draft-ietf-mpls-tp-mip-mep-map-07.txt   rfc7054.txt 
Network Working Group A. Farrel Internet Engineering Task Force (IETF) A. Farrel
Internet-Draft Juniper Networks Request for Comments: 7054 Juniper Networks
Intended status: Informational H. Endo Category: Informational H. Endo
Expires: October 24, 2013 Hitachi, Ltd. ISSN: 2070-1721 Hitachi, Ltd.
R. Winter R. Winter
NEC NEC
Y. Koike Y. Koike
NTT NTT
M. Paul M. Paul
Deutsche Telekom Deutsche Telekom
April 22, 2013 November 2013
Per-Interface MIP Addressing Requirements and Design Considerations Addressing Requirements and Design Considerations for
draft-ietf-mpls-tp-mip-mep-map-07 Per-Interface Maintenance Entity Group Intermediate Points (MIPs)
Abstract Abstract
The Framework for Operations, Administration and Maintenance (OAM) The framework for Operations, Administration and Maintenance (OAM)
within the MPLS Transport Profile (MPLS-TP) describes how Maintenance within the MPLS Transport Profile (MPLS-TP) describes how the
Entity Group Intermediate Points (MIPs) may be situated within Maintenance Entity Group Intermediate Points (MIPs) may be situated
network nodes at the incoming and outgoing interfaces. within network nodes at incoming and outgoing interfaces.
This document elaborates on important considerations for internal MIP This document elaborates on important considerations for internal MIP
addressing. More precisely it describes important restrictions for addressing. More precisely, it describes important restrictions for
any mechanism that specifies a way of forming OAM messages so that any mechanism that specifies a way of forming OAM messages so that
they can be targeted at MIPs on incoming or MIPs on outgoing they can be targeted at MIPs on either incoming or outgoing
interfaces and forwarded correctly through the forwarding engine. interfaces and forwarded correctly through the forwarding engine.
Furthermore, the document includes considerations for node Furthermore, the document includes considerations for node
implementations where there is no distinction between the incoming implementations where there is no distinction between the incoming
and outgoing MIP. and outgoing MIP.
Status of this Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document is not an Internet Standards Track specification; it is
Task Force (IETF). Note that other groups may also distribute published for informational purposes.
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
This Internet-Draft will expire on October 24, 2013. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7054.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................2
2. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Terminology .....................................................3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Summary of the Problem Statement ................................3
4. Summary of the Problem Statement . . . . . . . . . . . . . . . 4 4. Requirements and Design Considerations for Internal-MIP
5. Requirements and Design Considerations for Internal-MIP Addressing ......................................................6
Adressing . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations ........................................10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 6. Acknowledgments ................................................10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 7. References .....................................................10
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Normative References ......................................10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7.2. Informative References ....................................11
9.1. Normative References . . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
The Framework for Operations, Administration and Maintenance (OAM) The framework for Operations, Administration and Maintenance (OAM)
within the MPLS Transport Profile (MPLS-TP)(the MPLS-TP OAM within the MPLS Transport Profile (MPLS-TP)(the MPLS-TP OAM
Framework, [RFC6371]) distinguishes two configurations for Framework, [RFC6371]) distinguishes two configurations for the
Maintenance Entity Group Intermediate Points (MIPs) on a node. It Maintenance Entity Group Intermediate Points (MIPs) on a node. It
defines per-node MIPs and per-interface MIPs, where a per-node MIP is defines per-node MIPs and per-interface MIPs, where a per-node MIP is
a single MIP per node in an unspecified location within the node and a single MIP per node in an unspecified location within the node and
per-interface MIPs are two (or more) MIPs per node on each side of per-interface MIPs are two (or more) MIPs per node on each side of
the forwarding engine. the forwarding engine.
