One document matched: draft-pan-pwe3-protection-02.txt
Differences from draft-pan-pwe3-protection-01.txt
Network Working Group Ping Pan
Internet Draft (Hammerhead Systems)
Expiration Date: July 2006 February 2006
Pseudo Wire Protection
draft-pan-pwe3-protection-02.txt
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Copyright Notice
Copyright (C) The Internet Society (2006).
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Abstract
This document describes a mechanism that helps to protect and recover
user traffic when carried over pseudo-wires. The mechanism requires some
minor modification to the existing pseudo-wire setup procedure, and is
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fully backward compatible.
The proposed mechanism allows the network operators to setup one or
multiple backup pseudo-wires to protect a working pseudo-wire. Upon
network failure, user traffic can be switched over to the next "best"
pseudo-wire base on preference levels.
This document first describes the motivation of the work base on the
discussions with a number of carriers. Then we define the protocol
extension itself.
1. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.
2. Terminology
The reader is assumed to be familiar with the terminology in [LDP],
[PW-CTRL] and [MHOP-PW]. The new terms are the following:
Working Pseudo-wire: A pseudo-wire that carries user traffic,
and may be protected by one or multiple associated backup
pseudo-wires.
Backup Pseudo-wire: A pseudo-wire that is used to re-route user
traffic from a working pseudo-wire at head-end.
3. Introduction
Pseudo-wires have been deployed by a number of networks to carry
customer layer-2 data traffic. Each Layer-2 data flow (or Attachment
Circuit) is mapped to a pseudo-wire. Pseudo-wire setup, maintenance
and packet encapsulation have been extensively described in a number
of IETF PWE3 drafts [PWE3-CTRL, PWE3-TRANSPORT]. Recently, several
carriers have requested that, when offered as a service, pseudo-wires
need to possess the same protection and redundancy capabilities that
have been deployed in transport networks.
In this draft, we extend the LDP pseudo-wire proposal [PWE3-CTRL] to
support protection and restoration operation.
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Why is such work necessary?
When it comes to traffic protection, the carriers need to ensure
traffic protection on every network segment and in every layer of the
network. Just because most of the pseudo-wire traffic will go through
MPLS LSP's, we cannot therefore make the assumption that user traffic
will be protected via MPLS Fast-Reroute [MPLS-FRR] or RSVP path
protection.
Here are some of the deployment scenario where pseudo-wire protection
can be critically important:
3.1. Access Networks
Pseudo-wire has been in deployment for multi-service data access. One
reason is that pseudo-wire enables data aggregation, which in turn
improves bandwidth utilization. In a typical metro network access
location (Hub or CO), the statistical multiplexing gain is
approximately 3-4 [ATT-REPORT]. The earlier user flows get
aggregated, the better bandwidth utilization will be gained by the
carriers, especially at the access locations where bandwidth is still
expensive.
More importantly, pseudo-wire provides a common data transport layer,
where all layer-2 packets can be processed uniformly at provider
edge. This enables the carriers to migrate from the traditional
layer-2 (ATM or Frame Relay) circuits into high-speed Ethernet
without service distraction. A common deployment scenario can be
shown as the following:
+--------+ +------------+
AC's | |====== Ethernet ======| | AC's or PW's
------| Access | | Service |--------------
| Device |====== DS3 ===========| Aggregator |
+--------+ +------------+
Figure-1: Pseudo-wire network access
Note that given the size of access networks, the cost of access
device and access link management are some of the key deployment
considerations, such that the access devices may not be IP routers,
and the extensive IP routing and MPLS signaling (such as RSVP-TE) may
be not applied in this part of the network.
In this part of the network, one method may be to run pseudo-wires
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over the access links, and conduct traffic protection at per-pseudo-
wire level.
3.2. Metro Networks
First of all, many of the MPLS-enabled metro networks today do not
operate with RSVP-TE, which MPLS Fast-Reroute is based on. Secondly,
many of the metro networks have already deployed pseudo-wires in one
form or another (such as VPLS). Thus, pseudo-wire traffic protection
becomes vital.
