 General . 19
6.6 Group transmit . 20
6.6.1 General . 20
7 IP interworking scenarios . 20
7.1 General . 20
7.2 Sending unicast data . 21
7.3 Receiving multicast data . 22
Annex A (informative): Bibliography . 23
History . 24

ETSI

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4 ETSI TR 102 353 V1.2.1 (2015-12)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Satellite Earth Stations and Systems
(SES).
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI

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5 ETSI TR 102 353 V1.2.1 (2015-12)
1 Scope
The present document provides a guide to the underlying models and assumptions that have been used to specify the
BSM Satellite Independent Service Access Point (SI-SAP) interface.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI TR 101 984: "Satellite Earth Stations and Systems (SES); Broadband Satellite Multimedia
(BSM); Services and architectures".
[i.2] ETSI TS 102 292: "Satellite Earth Stations and Systems (SES); Broadband Satellite Multimedia
(BSM) services and architectures; Functional architecture for IP interworking with BSM
networks".
[i.3] ETSI TS 102 295: "Satellite Earth Stations and Systems (SES); Broadband Satellite Multimedia
(BSM) services and architectures; BSM Traffic Classes".
[i.4] ETSI TR 102 375: "Satellite Independent Service Access Point (SI-SAP) interface: Services".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
BSM_IDentity (BSM_ID): SI-SAP address that defines the BSM Subnetwork Point of Attachment (SNPA)
NOTE: The BSM_ID is divided into BSM Unicast ID (BSM_UID) and BSM Group ID (BSM_GID).
BSM Subnetwork Point of Attachment (SNPA): SI-SAP endpoint of the BSM data transport services
NOTE: The BSM_ID is used to address data sent to and received from the BSM Subnetwork Point of
Attachment.
ETSI

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6 ETSI TR 102 353 V1.2.1 (2015-12)
Queue IDentifier (QID): SI-SAP parameter that identifies an abstract queue at the SI-SAP
NOTE: The QID is used to identify a specific lower layer resource when sending (submitting) data via the
SI-SAP.
SI-SAP Instance (SAPI): specific independent instance of the SI-SAP in one ST
NOTE: A single unicast BSM_ID (UID) is associated with each instance of the SI-SAP (each SAPI). In addition
one or more group BSM_IDs (GIDs) may be associated with each instance of the SI-SAP.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ARP Address Resolution Protocol
ASM Any Source Multicast
BSM Broadband Satellite Multimedia
BSM_GID BSM Group Identity
BSM_ID BSM IDentity
BSM_UID BSM Unicast IDentity
CSF Client Server Function
Flowspec flow specification
GID Group ID
ID IDentity
IP Internet Protocol
IPv4 Internet Protocol version 4
IPv6 Internet Protocol version 6
L2Add Layer 2 Address
LL Lower Layer
LN Local Network
MAC Medium Access Control
NAT Network Address Translation
ND Neighbor Discovery
PEP Performance Enhancing Proxy
QID Queue IDentifier
QoS Quality of Service
RSVP Resource ReserVation Protocol
SAPI SI-SAP Instance
SD Satellite Dependent
SDAF Satellite Dependent Adaptation Functions
SD-ARP Satellite Dependent Address Resolution Protocol
SDU Service Data Unit
SI Satellite Independent
SIAF Satellite Independent Adaptation Functions
SI-SAP Satellite Independent Service Access Point
SN Satellite Network
SNPA BSM SubNetwork Point of Attachment
SSM Source Specific Multicast
ST Satellite Terminal
UID Unicast ID
UL Upper Layer
4 SI-SAP architecture
4.1 BSM functional architecture
The Satellite Independent Service Access Point (SI-SAP) is introduced in the BSM services and architectures report
(see ETSI TR 101 984 [i.1]) and a more detailed functional model of this interface is provided in the BSM functional
architecture (see ETSI TS 102 292 [i.2]).
ETSI

