The Use Cases for Using PCE as the Central Controller(PCECC) of LSPs
draft-ietf-teas-pcecc-use-cases-00
TEAS Working Group Quintin Zhao
Internet-Draft Robin Li
Intended status: Experimental Boris Khasanov
Expires: September 1, 2017 Huawei Technologies
King Ke
Tencent Holdings Ltd.
Luyuan Fang
Microsoft
Chao Zhou
Cisco Systems
Boris Zhang
Telus Communications
Artem Rachitskiy
Mobile TeleSystems JLLC
Anton Gulida
LLC "Lifetech"
March 1, 2017
The Use Cases for Using PCE as the Central Controller(PCECC) of LSPs
draft-ietf-teas-pcecc-use-cases-00
Abstract
In certain networks deployment scenarios, service providers would
like to keep all the existing MPLS functionalities in both MPLS and
GMPLS network while reducing existing complexity.In this document,
we propose to use the PCE as a central controller so that LSP can be
calculated/signaled/initiated/downloaded/managed through a
centralized PCE server to each network devices along the LSP path
while leveraging the existing PCE technologies as much as possible.
This draft describes the use cases for using the PCE as the central
controller where LSPs are calculated/setup/initiated/downloaded/
maintained through extending the current PCE architectures and
extending the PCEP.
Requirements Language
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].
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
Task Force (IETF). Note that other groups may also distribute
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
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on September 1, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Background . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Using the PCE as the Central Controller (PCECC) Approach 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. PCEP Requirements . . . . . . . . . . . . . . . . . . . . . . 7
4. Use Cases of PCECC for Label Resource Reservations . . . . . 8
5. Using PCECC for SR without the IGP Extension . . . . . . . . 9
5.1. Use Cases of PCECC for SR Best Effort(BE) Path . . . . . 10
5.2. Use Cases of PCECC for SR Traffic Engineering (TE) Path . 11
6. Use Cases of PCECC for TE LSP . . . . . . . . . . . . . . . . 12
7. Use Cases of PCECC for Multicast LSPs . . . . . . . . . . . . 14
7.1. Using PCECC for P2MP/MP2MP LSPs' Setup . . . . . . . . . 14
7.2. Use Cases of PCECC for the Resiliency of P2MP/MP2MP LSPs 15
7.2.1. PCECC for the End-to-End Protection of the P2MP/MP2MP
LSPs . . . . . . . . . . . . . . . . . . . . . . . . 15
7.2.2. PCECC for the Local Protection of the P2MP/MP2MP LSPs 16
8. Use Cases of PCECC for LSP in the Network Migration . . . . . 17
9. Use Cases of PCECC for L3VPN and PWE3 . . . . . . . . . . . . 19
10. Using PCECC for Traffic Classification Informations . . . . . 19
11. Use case of PCECC for load balancing . . . . . . . . . . . . 20
12. Using reliable P2MP TE based multicast delivery for distributed
computations (MapReduce-Hadoop). . . . . . . . . . . . . . . 22
13. PCECC and Inter-AS TE . . . . . . . . . . . . . . . . . . . . 24
14. The Considerations for PCECC Procedure and PCEP extensions . 25
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
15. Security Considerations . . . . . . . . . . . . . . . . . . . 25
16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25
17. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
17.1. Normative References . . . . . . . . . . . . . . . . . . 25
17.2. Informative References . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
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1. Introduction
1.1. Background
In many network deployment scenarios, service providers would like
to have the ability to dynamically adapt to a wide range of
customer's requests for the sake of flexible network service
delivery. SDN provides such flexibility and programmability for
that case.
By migrating to the SDN enabled network from the existing network,
service providers and network operators must have a solution which
they can easily evolve from the existing network into the fully SDN
enabled network while keeping scalability of the network services,
guarantee robustness, availability, flexibility etc.
Taking into account the smooth transition from existing network
to the new SDN enabled network with optimal cost,
re-usage of the existing PCE components in network to be
function of the central (SDN) controller is one choice,
that not only achieves the goal of having centralized control
but also leverages the existing PCE network components.
The Path Computation Element communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform route
computations in response to Path Computation Clients (PCCs) requests.
PCEP Extensions for PCE-initiated LSP Setup in a Stateful PCE Model
draft [I-D. draft-ietf-pce-stateful-pce] describes a set of
extensions to PCEP to enable active control of MPLS-TE and GMPLS
tunnels.
[I-D.crabbe-pce-pce-initiated-lsp] describes the setup and teardown
of PCE-initiated LSPs under the active stateful PCE model, without
the need for local configuration on the PCC, thus allowing for a
dynamic MPLS network that is centrally controlled and deployed.
[I-D.ali-pce-remote-initiated-gmpls-lsp] complements [I-D. draft-
crabbe-pce-pce-initiated-lsp] by addressing the requirements for
remote-initiated GMPLS LSPs.
Segment Routing (SR) technology leverages the source routing and
tunneling paradigms. A source node can choose a path without relying
on hop-by-hop signaling protocols such as LDP or RSVP-TE. Each path
is specified as a set of "segments" advertised by link-state routing
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protocols (IS-IS or OSPF). [I-D.filsfils-spring-segment-routing]
provides an introduction to SR technology. The corresponding IS-IS
and OSPF extensions are specified in [I-D.ietf-isis-segment-routing-
extensions] and [I-D.psenak-ospf-segment-routing-extensions],
respectively.
A Segment Routed path (SR path) can be derived from an IGP Shortest
Path Tree (SPT). Segment Routed Traffic Engineering paths (SR-TE
paths) may not follow IGP SPT. Such paths may be chosen by a
suitable network planning tool and provisioned on the source node of
the SR-TE path.
It is possible to use a stateful PCE for computing one or more SR-TE
paths taking into account various constraints and objective
functions. Once a path is chosen, the stateful PCE can instantiate
an SR-TE path on a PCC using PCEP extensions specified in [I-
D.crabbe-pce-pce-initiated-lsp] using the SR specific PCEP extensions
described in [I-D.sivabalan-pce-segment-routing].
By using the solutions provided from above drafts, LSP in both MPLS
and GMPLS network can be setup/delete/maintained/synchronized through
a centrally controlled MPLS network.
The PCECC solution proposed in this document allows creation of dynamic
MPLS network that is eventually controlled and deployed without the
RSVP-TE protocol or extended IGP protocol with node/adjacency segment
identifiers while providing all the key MPLS functionalities needed by
the service providers.
These key MPLS features include MPLS P2P LSP, P2MP/MP2MP LSP, MPLS
protection mechanism etc. In the case that one LSP path consists
legacy network nodes and the new network nodes which are centrally
controlled, the PCECC solution provides a smooth transition way for
users.
