Applicability Statement for Layer 1 Virtual Private Network (L1VPN) Basic Mode
RFC 5253
| Document | Type | RFC - Informational (July 2008; No errata) | |
|---|---|---|---|
| Author | Tomonori Takeda | ||
| Last updated | 2018-12-20 | ||
| Replaces | draft-takeda-l1vpn-applicability-basic-mode | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text html pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 5253 (Informational) | |
| Action Holders |
(None)
|
||
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | David Ward | ||
| Send notices to | (None) | ||
Network Working Group T. Takeda, Ed.
Request for Comments: 5253 NTT
Category: Informational July 2008
Applicability Statement for
Layer 1 Virtual Private Network (L1VPN) Basic Mode
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Abstract
This document provides an applicability statement on the use of
Generalized Multiprotocol Label Switching (GMPLS) protocols and
mechanisms to support Basic Mode Layer 1 Virtual Private Networks
(L1VPNs).
L1VPNs provide customer services and connectivity at Layer 1 over
Layer 1 networks. The operation of L1VPNs is divided into the Basic
Mode and the Enhanced Mode, where the Basic Mode of operation does
not feature any exchange of routing information between the Layer 1
network and the customer domain. This document examines how GMPLS
protocols can be used to satisfy the requirements of a Basic Mode
L1VPN.
Takeda Informational [Page 1]
RFC 5253 AS for L1VPN Basic Mode July 2008
Table of Contents
1. Introduction ....................................................3
1.1. Terminology ................................................3
2. Basic Mode Overview .............................................3
3. Supported Network Types .........................................4
3.1. Data Plane .................................................4
3.2. Control Plane ..............................................4
4. Addressing ......................................................5
5. Provider Control of Its Infrastructure ..........................5
5.1. Provisioning Model .........................................5
5.2. PE-to-PE Segment Control ...................................6
5.2.1. Path Computation and Establishment ..................6
5.2.2. Resource Management .................................7
5.2.3. Consideration of CE-to-PE Traffic Engineering
Information .........................................8
5.3. Connectivity Restriction ...................................8
6. Customer Control of Its L1VPN ...................................8
6.1. Topology Control ...........................................8
6.2. Note on Routing ............................................9
7. Scalability and Resiliency .....................................10
7.1. Scalability ...............................................10
7.2. Data Plane Resiliency .....................................11
7.3. Control Plane Resiliency ..................................12
8. Security Considerations ........................................12
8.1. Topology Confidentiality ..................................12
8.2. External Control of the Provider Network ..................13
8.3. Data Plane Security .......................................13
8.4. Control Plane Security ....................................14
9. Manageability Considerations ...................................15
10. References ....................................................15
10.1. Normative References .....................................15
10.2. Informative References ...................................16
11. Acknowledgments ...............................................17
Takeda Informational [Page 2]
RFC 5253 AS for L1VPN Basic Mode July 2008
1. Introduction
This document provides an applicability statement on the use of
Generalized Multiprotocol Label Switching (GMPLS) protocols and
mechanisms to Basic Mode Layer 1 Virtual Private Networks (L1VPNs) as
specified in [RFC4847].
The operation of L1VPNs is divided into the Basic Mode and the
Enhanced Mode. The Basic Mode of operation does not feature any
exchange of routing information between the Layer 1 network and the
customer domain, while the Enhanced Mode of operation features
exchange of routing information between the Layer 1 network and the
customer domain.
The main GMPLS protocols and mechanisms applicable to the L1VPN Basic
Mode are described in [RFC5251], [RFC5195], and [RFC5252], along with
several other documents referenced within this document.
Note that discussion in this document is focused on areas where GMPLS
protocols and mechanisms are relevant.
1.1. Terminology
The reader is assumed to be familiar with the terminology in
[RFC3031], [RFC3209], [RFC3471], [RFC3473], [RFC4202], [RFC4026], and
[RFC4847].
2. Basic Mode Overview
As described in [RFC4847], in the Basic Mode service model, there is
no routing exchange between the Customer Edge (CE) and the Provider
Edge (PE). CE-to-CE L1VPN connections (i.e., the CE-to-CE VPN
connection in RFC 4847) are set up by GMPLS signaling between the CE
and the PE, and then across the provider network. A L1VPN connection
is limited to the connection between CEs belonging to the same L1VPN.
