One document matched: draft-ginsberg-isis-l2bundles-00.xml
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<rfc category="std" docName="draft-ginsberg-isis-l2bundles-00.txt"
ipr="pre5378Trust200902">
<front>
<title abbrev="isis-l2bundles">Advertising L2 Bundle Member Link
Attributes in IS-IS</title>
<author fullname="Les Ginsberg" initials="L" surname="Ginsberg">
<organization>Cisco Systems</organization>
<address>
<postal>
<street>510 McCarthy Blvd.</street>
<city>Milpitas</city>
<code>95035</code>
<region>CA</region>
<country>USA</country>
</postal>
<email>ginsberg@cisco.com</email>
</address>
</author>
<author fullname="Ahmed Bashandy" initials="A" surname="Bashandy">
<organization>Cisco Systems</organization>
<address>
<postal>
<street>170 West Tasman Drive</street>
<city>San Jose</city>
<code>95134</code>
<region>Ca</region>
<country>US</country>
</postal>
</address>
</author>
<author fullname="Clarence Filsfils" initials="C" surname="Filsfils">
<organization>Cisco Systems</organization>
<address>
<postal>
<street/>
<city/>
<code/>
<region/>
<country/>
</postal>
<email>cf@cisco.com</email>
</address>
</author>
<author fullname="Stefano Previdi" initials="S" surname="Previdi">
<organization>Cisco Systems</organization>
<address>
<postal>
<street>Via Del Serafico 200</street>
<city>Rome</city>
<code>0144</code>
<country>Italy</country>
</postal>
<email>sprevidi@cisco.com</email>
</address>
</author>
<author fullname="Mohan Nanduri" initials="M" surname="Nanduri">
<organization>Microsoft</organization>
<address>
<postal>
<street/>
<city/>
<code/>
<country/>
</postal>
<email>mnanduri@microsft.com</email>
</address>
</author>
<author fullname="Ebben Aries" initials="E" surname="Aries">
<organization>Facebook</organization>
<address>
<postal>
<street/>
<city/>
<code/>
<country/>
</postal>
<email>exa@fb.com</email>
</address>
</author>
<date day="06" month="July" year="2015"/>
<area>Routing Area</area>
<workgroup>Networking Working Group</workgroup>
<keyword>Sample</keyword>
<abstract>
<t>This document introduces the ability for IS-IS to advertise the link
attributes of layer 2 (L2) bundle members.</t>
</abstract>
<note title="Requirements Language">
<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 RFC 2119 [RFC2119].</t>
</note>
</front>
<middle>
<section title="Introduction">
<t>There are deployments where the Layer 3 interface on which an IS-IS
adjacency is established is a Layer 2 interface bundle, for instance a
Link Aggregation Group (LAG) [IEEE802.1AX]. This reduces the number
of adjacencies which need to be maintained by the routing protocol in
cases where there are parallel links between the neighbors. However, if
there is still a desire to control traffic flows on individual physical
links, information about each of the L2 bundle members is required. This
document introduces a new TLV to advertise link attribute information
for each of the L2 bundle members.</t>
<t>[SR] introduces a new link attribute - adjacency segment identifier
(Adj-SID) - which can be used as an instruction to forwarding to send
traffic over a specific link. This document introduces additional
sub-TLVs to advertise Adj-SIDs for L2 Bundle members.</t>
</section>
<section title="L2 Bundle Member Attributes TLV">
<t>A new TLV is introduced to advertise L2 Bundle member attributes.
Although much of the information is identical to and uses the same
sub-TLVs included in Extended IS-Neighbor advertisements (TLVs 22 and
222), a new TLV is used so that changes to the advertisement of the L2
Bundle member link attributes does not trigger unnecessary action by the
[ISO10589] Decision process.</t>
<t>This new TLV utilizes the sub-TLV space defined for TLVs 22, 23, 141,
222, and 223.</t>
<t>The following new TLV is introduced:</t>
<t><figure>
<artwork><![CDATA[ L2 Bundle Member Attributes
Type: 25 (suggested - to be assigned by IANA)
Length: Number of octets to follow
Parent L3 Neighbor Descriptor
L3 Neighbor System ID + pseudonode ID (7 octets)
Flags: 1 octet field of following flags:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|P| |
+-+-+-+-+-+-+-+-+
where:
P-flag: When set to 1 one of the sub-TLVs described
in Section 2.1 immediately follows the flags field.
If the P-flag is set to 0, then none of the sub-TLVs
described in Section 2.1 are present.