Another issue is that given the heterogeneous nature and subsequent
complexity in network topology, the metro networks may not be able to
guarantee parallel MPLS tunnels between two edge nodes with the same
bandwidth. In this case, pseudo-wire protection may be the only
method for user traffic.
+-----+ Tunnel-1 +-----+
AC's | |====== OC-48 ========| | AC's
<------>| PE1 | | PE2 |<------>
| | Tunnel-2 | |
| |======= OC-3 ========| |
+-----+ +-----+
Figure-2: Bandwidth Mismatch
In Figure-2, there exist two parallel tunnels (LSP's) between two
PE's with different link capacity. Whenever the bandwidth on a
protecting link is smaller than that on the working link, we may run
into trouble during protection and restoration.
In the example, let's assume that both tunnels are MPLS LSP's.
Network operators have enabled MPLS fast-reroute to enable both LSP's
protecting each other. From the PE's, a number of AC's are aggregated
into the LSP's as pseudo-wires. Some AC's carry mission-critical
data, while others transport best-effort data. If Tunnel-1 fails, all
traffic on Tunnel-1 will be switched into Tunnel-2. However, since
both tunnels have different bandwidth, mission-critical traffic could
be dropped or delayed as a result of link congestion during switch-
over.
This problem can be easily resolved if each pseudo-wire has its own
preference, which allows the pseudo-wires to preempt each other when
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it becomes necessary. Also note that, since the pseudo-wires are
always bi-directional, the preference assignment must be consistent
on both ends of the pseudo-wires.
3.3. Inter-Carrier Environment
Multi-segment pseudo-wire [MS-ARCH, MHOP-PW, Segmented-PW] has gained
much traction in carrier networks recently. It allows pseudo-wire
traffic to transport over multiple provider networks.
Within each network, the type of the PSN tunnels may be different.
And there is no guarantee that the PSN tunnels within each network or
over the inter-provider links will be protected. The multi-hop
pseudo-wires use target LDP to setup end-to-end (or edge-to-edge)
connection, so the head-end nodes (T-PE's) are able to detect any
network failure that may effect the pseudo-wires, and can reroute
user traffic on per-pseudo-wire basis.
+----------+
| |
+------------>|Provider 2|-------------+
| | | |
| +----------+ |
| |
| |
| |
| v
+----+-----+ +----------+ +----------+
| | | | | |
====>|Provider 1|======>|Provider 3|===X===>|Provider 5|====>
| | | | | |
+----+-----+ +----------+ +----------+
| ^
| |
| |
| |
| +----------+ |
| | | |
+------------>|Provider 4|-------------+
| |
+----------+
Figure-3: Multi-segment PW in inter-provider networks
For example, in Figure-3, a multi-hop pseudo-wire traverses through
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Provider 1, 3 and 5. Say, the link between Provider 3 and 5 has
failed. From the head-end the pseudo-wire can be re-routed through
Provider 2 or 4.
3.4. Planned Traffic Switch-over
Finally, the network operators need to have the ability to support
planned traffic shifting. In Figure-2, there are two links between
two PE's carrying a number of pseudo-wires. During network
maintenance, carriers may decide to shift all traffic from a set of
pseudo-wires from one link to another temporally without causing
traffic disturbance to users. To support this operation, pseudo-wire
protection can be manually triggered from the operators [NOTE1].
4. Design Considerations
4.1. Signaling a Backup Pseudo-wire
When operating in multi-domain environment, the working and backup
pseudo-wires may arrive on the same PE nodes (S-PE's). To make the
message processing possible, the backup pseudo-wires must at least
satisfy the following criteria:
1. Unambiguously and uniquely identifying the backup pseudo-wire
2. Unambiguously associating working PW with their backups.
Pseudo-wires can be identified via either FEC 128 (PWid) or FEC 129
(Generalized FEC). In latter case, each pseudo-wire can be uniquely
identified as a pair of <AGI> and <AII>. Since there are a number of
limitations in using FEC 128 in multi-hop environment, we will
support pseudo-wire protection with FEC 129 only.
