One document matched: draft-ietf-teas-rsvp-te-domain-subobjects-03.xml
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<rfc ipr="trust200902" category="exp" docName="draft-ietf-teas-rsvp-te-domain-subobjects-03" obsoletes="" updates="" submissionType="IETF" xml:lang="en">
<front>
<title abbrev="DOMAIN SUBOBJ">Domain Subobjects for Resource
ReserVation Protocol - Traffic Engineering (RSVP-TE)</title>
<author initials="D" surname="Dhody" fullname="Dhruv Dhody">
<organization>Huawei Technologies</organization>
<address>
<postal>
<street>Divyashree Techno Park, Whitefield</street>
<city>Bangalore</city>
<region>Karnataka</region>
<code>560037</code>
<country>India</country>
</postal>
<email>dhruv.ietf@gmail.com</email>
</address>
</author>
<author initials="U" surname="Palle" fullname="Udayasree Palle">
<organization>Huawei Technologies</organization>
<address>
<postal>
<street>Divyashree Techno Park, Whitefield</street>
<city>Bangalore</city>
<region>Karnataka</region>
<code>560037</code>
<country>India</country>
</postal>
<email>udayasree.palle@huawei.com</email>
</address>
</author>
<author initials="V" surname="Kondreddy" fullname="Venugopal Reddy Kondreddy">
<organization>Huawei Technologies</organization>
<address>
<postal>
<street>Divyashree Techno Park, Whitefield</street>
<city>Bangalore</city>
<region>Karnataka</region>
<code>560037</code>
<country>India</country>
</postal>
<email>venugopalreddyk@huawei.com</email>
</address>
</author>
<author initials="R" surname="Casellas" fullname="Ramon Casellas">
<organization>CTTC</organization>
<address>
<postal>
<street>Av. Carl Friedrich Gauss n7</street>
<city>Castelldefels</city>
<region>Barcelona </region>
<code>08860</code>
<country>Spain</country>
</postal>
<email>ramon.casellas@cttc.es </email>
</address>
</author>
<date month="September" year="2015" />
<area>Routing</area>
<workgroup>TEAS Working Group</workgroup>
<abstract>
<t>The Resource ReserVation Protocol - Traffic Engineering (RSVP-TE)
specification and the Generalized Multiprotocol
Label Switching (GMPLS) extensions to RSVP-TE
allow abstract nodes and resources to be explicitly included in a path
setup. Further Exclude Routes extensions to RSVP-TE allow
abstract nodes and resources to be explicitly excluded in a path setup. </t>
<t>This document specifies new subobjects to include or exclude 4-Byte
Autonomous System (AS) and Interior Gateway Protocol (IGP) area
during path setup.
</t>
</abstract>
</front>
<middle>
<section title="Introduction" toc="default">
<t>The RSVP-TE specification <xref target="RFC3209"/> and the GMPLS extensions
to RSVP-TE <xref target="RFC3473"/> allow abstract nodes and resources to be
explicitly included in a path setup using the Explicit Route Object (ERO). </t>
<t>Further Exclude Routes extensions <xref target="RFC4874"/> allow abstract
nodes or resources to be excluded from the whole path using the Exclude Route
object (XRO). To exclude certain abstract nodes or resources between a specific
pair of abstract nodes present in an ERO, a Explicit Exclusion Route Subobject
(EXRS) is used. </t>
<t><xref target="RFC3209"/> already describes the notion of abstract nodes, where
an abstract node is a group of nodes whose internal topology is opaque to the
ingress node of the Label Switched Path (LSP). It further defines a subobject for
AS, but with a 2-Byte AS number only. </t>
<t>This document extends the notion of abstract nodes by adding new subobjects
for IGP Areas and 4-byte AS numbers (as per <xref target="RFC6793"/>). These
subobjects can be included in Explicit Route Object (ERO), Exclude Route Object
