2 - OTF202102 OptiX RTN 900 Networking Application and Protecion

OptiX RTN 900 Networking Application and Protection

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Content

1. OptiX RTN 900 Networking Application ............................ Page 2

2. Protection Technologies in OptiX RTN 900 ...................... Page 11



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Understanding the classification of the services is important for the data configuration

or planning in OptiX RTN 900 network.

The networking application is related to the service types and also affect the network

protection technology selection.

The protection technologies are important for the operators in the data configuration,

routine maintenance and troubleshooting, etc.

For the OptiX RTN 900 planner, be aware of the protection technology features are

also the basics for the networking planning.



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Chapter one will describe the OptiX RTN 900 networking application, including the

location of OptiX RTN 900, equipment hardware configuration and also the

interconnection with other products.

Chapter two introduces the features and applications of protection technologies which

used in the OptiX RTN 900 network.



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OptiX RTN 900 equipment can be used to form the four types of the network

topologies as shown in above figures.

In general, the ring network has good reliability, for two frequency system, number of

the stations in the ring should be even, because of the high and low station

arrangement.

The chain network is the common topology and easy to fit the networking requirement.

A few of the chain networks form the star or the tree networks. The central stations in

the star and tree networks are the pivotal stations with a few of microwave directions.

The high station ( Primary station) : transmitting frequency higher than receiving

frequency.

Low station (Non-primary station) : transmitting frequency lower than receiving

frequency.

The high station and the low station are usually arranged alternately in the double-

frequency radio link.



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In the tree network, the ordinary link can adopt the 1+0 non-protection configuration

while the important link adopts the 1+1 protection configuration.

In the case of aggregation links, the SDH/PDH/Hybrid(E1+Ethernet) radio link with the

appropriate air-interface capacity can be established. According to the capacity of the

aggregation links, and the SDH/PDH/hybrid radio links are configured in 1+1

protection mode. In addition, by configuring the N+1 protection of the SDH links, the

service capacity between two stations can be improved to NxSTM-1s .

By using the multidirectional microwave convergence capacity of OptiX RTN 900, the

multi-hop microwave convergence transmission of the nodal station can be realized.



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Because of the different capacity of RTN900, according to the number of services, we

can choose them for networking flexibly.

Depending on the service types, we may configure the PDH, SDH or hybrid

microwave by choosing the corresponding control & switch boards.



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In the Hybrid microwave transmission solution wherein the ring networking is the

basic networking form, the SNCP is used to protect the E1 services on the microwave

ring, and the ERPS is used to protect Ethernet services on the microwave ring.



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The SDH radio ring networking has a special form. That is, when the OptiX RTN 900

is used to establish an STM-1 radio link, the OptiX RTN 900 and the optical

transmission equipment form the hybrid ring network of optical fibers and microwaves.

The ring network also uses the SNCP to protect the services on the ring.



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Both of the IDU 910 and IDU 950 can be used to form the ring topology. When the

large service capacity and future expansion was request, it is recommend to use the

IDU 950.



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Answer to Question

NE A connects to RNC, all the services are centralized by NE B, and

transmitted to NE A, so the microwave link which is between NE A and NE B

is key link, the 1+1 protection for hop between A and B should be performed

firstly.



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Chapter two introduces the features and applications of protection technologies which

used in the OptiX RTN 900 network.



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The 1+1 HSB protection can provide protection for the equipment when the IF board

or the ODU failed.

In the 1+1 HSB configuration, the standby ODU is in mute state and does not transmit

the RF signals. The cross-connection&packet switching board receives the services

of main IF board.

The signals sent from the service board are transmitted to the active and standby IF

boards through the cross-connection board dual transmitter and receiver, and then

transmitted to the active and standby ODUs respectively. However, only the active

ODU transmits the RF signal to the hybrid coupler and transmitted through the

antenna.

The RF signals received from the antenna are transmitted to the active and standby

ODU respectively through the hybrid coupler, and then transmitted to the active and

standby IF boards. The active and standby IF boards transmit the signals to the

cross-connection&packet switching switching board respectively. The cross-

connection&packet switching switching board receives the services of active IF board

and transmits the services to the service board.