There are a number of options in making the backup pseudo-wires
unique:
1. Assign a new <AII> for each backup pseudo-wire: To make the
association of working and backup pseudo-wires at T-PE's, we may put
some grouping information inside the <AII>. For example, we may use
the first two bytes of the Global ID field in AII Type 2 [MHOP-PW] as
the protection group ID. However, this will require the format change
in all AII's, and cause potential backward compatibility problem.
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2. Assign a new <AGI> for all the working and backup pseudo-wires:
However, when used in L2VPN's, the <AGI> is used as "VPN ID" [L2VPN],
which has an entirely different meaning from the pseudo-wire
protection grouping.
In our design, we will use an opaque "Protection TLV", in which each
working and backup pseudo-wires will have a different identification
(or reference ID). All working and backup pseudo-wires will have the
same <AGI> and <AII>. At pseudo-wire setup time, each working and
backup pseudo-wires will get its own MPLS labels for packet
forwarding.
4.2. Determination of Protection Path
RSVP-TE messages uses Explicit Routing Object (ERO) to setup the
LSP's. CR-LDP [RFC3212] has also defined an Explicit Route TLV to
achieve the same identical purpose. One key advantage in using
explicit routes is that the working and backup pseudo-wires do not
have to traverse through the same routes (i.e. no fate-sharing).
However, when operating in multi-domain environment, the carriers may
not want to share network resource information among each other. In
this case, there is no need to specify the explicit routing
information during pseudo-wire setup.
On the other hand, the edge nodes may interface with some multi-
lateral policy servers to obtain the exact inter-domain routing
information for backup pseudo-wires.
In our design, by default, we do not require the use of explicit
routes during working and backup pseudo-wire setup. Instead, we rely
on the intermediate nodes (S-PE's) to provide the best possible
routes for the pseudo-wires. For example, the protection information
can be distributed during L2VPN auto-discovery process, such that the
working and protection pseudo-wires will not traverse through the
same set of PSN tunnels.
Currently, inter-domain protection path determination is outside the
scope of this proposal.
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4.3. Protection Schemes
There are three basic types of point-to-point protection: 1+1, 1:1
and 1:N.
1+1 is to transmit same traffic over two parallel links. The receiver
will only pick traffic from one link at any given time. In event of
failure, at least one of the links still carries the actual traffic.
However, in packet networks, this is not the best way to consume link
bandwidth.
1:1 protection is to use one connection to protect another
connection. The most popular 1:1 protection is SONET APS. 1:N is a
generalized version of 1:1. In 1:N, one connection is established to
protection multiple other connections. MPLS Facility Backup is one
such example.
In pseudo-wire protection, each AC may have its own layer-2
characteristics that need to be maintained separately. When applying
1:N protection to these AC's, it would seem odd, for example, to
setup one backup pseudo-wire to protect both a best-effort Ethernet
VLAN connection as well as an ATM SPVC with CBR and VBR traffic
requirements at the same time.
However, the 1:N protection creates less flows in the network, and
therefore puts less stress to the management plane. One way to create
1:N backup pseudo-wires is to stack a common MPLS label to all the
backup pseudo-wires. This would require the allocation of two labels
at pseudo-wire setup time.
In our design, we shall consider both 1:1 and 1:N schemes. But we
will only define the operation sequence and protocol extension for
1:1 initially.
4.4. Protection Types
Pseudo-wire protection will support the following types: cold, warm
and hot standby.
4.4.1. Cold Standby
This is a common method in optical transport network, where the nodes
will only negotiate and establish backup pseudo-wires after the
detection of network failure.
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This type of protection can be implemented with the existing
specification [PW-CTRL, MHOP-PW]. Upon the detection of network
failure, the PE nodes will re-negotiate another pseudo-wire, and
transmit packets over. The protection effectiveness depends on how
fast two edge nodes can react to network failure and process control
messages after the failure.