(XRO) or Explicit Exclusion Route Subobject (EXRS).</t>
<t>In case of per-domain path computation <xref target="RFC5152"/>, where the
full path of an inter-domain TE LSP cannot be or is not determined at the ingress
node, and signaling message could use domain identifiers. The use of these new
subobjects is illustrated in <xref target="SEC_E"/>.</t>
<t>Further, the domain
identifier could simply act as delimiter to specify where the domain boundary
starts and ends.</t>
<t>This is a companion document to Path Computation Element Protocol (PCEP)
extensions for the domain sequence <xref target="PCE-DOMAIN"/>. </t>
<section title="Scope" toc="default">
<t>The procedures described in this document are experimental. The
experiment is intended to enable research for the usage of Domain
subobjects for inter-domain path setup. For this purpose this
document specify new domain subobjects as well as how they
incorporate with existing subobjects.</t>
<t>This document does not change the procedures for handling
subobjects in RSVP-TE.</t>
<t>The new subobjects introduced by this document will not be
understood by legacy implementations. If one of the subobjects is
received in a RSVP-TE object that does not understand it, it will
behave as described in <xref target="RFC3209"/> and
<xref target="RFC4874"/>. Therefore, it is assumed
that this experiment will be conducted only when all nodes
processing the new subobject form part of the experiment.</t>
<t>When the result of implementation and deployment are available, this
document will be updated and refined, and then be moved from
Experimental to Standard Track.</t>
<t>It should be noted that there are other ways such as use of boundary
node to identify the domain (instead of domain identifier), the mechanism
defined in this document is just another tool in the toolkit for the
operator.</t>
</section>
<section title="Requirements Language" toc="default">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in <xref target="RFC2119"/>.</t>
</section>
</section>
<section title="Terminology" toc="default">
<t>The following terminology is used in this document.</t>
<t>
<list style="hanging">
<t hangText="AS:">Autonomous System.</t>
<t hangText="Domain:">As per <xref target="RFC4655"/>, any collection
of network elements within a common sphere of address management or path
computational responsibility. Examples of domains include Interior
Gateway Protocol (IGP) areas and Autonomous Systems (ASs).</t>
<t hangText="ERO:">Explicit Route Object</t>
<t hangText="EXRS:">Explicit Exclusion Route Subobject</t>
<t hangText="IGP:">Interior Gateway Protocol. Either of the two routing
protocols, Open Shortest Path First (OSPF) or Intermediate System to
Intermediate System (IS-IS).</t>
<t hangText="IS-IS:">Intermediate System to Intermediate System.</t>
<t hangText="OSPF:">Open Shortest Path First.</t>
<t hangText="PCE:">Path Computation Element. An entity (component,
application, or network node) that is capable of computing a network
path or route based on a network graph and applying computational
constraints.</t>
<t hangText="PCEP:">Path Computation Element Protocol.</t>
<t hangText="RSVP:">Resource Reservation Protocol</t>
<t hangText="TE LSP:">Traffic Engineering Label Switched Path.</t>
<t hangText="XRO:">Exclude Route Object</t>
</list>
</t>
</section>
<section title="Subobjects for Domains" toc="default">
<section title="Domains" toc="default">
<t><xref target="RFC4726"/> and <xref target="RFC4655"/> define domain
as a separate administrative or geographic environment within the network.
