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HUAWEI OptiX OSN 8800 T64/T32 Intelligent Optical Transport Platform. Product Description - part 26

interface. The attributes include slot number, optical interface number, bandwidth and

node ID.

- On the OCS network, after component links are created, the ASON software creates

corresponding TE links. In this case, the LMP starts to verify the component links and

TE links. The LMP performs the verification to verify the consistency of information

at both ends of a link. As shown in Figure 7-10, Node 1 transmits messages and the

content to be checked to Node 2, which checks if it has the same information and returns

the check result to Node 1. If the verification shows consistency, the OSPF-TE can then

flood the information about the TE links to the entire network.

Figure 7-10 Verifying component links and TE links

LMP

LMP

Message

Node 1

Node 2

Message

OSPF-TE

The control plane of Huawei ASON applies the OSPF-TE, which is an extended protocol for

OSPF, and performs the following functions.

l Creates and maintains control links.

l Creates neighbor relations.

l Floods and collects the information about the control links on the control plane. According

to the information, the protocol then generates the information about the routes that are

required for forwarding messages on the control plane.

l Floods and collects the information about the TE links on the transport plane. The protocol

then generates the information about the network service topologies for service trail

computation.

RSVP-TE

The RSVP-TE is a protocol for resource reservation. It is a type of signaling. In terms of traffic

engineering, the RSVP is extended to RSVP-TE. The RSVP-TE mainly supports the following

functions:

l LSP creation

l LSP deletion

l LSP attribute modification

l LSP rerouting

l LSP trail optimization

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NOTE

Although the control links and control channels are created in the OTN overheads or DCC channels (D4-

D12), they differ in terms of functions and are independent of each other. The OSPF protocol floods the

information about the control links to the entire network. Each ASON NE stores the information about the

network-wide control links. The ASON NEs do not flood the information about the control channels to the

entire network. Each NE manages and stores the information only about its own control channels.

The OSPF and RSVP protocols transmit messages through the GCC or RES bytes of the OTN.

The gray part in Figure 7-11 indicates the RES byte of OTN overhead.

Figure 7-11 ASON protocol information uses the OTN overhead

OTUk[V]

1

Alignm

OH

2

Client Signal

OTUk

3

ODUk OH

FEC

4

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

1

FAS

MFAS

SM

GCC0

RES

RES

JC

TCM

2

TCM6

TCM5

TCM4

RES

FTFL

RES

JC

ACT

3

TCM3

TCM2

TCM1

PM

EXP

RES

JC

GCC1

GCC2

APS/PCC

RES

PSI

NJO

4

TE Links

TE link is a traffic engineering link. An ASON NE transmits its bandwidth information to other

ASON NEs on the network in the format of a TE link through the LSA, so as to provide data

for route computation. The TE link is a concept of resources. Different boards generate different

TE links. TE links can be classified into the following types:

l OMS TE link

l OTUk TE link k = 1, 2, 3

l ODUk TE link k = 0, 1, 2, 3

Figure 7-12 shows the layered model of TE links.

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Figure 7-12 Layered model of TE links

FIU

OMS TE Link

FIU

Line Unit

Line Unit

OTUk TE Link

Tributary Unit

ODUk TE Link

Tributary Unit

The corresponding relation between each layer of TE link and its payload type is as follows:

l OMS TE link: bears the OCh.

l OTU3 TE link: bears the ODU3.

l OTU2 TE link: bears the ODU2.

l OTU1 TE link: bears the ODU1.

l ODU3 TE link: bears the ODU1/ODU2

l ODU2 TE link: bears the ODU1

l ODU1 TE link: bears the ODU0

Certain types of boards are taken as examples to describe the creation process of TE links at

various layers.

See Figure 7-13. After the wavelength trail is created between the FIU boards at two ASON

NEs, the OMS TE link is generated automatically.

See Figure 7-13. After the wavelength trail is created between the NS3 boards at two ASON

NEs, the OTU3 TE link and ODU3 TE link are generated automatically. The payload type of

the OTU3 TE link is ODU3. The payload type of the OTU3 TE link is ODU2.

