draft-ietf-ospf-xaf-te-03.txt   draft-ietf-ospf-xaf-te-04.txt 
LSR A. Smirnov LSR A. Smirnov
Internet-Draft Cisco Systems, Inc. Internet-Draft Cisco Systems, Inc.
Updates: 5786 (if approved) A. Retana Updates: 5786 (if approved) A. Retana
Intended status: Standards Track Huawei R&D USA Intended status: Standards Track Huawei R&D USA
Expires: April 6, 2019 M. Barnes Expires: April 25, 2019 M. Barnes
Cisco Systems, Inc. Cisco Systems, Inc.
October 3, 2018 October 22, 2018
OSPF Routing with Cross-Address Family Traffic Engineering Tunnels OSPF Routing with Cross-Address Family Traffic Engineering Tunnels
draft-ietf-ospf-xaf-te-03 draft-ietf-ospf-xaf-te-04
Abstract Abstract
When using Traffic Engineering (TE) in a dual-stack IPv4/IPv6 network When using Traffic Engineering (TE) in a dual-stack IPv4/IPv6
the Multiprotocol Label Switching (MPLS) TE Label Switched Paths network, the Multiprotocol Label Switching (MPLS) TE Label Switched
(LSP) infrastructure may be duplicated, even if the destination IPv4 Paths (LSP) infrastructure may be duplicated, even if the destination
and IPv6 addresses belong to the same remote router. In order to IPv4 and IPv6 addresses belong to the same remote router. In order
achieve an integrated MPLS TE LSP infrastructure, OSPF routes must be to achieve an integrated MPLS TE LSP infrastructure, OSPF routes must
computed over MPLS TE tunnels created using information propagated in be computed over MPLS TE tunnels created using information propagated
another OSPF instance. This is solved by advertising cross-address in another OSPF instance. This issue is solved by advertising cross-
family (X-AF) OSPF TE information. address family (X-AF) OSPF TE information.
This document describes an update to RFC5786 that allows for the easy This document describes an update to RFC5786 that allows for the easy
identification of a router's local X-AF IP addresses. identification of a router's local X-AF IP addresses.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 6, 2019. This Internet-Draft will expire on April 25, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 21 skipping to change at page 2, line 21
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Backward Compatibility . . . . . . . . . . . . . . . . . . . 5 4. Backward Compatibility . . . . . . . . . . . . . . . . . . . 5
4.1. Automatically Switched Optical Networks . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7 8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 7 8.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
TE Extensions to OSPFv2 [RFC3630] and to OSPFv3 [RFC5329] have been TE Extensions to OSPFv2 [RFC3630] and OSPFv3 [RFC5329] have been
described to support intra-area TE in IPv4 and IPv6 networks, described to support intra-area TE in IPv4 and IPv6 networks,
respectively. In both cases the TE database provides a tight respectively. In both cases, the TE database provides a tight
coupling between the routed protocol and TE signaling information in coupling between the routed protocol and advertised TE signaling
it. In other words, any use of the TE link state database is limited information. In other words, any use of the TE link state database
to IPv4 for OSPFv2 [RFC2328] and IPv6 for OSPFv3 [RFC5340]. is limited to IPv4 for OSPFv2 [RFC2328] and IPv6 for OSPFv3
[RFC5340].
In a dual stack network it may be desirable to set up common MPLS TE In a dual stack network, it may be desirable to set up common MPLS TE
LSPs to carry traffic destined to addresses from different address LSPs to carry traffic destined to addresses from different address
families on a router. The use of common LSPs eases potential families on a router. The use of common LSPs eases potential
scalability and management concerns by halving the number of LSPs in scalability and management concerns by halving the number of LSPs in
the network. Besides, it allows operators to group traffic based on the network. Besides, it allows operators to group traffic based on
business characteristics and/or applications or class of service, not business characteristics and/or applications or class of service, not
constrained by the network protocol which carries it. constrained by the network protocol used.