A domain could be further defined as a zone of routing or computational
ability. Under these definitions a domain might be categorized as an
AS or an IGP area.</t>
<t>As per <xref target="RFC3209"/>, an abstract node is a group of nodes
whose internal topology is opaque to the ingress node of the LSP. Using
this concept of abstraction, an explicitly routed LSP can be specified
as a sequence of IP prefixes or a sequence of Autonomous Systems. In this
document we extend the notion to include IGP area and 4-Byte AS number.</t>
<t>These sub-objects appear in RSVP-TE, notably in - </t>
<t>
<list style="symbols">
<t>Explicit Route Object (ERO): As per <xref target="RFC3209"/>, an explicit
route is a particular path in the network topology including abstract nodes
(including domains). </t>
<t>Exclude Route Object (XRO): As per <xref target="RFC4874"/>, an exclude
route identifies a list of abstract nodes (including domains),
that should not be
traversed along the path of the LSP being established. </t>
<t>Explicit Exclusion Route Subobject (EXRS): As per <xref target="RFC4874"/>,
used to specify exclusion of certain abstract nodes between a specific pair
of nodes. EXRS are a subobject carried inside the ERO. These subobjects can be
used to specify the domains to be excluded between two abstract nodes.</t>
</list>
</t>
</section>
<section title="Explicit Route Object (ERO)'s Subobjects" toc="default">
<t>As stated in <xref target="RFC3209"/>, an explicit route is a particular path
in the network topology. In addition to the ability to identify specific nodes
along the path, an explicit route can identify a group of nodes (abstract nodes)
to be traversed along the path. </t>
<t>Some subobjects are defined in <xref target="RFC3209"/>, <xref target="RFC3473"/>,
<xref target="RFC3477"/>, <xref target="RFC4874"/> and <xref target="RFC5553"/> but
new subobjects related to domains are needed.</t>
<t>This document extends the support for 4-Byte AS numbers and IGP Areas.</t>
<t>
<figure title="" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
Type Subobject
TBD1 Autonomous system number (4 Byte)
TBD2 OSPF Area id
TBD3 ISIS Area id
]]></artwork>
</figure>
</t>
<section title="Autonomous system" toc="default" anchor="sec_ero_as">
<t><xref target="RFC3209"/> already defines 2-Byte AS number.</t>
<t>To support 4-Byte AS numbers as per <xref target="RFC6793"/>, the following subobject is defined: </t>
<t>
<figure title="" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS-ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
</t>
<t>
<list style="hanging">
<t hangText="L:">The L bit is an attribute of the subobject as defined in
<xref target="RFC3209"/>, i.e., set if the subobject represents a
loose hop in the explicit route. If the bit is not set, the subobject
represents a strict hop in the explicit route.</t>
<t hangText="Type:">(TBD1 by IANA) indicating a 4-Byte AS Number.</t>
<t hangText="Length:">8 (Total length of the subobject in bytes).</t>
<t hangText="Reserved:">Zero at transmission, ignored at receipt.</t>
<t hangText="AS-ID:">The 4-Byte AS Number. Note that if 2-Byte AS numbers
are in use, the low order bits (16 through 31) MUST be used and the
high order bits (0 through 15) MUST be set to zero. For the purpose of
this experiment, it is advised to use 4-Byte AS number subobject as default.</t>
</list>
</t>
</section>
<section title="IGP Area" toc="default" anchor="sec_ero_area">
<t>Since the length and format of Area-id is different for OSPF and ISIS,
the following two subobjects are defined: </t>
<t>For OSPF, the area-id is a 32 bit number. The subobject is encoded
as follows: </t>
<t>
<figure title="" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OSPF Area Id (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
</t>
<t>
<list style="hanging">
<t hangText="L:">The L bit is an attribute of the subobject as defined
in <xref target="RFC3209"/>.</t>
<t hangText="Type:">(TBD2 by IANA) indicating a 4-Byte OSPF Area ID.</t>
<t hangText="Length:">8 (Total length of the subobject in bytes).</t>
<t hangText="Reserved:">Zero at transmission, ignored at receipt.</t>
<t hangText="OSPF Area Id:">The 4-Byte OSPF Area ID.</t>
</list>
</t>
<t>For IS-IS, the area-id is of variable length and thus the length of the
subobject is variable. The Area-id is as described in IS-IS by ISO standard
<xref target="ISO10589"/>. The subobject is encoded as follows:</t>
<t>
<figure title="" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Area-Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// IS-IS Area ID //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
</t>
<t>
<list style="hanging">
<t hangText="L:">The L bit is an attribute of the subobject as
defined in <xref target="RFC3209"/>.</t>
<t hangText="Type:">(TBD3 by IANA) indicating IS-IS Area ID.</t>
<t hangText="Length:">Variable. The Length MUST be at least 8, and MUST be a
multiple of 4.</t>
<t hangText="Area-Len:">Variable (Length of the actual (non-padded)
IS-IS Area Identifier in octets; Valid values are from 1 to 13
inclusive). </t>
<t hangText="Reserved:">Zero at transmission, ignored at receipt.</t>
<t hangText="IS-IS Area Id:">The variable-length IS-IS area identifier.