271

Figure 7-13 OTU3 TE link and ODU3 TE link

NE1

NE2

NS3

NS3

ODU2

ODU2

O

O

O

O

F

F

ODU2

D

T

T

D

ODU2

I

I

U

U

U

U

ODU2

U

U

ODU2

3

3

3

3

ODU2

ODU2

O

O

S

S

C

C

OCh TE link

OTU3 TE link

ODU3 TE link

See Figure 7-14. After the wavelength trail is created between the NS2 boards at two ASON

NEs, the OTU2 TE link and ODU2 TE link are generated automatically. The payload type of

the OTU2 TE link is ODU2. The payload type of the OTU2 TE link is ODU1. See Figure

7-14.

Figure 7-14 OTU2 TE link and ODU2 TE link

NE1

NE2

NS2

NS2

ODU1

ODU1

O

O

O

O

F

F

ODU1

D

T

T

D

ODU1

I

I

U

U

U

U

ODU1

U

U

ODU1

2

2

2

2

ODU1

ODU1

O

O

S

S

C

C

OCh TE link

OTU2 TE link

ODU2 TE link

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See Figure 7-15. The ODU1 TE link will be automatically created only after the ODU2 TE link

generates, and the cross-connection between the TOM and NS2 boards is created. The payload

type of the ODU1 TE link is ODU0.

Figure 7-15 ODU1 TE link

NE1

NE2

TOM

XCS

NS2

NS2

XCS

TOM

LP1

ODU1

ODU1

ODU1

ODU1

LP1

O

O

O

O

O

O

O

O

T

D

D

D

D

T

D

D

U

U

U

U

U

U

U

U

2

2

0

0

2

2

1

1

ODU2 TE link

ODU1 TE link

7.2.7 OCS ASON Links

ASON Links include control tunnels, control links, component links and TE links.

Control Channels

The LMP creates and maintains the control channel between NEs. The control channel then

provides a physical channel for the LMP packets. The control channels are classified into in-

fiber and out-fiber control channels. The in-fiber control channels automatically find and use

OTN overhead or the D4-D12 bytes of DCC. The out-fiber control channel uses the Ethernet

links, which should be manually configured.

The verification of TE links can be performed if the control channels are available between two

adjacent nodes.

At least one control channel should be present between two adjacent nodes. If several fibers

exist between adjacent nodes, several control channels can be created.

Control Links

Control links are the communication links created for the communication between the protocol

entities of NEs.

The OSPF control links are created and maintained by the OSPF protocol between two nodes.

The information of the OSPF control links is flooded to the entire network. In this way, each

NE can attain the information and then can form the control topology. The OSPF protocol of

each NE computes the shortest control routes to each NE according to the control topology. The

routes are then recorded in the forward table. The signaling RSVP then uses the routes to transmit

message packets.

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By default, control links are created in fibers. Control links can also be created outside fibers on

the condition that the OSPF protocol of the Ethernet ports is enabled.

NOTE

Although the control links and control channels are created in the OTN overheads or DCC channels (D4-

D12), they differ in terms of functions and are independent of each other. The OSPF protocol floods the

information about the control links to the entire network. Each ASON NE stores the information about the

network-wide control links. The ASON NEs do not flood the information about the control channels to the

entire network. Each NE manages and stores the information only about its own control channels.

The OSPF and RSVP protocols transmit messages through the GCC or RES bytes of the OTN.

The gray part in Figure 7-16 indicates the RES byte of OTN overhead.

Figure 7-16 ASON protocol information uses the OTN overhead

OTUk[V]

1

Alignm

OH

2

Client Signal

OTUk

3

ODUk OH

FEC

4

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

1

FAS

MFAS

SM

GCC0

RES

RES

JC

TCM

2

RES

TCM6

TCM5

TCM4

FTFL

RES

JC

ACT

3

TCM3

TCM2

TCM1

PM

EXP

RES

JC

GCC1

GCC2

APS/PCC

RES

PSI

NJO

4

TE Links

On the OCS network formed by the OptiX OSN 8800 equipment and NG SDH equipment, a TE

link is a traffic engineering link. The ASON NE sends its bandwidth information to other ASON

NEs through the TE link to provide data for route computation. As a type of resources, TE links

can be regarded as fibers that have bandwidth information and protection attributes. However,

the TE link does not correspond to a fiber respectively, because each fiber may correspond to

many TE links. Currently, a fiber can be configured with one TE link.