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7 ETSI TR 102 353 V1.2.1 (2015-12)
Figure 4.1.1, which is reproduced from the BSM functional architecture (see ETSI TS 102 292 [i.2]) presents the BSM
protocol stack for unicast services and figure 4.1.2 presents the same stack showing the multicast functions. Both
figures show the location of the Satellite Independent Service Access Point (SI-SAP) interface. This interface provides
the BSM with a layer of abstraction for the lower layer functions and makes use of a BSM specific identity, the
BSM_ID, to address the BSM subnetwork point of attachment (SNPA). It allows the BSM protocols developed in the
Satellite Independent layer to operate over any BSM family. Moreover, the SI-SAP also enables the use of standard
Internet protocols for example address resolution or multicast group management, directly over the BSM or with
minimal adaptation to lower layer physical characteristics. Lastly the SI-SAP even makes it possible to envisage
switching from one satellite system to another while preserving the BSM operator's investment in layer 3 software
development.
IPv4 and IPv6
IP Routing
IP QoS Management IP Security
IP Route Determination
BSM BSM BSM
BSM BSM QoS BSM QoS
Routing Traffic Security
Address
Address Resolution Adaptation Mgmt
Adaptation Manager Mgmt
Table
SIAF
IP Packet Forwarding
SI-C-SAP
SI-U-SAP SI-M-SAP
BSM SD
Segmentation
BSM
/ Queue
Address Resolution
Manager
encapsulation
SDAF
BSM BSM
Security
Resource
Satellite Data Unit Switching
Mgmt Mgmt
Satellite Link Control (SLC)
Satellite Medium Access Control (SMAC)
Satellite Physical (SPHY)

NOTE: This figure is taken from ETSI TS 102 292 [i.2].

Figure 4.1.1: BSM protocol stack for unicast services
ETSI

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8 ETSI TR 102 353 V1.2.1 (2015-12)
IPv4 and IPv6
IP Mcast
IP Multicast Routing
Security
BSM Multicast SI
BSM Multicast BSM Multicast Group
Routing Mcast
Address
Address Resolution Management
Adaptation Security
Table
SIAF
IP Packet Forwarding
SI-U-SAP SI-C-SAP SI-M-SAP
Segmentation
SD Multicast
BSM Multicast
/
Address Resolution Functions
encapsulation
SDAF
BSM SD
Resource Security
Satellite Data Unit Switching
Mgmt Mgmt
Satellite Link Control (SLC)
Satellite Medium Access Control (SMAC)
Satellite Physical (SPHY)

NOTE: This figure is taken from ETSI TS 102 292 [i.2].

Figure 4.1.2: BSM protocol stack for multicast services
4.2 Client-Server model
The BSM functional architecture (see ETSI TS 102 292 [i.2]) defines a Client-Server model that includes three logical
interfaces called Client Server Function (CSF) interfaces.
4.3 SI-SAP model
The SI-SAP model divides the protocol stack at an ST into two parts as illustrated in figure 4.3.1:
1) The Satellite Independent (SI) Upper Layers (UL).
2) The Satellite Dependent (SD) Lower Layers (LL).
The SI-SAP model also defines two adaptation layers. These are also shown in figure 4.3.1:
1) The Satellite Independent Adaptation Functions (SIAF) to adapt between the upper layers and the SI-SAP
services.
2) The Satellite Dependent Adaptation Functions (SDAF) to adapt between the lower layers and the SI-SAP
services.

ETSI

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9 ETSI TR 102 353 V1.2.1 (2015-12)
Upper
IPV4 / IPV6
Layers
(satellite
Satellite Independent Adaptation Functions
independent)
SI-SAP
Satellite Dependent Adaptation Functions
Lower
Satellite Link Control (SLC)
Layers
(satellite
Satellite Medium Access Control (SMAC)
dependent)
Satellite Physical (SPHY)

Figure 4.3.1: SI-SAP interface and the protocol stack
4.4 Protocols for the CSF-3 interface
The protocols that are used for the CSF-3 interface (see ETSI TS 102 292 [i.2]) can be divided into satellite independent
upper layer protocols and satellite dependent lower layer protocols as illustrated in figure 4.4.1.
NOTE: The adaptation functions (SIAF and SDAF) do not include any protocols. The protocols are assumed to
be located in either the IP layer (satellite independent case) or in the SLC/SMAC layer (satellite
dependent case).
Client Server
IP interworking IP Upper layer protocol IP interworking
IP
functions functions
SIAF SIAF
functions functions
Satellite
SI-SAP SI-SAP
SDAF SDAF
functions functions
Lower layer protocol
SLC/SMAC SLC/SMAC
functions functions
KEYKEY
IPIP fun funcctiontion
AAddaapptattatiion fon functiunctionon
SSDD f fuunctinctionon