Note that in L1VPNs, routing operates within the provider network.
Also note that routing may be used by PEs to exchange information
specific to the L1VPNs supported by the provider network (e.g.,
membership information).
In the L1VPN Basic Mode, the provider network is completely under the
control of the provider. This includes the PE-to-PE segment of the
CE-to-CE L1VPN connection that is controlled and computed by the
provider (PE-to-PE segment control). On the other hand, the L1VPN
itself, constructed from a set of CEs and the L1VPN connections
provided by the provider, is under the control of each customer.
This control includes that a customer can request between which CEs a
Takeda Informational [Page 3]
RFC 5253 AS for L1VPN Basic Mode July 2008
connection is to be established (topology control). Note that a
customer may outsource the management of its L1VPN to a third party,
including to the provider itself. There is a confidentiality
requirement between the provider and each customer.
[RFC5251], which extends [RFC4208], specifies GMPLS signaling to
establish CE-to-CE L1VPN connections.
[RFC5195] and [RFC5252] specify alternative mechanisms to exchange
L1VPN membership information between PEs, based on BGP and OSPF,
respectively.
3. Supported Network Types
3.1. Data Plane
The provider network can be constructed from any type of Layer 1
switches, such as Time Division Multiplexing (TDM) switches, Optical
Cross-Connects (OXCs), or Photonic Cross-Connects (PXCs).
Furthermore, a PE may be an Ethernet Private Line (EPL) type of
device, that maps Ethernet frames onto Layer 1 connections (by means
of Ethernet over TDM, etc.). The provider network may be constructed
from switches providing a single switching granularity (e.g., only
VC3 switches), or from switches providing multiple switching
granularities (e.g., from VC3/VC4 switches, or from VC3 switches and
OXCs). The provider network may provide a single type of L1VPN
connection (e.g., VC3 connections only), or multiple types of
connection (e.g., VC3/VC4 connections, or VC3 connections and
wavelength connections).
A CE does not have to have the capability to switch at Layer 1, but
it must be capable of receiving a Layer 1 signal and either switching
it or terminating it with adaptation.
As described in [RFC4847] and [RFC5251], a CE and a PE are connected
by one or more links. A CE may also be connected to more than one
PE, and a PE may have more than one CE connected to it.
A CE may belong to a single L1VPN, or to multiple L1VPNs, and a PE
may support one or more L1VPNs through a single CE or through
multiple CEs.
3.2. Control Plane
The provider network is controlled by GMPLS. L1VPN Basic Mode
provider networks are limited to a single AS within the scope of this
document. Multi-AS Basic Mode L1VPNs are for future study.
Takeda Informational [Page 4]
RFC 5253 AS for L1VPN Basic Mode July 2008
As described in [RFC4847] and [RFC5251], a CE and a PE need to be
connected by at least one control channel. It is necessary to
disambiguate control plane messages exchanged between a CE and a PE
if the CE-to-PE relationship is applicable to more than one L1VPN.
This makes it possible to determine to which L1VPN such control plane
messages apply. Such disambiguation can be achieved by allocating a
separate control channel to each L1VPN (either using a separate
physical channel, a separate logical channel such as an IP tunnel, or
using separate addressing).
GMPLS allows any type of control channel to be used, as long as there
is IP level reachability. In the L1VPN context, instantiation of a
control channel between a CE and a PE may differ depending on
security requirements, etc. This is discussed in Section 8.
4. Addressing
As described in [RFC5251], the L1VPN Basic Mode allows that customer
addressing realms overlap with each other, and also overlap with the
service provider addressing realm. That is, a customer network may
reuse addresses used by the provider network, and may reuse addresses
used in another customer network supported by the same provider
network. This is the same as in any other VPN model.
In addition, the L1VPN Basic Mode allows CE-to-PE control channel
addressing realms to overlap. That is, a CE-to-PE control channel
address (CE's address of this control channel and PE's address of
this control channel) is unique within the L1VPN that the CE-to-PE
control channel belongs to, but not necessarily unique across
multiple L1VPNs.