Other bits: MUST be zero when originated and ignored when
received.
One or more of the following:
L2 Bundle Attribute Descriptors
Length of L2 Bundle Attribute Descriptor (1 octet)
NOTE: This includes all fields described below.
Number of L2 Bundle Member Descriptors (1 octet)
L2 Bundle Member Link Local Identifiers
(4 * Number of L2 Bundle Member Descriptors octets)
NOTE: An L2 Bundle Member Descriptor is a Link Local
Identifier as defined in [RFC5307].
sub-TLV(s)
A sub-TLV may define an attribute common to all of
the bundle members listed or a sub-TLV may define an
attribute unique to each bundle member. Use of these
two classes of sub-TLVs is described in the following
sections.
]]></artwork>
</figure>NOTE: Only one Parent L3 Neighbor Descriptor is present in a
given TLV. Multiple L2 Bundle Attribute Descriptors may be present in a
single TLV.</t>
<section title="Parallel L3 Adjacencies">
<t>When there exist multiple L3 adjacencies to the same neighbor
additional information is required to uniquely identify the L3
Neighbor. One and only one of the following three sub-TLVs is used to
uniquely identify the L3 adjacency:</t>
<t><list style="symbols">
<t>IPv4 Interface Address (sub-TLV 6 defined in [RFC5305])</t>
<t>IPv6 Interface Address (sub-TLV 12 defined in [RFC6119])</t>
<t>Link Local/Remote Identifiers (sub-TLV 4 defined in
[RFC5307])</t>
</list></t>
<t>When the P-bit is set in the flags field in the Parent L3 Neighbor
Descriptor one and only one of the above sub-TLVs MUST be present. The
chosen sub-TLV MUST immediately follow the flags field described in
Section 2.</t>
<t>These sub-TLVs MAY be omitted if no parallel adjacencies to the
neighbor exist.</t>
</section>
<section title="Shared Attribute sub-TLVs">
<t>These sub-TLVs advertise a single copy of an attribute (e.g. link
bandwidth). The attribute applies to all of the L2 Bundle Members in
the set advertised under the preceding L2 Bundle Member
Attribute Descriptor. No more than one copy of a given sub-TLV in this
category may appear in the set of sub-TLVs under the preceding L2
Bundle Member Attribute Descriptor. If multiple copies of a given
sub-TLV are present both MUST be ignored.</t>
<t>The set of L2 Bundle Member Descriptors which may be advertised
under a single L2 Bundle Member Attribute Descriptor is therefore
limited to bundle members which share the set of attributes advertised
in the shared attribute sub-TLVs.</t>
<t>All existing sub-TLVs defined in the IANA Sub-TLVs for TLVs 22, 23,
141, 222, and 223 registry are in the category of shared attribute
sub-TLVs unless otherwise specified in this document.</t>
</section>
</section>
<section title="Advertising L2 Bundle Member Adj-SIDs">
<t>[SR] defines sub-TLVs to advertise Adj-SIDs for L3 adjacencies.
However these sub-TLVs only support a advertisement of a single Adj-SID.
As it is expected that each L2 Bundle member will have unique Adj-SIDs
in many deployments it is desirable to define a new sub-TLV which allows
more efficient encoding of a set of Adj-SIDs in a single sub-TLV. Two
new sub-TLVs are therefore introduced to support advertising Adj-SIDs
for L2 Bundle members. The format of the new sub-TLVs is similar to that
used for L3 adjacencies, but is optimized to allow advertisement of a
set of Adj-SIDs (one per L2 Bundle Member) in a single sub-TLV.</t>
<t>The two new sub-TLVs defined in the following sections do not fall
into the category of shared attribute sub-TLVs.</t>
<section title="L2 Bundle Member Adjacency Segment Identifier sub-TLV">
<t>This sub-TLV is used to advertise Adj-SIDs for L2 Bundle Members
associated with a parent L3 adjacency which is Point-to-Point. The
following format is defined for this sub-TLV:</t>
<t><figure>
<artwork><![CDATA[ Type: 41 (suggested value to be assigned by IANA) (1 octet)
Length: variable (1 octet)
Flags: 1 octet field of following flags:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|F|*|V|L|S| |
+-+-+-+-+-+-+-+-+
where:
* - Is a flag used in the L3 Adj-SID sub-TLV but which is NOT
used in this sub-TLV. These bits SHOULD be sent as 0 and MUST
be ignored on receipt
F-Flag: Address-Family flag. If unset, then the Adj-SID refers
to an L2 Bundle Member with outgoing IPv4 encapsulation. If set
then the Adj-SID refers to an L2 Bundle Member with outgoing
IPv6 encapsulation.