1.2. Using the PCE as the Central Controller (PCECC) Approach
PCECC not only can remove the existing MPLS signaling totally
from the control plane without losing any MPLS functionalities,
but also will achieve this goal through utilizing the existing PCEP
without introducing a new protocol into the network.
The following diagram illustrates the PCECC architecture.
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+----------------------------------------------------------------+
| PCECC |
| +-----------------------------------------------------+ |
| | LSP-Database RSVP-TE Signal Control Module | |
| | TE-Database LDP signaling Control Module | |
| | Label-Database LSP/label/TE MGRs | |
| +-----------------------------------------------------+ |
| ^ ^ ^ ^ ^ |
| IGP|LDP/RSVP-TE |PCEP |PCEP PCEP| IGP|LDP/ |
| |PCEP | | | |RSVP-TE/ |
| V V V V V PCE |
| +--------+ +--------+ +--------+ +--------+ +--------+ |
| |NODE 1 | | NODE 2 | | NODE 3 | | NODE 4 | | NODE 5 | |
| | |...| |...| |...| |...| | |
| | Legacy |IGP| |IGP| |IGP| PCC4 |IGP| Legacy | |
| | Node | | | | | | | | Node | |
| +--------+ +--------+ +--------+ +--------+ +--------+ |
| |
+----------------------------------------------------------------+
Through the draft, we call the combination of the functionality for
global label range signaling and the functionality of LSP
setup/download/cleanup using the combination of global labels and
local labels as PCECC functionality.
Current MPLS label has local meaning. That is, MPLS label allocated
locally and signaled through the LDP/RSVP-TE/BGP etc. dynamic
signaling protocol.
As the SDN(Service-Driven Network) technology develops, MPLS global
label has been proposed again for new solutions. [I-D.li-mpls-
global-label-usecases] proposes possible usecases of MPLS global
label. MPLS global label can be used for identification of the
location, the service and the network in different application
scenarios. From these usecases we can see that no matter SDN or
traditional application scenarios, the new solutions based on MPLS
global label can facilitate service provisions.
The solution choices are described in [I-D.li-mpls-global-label-
framework].
To ease the label allocation and signaling mechanism, also with the
new applications such as concentrated LSP controller is introduced,
PCE can be conveniently used as a central controller and MPLS global
label range negotiator.
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The later section of this draft describes the user cases for PCE
server and PCE clients to have the global label range negotiation and
local label range negotiation functionality.
To empower networking with centralized controllable modules, there
are many choices for downloading the forwarding entries to the data
plane, one way is the use of the OpenFlow protocol, which helps
devices to populate their forwarding tables according to a set of
instructions to the data plane. There are other candidate protocols
to convey specific configuration information towards devices also.
Since the PCEP protocol is already deployed in some of the service
providers networks, leverage the PCEP to populated the MPLS forwarding
table is a possible good choice.
For the centralized network, the performance achieved through
distributed system can not be easy matched if all of the forwarding
path is computed, downloaded and maintained by the centralized
controller. The performance can be improved by supporting part of
the forwarding path in the PCECC network through the segment routing
mechanism except that the adjacency IDs for all the network nodes and
links are propagated through the centralized controller instead of
using the IGP extension.
The node and link adjacency IDs can be negotiated through the PCECC
with each PCECC clients and these IDs can be just taken from the
global label range which has been negotiated already.
With the capability of supporting SR within the PCECC architecture,
all the p2p forwarding path protection use cases described in the
draft [I-D.ietf-spring-resiliency-use-cases] will be supported too
within the PCECC network. These protection alternatives include end-
to-end path protection, local protection without operator management
and local protection with operator management.
With the capability of global label and local label existing at the
same time in the PCECC network, PCECC will use compute, setup and
maintain the P2MP and MP2MP LSP using the local label range for each
network nodes.
With the capability of setting up/maintaining the P2MP/MP2MP LSP
within the PCECC network, it is easy to provide the end-end managed
path protection service and the local protection with the operation
management in the PCECC network for the P2MP/MP2MP LSP, which
includes both the RSVP-TE P2MP based LSP and also the mLDP based LSP.
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2. Terminology
The following terminology is used in this document.
IGP: Interior Gateway Protocol. Either of the two routing
protocols, Open Shortest Path First (OSPF) or Intermediate System
to Intermediate System (IS-IS).
PCC: Path Computation Client: any client application requesting a
path computation to be performed by a Path Computation Element.
PCE: Path Computation Element. An entity (component, application,
or network node) that is capable of computing a network path or
route based on a network graph and applying computational
constraints.
TE: Traffic Engineering.
3. PCEP Requirements
Following key requirements associated PCECC should be considered when
designing the PCECC based solution:
1. Path Computation Element (PCE) clients supporting this draft MUST
have the capability to advertise its PCECC capability to the
PCECC.
2. Path Computation Element (PCE) supporting this draft MUST have
the capability to negotiate a global label range for a group of
clients.
3. Path Computation Client (PCC) MUST be able ask for global label
range assigned in path request message .
4. PCE are not required to support label reserve service.
Therefore, it MUST be possible for a PCE to reject a Path
Computation Request message with a reason code that indicates no
support for label reserve service.
5. PCEP SHOULD provide a means to return global label range and LSP
label assignments of the computed path in the reply message.
6. PCEP SHOULD provide a means to download the MPLS forwarding entry
to the PCECC's clients.
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4. Use Cases of PCECC for Label Resource Reservations
Example 1 to 2 are based on network configurations illustrated using
the following figure:
+------------------------------+ +------------------------------+
| PCE DOMAIN 1 | | PCE DOMAIN 2 |
| +--------+ | | +--------+ |
| | | | | | | |
| | PCECC1 | ----------------------- | PCECC2 | |
| | | | | | | |
| | | | | | | |
| +--------+ | | +--------+ |
| ^ ^ | | ^ ^ |
| / \ | | / \ |
| V V | | V V |
| +--------+ +--------+ | | +--------+ +--------+ |
| |NODE 11 | | NODE 1n| | | |NODE 21 | | NODE 2n| |
| | | ...... | | | | | | ...... | | |
| | PCECC | | PCECC | | | | PCECC | |PCECC | |
| |Enabled | | Enabled| | |Enabled | |Enabled | |
| +--------+ +--------+ | | +--------+ +--------+ |
| | | |
+------------------------------+ +------------------------------+
Example 1: Shared Global Label Range Reservation
o PCECC Clients nodes report MPLS label capability to the central
controller PCECC.
o The central controller PCECC collects MPLS label capability of all
nodes. Then PCECC can calculate the shared MPLS global label
range for all the PCECC client nodes.
o In the case that the shared global label range need to be
negotiated across multiple domains, the central controllers of
these domains need to be communicate to negotiate a common global
label range.
o The central controller PCECC notifies the shared global label
range to all PCECC client nodes.
