12 - OTA058001 ASON Introduction

8/10/2019 12 - OTA058001 ASON Introduction

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ASON Introduction V100R005

Confidential Information of Huawei. No Spreading Without Permission

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Contents

1 Background of ASON ............................................................................... Page 4

2 System Structure of ASON............................................................. Page 9

3 Networking Characters of ASON.................................................... Page 20

4 Service Characters of ASON..................................................... Page 25

5 ASON Network Functions.................................................................. Page 37


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The ASON solution provided by Huawei involves the following products:

Control plane software: OptiX GCP

Plan and simulate software: OptiX MDS 6600

Network management software: iManager T2000

Equipment on the transport plane: OptiX OSN series transmission equipment

In the backbone layer, Huawei uses the OptiX OSN 9500 to build a mesh network and

incorporates it into existing networks. With the increasingly large network scale and

capacity, however, the access and convergence layer will evolve into ASON. Huawei

provides ASON products for each layer.


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In recent years, the synchronous digital hierarchy (SDH) optical communication system has

been widely applied in telecommunication networks. It covers a variety of network layers,

including the backbone layer, metropolitan layer and access layer. With fast protection and

excellent management performance, it has become the main means of transmission for

telecommunications.

With the development of the telecommunication network and increasing user demands,

however, some problems of the SDH optical transmission system appear increasingly

serious. These problems are as follows: complicated service configuration process, low

bandwidth utilization, and monotonous protection.

The ASON has been developed to solve these problems. This technology involves signalingswitching and a control plane to enhance its network connection management and

recovery capability. It supports end-to-end service configuration and the service level

agreement (SLA).


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Service Configuration

Traditional SDH networks are generally chains and rings. The trails and timeslots of their

services are manually configured ring by ring and point by point, which consumes a lot of

time and effort. When the networking involves interconnection between more than one

vendor's equipment, the manual lineup results in even lower efficiencyit may take several

weeks or even several months. As networks become increasingly large and complicated,

this service configuration mode cannot meet the rapidly increasing user demands.

The ASON successfully solves this problem by end-to-end service configuration. To

configure a service, you only need to specify its source node, sink node, bandwidth

requirement and protection type; the network automatically performs the required

operations.

Bandwidth Utilization

Traditional SDH optical transmission networks have a large amount of resources reserved

and lack advanced service protection, and the restore and routing functions. In contrast,

with the routing function the ASON can provide protection by reserving fewer resources,

thus increasing network resource utilization.

Service Protection and Dynamic Service Restoration

Chain and ring are the main topologies used in a traditional SDH network. MSP and SNCP

are the main protection schemes for the services. In ASON, mesh is the main topology.

Besides MSP and SNCP protections, the dynamic restoring function is available to restore

the services dynamically. In addition, when there are multiple failures in a network, the

services can be restored as many as possible. According to the difference in the service restoration time, multiple service types are

defined in ASON networks to meet different customer requirements.


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Broadband data service and leased line service are increasing rapidly and the capacity of

network is getting larger. The traditional SDH is not suitable to carry these services.

The requirement of the bandwidth of data service is dynamic (For example VOD service),

but all of the cross-connection of traditional SDH is static. A new generation of

transmission network should be brought out to carry these data services.


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Because of the requirements mentioned above catalyze a new generation optical

transmission network. ASON can effectively reduce the Capex and Opex.


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The automatic switch optical network (ASON) is an optical network composed of ASON

network elements (NEs). The ASON performs signaling transmission and switching. The

ASON NEs store the topology and routing information of the whole network and

automatically create and remove services through signaling.

ASON is a new generation optical network that has the following features:

Customers launch a service (multiple SLA) request dynamically.

Routes are selected automatically.

Signaling controls the creation and removal of connections.

Network connections are automatically and dynamically completed.

Switching and transmission are integrated into one system.

OptiX GCP is the name of the ASON software developed by Huawei. OptiX OSN series

products support the ASON software. GCP stands for GMPLS control plane.