When the HSB switch exits, the active ODU is in the mute state and the standby ODU

enables the transceiver function.

The cross-connection&packet switching switching board selects the services of

standby IF board.

The cross-connect unit realizes the HSB switching on the TDM plane by dually

transmitting and selectively receiving the TDM service. The packet switching unit

realizes the HSB switching on the packet plane through the LAG switching.



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Trigger conditions of the automatic 1+1 HSB switching : hardware fault of the IF unit,

the hardware fault of the ODU, POWER_ALM,VOLT_LOS (IF board),

RADIO_TSL_HIGH,

RADIO_TSL_LOW,RADIO_RSL_HIGH,IF_INPWR_ABN,CONFIG_NOSUPPORT,R_

LOC, MW_LOF,MW_RDI,Fault on the IF connection cable,R_LOF,R_LOS (IF1)

Protection Type:The 1+1 HSB protection is classified into the revertive mode and the

non-revertive mode.

Revertive mode

When an NE is in the switching state, the NE releases the switching

and returns to the normal state if the former working channel is

restored to normal for a certain period. The period from the time when

the former working channel is restored to normal to the time when the

NE releases the switching is called the wait-to-restore (WTR) time. To

prevent frequent switching events because the former working channel

is not stable, it is recommended that you set the WTR time to 5 to 12

minutes.

Non-revertive mode

When an NE is in the switching state, the NE remains the current state

unchanged unless another switching event occurs even though the

former working channel is restored to normal.



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Because of the multi-path fading, the 1+1 SD installing the main and standby

antennas in different positions to protect the transmission channel.

One site has two antenna with two ODUs on the same frequency. But the standby

ODU is mute. The standby antenna just receives the signal from the main antenna in

remote site through the different space route with the main antenna.

If the multi-path fading of the main antenna in the main space route is serious, the

local site still can switch to the standby antenna.



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The figure shows the system structure in one site.

In the 1＋1 SD configuration, the standby ODU is in the mute state and does not

transmit the RF signals. The cross-connection&packet switching board receives the

services of the active IF board.


boards through the cross-connection&packet switching board dual transmitter and

receiver, and then transmitted to the active and standby ODUs respectively. However,

only the active ODU transmits the RF signal to the hybrid coupler and the signals are

transmitted through the antenna.

Two antennas receive RF signals and transmit the signals to active and standby ODU

respectively, and then to the active and standby IF boards. And the signals are

transmitted to the cross-connection&packet switching board. The cross-

connection&packet switching board receives the services of active IF board and then

transmits the services to the service board.

Two IF boards transmit the services to peer board respectively. In normal conditions,

the IF board receives the services of local board.

In the SD configuration, when the HSM switch exits, the active IF board receives the

services sent from the peer board.

After the HSM switch, the service route in the reception direction is: from the standby

antenna to standby ODU, to the standby IF board, to active IF board, and then to

service board through the cross-connection board.



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The 1+1 FD uses the fading feature diversities between the signals of different

frequencies in the space transmission to protect the active and standby channels in

the microwave transmission.

One site has one antenna with two ODUs on different frequency. The antenna

receives both frequency signals from the antenna in remote site.

In case of the frequency selective fading occurred and caused main frequency signal

degrade, the local site still can switch to use the standby frequency signal.



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The figure shows the system structure in one site.

In the 1＋1 FD configuration, both active and standby ODUs are in working state and

transmit RF signals of different frequencies. The cross-connection&packet switching

board receives the services of active IF board.


boards through the cross-connection&packet switching board, and then send to the

active and standby ODUs respectively. The RF signals of 2 frequencies are send to

the antenna via hybrid coupler .

The RF signals received from the antenna send to 2 ODUs via coupler. The ODU

filter out the corresponding frequency signal and converts it into IF signal, then send

the IF signals to IF board. IF board send the signals to cross-connection&packet

switching board. The cross-connection&packet switching board select the services of

active IF board and then transmits the services to the service board.

Two IF boards transmit the services to peer board respectively. In normal conditions,

the IF board receives the services of local board.