In-band OAM messages are sent using the Generic Associated Channel In-band OAM messages are sent using the Generic Associated Channel
(G-ACh) [RFC5586]. OAM messages for the transit points of (G-ACh) [RFC5586]. OAM messages for the transit points of
pseudowires (PWs) or Label Switched Paths (LSPs) are delivered using pseudowires (PWs) or Label Switched Paths (LSPs) are delivered using
the expiration of the MPLS shim header time-to-live (TTL) field. OAM the expiration of the MPLS shim header Time-to-Live (TTL) field. OAM
messages for the end points of PWs and LSPs are simply delivered as messages for the end points of PWs and LSPs are simply delivered as
normal. normal.
OAM messages delivered to end points or transit points are OAM messages delivered to end points or transit points are
distinguished from other (data) packets so that they can be processed distinguished from other (data) packets so that they can be processed
as OAM. In LSPs, the mechanism used is the presence of the Generic as OAM. In LSPs, the mechanism used is the presence of the Generic
Associated Channel Label (GAL) in the Label Stack Entry (LSE) under Associated Channel Label (GAL) in the Label Stack Entry (LSE) under
the top LSE [RFC5586]. In PWs, the mechanism used is the presence of the top LSE [RFC5586]. In PWs, the mechanism used is the presence of
the PW Associated Channel Header (PWACH) [RFC4385] or the presence of the PW Associated Channel Header (PWACH) [RFC4385] or the presence of
a GAL [RFC6423]. a GAL [RFC6423].
In case multiple MIPs are present on a single node, these mechanisms If multiple MIPs are present on a single node, these mechanisms alone
alone provide no way to address one particular MIP out of the set of provide no way to address one particular MIP out of the set of MIPs.
MIPs. A mechanism that addresses this shortcoming has to obey a few A mechanism that addresses this shortcoming has to obey a few
important design considerations which are discussed in this document. important design considerations, which are discussed in this
document.
Note that the acronym "OAM" is used in conformance with [RFC6291].
2. Requirements notation
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. Terminology 2. Terminology
In this document we use the term in-MIP (incoming MIP) to refer to In this document, we use the term in-MIP (incoming MIP) to refer to
the MIP which processes OAM messages before they pass through the the MIP that processes OAM messages before they pass through the
forwarding engine of a node. An out-MIP (outgoing MIP) processes OAM forwarding engine of a node. An out-MIP (outgoing MIP) processes OAM
messages after they have passed the forwarding engine of the node. messages after they have passed the forwarding engine of the node.
The two together are referred to as internal MIPs. The two together are referred to as internal MIPs. The term
"forwarding engine" is used as defined in [RFC6371].
4. Summary of the Problem Statement Note that the acronym "OAM" is used in conformance with [RFC6291].
3. Summary of the Problem Statement
Figure 1 shows an abstract functional representation of an MPLS-TP Figure 1 shows an abstract functional representation of an MPLS-TP
node. It is decomposed as an incoming interface, a forwarding engine node. It is decomposed as an incoming interface (labeled "In"), a
(FW), and an outgoing interface. As per the discussion in [RFC6371], forwarding engine (FW), and an outgoing interface (labeled "Out").
MIPs may be placed in each of the functional interface components. As per the discussion in [RFC6371], MIPs may be placed in each of the
functional interface components.
------------------------ ------------------------
|----- -----| |----- -----|
| MIP | | MIP | | MIP | | MIP |
| | ---- | | | | ---- | |
----->-| In |->-| FW |->-| Out |->---- ----->-| In |->-| FW |->-| Out |->----
| i/f | ---- | i/f | | i/f | ---- | i/f |
|----- -----| |----- -----|
------------------------ ------------------------
Figure 1: Abstract Functional Representation of an MPLS-TP Node Figure 1: Abstract Functional Representation of an MPLS-TP Node
Several distinct OAM functions are required within this architectural Several distinct OAM functions are required within this architectural
model for both PWs and LSPs such as: model for both PWs and LSPs, such as:
o Connectivity Verification (CV) between a Maintenance Entity Group
End Point (MEP) and a MIP
o Connectivity Verification (CV) between a MEP and a MIP
o traceroute over an MPLS-TP LSP and/or an MPLS-TP PW containing o traceroute over an MPLS-TP LSP and/or an MPLS-TP PW containing
MIPs MIPs
o data-plane loopback configuration at a MIP o data-plane loopback configuration at a MIP
o diagnostic tests o diagnostic tests
The MIPs in these OAM functions may equally be the MIPs at the The MIPs in these OAM functions may also be the MIPs at the incoming
incoming or outgoing interfaces. or outgoing interfaces.