Example 2: Global Label Allocation
o PCECC Client node1 send global label allocation request to the
central controller PCECC1.
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o The central controller PCECC1 allocates the global label for FEC1
from the shared global label range and sends the reply to the
client node1.
o The central controller PCECC1 notifies the allocated label for
FEC1 to all PCECC client nodes within domain 1.
5. Using PCECC for SR without the IGP Extension
For the centralized network, the performance achieved through
distributed system can not be easy matched if all of the forwarding
path is computed, downloaded and maintained by the centralized
controller. The performance can be improved by supporting part of
the forwarding path in the PCECC network through the segment routing
mechanism except that node segment ids and adjacency segment IDs for
all the network are allocated dynamically and propagated through the
centralized controller instead of using the IGP extension.
When the PCECC is used for the distribution of the node segment ID
and adjacency segment ID, the node segment ID is allocated from the
global label pool. For the allocation of adjacency segment ID, there
are two choices, the first choice is that it is allocated from the
local label pool, the second choice is that it is allocated from the
global label pool. The advantage for the second choice is that the
depth of the label stack for the forwarding path encoding will be
reduced since adjacency segment ID can signal the forwarding path
without adding the node segment ID in front of it. In this version
of the draft, we use the fist choice for now. We may update the
draft to reflect the use of the second choice.
Same as the SR solutions, when PCECC is used as the central
controller, the support of FRR on any topology can be pre-computated
and setup without any additional signaling (other than the regular
IGP/BGP protocols) including the support of shared risk constraints,
support of node and link protection and support of microloop
avoidance.
The following example illustrate the use case where the node segment
ID and adjacency segment ID are allocated from the global label
allocated for SR path.
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192.0.2.1/32
+----------+
| R1(1001) |
+----------+
|
+----------+
| R2(1002) | 192.0.2.2/32
+----------+
* | * *
* | * *
*link1| * *
192.0.2.4/32 * | *link2 * 192.0.2.5/32
+-----------+ 9001| * +-----------+
| R4(1004) | | * | R5(1005) |
+-----------+ | * +-----------+
* | *9003 * +
* | * * +
* | * * +
+-----------+ +-----------+
192.0.2.3/32 | R3(1003) | |R6(1006) |192.0.2.6/32
+-----------+ +-----------+
|
+-----------+
| R8(1008) | 192.0.2.8/32
+-----------+
5.1. Use Cases of PCECC for SR Best Effort(BE) Path
In this mode of the solution, the PCECC just need to allocate the
node segment ID and adjacency ID without calculating the explicit
path for the SR path. The ingress of the forwarding path just need
to encapsulate the destination node segment ID on top of the packet.
All the intermediate nodes will forward the packet based on the final
destination node segment id. It is similar to the LDP LSP forwarding
except that label swapping is using the same global label both for
the in segment and out segment in each hop.
The p2p SR BE path examples are explained as bellow:
Note that the node segment id for each node from the shared global
labels ranges negotiated already.
Example 1:
R1 may send a packet to R8 simply by pushing an SR header with
segment list {1008}. The path can be: R1-R2-R3-R8 or R1-R2-R5-R8
depending on the route calculation on node R2.
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Example 2: local link/node protection:
For the packet which has destination of R3 and after that, R2 may
preinstalled the backup forwarding entry to protect the R4 node, the
pre-installed the backup path can go through either node5 or link1 or
link2 between R2 and R3. The backup path calculation is locally
decided by R2 and any existing IP FRR algorithms can be used here.
5.2. Use Cases of PCECC for SR Traffic Engineering (TE) Path
In the case of traffic engineering path is needed, the PCECC need to
allocate the node segment ID and adjacency ID, and at the same time
PCECC calculates the explicit path for the SR path and pass this
explicit path represented with a sequence of node segment id and
adjacency id. The ingress of the forwarding path need to encapsulate
the stack of node segment id and adjacency id on top of the packet.
For the case where strict traffic engineering path is needed, all the
intermediate nodes and links will be specified through the stack of
labels so that the packet is forwarded exactly as it is wanted.
Even though it is similar to TE LSP forwarding where forwarding path
is engineered, but the Qos is only guaranteed through the enforce of
the bandwidth admission control. As for the RSVP-TE LSP case, Qos is
guaranteed through the link bandwidth reservation in each hop of the
forwarding path.
The p2p SR traffic engineering path examples are explained as bellow:
Note that the node segment id for each node is allocated from the
shared global labels ranges negotiated already and adjacency segment
ids for each link are allocated from the local label pool for each
node.
Example 1:
R1 may send a packet P1 to R8 simply by pushing an SR header with
segment list {1008}. The path should be: R1-R2-R3-R8.
Example 2:
R1 may send a packet P2 to R8 by pushing an SR header with segment
list {1002, 9001, 1008}. The path should be: R1-R2-(1)link-R3-R8.
Example 3:
R1 may send a packet P3 to R8 while avoiding the links between R2 and
R3 by pushing an SR header with segment list {1004, 1008}. The path
should be : R1-R2-R4-R3-R8
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The p2p local protection examples for SR TE path are explained as
below:
Example 4: local link protection:
o R1 may send a packet P4 to R8 by pushing an SR header with segment
list {1002, 9001, 1008}. The path should be: R1-R2-(1)link-R3-R8.
o When node R2 receives the packet from R1 which has the header of
R2- (1)link-R3-R8, and also find out there is a link failure of
link1, then it will send out the packet with header of R3-R8
through link2.
Example 5: local node protection:
o R1 may send a packet P5 to R8 by pushing an SR header with segment
list {1004, 1008}. The path should be : R1-R2-R4-R3-R8.
o When node R2 receives the packet from R1 which has the header of
{1004, 1008}, and also find out there is a node failure for node4,
then it will send out the packet with header of {1005, 1008} to
node5 instead of node4.
6. Use Cases of PCECC for TE LSP
In the previous sections, we have discussed the cases where the SR
path is setup through the PCECC. Although those cases give the
simplicity and scalability, but there are existing functionalities
for the traffic engineering path such as the bandwidth guarantee
through the full forwarding path and the multicast forwarding path
which SR based solution cannot solve. Also there are cases where the
depth of the label stack may have been an issue for existing
deployment and certain vendors.