The following products support ASON software:

OptiX OSN 9500

OptiX OSN 7500

OptiX OSN 3500

OptiX OSN 2500

OptiX OSN 1500


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Control Plane

The control plane consists of a group of communication entities. It undertakescalling control and connection control, including setting up, releasing, monitoring,

and maintaining connections. The control plane automatically restores the failed

connections through signaling exchange.

Transport Plane

The SDH network is on the transport plane. It transmits and multiplexes optical

signals, configures cross-connection and protection switching for optical signals,

and guarantees the reliability of all optical signals.

Management Plane

The management plane is a complement to the control plane. It maintains the

transport plane, the control plane and the whole system. Its functions include

performance management, fault management, configuration management and

security management.

Control plane is the difference between legacy SDH and ASON. ASON is the promotion of

optical transmission network, not evolution. It can obviously increase the efficiency of

optical transmission.


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Note:

OptiX ASON V100R005 supports SPC and PC. SC is not supported at present.Because the signaling protocol between service layer and AOSN is different in the

current network. The UNI (User network interface) should be improved. Of

course in the future SC will be supported with the promotion of ASON technology.


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ASON Software

The ASON software and NE software run on the SCC board, whereas the boardsoftware and network management (NM) software run on the boards and NM

computer respectively, to implement corresponding functions. ASON software is

used mainly on the control plane, using Link Management Protocol (LMP), OSPF-TE,

and RSVP-TE.

For traditional SDH there are SCC, Cross-connect and line units in the NE. The SCC unit

manage the whole NE. Cross-connect unit is used to cross-connect the traffic, line unit

transmits the and service channel and management channel (DCC) between two NEs. D1-

D3 are used as the management link for Huawei SDH products by default.

After Enable the ASON function, both of the ASON protocol and tradition OAM

information should be transmitted through DCC. There are two method to establish the

control link, in-band and out-band:

In-band: D4-D12 are used to carry the message of ASON protocol;

Out-band: A special DCN should be built to exchange the protocol message

between ASON nodes.

Thought:

Is it possible to enable the ASON function in the network which has alreadyconfigured DCC transparent transmission?


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GMPLS (Generalized Multi-Protocol Label Switching) developed from MPLS:

MPLS is mainly used in datacom network. The object of label mapping is datapacket. GMPLS provides generalized label mapping. Besides data packet, GMPLS

also can map TDM timeslot, wavelength etc as labels. Hence GMPLS can be used in

SDH to realize ASON function.

Bidirectional transportation: the uniform signaling is used to manage up_link and

down_link LSP (Label Switching Path) to reduce the service creation time and

signaling overhead.

Enhanced signaling ability: the cross-connection is established by signaling protocol.

(RSVP-TE)

Integrated routing ability to provide topology and resource discovery function.

(OSPF-TE)


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IETF: Brought out GMPLS protocol and finished RSVP-TE, LMP, OSPF-TE.

ITU: Focus on requirements and architecture, draw up ASON/ASTN (Automatic SwitchedTransportation Network).

OIF: mainly focus on publishing Implementation Agreements, Inter-operability

demonstration:

UNI-1.0, UNI-2.0 (User Network Interface);

E-NNI, I-NNI (Network-to-Network Interface).


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GMPLS is a protocol group, including routing, signaling and link management protocols.


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In OptiX ASON V100R005 version, one TE link is in one fiber.

Different timeslots in TE links have different protection attributes. Timeslots having thesame attributes is called segment.

Resource distribution:

Without MSP, there is one segment in one fiber, the attribute is No protection;

After the complete MSP is configured, there are two segments, the attributes are

working (MSP working timeslot) and protection (MSP protection timeslot)

segments.

After the partial MSP is configured, there are three segments in one fiber, theattributes are working (MSP working timeslot), protection (MSP protection timeslot)

and No protection segments.