Furthermore, once a L1VPN connection has been established, the L1VPN
Basic Mode does not enforce any restriction on address assignment for
this L1VPN connection (treated as a link) for customer network
operation (e.g., IP network, MPLS network).
5. Provider Control of Its Infrastructure
5.1. Provisioning Model
As described in [RFC5251], for each L1VPN that has at least one
customer-facing port on a given PE, the PE maintains a Port
Information Table (PIT) associated with that L1VPN. A PIT provides a
cross-reference between Customer Port Indices (CPIs) and Provider
Port Indices (PPIs) and contains a list of <CPI, PPI> tuples for all
the ports within the L1VPN. In addition, for local PE ports of a
given L1VPN, the PE retains an identifier known as the VPN-PPI, and
this is stored in the PIT with the <CPI, PPI> tuples.
Takeda Informational [Page 5]
RFC 5253 AS for L1VPN Basic Mode July 2008
When a new CE belonging to one or more L1VPNs is added to a PE, PIT
entries associated to those L1VPNs need to be configured on the PE.
Section 4 of [RFC5251] specifies such procedures:
- If no PIT exists for the L1VPN on the PE, a new PIT is created by
the provider and associated with the VPN identifier.
- The PIT (new or pre-existing) is updated to include information
related to the newly added CE. The VPN-PPI, PPI, and CPI are
installed in the PIT. Note that the PPI is well-known by the PE,
but the CPI must be discovered either through manual configuration
or automatically by mechanisms such as the Link Management Protocol
(LMP) [RFC4204]. In addition, a CE-to-PE control channel needs to
be configured.
- The updated PIT information needs to be configured in the PITs on
the remote PE associated with the L1VPN. For such purposes, manual
configuration or some sort of auto-discovery mechanisms can be
used. [RFC5195] and [RFC5252] specify alternative auto-discovery
mechanisms.
- In addition, remote PIT information associated with the L1VPN needs
to be configured on this PE if the PIT has been newly created.
Again, this can be achieved through manual configuration or through
auto-discovery; see [RFC5195] and [RFC5252].
When L1VPN membership of an existing CE changes, or when a CE is
removed from a PE, similar procedures need to be applied to update
the local and remote PITs.
5.2. PE-to-PE Segment Control
In the L1VPN Basic Mode, a PE-to-PE segment of a CE-to-CE L1VPN
connection is completely under the control of the provider network.
5.2.1. Path Computation and Establishment
A PE-to-PE segment of a CE-to-CE L1VPN connection may be established
based on various policies. Those policies can be applied per L1VPN
or per L1VPN connection. The policy is configured by the provider,
possibly based on the contracts with each customer.
Examples of PE-to-PE segment connection establishment polices
supported in the L1VPN Basic Mode are as follows.
- Policy 1: On-demand establishment, on-demand path computation
- Policy 2: On-demand establishment, pre-computed path
- Policy 3: Pre-establishment, pre-computed path
Takeda Informational [Page 6]
RFC 5253 AS for L1VPN Basic Mode July 2008
In each policy, the PE-to-PE path may be computed by the local PE or
by a path computation entity outside of the local PE (e.g., a Path
Computation Element (PCE) [RFC4655] or a management system).
In policies 2 and 3, pre-computation of paths (and pre-establishment
if applicable) can be done at the network planning phase, or just
before signaling (e.g., triggered by an off-line customer request).
As the result of pre-computation (and pre-establishment), there could
be multiple PE-to-PE segments for a specific pair of PEs. When a PE
receives a Path message from a CE for a L1VPN connection, a PE needs
to determine which PE-to-PE segment to use. In such cases, the
provider may want to control:
- Which L1VPN uses which PE-to-PE L1VPN segment.
- Which CE-to-CE L1VPN connection uses which PE-to-PE L1VPN segment.
The former requires mapping between the PIT and the PE-to-PE segment.
The latter requires some more sophisticated mapping method, for
example:
- Mapping between individual PIT entries and PE-to-PE segments.
- Use of a Path Key ID [CONF-SEG] supplied by the provider to the CE,
and signaled by the CE as part of the L1VPN connection request.