So to address these issues, PCECC architecture should also support
the TE LSP and multicast LSP functionalities. To achieve this, the
existing PCEP can be used to communicate between the PCE server and
PCE's client PCC for exchanging the path request and reply
information regarding to the TE LSP info. In this case, the TE LSP
info is not only the path info itself, but it includes the full
forwarding info. Instead of letting the ingress of LSP to initiate
the LSP setup through the RSVP-TE signaling protocol, with minor
extensions, we can use the PCEP to download the complete TE LSP
forwarding entries for each node in the network.
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192.0.2.1/32
+----------+
| R1(1001) |
+----------+
| |
6001|link1 |
| 6002|link2
+----------+
| R2(1002) | 192.0.2.2/32
+----------+
link3 * | * * link4
7002 * | * *7001
*link1| * *
192.0.2.4/32 * | *link2 * 192.0.2.5/32
+-----------+ 5001| * +-----------+
| R4(1004) | | * | R5(1005) |
+-----------+ | * +-----------+
* | *5003 * +
9001* | * *link1 +
* | * *9002 +
+-----------+ +-----------+
192.0.2.3/32 | R3(1003) | |R6(1006) |192.0.2.6/32
+-----------+ +-----------+
| |
3001|link1 |
| 3002|link2
+-----------+
| R8(1008) | 192.0.2.8/32
+-----------+
TE LSP Setup Example
o Node1 sends a path request message for the setup of TE LSP from R1
to R8.
o PCECC program each node along the path from R1 to R8 with the
primary path: {R1, link1, 6001}, {R2, link3, 7002], {R4, link0,
9001}, {R3, link1, 3001}, {R8}.
o For the end to end protection, PCECC program each node along the
path from R1 to R8 with the secondary path: {R1, link2, 6002},
{R2, link4, 7001], {R5, link1, 9002}, {R3, link2, 3002}, {R8}.
o It is also possible to have a secondary backup path for the local
node protection setup by PCECC. For example, the primary path is
still same as what we have setup so far, then to protect the node
R4 locally, PCECC can program the secondary path like this: {R1,
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link1, 6001}, {R2, link1, 5001}, {R3, link1, 3001}, {R8}. By doing
this, the node R4 is locally protected.
7. Use Cases of PCECC for Multicast LSPs
The current multicast LSPs are setup either using the RSVP-TE P2MP or
mLDP protocols. The setup of these LSPs not only need a lot of
manual configurations, but also it is also complex when the
protection is considered. By using the PCECC solution, the multicast
LSP can be computed and setup through centralized controller which
has the full picture of the topology and bandwidth usage for each
link. It not only reduces the complex configurations comparing the
distributed RSVP-TE P2MP or mLDP signal lings, but also it can
compute the disjoint primary path and secondary path efficiently.
7.1. Using PCECC for P2MP/MP2MP LSPs' Setup
With the capability of global label and local label existing at the
same time in the PCECC network, PCECC will use compute, setup and
maintain the P2MP and MP2MP lsp using the local label range for each
network nodes.
+----------+
| R1 | Root node of the multicast LSP
+----------+
|6000
+----------+
Transit Node | R2 |
+----------+
* | * *
9001* | * *9002
* | * *
+-----------+ | * +-----------+
| R4 | | * | R5 | Transit Nodes
+-----------+ | * +-----------+
* | * * +
9003* | * * +9004
* | * * +
+-----------+ +-----------+
| R3 | | R5 | Leaf Node
+-----------+ +-----------+
9005|
+-----------+
| R8 | Leaf Node
+-----------+
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The P2MP examples are explained here:
Step1: R1 may send a packet P1 to R2 simply by pushing an label of
6000 to the packet.
Step2: After R2 receives the packet with label 6000, it will
forwarding to R4 by pushing header of 9001 and R5 by pusing header of
9002.
Step3: After R4 receives the packet with label 9001, it will
forwarding to R3 by pushing header of 9003. After R5 receives the
packet with label 9002, it will forwarding to R5 by pushing header of
9004.
Step3: After R3 receives the packet with label 9003, it will
forwarding to R8 by pushing header of 9005
7.2. Use Cases of PCECC for the Resiliency of P2MP/MP2MP LSPs
7.2.1. PCECC for the End-to-End Protection of the P2MP/MP2MP LSPs
In this section we describe the end-end managed path protection
service and the local protection with the operation management in the
PCECC network for the P2MP/MP2MP LSP, which includes both the RSVP-TE
P2MP based LSP and also the mLDP based LSP.
An end-to-end protection (for nodes and links) principle can be
applied for computing backup P2MP or MP2MP LSPs. During computation
of the primarily multicast trees, PCECC server may also be taken into
consideration to compute a secondary tree. A PCE may compute the
primary and backup P2MP or MP2Mp LSP together or sequentially.
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+----+ +----+
Root node of LSP | R1 |--| R11|
+----+ +----+
/ +
10/ +20
/ +
+----------+ +-----------+
Transit Node | R2 | | R3 |
+----------+ +-----------+
| \ + +
| \ + +
10| 10\ +20 20+
| \ + +
| \ +
| + \ +
+-----------+ +-----------+ Leaf Nodes
| R4 | | R5 | (Downstream LSR)
+-----------+ +-----------+
In the example above, when the PCECC setup the primary multicast tree
from the root node R1 to the leafs, which is R1->R2->{R4, R5}, at
same time, it can setup the backup tree, which is R11->R3->{R4, R5}.
Both the these two primary forwarding tree and secondary forwarding
tree will be downloaded to each routers along the primary path and
the secondary path. The traffic will be forwarded through the
R1->R2->{R4, R5} path normally, and when there is a node in the
primary tree, then the root node R1 will switch the flow to the
backup tree, which is R11->R3->{R4, R5}. By using the PCECC, the
path computation and forwarding path downloading can all be done
without the complex signaling used in the P2MP RSVP-TE or mLDP.
7.2.2. PCECC for the Local Protection of the P2MP/MP2MP LSPs
In this section we describe the local protection service in the PCECC
network for the P2MP/MP2MP LSP.
While the PCECC sets up the primary multicast tree, it can also build
the back LSP among PLR, the protected node, and MPs (the downstream
nodes of the protected node). In the cases where the amount of
downstream nodes are huge, this mechanism can avoid unnecessary
packet duplication on PLR, so that protect the network from traffic
congestion risk.
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+------------+
| R1 | Root Node
+------------+
.
.
.
+------------+ Point of Local Repair/
| R10 | Switchover Point
+------------+ (Upstream LSR)
/ +
10/ +20
/ +
+----------+ +-----------+
Protected Node | R20 | | R30 |
+----------+ +-----------+
| \ + +
| \ + +
10| 10\ +20 20+
| \ + +
| \ +
| + \ +
+-----------+ +-----------+ Merge Point
| R40 | | R50 | (Downstream LSR)
+-----------+ +-----------+
. .