Per-interface MIPs have the advantage that they enable a more Per-interface MIPs have the advantage that they enable a more
accurate localization and identification of faults and diagnostic accurate localization and identification of faults and diagnostic
tests. In particular, the identification of whether a problem is tests. In particular, the identification of whether a problem is
located between nodes or on a particular node and where on that node located between nodes or on a particular node and where on that node
is greatly enhanced. For obvious reasons, it is important to narrow is greatly enhanced. For obvious reasons, it is important to narrow
the cause of a fault down quickly to initiate a timely, and well- down the cause of a fault quickly to initiate a timely and well-
directed maintenance action to resume normal network operation. directed maintenance action to resume normal network operation.
The following two figures illustrate the fundamental difference of The following two figures illustrate the fundamental difference
using per-node and per-interface MEPs and MIPs for OAM. Figure 2 between using per-node and per-interface MEPs and MIPs for OAM.
depicts OAM using per-node MIPs and MEPs. For reasons of exposition Figure 2 depicts OAM using per-node MIPs and MEPs. For reasons of
we pick a location for the MIPs on the nodes but the standard does exposition, we pick a location for the MIPs on the nodes but the
not mandate the exact location for the per-node model. Figure 3 on standard does not mandate the exact location for the per-node model.
the other hand shows the same basic network but for OAM operations In the figure, a bidirectional LSP is depicted where in the forward
per-interface maintenance points are configured. Note that these (FWD) direction MEP1, MIP1, and MEP2 are located on the ingress
figures are merely examples. It is important to note that per- interface. In the backward (BWD) direction MEP1', MIP1' and MEP2'
interface MEPs or per-interface MIPs MUST logically be placed at a are located on the egress interface, i.e., the same interfaces. S1
point before (for in-MIP) or after (for out-MIP) passing the in the figure denotes the segment from PE1 In to P1 In and S2 denotes
forwarding engine as defined in [RFC6371]. It MUST be assured that the segment from PE1 In to P2 In. Figure 3, on the other hand, shows
all traffic for which the MEP/MIP is associated with must pass the same basic network, but per-interface maintenance points are
through or be terminated at that point. configured for OAM operations. Note that these figures are merely
examples. It is important to note that per-interface MEPs or per-
interface MIPs must logically be placed at a point before (for
in-MIP) or after (for out-MIP) passing the forwarding engine as
defined in [RFC6371]. All traffic associated with the MEP/MIP must
pass through or be terminated at that point.
Customer| Operator's administrative | Customer Customer| Operator's Administrative | Customer
Domain | Domain | Domain Domain | Domain | Domain
------> |<--------------------------------------->| <------ ------> |<--------------------------------------->| <------
CE1 | T-PE/PE1 S-PE/P1 T-PE/PE2 | CE2 CE1 | T-PE/PE1 S-PE/P1 T-PE/PE2 | CE2
| <--------> <--------> <--------> | | <--------> <--------> <--------> |
+---+ | +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ | +---+ +---+ | +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ | +---+
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
+---+ | +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ | +---+ +---+ | +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ | +---+
| In FW Out In FW Out In FW Out | | In FW Out In FW Out In FW Out |
| | | |
FWD PW/LSP | o-------------------------- > | FWD PW/LSP | o-------------------------- > |
| V-------------*-------------V | | V-------------*-------------V |
| MEP1 MIP1 MEP2 | | MEP1 MIP1 MEP2 |
BWD PW/LSP | <---------------------------o | BWD PW/LSP | <---------------------------o |
| V-------------*-------------V | | V-------------*-------------V |
| MEP1' MIP1' MEP2'| | MEP1' MIP1' MEP2'|
(S1)<============> (S1)<============>
(S2)<==========================> (S2)<==========================>
Figure 2: Example of OAM relying on per-node MIPs and MEPs Figure 2: Example of OAM Relying on Per-Node MIPs and MEPs
To illustrate the difference between these two modes of operation, we To illustrate the difference between these two modes of operation, we
use fault detection as an example. Consider the case where the use fault detection as an example. Consider the case where the
client traffic between CE1 and CE2 experiences a fault. Also assume client traffic between CE1 and CE2 experiences a fault. Also assume
that an on-demand CV test between PE1 and PE2 was successful. The that an on-demand CV test between PE1 and PE2 was successful. The
scenario in Figure 2 therefore leaves the forwarding engine (FW) of scenario in Figure 2 therefore leaves the forwarding engine (FW) of
PE2, the out-going interface of PE2, the transmission line between PE2, the out-going interface of PE2, the transmission line between
PE2 and CE2 or CE2 itself as a potential location of the fault as on- PE2 and CE2, or CE2 itself as a potential location of the fault as
demand CV can only be performed on segment S2. on-demand CV can only be performed on segment S2. Note that in this
scenario, the PWs or LSPs are to be understood as two examples (not
one), i.e., the figures do not show the layer structure of PWs and
LSPs.