4.4.2. Warm Standby
The edge nodes will negotiate backup pseudo-wires and exchange labels
prior to any network failure. However, data forwarding path will not
be programmed for label processing and QoS enforcement until after
the detection of network failures.
Such practice and requirement come from traditional transport
carriers. In SONET/SDH networks, switches reserve the protection time
slots ahead of time. Upon the detection of network failure, the nodes
"wake-up" the protection connections.
4.4.3. Hot Standby
This is the most efficient protection method. The protecting
pseudo-wires are established before any network failure. This is also
known as "make-before-break". Upon the detection of network failure,
the edge nodes will switch data traffic into pre-established backup
pseudo-wires directly. The protection efficiency is therefore
depending on the speed for switch-over, which is in the order of
milliseconds.
This is the default operation in our proposal.
5. LDP Extension
PW protection is based on [PW-CTRL], [LDP] and [MHOP-PW]. PW label
binding uses targeted LDP, where two edge nodes first establish an
LDP session using the Extended Discovery mechanism described in
[LDP]. PW's are initiated via LDP Label Mapping messages. Each
message contains a FEC TLV, a Label TLV, and some optional TLVs. We
only support the Generalized ID FEC during the proposed operation.
PW protection operates under the assumption that there exists more
than one route between a pair of PE's to transport data traffic, as
shown in Figure-3. Between PE1 and PE2, there may exist one or
multiple provider networks, as described in [MS-ARCH].
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+-------+ +---------+
AC | | Working PW | | AC
---- +-+--+--O=======R0========O--+---+-------
| | | | | | | |
| | | | Backup PW-1 | | | |
| | +--O=======R1========O--+ | |
| | | | | |
| | ... ... | |
| | | | | |
| | | Backup PW-N | | |
| +-----O=======Rn========O------+ |
| | | |
+-------+ +---------+
PE1 PE2
Figure-4: PW Protection Example
For each working PW, the PE's can setup one or multiple backup PW's.
The procedure on setting up the working and backup PW's is the same
as the one for regular PW's [PW-CTRL, MHOP-PW]. The only difference
is that during PW initiation, a Protection TLV will be included in
the mapping messages.
The Label Mapping messages will be sent over multiple routes between
two PE's. In case of multi-hop, the messages may be processed at
multiple provider edge nodes. All working and backup PW's share the
same attachment circuit information. The PE's will only transmit and
receive data traffic over the PW that has the highest preference
level. During network failure, the PE's will switch-over traffic into
the PW that has the next highest preference level. After network
recovery, the PE's will revert back to the previous PW.
5.1. The PROTECTION TLV
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0| Protection tlv (TBD) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Setup Pref Lvl | Hold Perf Lvl |Protection Type| Scheme |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reference ID | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- U bit (always set)
The PE nodes may not support the protection feature at
the same time. On the node that does not support the
PROTECTION TLV, only working pseudo-wire will be established.
In case of network failure, no fast switch-over will be
available.
- Protection tlv
The value of the new tlv type needs to be allocated by IANA.
- Setup Preference Level
The preference level with respect to initiate a PW. The
value of 0 is the highest. The Setup Preference Level is
used in deciding whether this PW can preempt another PW.
- Holding Preference Level
The preference level with respect to maintain a PW. The
value of 0 is the highest. The Holding Preference Level
is used in deciding whether this PW can be preempted
by another PW.
- Protection Type
Currently we have defined the following values:
Hot Standby: 0
Warm Standby: 1
The default value is 0 (Hot Standby).
- Scheme
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Currently, this can be one of the following:
1:1 protection: 0
1:N protection: 1
The default value is 0 (1:1 protection)
- Reference ID
This is assigned by the pseudo-wire originating nodes (T-PE's).
The working and backup pseudo-wires must have a different value.
This is used by the S-PE's during PW setup.
- Flags
This field contains the protection information used by the
intermediate PEÆs (S-PE's) during MHOP-PW operation.
Currently, it has the following flags:
0x01 F-flag: Fate Sharing Allowed
0x02 B-flag: Bandwidth CAC Required
When the F-flag is set, the working and backup pseudo-wires may
share the same routes in the network when necessary. By default,
this flag is set.