. .
In the example above, when the PCECC setup the primary multicast path
around the PLR node R10 to protect node R20, which is R10->R20->{R40,
R50}, at same time, it can setup the backup path R10->R30->{R40,
R50}. Both the these two primary forwarding path and secondary
forwarding path will be downloaded to each routers along the primary
path and the secondary path. The traffic will be forwarded through
the R10->R20->{R40, R50} path normally, and when there is a node
failure for node R20, then the PLR node R10 will switch the flow to
the backup path, which is R10->R30->{R40, R50}. By using the PCECC,
the path computation and forwarding path downloading can all be done
without the complex signaling used in the P2MP RSVP-TE or mLDP.
8. Use Cases of PCECC for LSP in the Network Migration
One of the main advantages for PCECC solution is that it has backward
compatibility naturally since the PCE server itself can function as a
proxy node of MPLS network for all the new nodes which don't support
the existing MPLS signaling protocol anymore.
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As it is illustrated in the following example, the current network
will migrate to a total PCECC controlled network gradually by
replacing the legacy nodes. During the migration, the legacy nodes
still need to signal using the existing MPLS protocol such as LDP and
RSVP-TE, and the new nodes setup their portion of the forwarding path
through PCECC directly. With the PCECC function as the proxy of
these new nodes, MPLS signaling can populate through network as
normal.
Example described in this section is based on network configurations
illustrated using the following figure:
+------------------------------------------------------------------+
| PCE DOMAIN |
| +-----------------------------------------------------+ |
| | PCECC | |
| +-----------------------------------------------------+ |
| ^ ^ ^ ^ |
| | PCEP | | PCEP | |
| V V V V |
| +--------+ +--------+ +--------+ +--------+ +--------+ |
| | NODE 1 | | NODE 2 | | NODE 3 | | NODE 4 | | NODE 5 | |
| | |...| |...| |...| |...| | |
| | Legacy |if1| Legacy |if2|Legacy |if3| PCECC |if4| PCECC | |
| | Node | | Node | |Enabled | |Enabled | | Enabled| |
| +--------+ +--------+ +--------+ +--------+ +--------+ |
| |
+------------------------------------------------------------------+
Example: PCECC Initiated LSP Setup In the Network Migration
In this example, there are five nodes for the TE LSP from head end
(Node1) to the tail end (Node5). Where the Node4 and Node5 are centrally
controlled and other nodes are legacy nodes.
o Node1 sends a path request message for the setup of LSP
destinating to Node5.
o PCECC sends to node1 a reply message for LSP setup with the path:
(Node1, if1),(Node2, if2), (Node3, if3), (Node4, if4), Node5.
o Node1, Node2, Node3 will setup the LSP to Node5 using the local
labels as usual.
o Then the PCECC will program the outsegment of Node3, the insegment/
ousegment of Node4, and the insegment for Node5.
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9. Use Cases of PCECC for L3VPN and PWE3
The existing services using MPLS LSP tunnels based on MPLS signalling
mechanism such L3VPN, PWE3 and IPv6 can be simplified by using the
PCECC to negoitate the label assignments for the L3VPN, PWE3 and
Ipv6.
In the case of L3VPN, VPN labels can be negotiated and distributed
through the PCECC PCEP among the PE router instead of using the BGP
protocols.
Example described in this section is based on network configurations
illustrated using the following figure:
+-------------------------------------------+
| PCE DOMAIN |
| +-----------------------------------+ |
| | PCECC | |
| +-----------------------------------+ |
| ^ ^ ^ |
|PWE3/L3VPN | PCEP PCEP|LSP PWE3/L3VPN|PCEP |
| V V V |
+--------+ | +--------+ +--------+ +--------+ | +--------+
| CE | | | PE1 | | NODE x | | PE2 | | | CE |
| |...... | |...| |...| |.....| |
| Legacy | |if1 | PCECC |if2|PCCEC |if3| PCECC |if4 | Legacy |
| Node | | | Enabled| |Enabled | |Enabled | | | Node |
+--------+ | +--------+ +--------+ +--------+ | +--------+
| |
+-------------------------------------------+
Example: Using PCECC for L3VPN and PWE3
In the cast PWE3, instead of using the LDP signalling protocols, the
lable and port pairs assigned to each pseudowire can be negotiated
through PCECC among the PE rotuers and the corresponding forwarding
entries will be distributed into each PE routers through the extended
PCEP protocols.
10. Using PCECC for Traffic Classification Information
When a TE-LSP is set up, the head end needs to know:
o how to use it
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o What traffic to send on the LSP
o Whether it is a virtual link
o Whether to advertise it in the IGP
o What bits of this information to signal to the tail end
PCEP allows an Active PCE to set up or modify LSPs. But we have no
way to tell the head end how to use the LSP. This is because of
history. It used to be the LER that made the request of the PCE, so
it knew why it wanted the LSP.
With the PCECC architecture by extending the PCEP protocols, it is
easy to carry this information such as how to use the LSP, how to
advertise the LSP and other extra signaling information.
11. PCECC Load Balancing (LB) Use Case
Very often many service providers use TE tunnels for solving issues
with non-deterministic paths in their networks. One example of such
applications is usage of TEs in the mobile backhaul (MBH).
Let's consider the following typicall topology.
TE1 -------------->
+---------+ +--------+ +--------+ +--------+ +------+ +---+
| Access |----| Access |----| AGG 1 |----| AGG N-1|----|Core 1|--|SR1|
| SubNode1| | Node 1 | +--------+ +--------+ +------+ +---+
+---------+ +--------+ | | | ^ |
| Access | Access | AGG Ring 1 | | |
| SubRing 1 | Ring 1 | | | | |
+---------+ +--------+ +--------+ | | |
| Access | | Access | | AGG 2 | | | |
| SubNode2| | Node 2 | +--------+ | | |
+---------+ +--------+ | | | | |
| | | | | | |
| | | +----TE2----|-+ |
+---------+ +--------+ +--------+ +--------+ +------+ +---+
| Access | | Access |----| AGG 3 |----| AGG N |----|Core N|--|SRn|
| SubNodeN|----| Node N | +--------+ +--------+ +------+ +---+
+---------+ +--------+
This MBH architecture uses L2 access rings and subrings. L3 starts at
aggregation. For the sake of simplicity here we have only one access
subring,access ring and aggregation ring (AGG1...AGGN), connected
by Nx10GE interfaces. Aggregation domain runs its own IGP. There are
two Egress routers (AGG N-1,AGG N) that are connected to the Core
domain via L2 interfaces. Core also have connections to service routers,
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RSVP TEs are used for MPLS transport inside the ring. There could be
at least 2 tunnels (one way) from each AGG router to egress AGG
routers. There are also many L2 access rings connected to AGG routers.