The L1VPN Basic Mode does not preclude usage of other methods, if
applicable.
In policy 3, stitching or nesting is necessary in order to map the
CE-to-CE L1VPN connection to a pre-established PE-to-PE segment.
5.2.2. Resource Management
The provider network may operate resource management based on various
policies. These policies can be applied per L1VPN or per L1VPN
connection. The policy is configured by the provider, possibly based
on the contracts with each customer.
For example, a provider may choose to partition the resources of the
provider network for limited use by different L1VPNs or customers.
Such a function might be achieved within the scope of the Basic Mode
using resource affinities [RFC3209], but the details of per-L1VPN
resource models (especially in terms of CE-to-PE routing) are
considered as part of the Enhanced Mode.
Takeda Informational [Page 7]
RFC 5253 AS for L1VPN Basic Mode July 2008
5.2.3. Consideration of CE-to-PE Traffic Engineering Information
[RFC5252] and [BGP-TE] allow CE-to-PE Traffic Engineering (TE) link
information to be injected into the provider network, and in
particular to be exchanged between PEs. This may be helpful for the
ingress PE to prevent connection setup failure due to lack of
resources or incompatible switching capabilities on remote CE-to-PE
TE links.
Furthermore, the L1VPN Basic Mode allows a remote CE to be reached
through more than one TE link connected to the same PE (single-homed)
or to different PEs (dual-homed). In such cases, to facilitate route
choice, the ingress CE needs to initiate signaling by specifying the
egress CE's router ID, not the egress CPI, in the Session Object and
the Explicit Route Object (ERO), if present, so as to not constrain
the choice of route within the provider network. Therefore, the CE's
router ID needs to be configured in the PITs.
Note that, as described in Section 7.2, consideration of the full
feature set enabled by dual-homing (such as resiliency) is out of
scope of the L1VPN Basic Mode.
5.3. Connectivity Restriction
The L1VPN Basic Mode allows restricting connection establishment
between CEs belonging to the same L1VPN for policy reasons (including
L1VPN security). Since the PIT at each PE is associated with a
L1VPN, this function can be easily supported. The restriction can be
applied at the ingress PE or at the egress PE according to the
applicable restriction policy, but note that applying the policy at
the egress may waste signaling effort within the network as L1VPN
connections are pointlessly attempted.
In addition, the L1VPN Basic Mode does not restrict use of any
advanced admission control based on various policies.
6. Customer Control of Its L1VPN
6.1. Topology Control
In the L1VPN Basic Mode, L1VPN connection topology is controlled by
the customer. That is, a customer can request
setup/deletion/modification of L1VPN connections using signaling
mechanisms specified in [RFC5251].
Takeda Informational [Page 8]
RFC 5253 AS for L1VPN Basic Mode July 2008
Also note that if there are multiple CE-to-PE TE links (single-homed
or multi-homed), a customer can specify which CE-to-PE TE link to use
to support any L1VPN connection. Alternatively, a customer may let
the provider choose the CE-to-PE TE link at the egress side, as
described in Section 5.2.3.
6.2. Note on Routing
A CE needs to obtain the remote CPI to which it wishes to request a
connection. Since, in the L1VPN Basic Mode, there is no routing
information exchange between a CE and a PE, there is no dynamic
mechanism supported as part of the Basic Mode L1VPN service, and the
knowledge of remote CPIs must be acquired in a L1VPN-specific way,
perhaps through configuration or through a directory server.
If an L1VPN is used by a customer to operate a private IP network,
the customer may wish to form routing adjacencies over the CE-to-CE
L1VPN connections. The L1VPN Basic Mode does not enforce any
restriction on such operation by a customer, and the use made of the
L1VPN connections is transparent to the provider network.
Furthermore, if an L1VPN is used by a customer to operate a private
Multiprotocol Label Switching (MPLS) or GMPLS network, the customer
may wish to treat a L1VPN connection as a TE link, and this requires
a CE-to-CE control channel. Note that a Forwarding Adjacency
[RFC4206] cannot be formed from the CE-to-CE L1VPN connection in the
Basic Mode because there is no routing exchange between CE and PE.