Figure 4.4.1: Protocols for the CSF-3 interface
ETSI

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10 ETSI TR 102 353 V1.2.1 (2015-12)
A given IP interworking function can be realized using either the upper layer protocols or the lower layer protocols as
follows:
a) Upper Layer protocol (figure 4.4.2): In this case the IP interworking functional exchanges between the Client
and Server are carried using a satellite independent upper layer protocol(s). This upper layer protocol is then
carried transparently by the SI-SAP U-plane data transport services. The upper layer protocols can be any
suitable network layer protocol; for example, standard IETF protocols; or adapted IETF protocols, or
non-standard network layer protocols.
b) Lower Layer protocol (figure 4.4.3): In this case, the IP interworking functional exchanges between the Client
and Server are carried using a satellite dependent lower layer protocol(s). The network layer at the Client and
the Server interwork these functions into an SI-SAP C-plane primitive. Below the SI-SAP these primitives
activate the appropriate lower layer protocol(s). The available set of SI-SAP C-plane primitives (and the
associated functions) is defined in clause 6 of the present document.
Client Server
IP interworking IP Upper layer protocol IP interworking
IP
functions
functions
SIAF SIAF
functions functions
Satellite
SI-SAP
SI-SAP
SDAF SDAF
functions functions
Lower layer protocol
SLC/SMAC SLC/SMAC
functions functions
KEYKEY
IP fIP fuunncctitioonn
AAddaapptatatitioonn fu funnccttiioonn
Functional interworking via upper layer protocol
SSDD fu funnccttiioonn
SDU transmission via SI-SAP U-plane

Figure 4.4.2: Interworking using upper layer protocols
Client Server
IP interworking IP Upper layer protocol IP interworking
IP
functions
functions
SIAF SIAF
functions functions
Satellite
SI-SAP SI-SAP
SDAF SDAF
functions functions
Lower layer protocol
SLC/SMAC SLC/SMAC
functions functions
KEYKEY
IIPP f funcuncttiionon
AAddapaptattatiionon fu funnccttiionon
Functional interworking via SI-SAP C-plane
SSD funD functioctionn

Figure 4.4.3: Interworking using lower layer protocols
ETSI

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11 ETSI TR 102 353 V1.2.1 (2015-12)
A given BSM network can only use either of the two aforementioned configurations. Hence, a given implementation
may only support a subset of the SI-SAP functions defined in clause 6. In more detail, upper layer protocols require the
exclusive use of the SI-SAP U-plane primitives, whereas the lower layer protocol require the use of SI-SAP C-plane
primitives to handle the IP interworking functions.
It is worth, however, remarking, that SI-SAP U-plane primitives will be also used in the latter configuration for the
transport of data traffic across the ETSI BSM architecture.
5 SI-SAP addresses and identifiers
5.1 General
The addresses and identifiers defined below represent a set of satellite independent addresses and identifiers that are
used as parameters in the SI-SAP primitives. These addresses and identifiers are designed to be directly mapped into the
appropriate satellite dependent identifiers by the Satellite Dependent Adaptation Functions (SDAF).
The SI-SAP provides an abstract interface allowing BSM protocols to be truly System Independent (SI) and to apply to
all BSM families. The SI-SAP is the interface at which services from the lower layers are translated into system
independent semantics.
For traffic handling the SI-SAP uses a BSM IDentity (BSM_ID) and a Queue IDentifier (QID):
• The BSM_ID uniquely identifies a BSM subnetwork point of attachment and allows IP layer address
resolution protocols (equivalent to ARP for IPv4 and ND for IPv6) to be used over the BSM subnetwork.
• The QID enables the BSM data transfer (IP packets) to be queued, policed and transmitted properly across the
BSM.
5.2 SI-SAP addressing
5.2.0 Overview
Table 5.2.0.1 summarizes the SI-SAP identities that are used as SI-SAP addresses. The table also shows their
relationships to each SI-SAP Instance (SAPI). These identities are described in more detail in clauses 5.2.1 to 5.2.4.
Table 5.2.0.1: SI-SAP addresses
IDentities Relationship Comment
BSM_UID per SAPI 1:1 The SAPI is uniquely identified by the BSM_UID
BSM_GID per SAPI N:1 {N = 0 to many} The same GID may be used at many SAPI