For example, an LSP created based on MPLS TE information propagated For example, an LSP created based on MPLS TE information propagated
by OSPFv2 instance can be defined to carry both IPv4 and IPv6 by an OSPFv2 instance can be used to transport both IPv4 and IPv6
traffic, instead of having both OSPFv2 and OSPFv3 to provision a traffic, as opposed to using both OSPFv2 and OSPFv3 to provision a
separate LSP for each address family. Even if in some cases the separate LSP for each address family. Even if in some cases the
address family-specific traffic is to be separated, the calculation address family-specific traffic is to be separated, calculation from
from a common database may prove operationally beneficial. a common database may prove to be operationally beneficial.
A requirement when creating a common MPLS TE infrastructure is the A requirement when creating a common MPLS TE infrastructure is the
ability to reliably map the X-AF family addresses to the ability to reliably map the X-AF family addresses to the
corresponding advertising tail-end router. This mapping is a corresponding advertising tail-end router. This mapping is a
challenge because the LSAs containing the routing information are challenge because the LSAs containing the routing information are
carried in one OSPF instance while the TE calculation may be done carried in one OSPF instance while the TE calculation may be done
using a TE database from a different instance. using a TE database from a different instance.
A simple solution to this problem is to rely on the Router ID to A simple solution to this problem is to rely on the Router ID to
identify a node in the corresponding OSPFv2 and OSPFv3 databases. identify a node in the corresponding OSPFv2 and OSPFv3 databases.
This solution would mandate both instances on the same router to be This solution would mandate both instances on the same router to be
configured with the same Router ID. However, relying on the configured with the same Router ID. However, relying on the
correctness of the configuration puts additional burden on network correctness of configuration puts additional burden and cost on the
management and adds cost to the operation of the network. The operation of the network. The network becomes even more difficult to
network becomes even more difficult to manage if OSPFv2 and OSPFv3 manage if OSPFv2 and OSPFv3 topologies do not match exactly, for
topologies do not match exactly, for example if area borders are example if area borders are chosen differently in the two protocols.
drawn differently in the two protocols. Also, if the routing Also, if the routing processes do fall out of sync (e.g., having
processes do fall out of sync (having different Router IDs, even if different Router IDs for local administrative reasons), there is no
for local administrative reasons), there is no defined way for other defined way for other routers to discover such misalignment and to
routers to discover such misalignment and to take any corrective take corrective measures (such as to avoid routing traffic through
measures (such as to avoid routing through affected TE tunnels or affected TE tunnels or alerting the network administrators). The use
issuing warning to network management). The use of misaligned router of misaligned Router IDs may result in delivering the traffic to the
IDs may result in delivering the traffic to the wrong tail-end wrong tail-end router, which could lead to suboptimal routing or even
router, which could lead to suboptimal routing or even traffic loops. traffic loops.
This document describes an update to [RFC5786] that allows for the This document describes an update to [RFC5786] that allows for the
easy identification of a router's local X-AF IP addresses. Routers easy identification of a router's local X-AF IP addresses. Routers
using the Node Attribute TLV [RFC5786] can include non-TE enabled using the Node Attribute TLV [RFC5786] can include non-TE enabled
interface addresses in their OSPF TE advertisements, and also use the interface addresses in their OSPF TE advertisements, and also use the
same sub-TLVs to carry X-AF information, facilitating the mapping same sub-TLVs to carry X-AF information, facilitating the mapping
mentioned above. described above.
The method described in this document can also be used to compute The method specified in this document can also be used to compute the
X-AF mapping of egress LSR for sub-LSPs of a Point-to-Multipoint LSP X-AF mapping of the egress Label Switching Router (LSR) for sub-LSPs
(see [RFC4461]). Considerations of using Point-to-Multipoint MPLS TE of a Point-to-Multipoint LSP [RFC4461]. Considerations of using
for X-AF traffic forwarding is outside the scope of this Point-to-Multipoint MPLS TE for X-AF traffic forwarding is outside
specification. the scope of this document.