That is, the customer network and the provider network do not share a
routing instance, and the customer control channel cannot be carried
within the provider control plane. But where the CE provides
suitable adaptation (for example, where the customer network is a
packet- switched MPLS or GMPLS network), the customer control channel
may be in-band and a routing adjacency may be formed between the CEs
using the L1VPN connection. Otherwise, CE-to-CE control plane
connectivity may form part of the L1VPN service provided to the
customer by the provider and may be achieved within the L1VPN
connection (for example, through the use of overhead bytes) or
through a dedicated control channel connection or tunnel. The
options available are discussed further in Section 10.2 of [RFC4847].
Takeda Informational [Page 9]
RFC 5253 AS for L1VPN Basic Mode July 2008
7. Scalability and Resiliency
7.1. Scalability
There are several factors that impact scalability.
o Number of L1VPNs (PITs) configured on each PE
With the increase of this number, information to be maintained on
the PE increases. Theoretically, the upper limit of the number of
L1VPNs supported in a provider network is governed by how the ID
associated with a L1VPN is allocated, and the number of PITs
configured on each PE is limited by this number. However,
implementations may impose arbitrary limits on the number of PITs
supported by any one PE.
o Number of CE-to-PE TE links for each L1VPN
With the increase of this number, information to be maintained in
each PIT increases. When auto-discovery mechanisms are used, the
amount of information that an auto-discovery mechanism can support
may restrict this number.
Note that [RFC5252] floods membership information not only among
PEs, but also to all P nodes. This may lead to scalability
concerns, compared to [RFC5195], which distributes membership
information only among PEs. Alternatively, a separate instance of
the OSPF protocol can be used just between PEs for distributing
membership information. In such a case, Ps do not participate in
flooding.
Note that in the L1VPN Basic Mode, a PE needs to obtain only CE-
to-PE TE link information, and not customer routing information,
which is quite different from the mode of operation of an L3VPN.
Therefore, the scalability concern is considered to be less
problematic.
o Number of L1VPN connections
With the increase of this number, information to be maintained on
each PE/P increases. When stitching or nesting is used, the state
to be maintained at each PE increases compared to when connectivity
is achieved without stitching or nesting.
However, in a Layer 1 core, this number is always bounded by the
available physical resource because each LSP uses a separate label
which is directly bound to a physical, switchable resource
Takeda Informational [Page 10]
RFC 5253 AS for L1VPN Basic Mode July 2008
(timeslot, lambda, or fiber). Thus, it can be safely assumed that
the PEs/Ps can comfortably handle the number of LSPs that they may
be called on to switch for a L1VPN.
7.2. Data Plane Resiliency
The L1VPN Basic Mode supports the following data plane recovery
techniques [RFC5251].
o PE-to-PE segment recovery
The CE indicates to protect the PE-to-PE segment by including
Protection Object specified in [RFC4873] in the Path message and
setting Segment Recovery Flags. The CE may also indicate the
branch and merge nodes by including a Secondary Explicit Route
Object.
Depending on the signaling mechanisms used within the provider
network, details on how to protect the PE-to-PE segment may differ
as follows.
- If LSP stitching or LSP hierarchy are used to provision the PE-
to-PE segment, then the PE-to-PE LSP may be protected using end-
to-end recovery within the provider network.
- If the CE-to-CE L1VPN connection is a single end-to-end LSP
(including if session shuffling is used), then the PE-to-PE LSP
segment may be protected using segment protection [RFC4873].
o CE-to-PE recovery and PE-to-PE recovery via link protection
The CE indicates to protect ingress and egress CE-to-PE links as
well as links within the provider network by including the
Protection Object specified in [RFC3473] and setting Link Flags in
the Path message.
- The ingress and egress CE-to-PE link may be protected at a lower
layer.
Depending on the signaling mechanisms used within the provider
network, details on how to protect links within the provider
network may differ as follows.
- If the PE-to-PE segment is provided as a single TE link
(stitching or hierarchy) so that the provider network can perform
simple PE-to-PE routing, then the TE link may offer link-level
protection through the instantiation of multiple PE-to-PE LSPs.
Takeda Informational [Page 11]
RFC 5253 AS for L1VPN Basic Mode July 2008
- The PE-to-PE segment may be provisioned using only link-protected
links within the core network.