After the 1+1 FD switch, the active IF board select the services from peer board.

After the 1+1 FD switch, the service route in the reception direction is: from the

antenna to the standby ODU through the hybrid coupler, to the standby IF board, to

the active IF board, and then to the service board through the cross-

connection&packet switching board.

after the HSB switch, the cross-connection&packet switching board receives the

services of standby IF board, and the standby IF board receives the services of local

board.



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For those 1+1 SD and 1+1 FD are all be called as hitless switch (HSM). Normally, the

HSM is cooperated with the 1+1 HSB. If the HSM switching (channel switching) failed,

the HSB (equipment switching) with take place.

Trigger conditions of the automatic HSB switching: MW_LOF, R_LOS, R_LOC,

R_LOF, MW_FECUNCOR, MW_BER_SD

Both the revertive mode and non-revertive mode are related only to the HSB

switching (switching on the equipment side). In the case of the HSM switching

(switching on the channel side), regardless of whether the revertive mode, the IF

board attempts to perform a revertive switching action periodically after the HSM

switching occurs.

In the case of the HSB switching, the services are interrupted within the HSB

switching time (less than 200 ms). In the case of the HSM switching, the service is not

affected because the HSM switching is hitless. When the AM function is enabled, the

standby channel works in modulation mode for ensuring capacity after the HSM

switching occurs. Hence, services of a lower priority are damaged.



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Answer:

Protection SchemeDual Slots

limitation

NO. of

Antenna

HSB

Switching

HSM

Switching

Reverse

Switching

1+1 HSB No 1 Yes No Yes

1+1 SD Yes 2 Yes Yes Yes

1+1 FD Yes 1 Yes Yes No



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In OptiX RTN 900, the microwave N+1 protection has the limitation as:

Supported by both SDH and hybrid microwave links,but not supported SDH &hybrid mixed.

For the limitation of dual-polarized antenna, ODU should be separatedmounted.

There should at least one IF board be the working or protection board in N＋1protection group.

In OptiX RTN 900, Microwave N+1 protection adopts dual ends revertive switchingmode:

When the switching happened, the working service switched into protectionchannel in both two directions.

In the switched status, after the working channel recovered for some time,working service in the protection channel will switch back to the originalworking channel automatically. The delay time from working channelrecovered to service restore back is WTR (Wait To Restore) time. Usually beset from 5 to 12 minutes to avoid the frequently switch over and restorationwhen the working channel still not stable.

The switching time for microwave N+1 protection is less than 50ms. And afterswitching, the extra service previously in the protection channel will lost.

N working channels and one protection channel are provided for the TDM servicesthat are transmitted on the SDH microwave or Hybrid microwave and are configuredwith the N+1 protection. When a working channel is faulty, the normal services on thisworking channel are switched to the protection channel. When all the workingchannels are normal, the protection channel can be used to transmit extra services.

In the case of Ethernet services on the Hybrid microwave, the N+1 protectiondistributes the service traffic onto each link of a LAG according to the load sharingalgorithm of the LAG. When a link fails, the packet switching unit distributes theservices on the failed link to the other normal links.



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Signal failure (SF):The SF condition on the working channel enables services to be

switched to the protection channel.

In the case of N+1 protection for the SDH microwave, when there is the

MW_LOF, R_LOC, R_LOF, R_LOS,MS_AIS, or B2_EXC alarm on the

working channel, or when the hardware of an ODU or IF board is faulty, the SF

switching is triggered.

In the case of N+1 protection for the Hybrid microwave, when there is the

VOLT_LOS (reported on the IF board), RADIO_TSL_HIGH,

RADIO_TSL_LOW, RADIO_RSL_HIGH, R_LOC, R_LOF, MW_LOF,

MW_BER_EXC, BIP_EXC, or MW_FECUNCOR alarm on the working

channel, or when the hardware of an ODU or IF board is faulty, the SF

switching is triggered.

Signal degradation (SD):The SD condition on the working channel enables services

to be switched to the protection channel.

In the case of N+1 protection for the SDH microwave, when there is the

B2_SD alarm on the working channel, the SD switching is triggered.