The per-interface model in Figure 3 allows more fine-grained OAM The per-interface model in Figure 3 allows more fine-grained OAM
operations to be performed. At first, CV on segment S'4 and in operations to be performed. At first, CV on segment S'4 and in
addition CV on segment S'5 can help to rule out e.g. the forwarding addition CV on segment S'5 can help to rule out, for example, the
engine of PE2. This is of course only a single example, and other forwarding engine of PE2. This is of course only a single example,
OAM functions and scenarios are trivially conceivable. The basic and other OAM functions and scenarios are trivially conceivable. The
message is that with the per-interface OAM model, an operator can basic message is that with the per-interface OAM model, an operator
configure smaller segments on a transport path to which OAM can configure smaller segments on a transport path to which OAM
operations apply. This enables a more fine-grained scoping of OAM operations apply. This enables a more fine-grained scoping of OAM
operations such as fault localization and performance monitoring operations, such as fault localization and performance monitoring,
which gives operators better information to deal with adverse which gives operators better information to deal with adverse
networking conditions. networking conditions.
Customer Operator's administrative Customer Customer| Operator's Administrative |Customer
Domain Domain Domain Domain | Domain |Domain
------->|<--------------------------------------->|<------ ------->|<--------------------------------------->|<------
CE1 | T-PE/PE1 S-PE/P1 T-PE/PE2 | CE2 CE1 | T-PE/PE1 S-PE/P1 T-PE/PE2 | CE2
| <--------> <--------> <--------> | | <--------> <--------> <--------> |
+---+ | +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ | +---+ +---+ | +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ | +---+
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
+---+ | +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ | +---+ +---+ | +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ | +---+
| In FW Out In FW Out In FW Out | | In FW Out In FW Out In FW Out |
| | | |
FWD PW/LSP | o-----------------------------------> | FWD PW/LSP | o-----------------------------------> |
| V-------*------*------*-----*-------V | | V-------*------*------*-----*-------V |
| MEP1 MIP1 MIP2 MIP3 MIP4 MEP2| | MEP1 MIP1 MIP2 MIP3 MIP4 MEP2|
| | | |
BWD PW/LSP | <-----------------------------------o | BWD PW/LSP | <-----------------------------------o |
| MEP1' MIP1' MIP2' MIP3' MIP4' MEP2'| | MEP1' MIP1' MIP2' MIP3' MIP4' MEP2'|
(S'1)<======> (S'1)<======>
(S'2)<=============> (S'2)<=============>
(S'3)<====================> (S'3)<====================>
(S'4)<==========================> (S'4)<==========================>
(S'5)<==================================> (S'5)<==================================>
Figure 3: Example of OAM relying on per-interface MIPs and MEPs Figure 3: Example of OAM Relying on Per-Interface MIPs and MEPs
5. Requirements and Design Considerations for Internal-MIP Adressing 4. Requirements and Design Considerations for Internal-MIP Addressing
OAM messages for transit points of PWs or LSPs are delivered using OAM messages for transit points of PWs or LSPs are delivered using
the expiration of the time-to-live (TTL) field in the top LSE of the the expiration of the TTL field in the top LSE of the MPLS packet
MPLS packet header. OAM messages for the end points of PWs and LSPs header. OAM messages for the end points of PWs and LSPs are simply