5.2.1 BSM_IDentity (BSM_ID)
The BSM_ID is an SI-SAP address that identifies the BSM subnetwork point of attachment (SNPA). The SNPA
corresponds to the endpoint of the BSM data transport services and the BSM_ID is the address that is used to address
the data that is sent to and received from that endpoint.
In some cases the BSM_ID may be identical to the Layer 2 Address (L2Add) of the lower layer air interface family.
However, in the most general case, the BSM_ID may be a separate intermediate address.
The BSM_ID is unique within the entire BSM subnetwork and it is intended that each BSM_ID is associated with a
unique Layer 2 Address (e.g. via a direct mapping).
ETSI

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12 ETSI TR 102 353 V1.2.1 (2015-12)
IPv4/ IPv6
IPAdd#1
IPAdd#1
SIAF
BSMID#1
SI-SAP Instance
BSM_ID#1
(SAPI)
BSMID#1
SDAF
L2Add#1
L2Add#1
Satellite Dependent
Lower Layers

Figure 5.2.1.1: SI-SAP address model
Figure 5.2.1.1 shows the relationship between the BSM_ID and the related addresses above and below the SI-SAP. The
BSM_ID is used to associate an upper layer IP address to the corresponding satellite dependent lower layer address:
• Above the SI-SAP, the BSM_ID is mapped to an IP address.
• Below the SI-SAP, the BSM_ID is mapped to a system dependent Layer 2 Address (L2Add); this
Layer 2 Address can either be a link address or a MAC address, or any other satellite dependent address.
The BSM_ID corresponding to a given IP address may be defined statically (e.g. by management configuration) or may
be discovered dynamically (on-demand) using the SI-SAP address resolution procedures described in clause 6.3.
5.2.2 Unicast and group BSM_IDs
Both unicast and group BSM_IDs are defined:
• A BSM Unicast ID (UID) defines a single SNPA. A given instance of an SI-SAP (SAPI) is associated with
exactly one UID.
• A BSM Group ID (GID) defines a lower layer multicast group. A given instance of an SI-SAP (SAPI) may be
associated with zero or more GIDs.
The UID and GIDs are assigned from the same numbering space, with no defined boundary between the UID portion
and the GID portion of the address space. The actual division between unicast and group addresses is dependent on the
lower layers (i.e. the GIDs are allocated as a satellite dependent subset of the overall BSM_ID address space).
NOTE 1: The above rule means that UID and GID formats are identical, and hence the same primitive parameter
can be used to encode UID or GID.
NOTE 2: The BSM GID differs from an Ethernet multicast address by allowing a variable portion of the address
space to be assigned for group addresses. It also differs by allowing dynamic address resolution for GIDs,
unlike the fixed mapping defined for Ethernet. A fixed (static) assignment can also be used and hence the
BSM GID could be mapped to Ethernet (or any other static assignment) as a special case.
5.2.3 IP unicast addressing
For IP unicast addressing, an IP unicast address is mapped to a BSM_UID. This IP unicast address corresponds to the
satellite-facing port of an IP router (or end host). This IP address is therefore the "next-hop" IP address that is used for
forwarding IP packets across the BSM satellite subnetwork.
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13 ETSI TR 102 353 V1.2.1 (2015-12)
An example of this interworking model is illustrated in figure 5.2.3.1. This shows two IP addressing domains - the
satellite network domain (SN addresses) and the local network domain (LN addresses). In the general case, these can be
separately managed domains, in which case the IP router in the ST performs Network Address Translation (NAT)
functions.
Satellite network IP addressing domain
Local network IP addressing domain
IP interworking/router
IPAdd#LN3 IPAdd#SN1
IP Addresses
SIAF
in attached hosts
IP Layer in End
Systems UID#1
SDAF
ES#2 ES#1
L2Add#1
IPAdd#LN2
IPAdd#LN1
SLC/MAC
Ethernet
PHY
Ethernet Ethernet

Figure 5.2.3.1: IP interworking example: unicast addressing
The IP unicast address is associated with a unique BSM Unicast ID (UID).The associated UID
...