V-Flag: Value flag. If set, then the Adj-SID carries a value.
By default the flag is SET.
L-Flag: Local Flag. If set, then the value/index carried by
the Adj-SID has local significance. By default the flag is
SET.
S-Flag. Set Flag. When set, the S-Flag indicates that the
Adj-SID refers to a set of L2 Bundle Members (and therefore
MAY be assigned to other L2 Bundle Members as well).
Other bits: MUST be zero when originated and ignored when
received.
Weight: 1 octet. The value represents the weight of the Adj-SID
for the purpose of load balancing. The use of the weight is
defined in [SR-ARCH].
NOTE: Flags and weight are shared by all L2 Bundle Members
listed in the L2 Bundle Attribute Descriptor.
L2 Bundle Member Adj-SID Descriptors. There MUST be one descriptor
for each of the L2 Bundle Members advertised under the preceding
L2 Bundle Member Attribute Descriptor. Each descriptor consists
of one of the following fields:
SID/Index/Label: according to the V and L flags, it contains
either:
* A 3 octet local label where the 20 rightmost bits are used
for encoding the label value. In this case the V and L
flags MUST be set.
* A 4 octet index defining the offset in the SID/Label space
advertised by this router. See [SR].
In this case V and L flags MUST be unset.
* A 16 octet IPv6 address. In this case the V flag MUST be
set. The L flag MUST be unset if the IPv6 address is
globally unique.
]]></artwork>
</figure></t>
</section>
<section title="L2 Bundle Member LAN Adjacency Segment Identifier sub-TLV">
<t>This sub-TLV is used to advertise Adj-SIDs for L2 Bundle Members
associated with a parent L3 adjacency which is a LAN adjacency. In LAN
subnetworks, the Designated Intermediate System (DIS) is elected and
originates the Pseudonode-LSP (PN-LSP) including all neighbors of the
DIS. When Segment Routing is used, each router in the LAN MAY
advertise the Adj-SID of each of its neighbors on the LAN. Similarly,
for each L2 Bundle Member a router MAY advertise an Adj-SID to each
neighbor on the LAN.</t>
<t>The following format is defined for this sub-TLV:</t>
<t><figure>
<artwork><![CDATA[ Type: 42 (suggested value to be assigned by IANA) (1 octet)
Length: variable (1 octet)
Neighbor System ID: 6 octets
Flags: 1 octet field of following flags:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|F|*|V|L|S| |
+-+-+-+-+-+-+-+-+
where:
* - Is a flag used in the L3 Adj-SID sub-TLV but which is NOT
used in this sub-TLV. These bits SHOULD be sent as 0 and MUST
be ignored on receipt
F-Flag: Address-Family flag. If unset, then the Adj-SID refers
to an L2 Bundle Member with outgoing IPv4 encapsulation. If set
then the Adj-SID refers to an L2 Bundle Member with outgoing
IPv6 encapsulation.
V-Flag: Value flag. If set, then the Adj-SID carries a value.
By default the flag is SET.
L-Flag: Local Flag. If set, then the value/index carried by
the Adj-SID has local significance. By default the flag is
SET.
S-Flag. Set Flag. When set, the S-Flag indicates that the
Adj-SID refers to a set of L2 Bundle Members (and therefore
MAY be assigned to other L2 Bundle Members as well).
Other bits: MUST be zero when originated and ignored when
received.
Weight: 1 octet. The value represents the weight of the Adj-SID
for the purpose of load balancing. The use of the weight is
defined in [SR-ARCH].
NOTE: Flags and weight are shared by all L2 Bundle Members
listed in the L2 Bundle Attribute Descriptor.
L2 Bundle Member LAN Adj-SID Descriptors. There MUST be one
descriptor for each of the L2 Bundle Members advertised
under the preceding L2 Bundle Member Attribute Descriptor.
Each descriptor consists of one of the following fields:
SID/Index/Label: according to the V and L flags, it contains
either:
* A 3 octet local label where the 20 rightmost bits are used
for encoding the label value. In this case the V and L
flags MUST be set.
* A 4 octet index defining the offset in the SID/Label space
advertised by this router. See [SR].
In this case V and L flags MUST be unset.
* A 16 octet IPv6 address. In this case the V flag MUST be
set. The L flag MUST be unset if the IPv6 address is
globally unique.