2. Requirements Language 2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Operation 3. Operation
[RFC5786] defined the Node IPv4 Local Address and Node IPv6 Local [RFC5786] defined the Node IPv4 Local Address and Node IPv6 Local
Address sub-TLVs of the Node Attribute TLV for a router to advertise Address sub-TLVs of the Node Attribute TLV for a router to advertise
additional local IPv4 and IPv6 addresses. To solve the problem additional local IPv4 and IPv6 addresses. However, [RFC5786] did not
outlined in [RFC5786] OSPFv2 would advertise and use only IPv4 describe the advertisement and usage of these sub-TLVs when the
addresses and OSPFv3 would advertise and use only IPv6 addresses. address family of the advertised local address differed from the
address family of the OSPF traffic engineering protocol.
This document updates [RFC5786] so that a router can also announce This document updates [RFC5786] so that a router can also announce
one or more local X-AF addresses using the corresponding Local one or more local X-AF addresses using the corresponding Local
Address sub-TLV. In other words, to implement the X-AF routing Address sub-TLV. In other words, to implement the X-AF routing
technique proposed in this document, OSPFv2 will advertise the Node technique described in this document, OSPFv2 will advertise the Node
IPv6 Local Address sub-TLV and OSPFv3 will advertise the Node IPv4 IPv6 Local Address sub-TLV and OSPFv3 will advertise the Node IPv4
Local Address sub-TLV, possibly in addition to advertising other IP Local Address sub-TLV, possibly in addition to advertising other IP
addresses as documented by [RFC5786]. addresses as documented by [RFC5786].
A node that implements X-AF routing SHOULD advertise in the A node that implements X-AF routing SHOULD advertise, in the
corresponding Node Local Address sub-TLV all X-AF IP addresses local corresponding Node Local Address sub-TLV, all X-AF IPv4 and IPv6
to the router that can be used by Constrained SPF (CSPF) to calculate addresses local to the router that can be used by Constrained SPF
MPLS TE LSPs. In general, OSPF SHOULD advertise the IP address (CSPF) to calculate MPLS TE LSPs. In general, OSPF SHOULD advertise
listed in the Router Address TLV of the X-AF instance maintaining the IP address listed in the Router Address TLV [RFC3630] [RFC5329]
MPLS TE database plus any additional local addresses advertised by of the X-AF instance maintaining the MPLS TE database, plus any
the X-AF OSPF instance in its Node Local Address sub-TLV. additional local addresses advertised by the X-AF OSPF instance in
Implementation MAY advertise other local X-AF addresses. its Node Local Address sub-TLVs. An implementation MAY advertise
other local X-AF addresses.
If the Node Attribute TLV carries both the Node IPv4 Local Address If the Node Attribute TLV carries both the Node IPv4 Local Address
sub-TLV and the Node IPv6 Local Address sub-TLV, then the X-AF sub-TLV and the Node IPv6 Local Address sub-TLV, then the X-AF
component must be considered for the consolidated calculation of MPLS component MUST be considered for the consolidated calculation of MPLS
TE LSPs. Both instances may carry the required information, it is TE LSPs. Both instances MAY advertise the required information and
left to local configuration to determine which database is used. it is left to local configuration to determine which database is
used.
On Area Border Routers (ABR), each advertised X-AF IP address MUST be On Area Border Routers (ABR), each advertised X-AF IP address MUST be
advertised into at most one area. If OSPFv2 and OSPFv3 area borders advertised into at most one area. If OSPFv2 and OSPFv3 area border
match (i.e. for each interface area number for OSPFv2 and OSPFv3 routers coincide (i.e., the areas for all OSPFv2 and OSPFv3
instances is numerically equal), then the X-AF addresses MUST be interfaces are the same), then the X-AF addresses MUST be advertised
advertised into the same area in both instances. This allows other into the same area in both instances. This allows other ABRs
ABRs connected to the same set of areas to know with which area to connected to the same set of areas to know with which area to
associate MPLS TE tunnels. associate computed MPLS TE tunnels.