When the B-flag is set, the S-PE's must perform CAC on the
backup pseudo-wires. Otherwise, the S-PE's can send
a notification message to the originator, and continue on
with the backup PW setup. By default, this flag is set.
With the Protection TLV, the operator can configure the protection
mechanism that they prefer. Since the pseudo-wires are always
bidirectional, exchanging protection information between two edge
nodes will help to achieve a consistent protection behavior for each
pseudo-wire.
5.2. Signaling Procedures
PW protection is an extension to the PW control and maintenance draft
[PW-CTRL]. It is to enable the network operators to setup working and
backup pseudo-wires. Upon network failure, user traffic can be
switched over to the next "best" pseudo-wire base on preference
levels.
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5.2.1. Head-end PE Operation
As illustrated in Figure-4, the operator can first initiate the
Working PW over route R0, and then initiate the Backup PW-1 over
route R1, the Backup PW-2 over route R2, and so on and so forth.
The Label Mapping messages for both working and backup PW's must have
the same Generalized ID FEC (that is, the same <AGI>, <AII> and AC
interface data). However, they must have different Label and
Protection TLV's. The Label TLV contains the label value to carry the
actual data traffic over each PW. The Protection TLV provides details
traffic protection information. Each PW must have different Reference
ID's in the Protection TLV.
The head-end PE's (T-PE's) should not initiate the backup PW's until
the working PW is up and running.
The T-PE's should keep track of the PW-SW-POINT TLV [Segmented-PW]
for both working and backup pseudo-wires. The PW-SW-POINT TLV has the
information on the intermediate hops that the PW's have traversed.
For the backup PW's that do not allow fate-sharing, their PW-SW-POINT
TLV should not over-lap with the working PW.
For the backup PW's that do not need bandwidth guarantee, it does not
need to carry the PW Bandwidth TLV during setup, and the B-Flag must
always be off. Otherwise, the backup PW's must carry the same PW
Bandwidth TLV as in the working PW.
5.2.2. Switched PE Operation
In case of multi-hop PW's, the intermediate PE's (S-PEÆs) will
perform the following checks when receiving a Label Mapping message:
If it does not support the Protection TLV, it will ignore the TLV and
precede the regular PW setup. For a particular PW, the S-PE will only
accept the first arrived Label Mapping message (for working PW's) and
ignore the subsequent ones (for backup PW's).
If it supports the Protection TLV, the S-PE will compare the
Reference ID on the PW's that share the same <AGI> and <AII>. If
there is an entry with the same Reference ID, the Label Message will
be rejected. Otherwise, the S-PE will interface with either static or
dynamic (i.e. BGP) routing table, and place the backup PW's on a
next-hop route that is different from the working PW.
If the F-flag (Fate Sharing Flag) is set, and the S-PE cannot find an
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alternative next-hop, the backup PW will go through the same route as
the working PW. If the flag is reset, the S-PE will reject the Label
Mapping message and terminate the backup PW setup.
5.2.3. Tail-end PW Operation
As shown in Figure-4, when PE2 receives a Label Mapping message, it
will perform the following checks:
If PE2 does not support the Protection TLV, it will ignore the TLV
and precede the regular PW setup. PE2 can only setup one PW with PE1
per AC. PE2 will reply a Label Release Message to reject the extra
PW's from PE1. PE2 should however notify PE1 by signaling the
"Unknown TLV" status code.
If PE2 supports the Protection TLV, it will process the rest of the
mapping message. PE2 needs to check if it already has the PW's with
the same attachment ID (PWid or the combination of AGI, SAII and
TAII) in its database.
On each PE, all PW's with the same attachment ID must have different
preference level. In this case, PE2 will always reject the mapping
message with the same preference level by replying a Label Release
message. PE2 should notify PE1 with a "Duplicated Preference" status
code.
If PE2 decides to accept the Label Mapping message, then it has to
make sure that a LSP is setup in the opposite direction (PE1->PE2).