]]></artwork>
</figure></t>
</section>
</section>
<section anchor="IANA" title="IANA Considerations">
<t>This document adds the following new TLV to the IS-IS TLV Codepoints
registry.</t>
<t>Value: 25 (suggested - to be assigned by IANA)</t>
<t>Name: L2 Bundle Member Attributes</t>
<t>The name of the Sub-TLVs for TLVs 22, 23, 141, 222, and 223 registry
needs to be changed to Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223
registry. An additional column needs to be added to the registry to
indicate which sub-TLVs may appear in the new L2 Bundle Member
Attributes TLV. The following table indicates the appropriate settings
for all currently defined sub-TLVs as regards their use in the new L2
Bundle Member Attributes TLV.</t>
<t><figure>
<artwork><![CDATA[ 3 Administrative group (color) y
4 Link Local/Remote Identifiers y
6 IPv4 interface address y
8 IPv4 neighbor address y
9 Maximum link bandwidth y
10 Maximum reservable link bandwidth y
11 Unreserved bandwidth y
12 IPv6 Interface Address y
13 IPv6 Neighbor Address y
14 Extended Administrative Group y
18 TE Default metric y
19 Link-attributes y
20 Link Protection Type y
21 Interface Switching Capability Descriptor y
22 Bandwidth Constraints y
23 Unconstrained TE LSP Count y
24 Remote AS number n
25 IPv4 remote ASBR Identifier n
26 IPv6 remote ASBR Identifier n
27 Interface Adjustment Capability Descriptor (IACD) y
28 MTU n
29 SPB-Metric y
30 SPB-A-OALG y
]]></artwork>
</figure></t>
<t>This document adds the following new sub-TLVs to the sub-TLVs for
TLVs 22, 23, 25, 141, 222, and 223 registry.</t>
<t>Value: 41 (suggested - to be assigned by IANA)</t>
<t>Name: L2 Bundle Member Adj-SID</t>
<t>This sub-TLV is allowed in the following TLVs:</t>
<t><figure>
<artwork><![CDATA[ 22 23 25 141 222 223
n n y n n n
]]></artwork>
</figure></t>
<t>Value: 42 (suggested to be assigned by IANA)</t>
<t>Name: L2 Bundle Member LAN Adj-SID</t>
<t>This sub-TLV is allowed in the following TLVs:</t>
<t><figure>
<artwork><![CDATA[ 22 23 25 141 222 223
n n y n n n
]]></artwork>
</figure></t>
</section>
<section anchor="Security" title="Security Considerations">
<t>None.</t>
</section>
<section anchor="Acknowledgements" title="Acknowledgements">
<t>The authors would like to thank Jon MItchell for his careful
review.</t>
</section>
</middle>
<back>
<references title="Normative References">
<reference anchor="ISO10589">
<front>
<title>Intermediate system to Intermediate system intra-domain
routeing information exchange protocol for use in conjunction with
the protocol for providing the connectionless-mode Network Service
(ISO 8473)</title>
<author>
<organization abbrev="ISO">International Organization for
Standardization</organization>
</author>
<date month="Nov" year="2002"/>
</front>
<seriesInfo name="ISO/IEC" value="10589:2002, Second Edition"/>
</reference>
<reference anchor="IEEE802.1AX">
<front>
<title>IEEE Standard for Local and Metropolitan Area Networks - Link
Aggregation.</title>
<author>
<organization abbrev="IEEE">Institute of Electrical and
Electronics Engineers</organization>
</author>
<date month="Nov" year="2008"/>
</front>
<seriesInfo name="ISO/IEC" value="10589:2002, Second Edition"/>
</reference>
<?rfc include="reference.RFC.2119"?>
<?rfc include='reference.RFC.5305'?>
<?rfc include='reference.RFC.5307'?>
<?rfc include='reference.RFC.6119'?>
</references>
<references title="Informational References">
<reference anchor="SR">
<front>
<title>IS-IS Extensions for Segment Routing,
draft-ietf-isis-segment-routing-extensions-05(work in
progress)</title>
<author fullname="Previdi S., et al,"/>
<date month="June" year="2015"/>
</front>
</reference>
<reference anchor="SR-ARCH">
<front>
<title>Segment Routing Architecture,
draft-ietf-spring-segment-routing-03(work in progress)</title>
<author fullname="Filsfils C., et al,"/>
<date month="May" year="2015"/>
</front>
</reference>
</references>
</back>
</rfc>
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