Internet DRAFT - draft-wang-lsr-passive-interface-attribute
draft-wang-lsr-passive-interface-attribute
LSR Working Group A. Wang
Internet-Draft China Telecom
Intended status: Standards Track Z. Hu
Expires: January 13, 2022 Huawei Technologies
G. Mishra
Verizon Inc.
J. Sun
ZTE Corporation
July 12, 2021
Passive Interface Attribute
draft-wang-lsr-passive-interface-attribute-08
Abstract
This document describes the mechanism that can be used to
differentiate the passive interfaces from the normal interfaces
within ISIS or OSPF domain.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 13, 2022.
Copyright Notice
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. Consideration for flagging passive interface . . . . . . . . 3
4. Passive Interface Attribute . . . . . . . . . . . . . . . . . 4
4.1. OSPFv2 Extended Stub-Link TLV . . . . . . . . . . . . . . 4
4.2. OSPFv3 Router-Stub-Link TLV . . . . . . . . . . . . . . . 5
4.3. ISIS Stub-link TLV . . . . . . . . . . . . . . . . . . . 6
4.4. Stub-Link Prefix Sub-TLV . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Passive interfaces are used commonly within an operators enterprise
or service provider networks. One of the most common use cases for
passive interface is in a data center Layer 2 and Layer 3 Top of
Rack(TOR) switch where the inter connected links between the TOR
switches and uplinks to the Core switch are only a few links and a
majority of the links are Layer 3 VLAN switched virtual interface
trunked between the TOR switches serving Layer 2 broadcast domains.
In this scenario all the VLANs are made passive as it is recommended
to limit the number of network LSAs between routers and switches to
avoid unnecessary hello processing overhead.
Another common use case is an inter-as routing scenario where the
same routing protocol but different IGP instance is running between
the adjacent BGP domains. Using passive interface on the inter-as
connections can ensure that prefixes contained within a domain are
only reachable within the domain itself and not allow the link state
database to be merged between domain which could result in
undesirable consequences.
For operator which runs different IGP domains that interconnect with
each other via the passive interfaces, there is desire to obtain the
inter-as topology information as described in
[I-D.ietf-idr-bgpls-inter-as-topology-ext]. If the router that runs
BGP-LS within one IGP domain can distinguish passive interfaces from
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other normal interfaces, it is then easy for the router to report
these passive links using BGP-LS to a centralized PCE controller.
Draft [I-D.dunbar-lsr-5g-edge-compute-ospf-ext] describes the case
that edge compute server attach the network and needs to flood some
performance index information to the network to facilitate the
network select the optimized application resource. The edge compute
server will also not run IGP protocol.
And, passive interfaces are normally the boundary of one IGP domain,
knowing them can facilitate the operators to apply various policies
on such interfaces, for example, to secure their networks, or
filtering the incoming traffic with scrutiny.
But OSPF and ISIS have no position to flag such passive interface and
their associated attributes now.
This document defines the protocol extension for OSPF and ISIS to
indicate the passive interfaces and their associated attributes.
2. Conventions used in this document
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 [RFC2119] .
3. Consideration for flagging passive interface
ISIS [RFC5029] defines the Link-Attributes Sub-TLV to carry the link
attribute information, but this Sub-TLV can only be carried within
the TLV 22, which is used to described the attached neighbor. For
passive interface, there is no ISIS neighbor, then it is not
appropriate to use this Sub-TLV to indicate the passive attribute of
the interface.
OSPFv2[RFC2328] defines link type field within Router LSA, the type 3
for connections to a stub network can be used to identified the
passive interface. But in OSPFv3 [RFC5340], type 3 within the
Router-LSA has been reserved. The information that associated with
stub network has been put in the Intra-Area-Prefix-LSAs.
It is necessary to define one general solution for ISIS and OSPF to
flag the passive interface and transfer the associated attributes
then.
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4. Passive Interface Attribute
The following sections define the protocol extension to indicate the
passive interface and associated attributes in OSPFv2/v3 and ISIS.
4.1. OSPFv2 Extended Stub-Link TLV
[RFC7684] defines the OSPFv2 Extended Link Opaque LSA to contain the
additional link attribute TLV. Currently, only OSPFv2 Extended Link
TLV is defined to contain the link related sub-TLV. Because passive
interface is not the normal link that participate in the OSPFv2
process, we select to define one new top TLV within the OSPFv2
Extended Link Opaque LSA to contain the passive interface related
attribute information.