Padded with trailing zeroes to a four-byte boundary.</t>
</list>
</t>
</section>
<section title="Mode of Operation" toc="default">
<t>The new subobjects to support 4-Byte AS and IGP (OSPF / ISIS) Area
could be used in the ERO to specify an abstract node (a group of
nodes whose internal topology is opaque to the ingress node of the LSP). </t>
<t>All the rules of processing (for example Next Hop Selection, L bit
processing, unrecognized subobjects etc) are as per the
<xref target="RFC3209"/>. Note that if a node is called upon to
process subobject defined in this
document, and it does not recognize, it will behave as described
in <xref target="RFC3209"/> when
an unrecognized ERO subobject is encountered. This means that this
node will return a PathErr with error code "Routing Error" and error
value "Bad EXPLICIT_ROUTE object" with the EXPLICIT_ROUTE object
included, truncated (on the left) to the offending subobject.</t>
</section>
</section>
<section title="Exclude Route Object (XRO)'s Subobjects" toc="default">
<t>As stated in <xref target="RFC4874"/>, the exclude route identifies
a list of abstract nodes that to exclude (not be traversed) along the path
of the LSP being established. </t>
<t>Some subobjects are defined in <xref target="RFC3209"/>,
<xref target="RFC3477"/>, <xref target="RFC4874"/> and
<xref target="RFC6001"/> but new subobjects related to
domains are needed.</t>
<t>This document extends the support for
4-Byte AS numbers and IGP Areas.</t>
<t>
<figure title="" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
Type Subobject
TBD1 Autonomous system number (4 Byte)
TBD2 OSPF Area id
TBD3 ISIS Area id
]]></artwork>
</figure>
</t>
<section title="Autonomous system" toc="default">
<t><xref target="RFC3209"/> and <xref target="RFC4874"/> already
define a 2-Byte AS number.</t>
<t>To support 4-Byte AS numbers as per <xref target="RFC6793"/>,
a subobject is with the same format as defined in
<xref target="sec_ero_as"/> with following difference:</t>
<t>The meaning of the L bit is as per <xref target="RFC4874"/>, where.</t>
<t>
<list style="hanging">
<t hangText="0:">indicates that the abstract node specified
MUST be excluded.</t>
<t hangText="1:">indicates that the abstract node specified
SHOULD be avoided.</t>
</list>
</t>
</section>
<section title="IGP Area" toc="default">
<t>Since the length and format of Area-id is different for OSPF
and ISIS, the following two subobjects are defined: </t>
<t>For OSPF, the area-id is a 32 bit number.
Subobjects for OSPF and IS-IS are of the
same format as defined in
<xref target="sec_ero_area"/> with following difference:
</t>
<t>The meaning of the L bit is as per <xref target="RFC4874"/>.</t>
</section>
<section title="Mode of Operation" toc="default">
<t>The new subobjects to support 4-Byte AS and IGP (OSPF / ISIS)
Area could also be used in the XRO to specify exclusion of an
abstract node (a group of nodes whose internal topology is
opaque to the ingress node of the LSP). </t>
<t>All the rules of processing are as per the <xref target="RFC4874"/>. </t>
<t>Note that if a node is called upon to
process a subobject defined in this
document, and it does not recognize, it will behave as described
in <xref target="RFC4874"/> when
an unrecognized XRO subobject is encountered, i.e. to ignore it.
In this case the desired exclusion will not be carried out.</t>
</section>
</section>
<section title="Explicit Exclusion Route Subobject" toc="default">
<t>As per <xref target="RFC4874"/>, the Explicit Exclusion Route
is used to specify exclusion of certain abstract nodes between a
specific pair of nodes or
resources in the explicit route. EXRS is an ERO subobject that
contains one or more subobjects of its own, called EXRS subobjects.</t>
<t>The EXRS subobject could carry any of the subobjects defined for
XRO, thus the new subobjects to support 4-Byte AS and IGP
(OSPF / ISIS) Area can also be used in the EXRS. The meanings of
the fields of the new XRO subobjects are unchanged when the
subobjects are included in an EXRS, except that scope of the
exclusion is limited to the single hop between the previous
and subsequent elements in the ERO.</t>
<t>All the rules of processing are as per the <xref target="RFC4874"/>. </t>
</section>
</section>
<section title="Interaction with Path Computation Element (PCE)" toc="default">
<t>The domain subobjects to be used in Path Computation Element Protocol (PCEP) are referred to in <xref target="PCE-DOMAIN"/>. Note that the
new domain subobjects follow the principle that subobjects used in
PCEP <xref target="RFC5440"/> are identical to the subobjects used in RSVP-TE and
thus are interchangeable between PCEP and RSVP-TE.</t>
</section>
<section title="IANA Considerations" toc="default">
<section title="New Subobjects" toc="default">
<t>IANA maintains the "Resource Reservation Protocol (RSVP) Parameters"
at http://www.iana.org/assignments/rsvp-parameters/rsvp-parameters.xhtml.