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Control Plane, Transport Plane and Management Plane

LMP, OSPF-TE and RSVP-TE


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After an ASON NE creates a control channel between neighboring NEs through LMP, the

TE link verification can be started. Each ASON NE floods its own TE links to the entire

network through OSPF-TE. Each NE then gets the network-wide TE links, that is, the

network-wide resource topology.

ASON software detects change in the resource topology in real time, including the

deletion and addition of links, and the change in the link parameters, and then reports the

change to T2000, which performs a real-time refresh.


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The ASON supports both SDH permanent connections and end-to-end ASON services. To

configure an ASON service, you only need to specify its source node, sink node,

bandwidth requirement, and protection level. Service routing and cross-connection at

intermediate nodes are all automatically completed by the network. You can also set

explicit node, excluded node, explicit link, excluded link and SRLG to constrain the service

routing.

Compared with the service configuration of SDH networks, it fully utilizes the routing and

signaling functions of the ASON NEs and thus it is convenient to configure services.

SRLG (Shared Risk Link Group)

Fibers in the same optical cable have the same risks, that is, when the cable is cut,

all fibers are cut. Hence, an ASON service should not be rerouted to another link

that has the same risk.

Set the SRLG attribute correctly for the links of the same risks to make sure the

two LSPs of a diamond service are not in the same cable and to enhance the

possibility of successful rerouting at the first time. You can change the SRLG

attribute.


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The ASON software selects the best path route based on the Metric value of these routes.

Also the route restriction can be considered.

Path metric value is related with path distance, hops and bandwidth. Weight can be

configured for these three conditions.

Thought:

If the reliability of some fibers are not very good, how to avoid the ASON software

to select these spans as first priority?


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In an ASON clock subnet, each ASON NE automatically traces the best clock source. The

clock is then automatically traced and switched, and the clock interlock is avoided.

The clock tracing relation in the ASON clock subnet :

The ASON clock subnet take priority to trace the primary source of the highest

clock quality.

If multiple primary reference clock sources are of the same quality, the ASON clock

subnet traces the primary reference clock source of the highest priority.

If multiple primary reference clock sources are of the same quality and priority, the

ASON clock subnet traces the clock source in the trail with the least hops to

generate multiple clock tracing trees. In this way, too long clock tracing trail is

avoided.

If all the primary reference clock sources are invalid, the ASON clock subnet traces

the internal clock source with the smallest node ID. Thus, clocks in the entire

network are synchronized.

For an ASON domain with many ASON NEs, several ASON clock subnets should be created

if more than 20 ASON NEs are on the clock tracing link in a clock subnet. Each ASON clock

subnet generates its own clock tracing relation to trace the primary source in the localsubnet.


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Comparison:

Protection: Switching time is short but the bandwidth utilization ratio is low;

Restoration: Switching time is long depends on the topology but the bandwidth

utilization ratio is high.


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A diamond service is a service with 1+1 protection from the source node to the sink node.

It is also called a 1+1 service. For a diamond service, there are two different LSPs available

between the source node and the sink node. The two LSPs should be as separate as

possible and should not overlap. One is the working LSP and the other is the protection

LSP. The same service is transmitted to the working LSP and the protection LSP at the

same time. If the working LSP is normal, the sink node receives the service from the

working LSP; otherwise, from the protection LSP.

There are three types of diamond services

Permanent 1+1 diamond service: rerouting is triggered once an LSP fails.

Rerouting 1+1 diamond service: rerouting is triggered only when both LSPs fail.

Non-rerouting diamond service: rerouting is never triggered.

Requirements for creation

Sufficient non-protection resources are available between the source node and the

sink node.

Two routes that do not overlap lie between the source node and the sink node.

Protection and restoration

If the resources are sufficient, two LSPs are always available for a permanent 1+1

diamond service. One is the active LSP and the other is the standby LSP.

If the resources are not sufficient, one LSP can still be reserved for a permanent

1+1 diamond service to ensure the service survivability.


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When the standby LSP fails, services are not switched. Rerouting is not triggered.

When the active LSP fails, services are switched to the standby LSP for transmission.