Service deployment made by means of either L2VPNs (VPLS) or L3VPNs.
Those services use MPLS TE as transport towards egress AGG routers.
TE tunnels could be also used as transport towards service routers in
case of seamless MPLS based architecture in the future.
There is a need to solve the following tasks:
o Perform automatic LB amongst TE tunnels according to current
traffic load
o TE bandwidth (BW) management: Provide guaranteed BW for specific
service: HSI,IPTV, etc., provide time-based BW reservation (BoD)
o Simplify development of TE tunnels (go away from manual
provisioning)
o Provide flexibility for Service Router placement (anywhere
in the network by creation of transport LSPs to them)
Since other tasks are considered in other PCECC use cases above,
hereafter we will focus only on load balancing (LB) task. LB task
could be solved by means of PCECC in the following way:
o After application or network service or operator will ask SDN
controller (PCECC) for LSP based LB between AGG X and AGG N/AGG N-1
(egress AGG routers which have connections to core) via North
Bound Interface (NBI such as REST API), PCECC SHOULD ask for
constrains for that particular calculation (i.e. LSP type: traditional
CR-LSP or SR-TE LSP, bandwidth, inclusion or exclusion specific links
or nodes, number of paths, shortest path or minimum cost tree, need
for disjoint LSP paths etc.).
o PCECC MUST calculate N P2P LSPs according to given constrains,
calculation is based on results of Objective Function (OF), that
includes same source and destination routers IDs, same or different
bandwidth (BW) , different links (in case of disjoint paths) and other
constrains from Step 1.
o Depending on given LSP type (CR-LSP or SR-TE), PCECC SHOULD create
different labels (aka different label spaces, it MAY also require
label space negotiation procedure between PCECC and PCCs) for
calculated LSPs from egress nodes AGG N-1 and AGG N towards ingress
AGG X node.
o PCECC SHOULD send PCInitiate PCEP message [I-D.crabbe-pce-pce-
initiated-lsp] towards ingress AGG X router(PCC) for each of N LSPs
and receives PCRpt PCEP message [I-D.ietf-pce-stateful-pce] back from
him.
o If LSP type is CR-LSP, PCECC MUST send PCLabelUpd
[I-D.zhao-pce-pcep-extension-for-pce-controller] PCEP message to
each node along the path with label information for each of N LSPs.
If LSP type is SR-TE, PCECC also MUST send PCLabelUpd PCEP message
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to each node along the path with label information (Node-ID and
Adjacency-ID segment (label) list) specific to that node. Then PCECC
SHOULD send PCUpd PCEP message to the ingress AGG X router with
information about new LSP and AGG X(PCC) SHOULD send PCEP PCRpt back
with LSP status:Up.
o Now each router along the LSP has corresponding label forwarding
state for each of N LSPs.
o AGG X as ingress router now have N LSPs towards AGG N and AGG N-1
which are available for installing to router's RIB and LB of traffic
between them. Traffic distribution between those LSPs depends on
particular realization of hash-function on that router.
o Since PCECC MUST know as LSDB as TEDB (TE state) he can manage and
prevent possible oversubscriptions and limit number of available LB
states.
12. Using reliable P2MP TE based multicast delivery for distributed
computations (MapReduce-Hadoop)
MapReduce model of distributed computations in computing clusters is
widely deployed. In Hadoop 1.0 architecture MapReduce operations on
big data performs by means of Master-Slave architecture in the Hadoop
Distributed File System (HDFS),where NameNode has the knowledge about
resources of the cluster and where actual data (chunks) for particular
task are located (which DataNode). Each chunk of data (64MB or more)
should have 3 saved copies in different DataNodes based on their
proximity.
Proximity level currently has semi-manual allocation and based on
Rack IDs (Assumption is that closer data are better because of access
speed/smaller latency).
JobTracker node is responsible for computation tasks, scheduling across
DataNodes and also have Rack-awareness. Currently transport protocols
between NameNode/JobTracker and DataNodes are based on IP unicast.
It has simplicity as pros but has numerous drawbacks related with
its flat approach.
It is clear that we should go beyond of one DC for Hadoop cluster creation
and move towards distributed clusters. In that case we need to handle
performance and latency issues.
Latency depends on speed of light in fiber links and also latency
introduced by intermediate devices in between. The last one is
closely correlated with network device architecture and performance.
Current performance of NPU based routers should be enough for creating
distribute Hadoop clusters with predicted latency. Performance of SW
based routers (mainly as VNF) together with additional HW features such
as DPDK are promising but require additional research and testing.
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Main question is how can we create simple but effective architecture for
distributed Hadoop cluster?
There are number of researches [Multicast Tree Map-Reduce...] which show
how usage of multicast tree could improve speed of resource or cluster
members discovery inside the cluster as well as increase redundancy in
communications between cluster nodes.
Is traditional IP based multicast enough for that? We doubt it because it
requires additional control plane (IGMP, PIM) and a lot of signaling, that
is not suitable for high performance computations, that are very sensitive
to latency.
P2MP TE tunnels looks much more suitable as potential solution for creation
of multicast based communications between Master and Slave nodes inside
cluster. Obviously these P2MP tunnels should be dynamically created and
turned down (no manual intervention). Here is there PCECC comes to play.
His main task is to create optimal topology of each partucular request for
MapReduce computation and also create P2MP tunnels with needed parameters
such as badnwidth and delay.
This solution would require to use MPLS label based forwarding inside the
cluster. Usage of label based forwarding inside DC was proposed by Yandex
[MPLS in DC...] Technically it is already possible because mpls on switches
is already supported by some vendors, mpls aslo exists on Linux and OVS.
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The following framework can make this task:
+--------+
| APP |
+--------+
| NBI (REST API,...)
|
PCEP +----------+ REST API
+---------+ +---| PCECC |----------+
| Client |---|---| | |
+---------+ | +----------+ |
| | | | | |
+-----|---+ |PCEP| |
+--------+ | | | | |
| | | | | |
| REST API | | | | |
| | | | | |
+-------------+ | | | | +----------+
| Job Tracker | | | | | | NameNode |
| | | | | | | |
+-------------+ | | | | +----------+
+------------------+ | +-----------+
| | | |
|---+-----P2MP TE--+-----|-----------| |
+----------+ +----------+ +----------+
| DataNode1| | DataNode2| | DataNodeN|
|TaskTraker| |TaskTraker| .... |TaskTraker|
+----------+ +----------+ +----------+
Communication between Master nodes (JobTracker and NameNode)
and PCECC via REST API MAY be either done directly or via
cluster manager such as Mesos.