are simply delivered as normal. These messages are distinguished delivered as normal. These messages are distinguished from other
from other (data) packets so that they can be processed as OAM. In (data) packets so that they can be processed as OAM. In LSPs, the
LSPs, the mechanism used is the presence of the Generic Associated mechanism used is the presence of the GAL in the LSE under the top
Channel Label (GAL) in the LSE under the top LSE [RFC5586]. In PWs, LSE [RFC5586]. In PWs, the mechanism used is the presence of the PW
the mechanism used is the presence of the PW Associated Channel Associated Channel Header [RFC4385] or the presence of a GAL
Header [RFC4385] or the presence of a GAL [RFC6423]. In addition, [RFC6423]. In addition, two sets of identifiers exist that can be
two sets of identifiers exist that can be used to address MIPs which used to address MIPs, which are defined in [RFC6370] and [RFC6923]
are defined in [RFC6370] and [I-D.ietf-mpls-tp-itu-t-identifiers]
Any solution for sending OAM messages to the in and out-MIPs must fit Any solution for sending OAM messages to the in- and out-MIPs must
within these existing models of handling OAM. fit within these existing models of handling OAM.
Additionally, many MPLS-TP nodes are implemented in a way that all Additionally, many MPLS-TP nodes are implemented in a way that all
queuing and the forwarding function is performed at the incoming queuing and the forwarding function are performed at the incoming
interface. The abstract functional representation of such a node is interface. The abstract functional representation of such a node is
shown in Figure 4. As shown in the figure, the outgoing interfaces shown in Figure 4. As shown in the figure, the outgoing interfaces
are minimal and for this reason it may not be possible to include MIP are minimal and for this reason it may not be possible to include
functions on those interfaces. This is in particular the case for MIP functions on those interfaces. This is the case for existing
existing deployed implementations. deployed implementations in particular.
Any solution that attempts to send OAM messages to the outgoing Any solution that attempts to send OAM messages to the outgoing
interface of an MPLS-TP node must not cause any problems when such interface of an MPLS-TP node must not cause any problems when such
implementations are present (such as leaking OAM packets with a TTL implementations are present (such as leaking OAM packets with a TTL
of 0). of 0).
---------------------
|------------ |
| MIP | |
| ---- | |
----->-| In | FW | |-->-Out-|->---
| i/f ---- | i/f |
|------------ |
---------------------
------------------ Figure 4: Abstract Functional Representation of
|------------ | Some Existing MPLS-TP Nodes
| MIP | |
| ---- | |
----->-| In | FW | |-->--|->---
| i/f ---- | |
|------------ |
------------------
Figure 4: Abstract Functional Representation of Some Existing MPLS-TP
Nodes
OAM must operate on MPLS-TP nodes that are branch points on point-to- OAM must operate on MPLS-TP nodes that are branch points on point-to-
multipoint (P2MP) trees. That means that it must be possible to multipoint (P2MP) trees. This means that it must be possible to
target individual outgoing MIPs as well as all outgoing MIPs in the target individual outgoing MIPs as well as all outgoing MIPs in the
abstract functional representation shown in Figure 5, as well as to abstract functional representation shown in Figure 5, and to handle
handle the P2MP node implementations as shown in Figure 6 without the P2MP node implementations as shown in Figure 6 without causing
causing problems. problems.