Within this registry IANA maintains two sub-registries:
<list style="symbols">
<t>"EXPLICIT_ROUTE subobjects":
http://www.iana.org/assignments/rsvp-parameters/rsvp-parameters.xhtml#rsvp-parameters-25</t>
<t>"EXCLUDE_ROUTE subobjects":
http://www.iana.org/assignments/rsvp-parameters/rsvp-parameters.xhtml#rsvp-parameters-95</t>
</list>
</t>
<t>Upon approval of this document, IANA is requested to make identical additions to these registries as follows, in sync with <xref target="PCE-DOMAIN"/>:</t>
<t>
<figure title="" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
Subobject Type Reference
TBD1 4-Byte AS number [This I.D.]
TBD2 OSPF Area ID [This I.D.]
TBD3 IS-IS Area ID [This I.D.]
]]></artwork>
</figure>
</t>
</section>
</section>
<section title="Security Considerations" toc="default">
<t></t>
<t>Security considerations for MPLS-TE and GMPLS signaling are
covered in <xref target="RFC3209"/> and <xref target="RFC3473"/>.
This document does not introduce any new messages or any
substantive new processing, and so those security
considerations continue to apply. Further, general
considerations for securing RSVP-TE in MPLS-TE and GMPLS networks can
be found in <xref target="RFC5920"/>.</t>
<t>The route exclusion security consideration are covered in
<xref target="RFC4874"/> and continue to apply. </t>
</section>
<section title="Acknowledgments" toc="default">
<t>We would like to thank Adrian Farrel, Lou Berger, George Swallow, Chirag Shah,
Reeja Paul, Sandeep Boina and Avantika for their useful comments and suggestions.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include="reference.RFC.2119.xml" ?>
<?rfc include="reference.RFC.3209.xml" ?>
<?rfc include="reference.RFC.3473.xml" ?>
<?rfc include="reference.RFC.3477.xml" ?>
<?rfc include="reference.RFC.4874.xml" ?>
<!--ISO-->
<reference anchor="ISO10589">
<front>
<title>
Intermediate system to Intermediate system routing information
exchange protocol for use in conjunction with the Protocol for
providing the Connectionless-mode Network Service (ISO
8473)
</title>
<author fullname="ISO">
<organization >ISO</organization>
</author>
<date month="" year="1992"/>
</front>
<seriesInfo name="ISO/IEC" value="10589:2002"/>
</reference>
<!--PCE-DOMAIN-->
<reference anchor="PCE-DOMAIN">
<front>
<title>Standard Representation Of Domain Sequence. (draft-ietf-pce-pcep-domain-sequence)</title>
<author initials="D" surname="Dhody" fullname="Dhody D">
<organization />
</author>
<author initials="U" surname="Palle" fullname="Palle U">
<organization />
</author>
<author initials="R" surname="Casellas" fullname="Casellas R">
<organization />
</author>
<date month="September" year="2015" />
</front>
</reference>
</references>
<references title="Informative References">
<?rfc include="reference.RFC.4655.xml" ?>
<?rfc include="reference.RFC.4726.xml" ?>
<?rfc include="reference.RFC.5152.xml" ?>
<?rfc include="reference.RFC.5440.xml" ?>
<?rfc include="reference.RFC.5553.xml" ?>
<?rfc include="reference.RFC.5920.xml" ?>
<?rfc include="reference.RFC.6001.xml" ?>
<?rfc include="reference.RFC.6793.xml" ?>
</references>
<section title="Examples" toc="default" anchor="SEC_E">
<t>These examples are for illustration purposes only, to show
how the new subobjects could be encoded. They are not meant to be an
exhaustive list of all possible usecases and combinations.</t>
<section title="Inter-Area LSP Path Setup" toc="default">