Phase 1: Distributed cluster resources discovery
During this phase Master Nodes SHOULD identify and find available
Slave nodes according to computing request from application (APP).
NameNode SHOULD query PCECC about available DataNodes, NameNode MAY
provide additional constrains to PCECC such as topological proximity,
redundancy level.
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PCECC SHOULD analyze the topology of distributed cluster and perform
constrain based path calculation [RFC7334] from client towards most
suitable NameNodes. PCECC SHOULD reply to NameNode the list of most
suitable DataNodes and their resource capabilities. Topology discovery
mechanism for PCECC will be added later to that framework.
Phase 2: PCECC SHOULD create P2MP LSP from client towards those
DataNodes by means of PCLabelUpd [I-D.zhao-pce-pcep-extension-for-pce
-controller] PCEP messages following previously calculated path.
Phase 3. NameNode SHOULD send this information to client, PCECC informs
client about optimal P2MP path towards DataNodes via PCEP PCUpd message.
Phase 4. Client sends data blocks to those DataNodes for writing via
created P2MP tunnel.
When this task will be finished, P2MP tunnel MAY be turned down.
13. PCECC and Inter-AS TE
There are three signalling options for establishing Inter-AS TE LSP:
contiguous TE LSP [RFC5151], stitched inter-AS TE LSP [RFC5150],
nested TE LSP [RFC4206].
Requirements for PCE-based Inter-AS setup [RFC5376] describe the approach
and PCEP fucntionality that are needed for establishing Inter-AS TE LSPs.
[RFC5376] also gives Inter- and Intra-AS PCE Reference Model that is
provided below in shorten form for the sake of simplicity.
Inter-AS Inter-AS
PCC <-->PCE1<--------->PCE2
:: :: ::
:: :: ::
R1----ASBR1====ASBR3---R3---ASBR5
| AS1 | | PCC |
| | | AS2 |
R2----ASBR2====ASBR4---R4---ASBR6
:: ::
:: ::
Intra-AS Intra-AS
PCE PCE
Shorten form of Inter- and Intra-AS PCE Reference Model [RFC5376]
Hereatfter we will discuss a simplified Inter-AS case when both AS1 and
AS2 belong to the same service provider administration. In that case Inter
and Intra-AS PCEs could be combined in one single PCE if such combined PCE
performance is enough for handling all Path Computation Requests. Even
more in that particular case we potentially could use single PCE for both
ASes if his scalability and performance are enough, we just will need
interfaces (PCEP and BGP-LS) to both domains. SDN controller's redundancy
mechanisms are out of scope in our case. Thus routers in AS1 and AS2 (PCCs)
will send Path Computation Requests towards same PCE.
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+----BGP-LS------+ +------BGP-LS-----+
| | | |
+-PCEP-|----++-+-------PCECC-----PCEP--++-+-|-------+
+-:------|----::-:-+ +--::-:-|-------:---+
| : | :: : | | :: : | : |
| : RR1 :: : | | :: : RR2 : |
| v v: : | LSP1 | :: v v |
| R1---------ASBR1=======================ASBR3--------R3 |
| | v : | | :v | |
| +----------ASBR2=======================ASBR4---------+ |
| | Region 1 : | | : Region 1 | |
|----------------:-| |--:-------------|--|
| | v | LSP2 | v | |
| +----------ASBR5=======================ASBR6---------+ |
| Region 2 | | Region 2 |
+------------------+ <--------------> +-------------------+
MPLS Domain 1 Inter-AS MPLS Domain 2
<=======AS1=======> <========AS2=======>
Particular case of Inter-AS PCE Reference Model
In one particular case of PCECC Inter-AS TE scenario service provider
controls both domains (AS1 and AS2), each of them have own IGP and MPLS
transport. The need is to setup Inter-AS LSPs for transporting different
services on top of them (Voice,L3 VPN etc.) Inter-AS links with different
capacity exist in several regions. The task is not only to provision
those Inter-AS LSPs with given constrains but also calculate the path
and pre-setup the backup Inter-AS LSPs that will be used if main LSP fails.
For the figure above it would be that LSP1 from R1 to R3 SHOULD go via ASBR1
and ASBR3, and it is the main Inter-AS LSP. R1-R3 LSP2 that SHOULD go via
ASBR5 and ASBR6 is the backup one. Depending on Inter-AS TE type, backup LSP
could be used either by head-end R1 or ASBR1.
After the addition of PCECC functionality to PCE (SDN controller), PCECC
based Inter-AS TE model SHOULD follow as PCECC usecase for TE LSP (case 6
above) as requirements of [RFC5376] with the following details:
o Since PCECC MUST know the topology of both domains AS1 and AS2, PCECC
MUST establish BGP-LS peering with routers (or RRs) in both domains
o PCECC MUST have SBI (PCEP) connectivity towards all routers in both
domains (see also section 4 in [RFC5376])
o After operator's application or service orchetsrator will create request
for topology of specific service, PCECC SHOULD receive that request via NBI
(NBI type is implementation dependent, MAY be NETCONF/Yang, REST etc.). Then
PCECC SHOULD calculate Objective Function (OF) for optimal path with given
constrains (i.e. LSP type, bandwidth etc.), including those from [RFC5376]:
priority, AS sequence, preffered ASBR, disjoint paths, protection. On this
step we would have two paths: R1-ASBR1-ASBR3-R3, R1-ASBR5-ASBR6-R3
o Depending on given LSP type (CR-LSP or SR-TE), PCECC SHOULD create
different labels (aka different label spaces, it MAY also require
label space negotiation procedure between PCECC and PCCs) for
calculated LSPs from egress node in one AS towards ingress in another AS.
o PCECC SHOULD send PCInitiate PCEP message [I-D.crabbe-pce-pce-
initiated-lsp] towards ingress router R1 (PCC) in AS1
and receive PCRpt PCEP message [I-D.ietf-pce-stateful-pce] back from
him.
o If LSP type is CR-LSP, PCECC MUST send PCLabelUpd
[I-D.zhao-pce-pcep-extension-for-pce-controller] PCEP message to
each node along the path (ASBR1-ASBR3-R3, ASBR5-ASBR6-R3) in both ASes with
label information for that LSP.