--------------------------
-------------------------- | -----|
| -----| | | MIP |
| | MIP | | ->-| |->----
| ->-| |->---- | | | Out |
| | | Out | | | | i/f |
| | | i/f | | | -----|
| | -----| |----- | -----|
|----- | -----| | MIP | ---- | | MIP |
| MIP | ---- | | MIP | | | | |- | |
| | | |- | | ----->-| In |->-| FW |--->-| Out |->----
----->-| In |->-| FW |--->-| Out |->---- | i/f | | |- | i/f |
| i/f | | |- | i/f | |----- ---- | -----|
|----- ---- | -----| | | -----|
| | -----| | | | MIP |
| | | MIP | | | | |
| | | | | ->-| Out |->----
| ->-| Out |->---- | | i/f |
| | i/f | | -----|
| -----| --------------------------
--------------------------
Figure 5: Abstract Functional Representation of an MPLS-TP Node
Supporting P2MP
------------------ Figure 5: Abstract Functional Representation of an
| ->-|->---- MPLS-TP Node Supporting P2MP
| | | ----------------------
|------------ | | | ->-Out-|->----
| | | | | | i/f |
| MIP ---- | | | |------------ | |
| | | |- | | | | |
----->-| In | FW | |--->-|->---- | MIP ---- | | |
| i/f | | |- | | | | |- |
| ---- | | | ----->-| In | FW | |--->-Out-|->----
| | | | | i/f | | |- i/f |
|------------ | | | ---- | | |
| | | | | | |
| ->-|->---- |------------ | |
------------------ | | Out |
| ->-i/f-|->----
----------------------
Figure 6: Abstract Functional Representation of Some Existing MPLS-TP Figure 6: Abstract Functional Representation of
Nodes Supporting P2MP Some Existing MPLS-TP Nodes Supporting P2MP
In summary, the solution for OAM message delivery must behave as In summary, the solution for OAM message delivery must behave as
follows: follows:
o Delivery of OAM messages to the correct MPLS-TP node. o Delivery of OAM messages to the correct MPLS-TP node.
o Delivery of OAM instructions to the correct MIP within an MPLS-TP o Delivery of OAM instructions to the correct MIP within an MPLS-TP
node. node.
o Forwarding of OAM packets exactly as data packets. o Forwarding of OAM packets exactly as data packets.
o Packet inspection at the incoming and outgoing interfaces must be o Packet inspection at the incoming and outgoing interfaces must be
minimized. minimized.
The first and second bullet point are obvious. The third bullet The first and second bullet points are obvious. However, the third
point however is also vital. To illustrate the importance, a bullet point is also vital. To illustrate the importance, a rejected
rejected solution is depicted in Figure 7. In the figure, all data solution is depicted in Figure 7. In the figure, all data and non-
and non-local OAM is handled as normal. Local OAM is intercepted at local OAM is handled as normal. Local OAM is intercepted at the
the incoming interface and delivered to the MIP at the incoming incoming interface and delivered to the MIP at the incoming
interface. If the OAM is intended for the incoming MIP it is handled interface. If the OAM is intended for the incoming MIP, it is
there with no issue. If the OAM is intended for the outgoing MIP it handled there with no issue. If the OAM is intended for the outgoing
is forwarded to that MIP using some internal messaging system that is MIP, it is forwarded to that MIP using some internal messaging system
implementation-specific. that is implementation specific.
------------------------ ------------------------
|----- -----| |----- -----|
local OAM ----->-| MIP |----->------| MIP | local OAM ----->-| MIP |----->------| MIP |
| | ---- | | | | ---- | |
data =====>=| In |=>=| FW |=>=| Out |=>==== data data =====>=| In |=>=| FW |=>=| Out |=>==== data
non-local OAM ~~~~~>~| i/f |~>~| |~>~| i/f |~>~~~~ non-local OAM non-local OAM ~~~~~>~| i/f |~>~| |~>~| i/f |~>~~~~ non-local OAM
|----- ---- -----| |----- ---- -----|
------------------------ ------------------------
Figure 7: OAM Control Message Delivery Bypassing the Forwarding Figure 7: OAM Control Message Delivery Bypassing
Engine the Forwarding Engine
This solution is fully functional for the incoming MIP. It also This solution is fully functional for the incoming MIP. It also
supports control of data loopback for the outgoing MIP, and can supports control of data loopback for the outgoing MIP and can
adequately perform some OAM features such as interface identity adequately perform some OAM features such as interface identity
reporting at the outgoing MIP. reporting at the outgoing MIP.