<t>In an inter-area LSP path setup where the ingress and the egress
belong to different IGP areas within the same AS, the domain
subobjects could be represented using an ordered list of IGP area
subobjects in an ERO. </t>
<t>
<figure title="Domain Corresponding to IGP Area" anchor="fig1" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
D2 Area D
|
|
D1
|
|
********BD1******
* | *
* | * Area C
Area A * | *
* | *
Ingress------A1-----ABF1------B1------BC1------C1------Egress
/ * | *
/ * | *
/ * Area | B *
F1 * | *
/ ********BE1******
/ |
/ |
F2 E1
|
Area F |
E2 Area E
* All IGP Area in one AS (AS 100)
]]></artwork>
</figure>
</t>
<t>As per <xref target="fig1"/>, the signaling at Ingress could be - </t>
<t>ERO:(A1, ABF1, Area B, Area C, Egress)</t>
<t>It should be noted that there are other ways to achieve the
desired signaling, the area subobject provides another tool in the
toolkit and can have operational benefits when -
<list style="symbols">
<t>Use of PCEP like domain-sequence <xref target="PCE-DOMAIN"/> configurations in
explicit path such that area subobjects can be used to signal the loose path.</t>
<t>Alignment of subobjects and registries between PCEP and RSVP-TE,
thus allowing easier interworking between path computation and signaling
i.e. to and fro of subobjects between signalling and path computation (if need be).</t>
</list>
</t>
</section>
<section title="Inter-AS LSP Path Setup" toc="default">
<section title="Example 1" toc="default">
<t>In an inter-AS LSP path setup where the ingress and the egress
belong to different AS, the domain subobjects (AS) could be used in an ERO. </t>
<t>
<figure title="Domain Corresponding to AS" anchor="fig2" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
AS A AS E AS C
<-------------> <----------> <------------->
A4----------E1---E2---E3---------C4
/ / \
/ / \
/ / AS B \
/ / <----------> \
Ingress------A1---A2------B1---B2---B3------C1---C2------Egress
\ / /
\ / /
\ / /
\ / /
A3----------D1---D2---D3---------C3
<---------->
AS D
* All AS have one area (area 0)
]]></artwork>
</figure>
</t>
<t>As per <xref target="fig2"/>, the signaling at Ingress could be - </t>
<t>ERO:(A1, A2, AS B, AS C, Egress); or </t>
<t>ERO:(A1, A2, AS B, Area 0, AS C, Area 0, Egress). </t>
<t>Each AS has a single IGP area (area 0), Area subobject is optional. </t>
<t>Note that to get a domain disjoint path, the ingress could also
signal the backup path with -</t>
<t>XRO:(AS B)</t>
</section>
<section title="Example 2" toc="default">
<t>As shown in <xref target="fig3"/>, where AS 200 is made up of
multiple areas, the signaling can include both AS and Area subobject
to uniquely identify a domain. </t>
<t>
<figure title="Domain Corresponding to AS and Area" anchor="fig3" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
Ingress *
| *
| *
| *
X1 *
\\ *
\ \ *
\ \* Inter-AS
AS 100 \* \ Link
* \ \
* \ \
* \ \
\ \ D2 Area D
AS 200 \ \ |
\ \ |
Inter \ \ D1
-AS \ \ |
Link \ \|
\ ********BD1******
\ * | *
\ * | * Area C
Area A \ * | *
\* | *
A2------A1------AB1------B1------BC1------C1------Egress
* | *
* | *
* | *
* Area | B *
********BE1******
|
|
E1
|
|
E2 Area E
]]></artwork>
</figure>
</t>
<t>As per <xref target="fig3"/>, the signaling at Ingress could be - </t>
<t>ERO:(X1, AS 200, Area B, Area C, Egress). </t>
</section>
</section>
</section>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 02:55:49 |