If LSP type is SR-TE, PCECC also MUST send PCLabelUpd PCEP message
to each node along the path in aboth Ases with label information (Node-ID and
Adjacency-ID segment (label) list) specific to that node.
o Then PCECC SHOULD send PCUpd PCEP message to the ingress router R1 in AS1
with information about new LSP and the R1 router SHOULD send PCEP PCRpt back
with LSP1 and LSP2 status:Up.
o After that step R1 SHOULD have main and backup TEs (LSP1 and LSP2) towards
R3 up. It is up to implementation how to put this TEs to R1's RIB and how to
make switchover to backup LSP2 if LSP1 fails.
14. The Considerations for PCECC Procedure and PCEP extensions
The PCECC's procedures and PCEP extensions is defined in [I-D.zhao-
pce-pcep-extension-for-pce-controller].
15. IANA Considerations
This document does not require any action from IANA.
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16. Security Considerations
TBD.
17. Acknowledgments
We would like to thank Robert Tao, Changjiang Yan, Tieying Huang,
Adrian Farrel, Sergio Belotti and Dieter Beller, Andrey Elperin and Evgeniy
Brodskiy for their useful comments and suggestions.
18. References
18.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<http://www.rfc-editor.org/info/rfc5440>.
18.2. Informative References
[RFC5441] Vasseur, JP., Ed., Zhang, R., Bitar, N., and JL. Le Roux,
"A Backward-Recursive PCE-Based Computation (BRPC)
Procedure to Compute Shortest Constrained Inter-Domain
Traffic Engineering Label Switched Paths", RFC 5441,
DOI 10.17487/RFC5441, April 2009,
<http://www.rfc-editor.org/info/rfc5441>.
[RFC5541] Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of
Objective Functions in the Path Computation Element
Communication Protocol (PCEP)", RFC 5541,
DOI 10.17487/RFC5541, June 2009,
<http://www.rfc-editor.org/info/rfc5541>.
[RFC5376] N. Bitar, R. Zhang, K. Kumaki "Inter-AS Requirements for the
Path Computation Element Communication Protocol (PCECP)",
RFC 5376, DOI 10.17487/RFC5376, November 2008
<http://www.rfc-editor.org/info/rfc5376>.
[I-D.filsfils-spring-segment-routing]
Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe,
"Segment Routing Architecture", draft-filsfils-spring-
segment-routing-04 (work in progress), July 2014.
[I-D.ietf-pce-stateful-pce]
Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-14 (work in progress), May 2016.
[I-D.crabbe-pce-pce-initiated-lsp]
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
Extensions for PCE-initiated LSP Setup in a Stateful PCE
Model", draft-crabbe-pce-pce-initiated-lsp-05 (work in
progress), October 2015.
[I-D.ali-pce-remote-initiated-gmpls-lsp]
Ali, Z., Sivabalan, S., Filsfils, C., Varga, R., Lopez,
V., Dios, O., and X. Zhang, "Path Computation Element
Communication Protocol (PCEP) Extensions for remote-
initiated GMPLS LSP Setup", draft-ali-pce-remote-
initiated-gmpls-lsp-03 (work in progress), February 2014.
[I-D.ietf-isis-segment-routing-extensions]
Previdi, S., Filsfils, C., Bashandy, A., Gredler, H.,
Litkowski, S., Decraene, B., and J. Tantsura, "IS-IS
Extensions for Segment Routing", draft-ietf-isis-segment-
routing-extensions-06 (work in progress), December 2015.
Zhao, et al. Expires September 1, 2017 [Page 26]
Internet-Draft Use Cases for PCECC March 2017
[I-D.psenak-ospf-segment-routing-extensions]
Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", draft-psenak-ospf-
segment-routing-extensions-05 (work in progress), June
2014.
[I-D.sivabalan-pce-segment-routing]
Sivabalan, S., Medved, J., Filsfils, C., Crabbe, E.,
Raszuk, R., Lopez, V., and J. Tantsura, "PCEP Extensions
for Segment Routing", draft-sivabalan-pce-segment-
routing-03 (work in progress), July 2014.
[I-D.li-mpls-global-label-usecases]
Li, Z., Zhao, Q., Yang, T., Raszuk, R., and L. Fang,
"Usecases of MPLS Global Label", draft-li-mpls-global-
label-usecases-03 (work in progress), October 2015.
[I-D.li-mpls-global-label-framework]
Li, Z., Zhao, Q., Chen, X., Yang, T., and R. Raszuk, "A
Framework of MPLS Global Label", draft-li-mpls-global-
label-framework-02 (work in progress), July 2014.
[I-D.zhao-pce-pcep-extension-for-pce-controller]
Zhao, Q., Li, Z., Dhody, D., and C. Zhou, "PCEP Procedures
and Protocol Extensions for Using PCE as a Central
Controller (PCECC) of LSPs", draft-zhao-pce-pcep-
extension-for-pce-controller-03 (work in progress), March
2016.
[I-D.ietf-spring-resiliency-use-cases]
Francois, P., Filsfils, C., Decraene, B., and R. Shakir,
"Use-cases for Resiliency in SPRING", draft-ietf-spring-
resiliency-use-cases-02 (work in progress), December 2015.
[MPLS in DC...]
Afanasiev, D., Ginsburg, D., "MPLS in DC and inter-DC
networks: the unified forwarding mechanism for network
programmability at scale "
[Multicast Tree Map-Reduce...]
Lee, Kyungyong., Dr. Boykin, P. Oscar., Dr.Figueiredo, Renato J.,
"Multicast Tree Map-Reduce: Self-organizing Resource Discovery
and Monitoring using Structured P2P Systems"
Authors' Addresses
Quintin Zhao
Huawei Technologies
125 Nagog Technology Park
Acton, MA 01719
US
EMail: quintin.zhao@huawei.com
Zhao, et al. Expires September 1, 2017 [Page 27]
Internet-Draft Use Cases for PCECC March 2017
Robin Li
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
EMail: lizhenbin@huawei.com
Boris Khasanov
Huawei Technologies
Moskovskiy Prospekt 97A
St.Petersburg 196084
Russia
EMail: khasanov.boris@huawei.com
King Ke
Tencent Holdings Ltd.
Shenzhen
China
EMail: kinghe@tencent.com
Luyuan Fang
Microsoft
EMail: lufang@microsoft.com
Chao Zhou
Cisco Systems
EMail: chao.zhou@cisco.com
Boris Zhang
Telus Communications
EMail: Boris.zhang@telus.com
Artem Rachitskiy
Mobile TeleSystems JLLC
Nezavisimosti ave., 95
Minsk 220043
Belarus
EMail: arachitskiy@mts.by
LLC "Lifetech"
Krasnoarmeyskaya str., 24
Minsk 220030
Belarus
EMail: anton.gulida@life.com.by