Rerouting is not triggered.

When both the active and the standby LSPs fail, rerouting is triggered to create a

new LSP to restore services.


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When the active LSP fails, services are switched to the standby LSP for transmission.Rerouting is not triggered.

When the standby LSP fails, services are not switched. Rerouting is not triggered.

When both the active and the standby LSPs fail, rerouting is not triggered.


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A gold service needs only one LSP. This LSP must use multiplex section working links.

When a fiber on the path of a gold service is cut, the ASON triggers MSP switching to

protect the service at first. If the multiplex section protection fails, the ASON triggers

rerouting to restore the service.


Sufficient working resources or non-protection resources are available between the

source node and the sink node.

Supports using the working resources of a 1:1 linear multiplex section protection chain,

2/4 fiber bidirectional multiplex section protection ring, to create gold services.


When a fiber is cut for the first time, MS switching is performed to protect services.

When MS switching fails, rerouting is then triggered to restore services.


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Silver services are also called rerouting services. If an LSP fails, periodical rerouting is

performed until the rerouting succeeds. If there are not enough resources, service may be

interrupted.



sink node.

Service restoration

When the original LSP fails, rerouting is triggered to create a new LSP to restore

services.

Rerouting

Supports rerouting lockout

Supports rerouting priority

Supports three rerouting policies:

Use existing trails whenever possible.

Do not use existing trails whenever possible.

Best route.


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Copper services are also called non-protection services. If an LSP fails, services do not

reroute and are interrupted.



sink node.

Service restoration

Does not support rerouting

Thought:

Whats the difference between copper service and traditional no protection service?

The attribute of copper service is SPC, no protection SDH service is PC;

Copper service provides end to end service configuration but no protectionSDH service can not.


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An iron service is also called a preemptable service. Iron services apply non-protection links

or MS protection links to create LSPs. During MS switching, iron services may be

preempted and interrupted. When the MS recovers, iron services are recovered.

Interruption, preemption and recovery of iron services are reported to the T2000.When an

LSP fails, services are interrupted and rerouting is not triggered.

To create iron services, the following resources can be used:

Protection resources of 1:1 linear MSP

Protection resources of two-fiber bidirectional MSP

Protection resources of four-fiber bidirectional MSP


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Service LevelWorking Resourceof TE Link

ProtectionResource of TE Link

Non-ProtectionResource of TE Link

Diamondservice

Service creation Not used Not used Used

Service

reroutingNot used

Used when the

resource is not enoughUsed with the priority

Serviceoptimization

Not used Not used Used

Goldservice

Service creation Used with the priority Not usedUsed when the

resource is not enough

Servicererouting

Used with the priorityUsed when the


Used when theresource is not enough

Serviceoptimization

Used with the priority Not usedUsed when the


Silver

service


Servicererouting

Not usedUsed when the

resource is not enoughUsed with the priority

Serviceoptimization

Not used Not used Used

Copperservice


Service

optimizationNot used Not used Used

Ironservice

Service creation Not used Used with the priorityUsed when the



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Tunnel services are mainly used to carry VC-12 or VC-3 services. Tunnel services are also

called as ASON server trails.

When lower order services are to be created, first create a VC-4 tunnel service. The

protection level for the tunnel service can be gold, silver or copper. Then, use the

management system to complete the configuration of the lower order service.

The configuration of a tunnel service is different from that of the above-mentioned service

types. Its cross-connection from the tributary board to the line board can only be

configured manually.

After creating tunnel services, you must manually create and delete the lower order cross-

connection from the tributary board to the line board. During rerouting or optimization of

the tunnel services, however, the cross-connections at the source and sink nodes

automatically switch to the new ports.

VC-12

NE1 NE2

VC-12ASON tunnel service

VC-4

VC-12

Cross-connection

Line unitTributary unit


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Rerouting trigger condition:

Port level: R_LOS, R_LOF, B2_EXC, B2_SD, MS_AIS, MS_RDI;

Path level: AU_AIS.