However, because the OAM message is not forwarded through the However, because the OAM message is not forwarded through the
forwarding engine, this solution cannot correctly perform OAM forwarding engine, this solution cannot correctly perform OAM
loopback, connectivity verification, LSP tracing, or performance loopback, connectivity verification, LSP tracing, or performance
measurement. measurement.
The last bullet point is also an important requirement for any The last bullet point is also an important requirement for any
solution to the internal-MIP addressing problem. Since OAM packets solution to the internal-MIP addressing problem. Since OAM packets
that target an out-MIP need to be sent through the forwarding engine that target an out-MIP need to be sent through the forwarding engine
and treated exactly as regular data packets, the determination of and treated exactly as regular data packets, the determination of
whether to forward the packet or process it at the incoming MIP needs whether to forward the packet or process it at the incoming MIP needs
to be fast and therefore the processing overhead must be kept to a to be fast; therefore, the processing overhead must be kept to a
minimum. In addition, there are a few OAM procedures that operate at minimum. In addition, there are a few OAM procedures that operate at
line rate such as OAM loopback. This adds to the requirement of line rate such as OAM loopback. This adds to the requirement of
minimal processing overhead for both the in-MIP and out-MIP. minimal processing overhead for both the in-MIP and out-MIP.
Most of the above superficially appears to be an implementation Most of the above superficially appears to be an implementation
matter local to an individual node, the format of the message needs matter local to an individual node; however, the format of the
to be standardised so that: message needs to be standardized so that:
o A MEP can correctly target the outgoing MIP of a specific MPLS-TP o A MEP can correctly target the outgoing MIP of a specific MPLS-TP
node. node.
o A node can correctly filter out any OAM messages that were o A node can correctly filter out any OAM messages that were
intended for its upstream neighbor's outgoing MIP, but which were intended for its upstream neighbor's outgoing MIP, but which were
not handled there because the upstream neighbor is an not handled there because the upstream neighbor is an
implementation as shown in Figure 4 or Figure 6. implementation as shown in Figures 4 and 6.
Note that the last bullet point describes a safety net and an Note that the last bullet point describes a safety net in case OAM
implementation should avoid that this situation ever arises. messages leak beyond their intended scope, but implementations should
take care that messages do not leak so that the safety net does not
need to be used.
6. Security Considerations 5. Security Considerations
OAM security is discussed in [RFC6371] and security aspects specific OAM security is discussed in [RFC6371] and security aspects specific
to MPLS-TP in general are outlined in to MPLS-TP in general are outlined in [RFC6941].
[I-D.ietf-mpls-tp-security-framework].
OAM can provide useful information for detecting and tracing security OAM can provide useful information for detecting and tracing security
attacks. attacks.
OAM can also be used to illicitly gather information or for denial of OAM can also be used to illicitly gather information or for denial-
service attacks and other types of attack. Implementations therefore of-service attacks and other types of attack. Implementations
are required to offer security mechanisms for OAM. Deployments are therefore are required to offer security mechanisms for OAM.
strongly advised to use such mechanisms. Deployments are therefore strongly advised to follow the security
advice provided in RFCs 6371 and 6941.
Mixing of per-node and per-interface OAM on a single node is not Mixing of per-node and per-interface OAM on a single node is not
advised as OAM message leakage could be the result. advised as OAM message leakage could be the result.
7. IANA Considerations 6. Acknowledgments
This revision of this document does not make any requests of IANA.
8. Acknowledgments
The authors gratefully acknowledge the substantial contributions of The authors gratefully acknowledge the substantial contributions of
Zhenlong Cui. We would also like to thank Eric Gray, Sami Boutros and Zhenlong Cui. We would also like to thank Eric Gray, Sami Boutros,
Shahram Davari for interesting input to this document through and Shahram Davari for interesting input to this document through
discussions. discussions.