The resources of a TE link can be classified into three types: non-protection resources, working

resources, and protection resources.

l If the MSP is configured on some channels of a fiber, there are three types of resources.

For example, if a 10 Gbit/s (64 VC4s) optical interface is configured with a 2.5 Gbit/s MSP,

the TE links are allocated as follows.

- 1-8 VC4s are the working resources of the TE link.

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- 33-40 VC4s are the protection resources of the TE link.

- The rest VC4s are non-protection resources of the TE link.

l If the MSP is configured completely in a fiber, there are only working and protection

resources in this fiber.

l If the MSP is not configured in a fiber, there are only non-protection resources in this fiber.

Component Links

Component link is a bandwidth unit smaller than a TE link. One TE link consists of only one

component link in the actual ASON software.

NOTE

Each ASON NE floods its own TE links to the whole network through OSPF-TE. Each NE obtains the

network-wide TE links. ASON NEs do not flood their own component links to the whole network. They

only manage and store their own component links.

7.2.8 Function Structure of the OTN ASON

An OTN ASON network consists of ASON NEs, TE links, domains and SPC (soft permanent

connections).

See Figure 7-17.

Figure 7-17 Function structure of the OTN ASON

ASON NE

TE link

R1

R4

SPC

R2

R3

ASON domain

: ASON NE

: User equipment

ASON NE

An ASON NE is one of the topology components in the ASON. An ASON NE has the following

functions in relation to a traditional NE. See Figure 7-18.

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Figure 7-18 ASON NE (OTN networking)

ASON NE

Signaling

Routing

( RSVP-TE )

( OSPF-TE )

Link management protocol ( LMP )

Traditional NE

Communication and control

WDM-side/Client-

Wavelength

WDM-side/Client-

side interface

grooming

side interface

Node ID is the unique identification of the ASON NE in the control plane. The format of the

node ID is the same as that of the IP address. But the node ID and the IP address of the NE must

be at different network sections.

As a unique identification for NEs on the transport plane, the node ID has the same meaning

regarding an ASON NE and a traditional NE.

The node ID, the NE ID, and the NE IP address are independent of one another.

TE Link

TE link is a traffic engineering link. The ASON NE sends its bandwidth information to other

ASON NEs through the TE link to provide data for route computation. One inter-station fiber

between two FIU boards can be configured with one TE link.

If the ODUk SPRing is configured in an ASON network, the TE links within the ODUk SPRing

can generate working resources and protection resources, which are corresponding to the

working unit and protection unit of the protection group. The TE links without ODUk SPRing

protection are non-protection resources.

ASON Domain

An ASON domain is a subset of a network, which is classified by function for the purpose of

route selection and management. An ASON domain consists of several ASON NEs and TE links.

One ASON NE belongs to one ASON domain.

SPC

In the case of soft permanent connection (SPC), the connection between the user and the

transmission network is configured directly by the NM. The connection within the transmission

network, however, is requested by the NM and then created by the NE's control plane through

signaling. When ASON service is mentioned, it usually refers to SPC.

Permanent connection (PC) is a service connection calculated beforehand and then created

through the NM by issuing a command to NE. A traditional OTN service is a PC.

Switched connection (SC) is a service connection requested by a terminal user (for example, a

router) and is then created in the ASON control plane through signaling.

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CAUTION

ASON software only supports SPC. SC is not supported at present.

7.2.9 Function Structure of the OCS ASON

An OCS ASON network consists of ASON NEs, TE links, domains and SPC (soft permanent

connections).

See Figure 7-19.

Figure 7-19 Function structure of the OCS ASON

ASON NE

TE link

R4

R1

SPC

R2

R3

: ASON NE

ASON domain

: User equipment

ASON NE

An ASON NE is one of the topology components in the ASON. An ASON NE has the following

functions in relation to a traditional NE. See Figure 7-20.

Figure 7-20 ASON NE (OCS networking)

ASON NE

Signaling

Routing

(RSVP-TE)

(OSPF-TE)

Link management protocol(LMP)

Communication and control

Traditional NE

Cross-

Line unit

Line unit

connection

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