During the X-AF routing calculation, X-AF IP addresses are used to During the X-AF routing calculation, X-AF IP addresses are used to
map locally created LSPs to tail-end routers in the LSDB. The map locally created LSPs to tail-end routers in the Link State
mapping algorithm can be described as: Database (LSDB). The mapping algorithm can be described as:
Walk the list of all MPLS TE tunnels for which the computing Walk the list of all MPLS TE tunnels for which the computing
router is a head-end. For each MPLS TE tunnel T: router is a head-end. For each MPLS TE tunnel T:
1. If T's destination IP address is from the same address family as 1. If T's destination IP address is from the same address family as
the computing OSPF instance, then the tunnel must have been the computing OSPF instance, then the tunnel must have been
signaled based on MPLS TE information propagated in the same OSPF signaled based on MPLS TE information propagated in the same OSPF
instance. Process the tunnel as per [RFC3630] or [RFC5329]. instance. Process the tunnel as per [RFC3630] or [RFC5329].
2. Otherwise it is a X-AF MPLS TE tunnel. Note tunnel's destination 2. Otherwise it is a X-AF MPLS TE tunnel. Note tunnel's destination
IP address. IP address.
3. Walk the X-AF IP addresses in the LSDBs of all connected areas. 3. Walk the X-AF IP addresses in the LSDBs of all connected areas.
If a matching IP address is found, advertised by router R in area If a matching IP address is found, advertised by router R in area
A, then mark the tunnel T as belonging to area A and terminating A, then mark the tunnel T as belonging to area A and terminating
on tail-end router R. Assign an intra-area SPF cost to reach on tail-end router R. Assign the intra-area SPF cost to reach
router R within area A as the IGP cost of tunnel T. router R within area A as the IGP cost of tunnel T.
After completing this calculation, each TE tunnel is associated with After completing this calculation, each TE tunnel is associated with
an area and tail-end router in terms of the routing LSDB of the an area and tail-end router in terms of the routing LSDB of the
computing OSPF instance and has a metric. computing OSPF instance and has a cost.
The algorithm described above is to be used only if Node Local
Address sub-TLV include X-AF information.
Note that for clarity of description the mapping algorithm is Note that for clarity of description the mapping algorithm is
specified as a single calculation. Actual implementations for the specified as a single calculation. Actual implementations for the
efficiency may choose to support equivalent mapping functionality efficiency may choose to support equivalent mapping functionality
without implementing the algorithm exactly as it is described. without implementing the algorithm exactly as it is described.
As an example lets consider a router in dual-stack network running As an example, consider a router in a dual-stack network respectively
OSPFv2 and OSPFv3 for IPv4 and IPv6 routing correspondingly. Suppose using OSPFv2 and OSPFv3 for IPv4 and IPv6 routing. Suppose the
OSPFv2 instance is used to propagate MPLS TE information and the OSPFv2 instance is used to propagate MPLS TE information and the
router is configured to accept TE LSPs terminating at local addresses router is configured to accept TE LSPs terminating at local addresses
198.51.100.1 and 198.51.100.2. Then the router will advertise into 198.51.100.1 and 198.51.100.2. The router advertises in OSPFv2 the
OSPFv2 instance IPv4 address 198.51.100.1 in the Router Address TLV, IPv4 address 198.51.100.1 in the Router Address TLV, the additional
additional local IPv4 address 198.51.100.2 in the Node IPv4 Local local IPv4 address 198.51.100.2 in the Node IPv4 Local Address sub-
Address sub-TLV, plus other Traffic Engineering TLVs as required by TLV, and other Traffic Engineering TLVs as required by [RFC3630]. If
[RFC3630]. If OSPFv3 instance in the network is enabled for X-AF TE the OSPFv3 instance in the network is enabled for X-AF TE routing
routing (that is, to use for IPv6 routing MPLS TE LSPs computed by (that is, to use MPLS TE LSPs computed by OSPFv2 for IPv6 routing),
OSPFv2), then the OSPFv3 instance of the router will advertise the then the OSPFv3 instance of the router will advertise the Node IPv4
Node IPv4 Local Address sub-TLV listing local IPv4 addresses Local Address sub-TLV listing the local IPv4 addresses 198.51.100.1
198.51.100.1 and 198.51.100.2. Other routers in the OSPFv3 network and 198.51.100.2. Other routers in the OSPFv3 network will use this
will use this information to reliably identify this router as egress information to reliably identify this router as the egress LSR for
LSR for MPLS TE LSPs terminating at either 198.51.100.1 or MPLS TE LSPs terminating at either 198.51.100.1 or 198.51.100.2.