9. References 7. References
9.1. Normative References
[I-D.ietf-mpls-tp-itu-t-identifiers]
Winter, R., Gray, E., Helvoort, H., and M. Betts, "MPLS-TP
Identifiers Following ITU-T Conventions",
draft-ietf-mpls-tp-itu-t-identifiers-08 (work in
progress), February 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 7.1. Normative References
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson, [RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson,
"Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for
Use over an MPLS PSN", RFC 4385, February 2006. Use over an MPLS PSN", RFC 4385, February 2006.
[RFC5586] Bocci, M., Vigoureux, M., and S. Bryant, "MPLS Generic [RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
Associated Channel", RFC 5586, June 2009. "MPLS Generic Associated Channel", RFC 5586, June 2009.
[RFC6370] Bocci, M., Swallow, G., and E. Gray, "MPLS Transport [RFC6370] Bocci, M., Swallow, G., and E. Gray, "MPLS Transport
Profile (MPLS-TP) Identifiers", RFC 6370, September 2011. Profile (MPLS-TP) Identifiers", RFC 6370, September 2011.
[RFC6371] Busi, I. and D. Allan, "Operations, Administration, and [RFC6371] Busi, I., Ed., and D. Allan, Ed., "Operations,
Maintenance Framework for MPLS-Based Transport Networks", Administration, and Maintenance Framework for MPLS-Based
RFC 6371, September 2011. Transport Networks", RFC 6371, September 2011.
[RFC6423] Li, H., Martini, L., He, J., and F. Huang, "Using the [RFC6423] Li, H., Martini, L., He, J., and F. Huang, "Using the
Generic Associated Channel Label for Pseudowire in the Generic Associated Channel Label for Pseudowire in the
MPLS Transport Profile (MPLS-TP)", RFC 6423, MPLS Transport Profile (MPLS-TP)", RFC 6423, November
November 2011. 2011.
9.2. Informative References [RFC6923] Winter, R., Gray, E., van Helvoort, H., and M. Betts,
"MPLS Transport Profile (MPLS-TP) Identifiers Following
ITU-T Conventions", RFC 6923, May 2013.
[I-D.ietf-mpls-tp-security-framework] 7.2. Informative References
Fang, L., Niven-Jenkins, B., Mansfield, S., and R.
Graveman, "MPLS-TP Security Framework",
draft-ietf-mpls-tp-security-framework-09 (work in
progress), February 2013.
[RFC6291] Andersson, L., van Helvoort, H., Bonica, R., Romascanu, [RFC6291] Andersson, L., van Helvoort, H., Bonica, R., Romascanu,
D., and S. Mansfield, "Guidelines for the Use of the "OAM" D., and S. Mansfield, "Guidelines for the Use of the "OAM"
Acronym in the IETF", BCP 161, RFC 6291, June 2011. Acronym in the IETF", BCP 161, RFC 6291, June 2011.
[RFC6941] Fang, L., Ed., Niven-Jenkins, B., Ed., Mansfield, S., Ed.,
and R. Graveman, Ed., "MPLS Transport Profile (MPLS-TP)
Security Framework", RFC 6941, April 2013.
Authors' Addresses Authors' Addresses
Adrian Farrel Adrian Farrel
Juniper Networks Juniper Networks
Email: adrian@olddog.co.uk EMail: adrian@olddog.co.uk
Hideki Endo Hideki Endo
Hitachi, Ltd. Hitachi, Ltd.
Email: hideki.endo.es@hitachi.com EMail: hideki.endo.es@hitachi.com
Rolf Winter Rolf Winter
NEC NEC
Email: rolf.winter@neclab.eu EMail: rolf.winter@neclab.eu
Yoshinori Koike Yoshinori Koike
NTT NTT
Email: koike.yoshinori@lab.ntt.co.jp EMail: koike.yoshinori@lab.ntt.co.jp
Manuel Paul Manuel Paul
Deutsche Telekom Deutsche Telekom
Email: Manuel.Paul@telekom.de EMail: Manuel.Paul@telekom.de
 End of changes. 75 change blocks. 
272 lines changed or deleted 268 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/