The OSPFv2 Extended Stub-Link TLV has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type(Stub-Link) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Type | Reserved | Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: OSPFv2 Extended Stub-Link TLV
Type: The TLV type. The value is 2(TBD) for this stub-link type
Length: Variable, dependent on sub-TLVs
Link Type: Define the type of the stub-link. This document defines
the followings type:
o 0: Reserved
o 1: AS boundary link
o 2: Loopback link
o 3: Vlan interface link
o 4-255: For future extension
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Metric: Link metric used for inter-AS traffic engineering.
Link ID: Link ID is defined in Section A.4.2 of [RFC2328]
Link Data: Link Data is defined in Section A.4.2 of [RFC2328]
Sub-TLVs: Existing sub-TLV that defined within "OSPFv2 Extended Link
TLV Sub-TLV" can be included if necessary, the definition of new sub-
TLV can refer to Section 4.4
If this TLV is advertised multiple times in the same OSPFv2 Extended
Link Opaque LSA, only the first instance of the TLV is used by
receiving OSPFv2 routers. This situation SHOULD be logged as an
error.
If this TLV is advertised multiple times for the same link in
different OSPFv2 Extended Link Opaque LSAs originated by the same
OSPFv2 router, the OSPFv2 Extended Stub-Link TLV in the OSPFv2
Extended Link Opaque LSA with the smallest Opaque ID is used by
receiving OSPFv2 routers. This situation may be logged as a warning.
It is RECOMMENDED that OSPFv2 routers advertising OSPFv2 Extended
Stub-Link TLVs in different OSPFv2 Extended Link Opaque LSAs re-
originate these LSAs in ascending order of Opaque ID to minimize the
disruption.
This document creates a registry for Stub-Link attribute in
Section 6.
4.2. OSPFv3 Router-Stub-Link TLV
[RFC8362] extend the LSA format by encoding the existing OSPFv3 LSA
[RFC5340] in TLV tuples and allowing advertisement of additional
information with additional TLV.
This document defines the Router-Stub-Link TLV to describes a single
router passive interface. The Router-Stub-Link TLV is only
applicable to the E-Router-LSA. Inclusion in other Extended LSA MUST
be ignored.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type(Router-Stub-Link) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Type | Reserved | Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs(Variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: OSPFv3 Router-Stub-Link TLV
Type: OSPFv3 Extended-LSA TLV Type. Value is 10(TBD) for Router-
Stub-Link TLV.
Length: Variable, dependent on sub-TLVs
Link Type: Define the type of the stub-link. This document defines
the followings type:
o 0: Reserved
o 1: AS boundary link
o 2: Loopback link
o 3: Vlan interface link
o 4-255: For future extension
Metric: Link metric used for inter-AS traffic engineering.
Interface ID: 32-bit number uniquely identifying this interface among
the collection of this router's interfaces. For example, in some
implementations it may be possible to use the MIB-II IfIndex
[RFC2863].
Sub-TLVs: Existing sub-TLV that defined within "OSPFv3 Extended-LSA
Sub-TLV" can be included if necessary. The definition of new sub-TLV
can refer to Section 4.4.
4.3. ISIS Stub-link TLV
This document defines one new top TLV to contain the passive
interface attributes, which is shown in Figure 4:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type(Stub-Link) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Type | Reserved | Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs(Variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: ISIS Stub-Link TLV
Type: ISIS TLV Codepoint. Value is 28(TBD) for stub-link TLV.
Length: Variable, dependent on sub-TLVs
Link Type: Define the type of the stub-link. This document defines
the followings type:
o 0: Reserved
o 1: AS boundary link
o 2: Loopback link
o 3: Vlan interface link
o 4-255: For future extension
Metric: Link metric used for inter-AS traffic engineering.
Interface ID: 32-bit number uniquely identifying this interface among
the collection of this router's interfaces. For example, in some
implementations it may be possible to use the MIB-II IfIndex
[RFC2863].
Sub-TLVs: Existing sub-TLV that defined within "Sub-TLVs for TLVs 22,
23, 25, 141, 222, and 223" can be included if necessary. The
definition of new sub-TLV can refer to Section 4.4.
4.4. Stub-Link Prefix Sub-TLV
This document defines one new sub-TLV that can be contained within
the OSPFv2 Extended Stub-Link TLV , OSPFv3 Router-Stub-Link TLV or
ISIS Stub-Link TLV, to describe the prefix information associated
with the passive interface.