Note that it is not possible to protect only the CE-to-PE portion or
the PE-to-PE portion by link protection because the CE-to-CE
signaling request asks for a certain level of link protection on all
links used by the LSP. Also, it is not possible to protect the CE-
to-PE portion by link recovery and the PE-to-PE portion by segment
recovery at the same time.
CE-to-CE recovery through the use of connections from one CE to
diverse PEs (i.e., dual-homing) is not supported in the L1VPN Basic
Mode.
7.3. Control Plane Resiliency
The L1VPN Basic Mode allows use of GMPLS control plane resiliency
mechanisms. This includes, but is not limited to, control channel
management in LMP [RFC4204] and fault handling in RSVP-TE ([RFC3473]
and [RFC5063]) between a CE and a PE, as well as within the provider
network.
8. Security Considerations
Security considerations are described in [RFC4847], and this section
describes how these considerations are addressed in the L1VPN Basic
Mode.
Additional discussion of GMPLS security can be found in [GMPLS-SEC].
8.1. Topology Confidentiality
As specified in [RFC5251], a provider's topology confidentiality is
preserved by the Basic Mode. Since there is no routing exchange
between PE and CE, the customer network can gather no information
about the provider network. Further, as described in Section 4 of
[RFC4208], a PE may filter the information present in a Record Route
Object (RRO) that is signaled from the provider network to the
customer network. In addition, as described in Section 5 of
[RFC4208] and Section 4.4 of [RFC5251], when a Notify message is sent
to a CE, it is possible to hide the provider internal address. This
is accomplished by a PE updating the Notify Node Address with its own
address when the PE receives a NOTIFY_REQUEST object from the CE.
Even in the case of pre-computed and/or pre-signaled PE-to-PE
segments, provider topology confidentiality may be preserved through
the use of path key IDs [CONF-SEG].
Takeda Informational [Page 12]
RFC 5253 AS for L1VPN Basic Mode July 2008
The customer's topology confidentiality cannot be completely hidden
from the provider network. At the least, the provider network will
know about the addresses and locations of CEs. Other customer
topology information will remain hidden from the provider in the
Basic Mode, although care may be needed to protect the customer
control channel as described in Section 8.4.
The provider network is responsible for maintaining confidentiality
of topology information between customers and across L1VPNs. Since
there is no distribution of routing information from PE to CE in the
Basic Mode, there is no mechanism by which the provider could
accidentally, or deliberately but automatically, distribute this
information.
8.2. External Control of the Provider Network
The provider network is protected from direct control from within
customer networks through policy and through filtering of signaling
messages.
There is a service-based policy installed at each PE that directs how
a PE should react to a L1VPN connection request received from any CE.
Each CE is configured at the PE (or through a policy server) for its
membership of a L1VPN, and so CEs cannot dynamically bind to a PE or
join a L1VPN. With this configuration comes the policy that tells
the PE how to react to a L1VPN connection request (for example,
whether to allow dynamic establishment of PE-to-PE connections).
Thus, the provider network is protected against spurious L1VPN
connection requests and can charge for all L1VPN connections
according to the service agreement with the customers. Hence, the
provider network is substantially protected against denial-of-service
(DoS) attacks.
At the same time, if a Path message from a CE contains an Explicit
Route Object (ERO) specifying the route within provider network, it
is rejected by the PE. Thus, the customer network has no control
over the resources in the provider network.
8.3. Data Plane Security
As described in [RFC4847], at Layer 1, data plane information is
normally assumed to be secure once connections are established since
the optical signals themselves are normally considered to be hard to
intercept or modify, and it is considered difficult to insert data
into an optical stream. The very use of an optical signal may be
considered to provide confidentiality and integrity to the payload
data. Furthermore, as indicated in [RFC4847], L1VPN connections are
Takeda Informational [Page 13]
RFC 5253 AS for L1VPN Basic Mode July 2008
each dedicated to a specific L1VPN by which an additional element of
security for the payload data is provided.