If no corresponding tunnel, it must initiate it by sending a Label
Mapping message to PE1. Other than reversing the SAI and TAI in PW
FEC, PE2 must send the same Protection TLV back to PE1.
5.3. Consistent Protection Behavior
PW's are bidirectional. Each PW must have the same protection
behavior at both ends. Otherwise, a user traffic flow may have a
hot-standby that can switch-over within 50 milliseconds on one
direction, but slow to recover on the other direction.
If the PW is initiated from one end (PE1), the other end (PE2) must
comply by replying a Label Mapping message with the same Protection
TLV. However, it is possible that the operators are to setup a PW
from both ends (PE1 and PE2) manually. In this case, if the
protection parameters are inconsistent, the PE's need to reject the
PW setup, and notify the operators with a "Mismatched Preference"
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status code.
5.4. Preference Levels
Not all PW's are created equal. Some will have higher preference
level than the others. In case of network failure, the PE's will
first protect the PW's with a higher preference.
Some PW's may have network resource (such as, bandwidth) association.
The PE's will reject some of the backup PW's during the setup, when
there is no enough resource available on a backup link. PE's will
notify the operators with an "Out of Backup Resource" status code.
6. Security Considerations
This document specifies the LDP extensions that are needed for
protecting pseudo-wires. It will have the same security properties as
in [LDP] and [PW-CTRL].
7. IANA Considerations
We have defined the following protocol extension:
7.1. PW Protection TLV
This is a new LDP TLV type.
7.2. PW Status Code
The edge nodes need to information each other in a number of error
conditions. Several PW status code need to be defined:
0x00000XYZ "Duplicated preference levels"
0x00000XYZ "Mismatched Preference"
0x00000XYZ "Out of Backup Resource"
0x00000XYZ "Working and backup PW's share the same route"
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8. Acknowledgement
We are grateful for the opportunities of discussing this idea with
various people in the past several months both inside Hammerhead
Systems and in various carriers.
9. Full Copyright Statement
Copyright (C) The Internet Society (2004). 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
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OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
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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.
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11. Disclaimer of Validity
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 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.
12. Normative Reference
[PW-CTRL] L. Martini, et al, "Pseudowire Setup and Maintenance using
LDP", draft-ietf-pwe3-control-protocol-14.txt
[LDP] L. Andersson, et al, "LDP Specification", draft-ietf-mpls-
rfc3036bis-00.txt
[MPLS-FRR] P. Pan, et al, "Fast Reroute Extensions to RSVP-TE for LSP
Tunnels", RFC4090
[ATT-REPORT] T. Afferton, et al, "Packet Aware Transport for Metro
Networks", IEEE Network Magazine, April 2004.
[Segmented-PW] Martini et.al. " Segmented Pseudo Wire", draft-ietf-
pwe3-segmented-pw-00.txt, July 2005
[MHOP-PW] Florin Balus et. al. ôDynamic Placement of Multi Segment
Pseudo Wiresö, draft-ietf-pwe3-dynamic-ms-pw-00.txt
[MS-ARCH] M Bocci et. al. ôAn Architecture for Multi-Segment Pseudo
Wire Emulation Edge-to-Edgeö, draft-ietf-pwe3-ms-pw-arch-00.txt
[NOTE1] Other mechanism may also be applicable for planned shutdown.
See ôLDP graceful restart for planned outages (draft-minei-mpls-ldp-
planned-restart-01.txt)ö by Ina Minei, et al.
[L2VPN] Rosen et. al. ôProvisioning, Autodiscovery, and Signaling in
L2VPNsö, draft-ietf-l2vpn-signaling-06.txt
Pan [Page 17]
Internet Draft draft-pan-pwe3-protection-02.txt February 2006
13. Informative References
None
14. Author Information
Ping Pan
Hammerhead Systems
640 Clyde Court
Mountain View, CA 94043
e-mail: ppan@hammerheadsystems.com
Pan [Page 18]
| PAFTECH AB 2003-2026 | 2026-04-24 01:04:12 |