198.51.100.2.
4. Backward Compatibility 4. Backward Compatibility
Node Attribute TLV and Node Local Address sub-TLVs and their usage
are defined in [RFC5786] and updated by [RFC6827]. Way of using
these TLVs as specified in this document is fully backward compatible
with previous standard documents.
An implementation processing Node Attribute TLV MUST interpret its
content as follows:
o If the Node Attribute TLV contains Local TE Router ID sub-TLV then
this Node Attribute TLV MUST be treated as carrying routing
information for ASON (Automatically Switched Optical Network) and
processed as specified in [RFC6827].
o Otherwise Node Attribute TLV contains one or more instance(s) of
Node IPv4 Local Address and/or Node IPv6 Local Address sub-TLVs.
Meaning of each Local Address sub-TLV has to be identified
separately.
* If Node Local Address sub-TLV belongs to the same address
family as instance of OSPF protocol advertising it then address
carried in the sub-TLV MUST be treated as described in
[RFC5786].
* Otherwise the address is used for X-AF tunnel tail-end mapping
as defined by this document.
Only routers that serve as endpoints for one or more TE tunnels MUST Only routers that serve as endpoints for one or more TE tunnels MUST
be upgraded to support procedures described in this document: be upgraded to support the procedures described herein:
o Tunnel tailends need to advertise Node IPv4 Local Address and/or o Tunnel tailend routers advertise the Node IPv4 Local Address sub-
Node IPv6 Local Address sub-TLVs as described in this TLV and/or the Node IPv6 Local Address sub-TLV.
specification
o Tunnel headends need to perform X-AF routing calculation as o Tunnel headend routers perform the X-AF routing calculation.
described in this specification
Other routers in the network do not need to support X-AF procedures. Other routers in the network do not need to support X-AF procedures.
4.1. Automatically Switched Optical Networks
[RFC6827] updates [RFC5786] by defining extensions to be used in an
Automatically Switched Optical Network (ASON). The Local TE Router
ID Sub-TLV is required for determining ASON reachability. The
implication is that if the Local TE Router ID Sub-TLV is present in
the Node Attribute TLV, then the procedures in [RFC6827] apply,
regardless of whether any X-AF information is advertised.
5. Security Considerations 5. Security Considerations
This document introduces no new security concerns. Security This document describes the use of the Local Address sub-TLVs to
considerations of using Node Attribute TLV are discussed in provide X-AF information. The advertisement of these sub-TLVs, in
[RFC5786]. any OSPF instance, is not precluded by [RFC5786]. As such, no new
security threats are introduced beyond the considerations in OSPFv2
[RFC2328], OSPFv3 [RFC5340], and [RFC5786].
The X-AF information is not used for SPF computation or normal
routing, so the mechanism specified here has no affect on IP routing.
However, generating incorrect information, or tampering with the sub-
TLVs may have an effect on traffic engineering computations.
Specifically, TE traffic may be delivered to the wrong tail-end
router, which could lead to suboptimal routing or even traffic loops.
These threats are already present in other TE-related specifications,
and their considerations apply here as well, including [RFC3630] and
[RFC5329].
6. IANA Considerations 6. IANA Considerations
This document has no IANA actions. This document has no IANA actions.
7. Acknowledgements 7. Acknowledgements
The authors would like to thank Peter Psenak and Eric Osborne for The authors would like to thank Peter Psenak and Eric Osborne for
early discussions and Acee Lindem for discussing compatibility with early discussions and Acee Lindem for discussing compatibility with
ASON extensions. ASON extensions.
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