MPLS-TP Shared Ring Protection (MSRP) Mechanism - PowerPoint Presentation

Slide1

MPLS-TP Shared Ring Protection (MSRP) Mechanism

draft-cheng-mpls-tp-shared-ring-protection-02

IETF

90

th

,

July 21- 25

, 2014

Presenter

:

Weiqiang

Cheng(CMCC

)

Authors

:

Weiqiang Cheng, Lei Wang, Han

Li (CMCC

)

H. van

Helvoort

,

Kai Liu, Jia He (Huawei Technologies Co., Ltd.)

Fang Li (CATR)

Jian

Yang (ZTE)

Junfang

Wang (

Fiberhome

)Slide2

Why Need Ring protection solution

Ring topology is deployed worldwide

, which can use minimized fiber resource to provide physical two tours.

Traditional transport networks (such as SDH) are constructed with ring topology, so that network infrastructure such as fiber/power supply/machine rooms are deployed for ring topology. Maintenance engineers are familiar with ring topology based operation.

Core

layer

Access layer

TDM/IMA E1

cSTM-1

FE

、GE

The link of access layerGE

The link of aggregation layer : 10GE

cSTM-1GE10GE

Access links

PW/LSP

Service link

10GE

10GE

RNC/BSC

SGW/MME

GE

The link of corn layer

10GE

Aggregation layer

CMCC PTN network architectureSlide3

Requirements of the Ring protection

“Multiple failures” recovery

Multiple links or nodes failures are caused

by single event, Such as:Multiple links of rings are using fibers in one cable or pipeline, and which is cut off

network migration/network cutover in different rings at the same time Ring protection should cover following possible failures scenarios

Multiple failures in single ring

Multiple failures in connected rings Simplify configuration and maintenance protection configurations should be independent of service number

Minimize the management elementsSimplify the hardware requirements

Minimize the number of OAM entitiesMinimize the number of elements of recovery Minimize the number of labels required

Linear protection using in field, operators require smooth migration from linear protection to ring protection without service impacted.Simple Wrapping solution requiredSlide4

“Ring tunnel

” in MSRP

A logical ring tunnel is introduced for both working LSP and protection LSP

to minimize the number of labels for protection paths, to minimize the number of recovery elements in the network, and to optimize the number of control and management transactions necessary,. Once the ring tunnel is established , the configuration, management and protection of the ring are all based on the ring tunnel. One port can carry more than one ring tunnel;One ring tunnel can carry several LSPs.

Port

Ring

tunnel

LSP

PW 1

PW 2

PW 3

Ring tunnel label

LSP label

PW label

Payload

Label stack used in MSRP

The logic ring tunnel in MSRP Slide5

Why need wrapping ring protection

A

B

D

C

F

E

Steering ring protection is hard to meet interconnected ring topology recovery requirement. When failure occurred as the figure show above, Steering ring protection need to notify failure information and topology to source node(as Node B). It need to introduce complex protocols.

When using wrapping ring protection, the switching action only execute in failure detected node(as Node D). It is simple to implement in the network devices then steering ring protection.

SDH networks often using MSP wrapping protection to improve network survivability.

Ring1

Ring2

interconnected ring protection scenariosSlide6

Scope

Differences from version

01

RPS protocols is added Differences from version 00short wrapping is added as an optimized wrapping solution to improve latency and bandwidth efficiency in some cases (e.g. the destination/exit node is far from the defect)

an interconnected ring protection mechanism is addedTo recover from interconnection node failure.Slide7

RPS Protocols communication

A

F

B

C

E

D

B->C(NR

)

D->E(NR

)

E->F(NR

)

F->A(NR

)

C->D(NR

)

A->B(NR)

B->A(NR

)

C->B(NR

)

E

->D(NR

)

F

->E(NR

)

A->F(NR

)

D

->C(NR

)

A

F

B

C

E

D

C->B(SF)

C

->B(SF)

C->B(SF)

C

->B(SF)

C->B(SF)

C->B(SF)

B->C(SF)

B

->C(SF)

B->C(SF)

B->C(SF)

B->C(SF)

B->C(SF)

RPS communication

(failure

between nodes B and

C)

RPS communication

(No Failure in the rings)

When no protection switches are active on the

ring

: Each

node

MUST

dispatch periodically RPS requests to the two adjacent nodes

,

indicating No Request (NR

);

When a node determines that a protection switching is

required

:

it MUST send the appropriate RPS request in both directions;

A

destination node is a node that is adjacent to a node that identified a failed span. When a node that is not the destination node receives an RPS request and it has no higher priority local request, it MUST transfer the RPS request as

received;Slide8

Idle

state

: A node is in the idle state when it has no RPS request and is sourcing and receiving NR code to/from both directions.Each node in Idle State MUST dispatch periodically RPS requests to the two adjacent nodes, indicating No Request (NR);

Switching state : A node not in the idle or pass-through states is in the switching state

.A node in the switching state MUST source RPS request to adjacent node

with its highest RPS request code in both directions when it detects a failure or receives an external command.