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The format of the sub-TLV is the followings:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Prefix or IPv6 Prefix Subobject |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Stub-Link Prefix Sub-TLV
Type: The TLV type. The value is 01(TBD) for this Stub-Link Prefix
type
Length: Variable, dependent on associated subobjects
Subobject: IPv4 prefix subobject or IPv6 prefix subobject, as that
defined in [RFC3209]
If the passive interface has multiple address, then multiple
subobjects will be included within this sub-TLV.
5. Security Considerations
Security concerns for ISIS are addressed in [RFC5304] and[RFC5310]
Security concern for OSPFv3 is addressed in [RFC4552]
Advertisement of the additional information defined in this document
introduces no new security concerns.
6. IANA Considerations
IANA is requested to the allocation in following registries:
+=========================+===========+======================+
| Registry | Type | Meaning |
+=========================+===========+======================+
|OSPFv2 Extended Link | 2 |Stub-Link TLV |
|Opaque LSA TLV | | |
+-------------------------+-----------+----------------------+
|OSPFv3 Extended-LSA TLV | 10 |Router-Stub-Link TLV |
+-------------------------+-----------+----------------------+
|IS-IS TLV Codepoint | 28 |Stub-Link TLV |
+-------------------------+-----------+----------------------+
Figure 5: Newly defined TLV in existing IETF registry
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IANA is requested to allocate one new registry that can be referred
by OSPFv2, OSPFv3 and ISIS respectively.
+=========================+==================================+
| New Registry | Meaning |
+=========================+==================================+
|Stub-Link Attribute | Attributes for stub-link |
+-------------------------+----------------------------------+
Figure 6: Newly defined Registry for stub-link attributes
One new sub-TLV is defined in this document under this registry
codepoint:
+=========================+===========+===============================+
| Registry | Type | Meaning |
+=========================+===========+===============================+
|Stub-Link Attribute | 0 | Reserved
+=========================+===========+===============================+
| | 1 |Stub-Link Prefix sub-TLV |
+-------------------------+-----------+-------------------------------+
| | 2-65535 |Reserved |
+-------------------------+-----------+-------------------------------+
Figure 7: Stub-Link Prefix Sub-TLV
7. Acknowledgement
Thanks Shunwan Zhang, Tony Li, Les Ginsberg, Acee Lindem, Dhruv
Dhody, Jeff Tantsura and Robert Raszuk for their suggestions and
comments on this idea.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>.
[RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group
MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000,
<https://www.rfc-editor.org/info/rfc2863>.
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[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
[RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality
for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006,
<https://www.rfc-editor.org/info/rfc4552>.
[RFC5029] Vasseur, JP. and S. Previdi, "Definition of an IS-IS Link
Attribute Sub-TLV", RFC 5029, DOI 10.17487/RFC5029,
September 2007, <https://www.rfc-editor.org/info/rfc5029>.
[RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic
Authentication", RFC 5304, DOI 10.17487/RFC5304, October
2008, <https://www.rfc-editor.org/info/rfc5304>.
[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, DOI 10.17487/RFC5310, February
2009, <https://www.rfc-editor.org/info/rfc5310>.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
<https://www.rfc-editor.org/info/rfc5340>.
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <https://www.rfc-editor.org/info/rfc7684>.
[RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and
U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4
and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794,
March 2016, <https://www.rfc-editor.org/info/rfc7794>.
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>.
8.2. Informative References
[I-D.dunbar-lsr-5g-edge-compute-ospf-ext]
Dunbar, L., Chen, H., and A. Wang, "OSPF extension for 5G
Edge Computing Service", draft-dunbar-lsr-5g-edge-compute-
ospf-ext-04 (work in progress), March 2021.
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[I-D.ietf-idr-bgpls-inter-as-topology-ext]
Wang, A., Chen, H., Talaulikar, K., and S. Zhuang, "BGP-LS
Extension for Inter-AS Topology Retrieval", draft-ietf-
idr-bgpls-inter-as-topology-ext-09 (work in progress),
September 2020.
Authors' Addresses
Aijun Wang
China Telecom
Beiqijia Town, Changping District
Beijing 102209
China
Email: wangaj3@chinatelecom.cn
Zhibo Hu
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: huzhibo@huawei.com
Gyan S. Mishra
Verizon Inc.
13101 Columbia Pike
Silver Spring MD 20904
United States of America
Email: gyan.s.mishra@verizon.com
Jinsong Sun
ZTE Corporation
No. 68, Ziijnhua Road
Nan Jing 210012
China
Email: sun.jinsong@zte.com.cn
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