Misconnection remains a security vulnerability for user data. If a
L1VPN connection were to be misconnected to the wrong destination,
user data would be delivered to the wrong consumers. In order to
protect against mis-delivery, each L1VPN connection is restricted to
use only within a single L1VPN. That is, a L1VPN connection does not
connect CEs that are in different L1VPNs. In order to realize this,
the identity of CEs is assured as part of the service contract. And
upon receipt of a request for connection setup, the provider network
assures that the connection is requested between CEs belonging to the
same L1VPN. This is achieved as described in Section 5.3.
Furthermore, users with greater sensitivity to the security of their
payload data should apply appropriate security measures within their
own network layer. For example, a customer exchanging IP traffic
over a L1VPN connection may choose to use IPsec to secure that
traffic (i.e., to operate IPsec on the CE-to-CE exchange of IP
traffic).
8.4 Control Plane Security
There are two aspects for control plane security.
First, the entity connected over a CE-to-PE control channel must be
identified. This is done when a new CE is added as part of the
service contract and the necessary control channel is established.
This identification can use authentication procedures available in
RSVP-TE [RFC3209]. That is, control plane entities are identified
within the core protocols used for signaling, but are not
authenticated unless the authentication procedures of [RFC3209] are
used.
Second, it must be possible to secure communication over a CE-to-PE
control channel. If a communication channel between the customer and
the provider (control channel, management interface) is physically
separate per customer, the communication channel could be considered
as secure. However, when the communication channel is physically
shared among customers, security mechanisms need to be available and
should be enforced. RSVP-TE [RFC3209] provides for tamper-protection
of signaling message exchanges through the optional Integrity object.
IPsec tunnels can be used to carry the control plane messages to
further ensure the integrity of the signaling messages.
Note that even in the case of physically separate communication
channels, customers may wish to apply security mechanisms, such as
Takeda Informational [Page 14]
RFC 5253 AS for L1VPN Basic Mode July 2008
IPsec, to assure higher security, and such mechanisms must be
available.
Furthermore, the provider network needs mechanisms to detect DoS
attacks and to protect against them reactively and proactively. In
the Basic Mode, this relies on management systems. For example,
management systems collect and analyze statistics on signaling
requests from CEs, and protect against malicious behaviors where
necessary.
Lastly, it should be noted that customer control plane traffic
carried over the provider network between CEs needs to be protected.
Such protection is normally the responsibility of the customer
network and can use the security mechanisms of the customer signaling
and routing protocols (for example, RSVP-TE [RFC3209]) or may use
IPsec tunnels between CEs. CE-to-CE control plane security may form
part of the data plane protection where the control plane traffic is
carried in-band in the L1VPN connection. Where the CE-to-CE control
plane connectivity is provided as an explicit part of the L1VPN
service by the provider, control plane security should form part of
the service agreement between the provider and customer.
9. Manageability Considerations
Manageability considerations are described in [RFC4847]. In the
L1VPN Basic Mode, we rely on management systems for various aspects
of the different service functions, such as fault management,
configuration and policy management, accounting management,
performance management, and security management (as described in
Section 8).
In order to support various management functionalities, MIB modules
need to be supported. In particular, the GMPLS TE MIB (GMPLS-TE-STD-
MIB) [RFC4802] can be used for GMPLS-based traffic engineering
configuration and management, while the TE Link MIB (TE-LINK-STD-MIB)
[RFC4220] can be used for configuration and management of TE links.
10. References
10.1. Normative References
[RFC3031] Rosen, E., Viswanathan, A. and R. Callon, "Multiprotocol
label switching Architecture", RFC 3031, January 2001.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,
V., and G. Swallow, "RSVP-TE: Extensions to RSVP for
LSP Tunnels", RFC 3209, December 2001.
Takeda Informational [Page 15]
RFC 5253 AS for L1VPN Basic Mode July 2008
[RFC3471] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description", RFC
3471, January 2003.
[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling - Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC
3473, January 2003.
[RFC4026] Anderssion, L. and Madsen, T., "Provider Provisioned
Virtual Private Network (VPN) Terminology", RFC 4026,
March 2005.
[RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing
Extensions in Support of Generalized Multi-Protocol
Label Switching (GMPLS)", RFC 4202, October 2005.