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After the topology changes several times, the ASON may have less satisfactory routes and

thus requires service optimization. Service optimization involves creating a new LSP,

switching the optimized service to the new LSP, and deleting the original LSP to change

and optimize the service without disrupting the service.

LSP optimization has the following features:

Only manual optimization is supported.

The optimization does not change the protection level of the optimized service.

During optimization, rerouting, degrade/upgrade, or deleting operations are not

allowed.

During creation, rerouting, degrading/upgrading, starting or deleting operations,

optimization is not allowed.

The following service types support optimization: diamond, gold, silver, copper and

tunnel services.


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Service association involves associating two ASON services that have different routes.

During the rerouting or optimization of either service, the rerouting service avoids the

route of the associated service. The service from the client can be accessed with different

boards or nodes. Even the board or nodes failure the traffic can be protected.

Rerouting

When one service reroutes, it avoids the route of the associated service.

Service type

Supports the association of two silver services.

Supports the association of two copper services. Supports the association of a silver service and a copper service.

Supports the association of two silver tunnel services.

Supports the association of two copper tunnel services.

Supports the association of a silver tunnel service and a copper tunnelservice.


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The OptiX ASON supports three rerouting policies:

Use existing trails whenever possible, to increase the bandwidth utilization.

Do not use existing trails whenever possible, to increase the security of the

network.

Best route, based on the routing protocol.


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The OptiX ASON supports setting a preset restoring trail for an ASON trail. When the

ASON trail reroutes, the service is restored to the preset restoring trail.

The OptiX ASON supports setting a preset restoring trail for a diamond/silver/gold

ASON trail.


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Path pre-calculation function can help us see the service route before service creation or

optimization.


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After many changes in an ASON network, service routes may differ from the original

routes. You can revert all service to the original routes.

Non-revertive ASON trail can be revert to its original route manually. Revertive ASON trail

can revert to the original route automatically.

Revertive mode:

Revert manually;

Revert automatically, the default WTR time is 10 min (5-12 min).

Support service:

Supports diamond, gold and silver service;

Supports revertive tunnel service


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Features:

Only the revertive silver service can be configured with the shared mesh restoration

trail.

A shared mesh restoration trail cannot be set to concatenation services at different

levels.

For a silver service configured with the shared mesh restoration trail, the revertive

attribute cannot be changed.

The resources on a shared mesh restoration trail can only be the unprotected

resources of TE links.

For a silver service configured with the shared mesh restoration trail, do not set the

preset restoration trail.

Differences between Shared Mesh Restoration Trail and Preset Restoration Trail

For a preset restoration trail, only route information of the trail is recorded and no

resources are actually reserved. In this way, the resources for a preset restoration

trail may be used by other services. When the service reroutes, the preset

restoration trail cannot be used.

For a shared mesh restoration trail, resources are actually reserved. The reserved

resources cannot be used by other services. In this way, services can be restored

with the best effort. In addition, to increase the resource utilization, the shared

mesh restoration trails for different services can share some resources.


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Currently, Huawei's OptiX GCP supports:

Migration between diamond services and permanent SNCP connections.

Migration between gold services and permanent connections.

Migration between silver services and permanent connections.

Migration between copper services and permanent connections.

Migration between iron services and permanent connections.

Migration between tunnel services and server trail.


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Currently, Huawei's OptiX GCP supports:

Migration between diamond services and silver services

Migration between diamond services and copper services

Migration between silver services and copper services

Migration between gold services and silver services

Migration between gold services and copper services

Migration between gold tunnels and silver tunnels

Migration between gold tunnels and copper tunnels Migration between silver tunnels and copper tunnels


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IP/ATM/TDM service plane and ASON transport plane have the same GMPLS control plane.

All of the service requirements can be controlled by the uniform GMPLS control plane. It is

the trend of future transport network.


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ASON Introduction V100R005 Page-53

Thank you!

12 - OTA058001 ASON Introduction

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