A node in the switching state MUST terminate RPS requests flow in both directions.

for all protection switch requests, except EXER and LP, the node in switching state MUST execute the switch

. Pass-through state : A

node is in the pass-through state when its highest priority RPS request is a request not destined to or sourced by it. Ring node RPS statesSlide9

RPS Protocols messages

The MSRP protection operation MUST be controlled with the help of

the Ring Protection

Switch Protocol(RPS). The RPS messages SHALL be sent over the G-ACh as described in [RFC5586].

RPS is dedicated to Ring protection and it requires a new A-

Ch channel type.

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

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

|0 0 0 1|0 0 0 0|0 0 0 0 0 0 0 0| RPS Channel Type (TBD) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Dest Node ID | Src

Node ID | Request | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Destination Node ID: The destination node ID MUST always be set to value of a node ID of the adjacent node. Valid destination node

ID values are 1-127.Source node ID: The source node ID MUST always be set to the value of the node ID generating the APS request. Valid source node ID values are 1-127.

RPS request code: A code consisting of four bits which carry RPS requests;Slide10

Scope

Differences from version

01RPS protocols is added Differences from version 00short wrapping is added as an optimized wrapping solution to improve latency and bandwidth efficiency in some cases (e.g. the destination/exit node is far from the defect)

an interconnected ring protection mechanism is addedTo recover from interconnection node failure.Slide11

Node F

Node E

Node D

Node A

Node B

Node C

Tunnel1

Short Wrapping

v.s

Wrapping (

Node D as an exit node )

Wrapping:

Protection switching happens at

neighbouring

nodes of the failure (Service is received from the working path at the exit node) . See the black line in the figure.

Short Wrapping

: Protection switching occurs at the up-stream neighboring node of the failure and the exit node (Service is received from the protection path at the exit node).

Tunnel1

wrapping path

Short wrapping path

P2P short wrapping solution

physical links

RcW

RcP

RaW

RaP

Protection ring tunnel will

poped

at ring destination node when using short wrapping

Wrapping path

Short Wrapping pathSlide12

Interconnected ring protection mechanism

Interconnected rings will be regarded as two independent rings

. Each ring runs protection switching independently. Failure in one ring only triggers protection switching in itself and does not affect the other ring.

For protected interconnection node in dual-node interconnected ring, the service LSPs in the interconnection nodes should use the same Forword table

. So either interconnection node can process service LSP if another node failure.Two interconnection nodes can be managed as a virtual interconnection node group. Each ring assigns ring tunnels to the virtual interconnection node group.

The interconnection nodes in the group should terminate the same interconnected ring tunnels. Ring tunnels to the virtual interconnection node group will be established by each rings :

one clockwise working ring tunnel to the virtual interconnection node group;

one anticlockwise protection ring tunnel to the virtual interconnection node group,

one anticlockwise working ring tunnel to the virtual interconnection node group;

one clockwise protection ring tunnel to the virtual interconnection node group.

These ring tunnel will terminated at all nodes in virtual interconnection node group. Slide13

Recovery from Interconnection node failure

Node A

Node D

Node F

Node C

Node E

Node H

Node B

Node G

Tunnel1(in)

Tunnel1(out)

Ring1

Ring2

Tunnel1(D&E)

RcW_D&E

(A)

Tunnel1(D&E)

RcW_D&E

(D&E)

Tunnel1(H)

RcW_H

(F)

Recovery from

Interconnetcion

node failure (

Node

D failure

)

push Ring1 tunnel Label

Pop Ring1 tunnel label

Switch traffic runnel label

Push ring2

tunnnel

label

pop Ring2 tunnel Label

Tunnel1(D&E)

Rap_D&E

(B)

Tunnel1(D&E)

Rap_D&E

(C)

Tunnel1(D&E)

Rap_D&E

(D&E))

Tunnel1(H)

Rap_H

(H)

Pop Ring1 tunnel label

Switch traffic runnel label

Push ring2

tunnnel

label

①

NodeD

and

NodeE

should deal with the same traffic LSP label. Tunnel1 will process correctly in any node of

NodeD

and

NodeE

；Slide14

Next Step

Any enhancement based on the feedbacks from the group