[RFC4208] Swallow, G., Drake, J., Ishimatsu, H., and Y. Rekhter,
"Generalized Multiprotocol Label Switching (GMPLS)
User-Network Interface (UNI): Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Support for the
Overlay Model", RFC 4208, October 2005.
[RFC4847] Takeda, T., Ed., "Framework and Requirements for Layer 1
Virtual Private Networks", RFC 4847, April 2007.
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A.
Farrel, "GMPLS Segment Recovery", RFC 4873, May 2007.
[RFC5195] Ould-Brahim, H., Fedyk, D., and Y. Rekhter, "BGP-Based
Auto-Discovery for Layer-1 VPNs", RFC 5195, June 2008.
[RFC5251] Fedyk, D., Ed., Rekhter, Y., Ed., Papadimitriou, D.,
Rabbat, R., and L. Berger, "Layer 1 VPN Basic Mode", RFC
5251, July 2008.
[RFC5252] Bryskin, I. and Berger, L., "OSPF-Based Layer 1 VPN Auto-
Discovery", RFC 5252, July 2008.
10.2. Informative References
[RFC4204] Lang, J., Ed., "Link Management Protocol (LMP)", RFC
4204, October 2005.
[RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP)
Hierarchy with Generalized Multi-Protocol Label
Switching (GMPLS) Traffic Engineering (TE)", RFC 4206,
October 2005.
Takeda Informational [Page 16]
RFC 5253 AS for L1VPN Basic Mode July 2008
[RFC4220] Dubuc, M., Nadeau, T., and J. Lang, "Traffic Engineering
Link Management Information Base", RFC 4220, November
2005.
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
August 2006.
[RFC4802] Nadeau, T., Ed., and A. Farrel, Ed., "Generalized
Multiprotocol Label Switching (GMPLS) Traffic
Engineering Management Information Base", RFC 4802,
February 2007.
[RFC5063] Satyanarayana, A., Ed., and R. Rahman, Ed., "Extensions
to GMPLS Resource Reservation Protocol (RSVP) Graceful
Restart", RFC 5063, October 2007.
[BGP-TE] Ould-Brahim, H., Fedyk, D., and Y. Rekhter, "Traffic
Engineering Attribute", Work in Progress, January 2008.
[CONF-SEG] Bradford, R., Ed., Vasseur, JP., and A. Farrel,
"Preserving Topology Confidentiality in Inter-Domain
Path Computation Using a Key-Based Mechanism", Work in
Progress, May 2008.
[GMPLS-SEC] Fang, L., Ed., " Security Framework for MPLS and GMPLS
Networks", Work in Progress, February 2008.
11. Acknowledgments
The authors would like to thank Ichiro Inoue for valuable comments.
In addition, the authors would like to thank Marco Carugi and Takumi
Ohba for valuable comments in the early development of this document.
Thanks to Tim Polk and Mark Townsley for comments during IESG review.
Takeda Informational [Page 17]
RFC 5253 AS for L1VPN Basic Mode July 2008
Authors' Addresses
Tomonori Takeda (editor)
NTT Network Service Systems Laboratories, NTT Corporation
3-9-11, Midori-Cho
Musashino-Shi, Tokyo 180-8585 Japan
Phone: +81 422 59 7434
EMail: takeda.tomonori@lab.ntt.co.jp
Deborah Brungard
AT&T
Rm. D1-3C22 - 200 S. Laurel Ave.
Middletown, NJ 07748, USA
Phone: +1 732 4201573
EMail: dbrungard@att.com
Adrian Farrel
Old Dog Consulting
Phone: +44 (0) 1978 860944
EMail: adrian@olddog.co.uk
Hamid Ould-Brahim
Nortel Networks
P O Box 3511 Station C
Ottawa, ON K1Y 4H7 Canada
Phone: +1 (613) 765 3418
EMail: hbrahim@nortel.com
Dimitri Papadimitriou
Alcatel-Lucent
Francis Wellensplein 1,
B-2018 Antwerpen, Belgium
Phone: +32 3 2408491
EMail: dimitri.papadimitriou@alcatel-lucent.be
Takeda Informational [Page 18]
RFC 5253 AS for L1VPN Basic Mode July 2008
Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Takeda Informational [Page 19]