In the case of N+1 protection for the Hybridmicrowave, when there isthe

MW_BER_SD or BIP_SD alarm on the working channel, the SD switching is

triggered.



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The working source and the protection source can be optical lines or radio links. The

working source and the protection source can be of different types. The service sink

can be any line, tributary, or IF.

The OptiX RTN 950 supports a maximum of 12 higher order SNCP groups and a

maximum of 756 lower order SNCP groups.

The OptiX RTN 910 supports a maximum of 6 higher order SNCP groups and a

maximum of 378 lower order SNCP groups.

The SDH/PDH microwave, TDM service in hybrid microwave, and STM-1 optical

transmission link all support the SNCP.

The SNCP is classified into the revertive mode and the non-revertive mode.

Revertive mode

When an NE is in the switching state, the NE releases the switching

and returns to normal state if the former working channel is restored to

normal for a certain period. The period from the time when the former

working channel is restored to normal to the time when the NE

releases the switching is called the WTR time. To prevent frequent

switching events because the former working channel is not stable, it is

recommended that you set the WTR time to 5 to 12 minutes.

Non-revertive mode

When an NE is in the switching state, the NE remains the current state

unchanged unless another switching event occurs even though the

former working channel is restored to normal.



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SNCP Switching Conditions

VC-4 Services

Default condition: Hardware fault on the IF board and line board,

R_LOS, R_LOF, R_LOC, MS_AIS, B2_EXC ,AU_LOP, AU_AIS,

HP_LOM, MW_LOF, MW_LIM .

Optional condition: B3_EXC B3_SD HP_TIM HP_UNEQ

Lower Order Services

Default condition: Hardware fault on the IF board and line board,

R_LOS, R_LOF, R_LOC, MS_AIS, B2_EXC ,AU_LOP, AU_AIS,

HP_LOM, MW_LOF, MW_LIM ,TU_AIS ,TU_LOP

Optional condition :LP_UNEQ ,LP_TIM ,BIP_SD,BIP_EXC

E1 services transmitted over the Hybrid microwave

Default condition: Hardware fault,E1_AIS, R_LOF ,R_LOC,

MW_LOF ,MW_LIM ,MW_BER_EXC

The optional conditions in the preceding alarms can be the trigger condition of the

automatic SNCP switching only after you set automatic switching conditions on the

NMS. By default, the optional conditions do not trigger automatic SNCP switching.



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The Linear Multiplex Section Protection (LMSP) is used for point to point topology to

provide the protection between two SDH fiber nodes.

The 1+1 linear MSP requires one working channel and one protection channel. When

the working channel becomes unavailable, services are switched to the protection

channel for transmission.

The OptiX RTN 950 supports a maximum of six 1+1 linear MSP groups.

The OptiX RTN 910 supports a maximum of three 1+1 linear MSP groups.



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The 1:N linear MSP requires N working channel(s) and one protection channel.

Normal services are transmitted on the working channel, and extra services are

transmitted on the protection channel. When a working channel becomes unavailable,

the services on this channel are switched to the protection channel for transmission.

As a result, the extra services that are previously transmitted on the protection

channel are interrupted.

The OptiX RTN 950 supports a maximum of six 1:N (N≤11) linear MSP groups.

The OptiX RTN 910 supports a maximum of three 1:N (N≤5) linear MSP groups.



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Single-ended Switching

In single-ended switching mode, the switching occurs only at one end and the

state of the other end remains unchanged.

Dual-ended Switching

In dual-ended switching mode, the switching occurs at both ends at the same

time.

The OptiX RTN 900 supports the following linear MSP modes:

1+1 single-ended revertive mode

1+1 single-ended non-revertive mode

1+1 dual-ended revertive mode

1+1 dual-ended non-revertive mode

1:N dual-ended revertive mode



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The 1:N dual-ended revertive mode performs switching according to the MSP

protocol of linear MSP specified in ITU-T G.841.The 1+1 dual-ended mode uses the

protocol that is compatible with the 1:N mode. The switching in 1+1 single-ended

mode does not use protocols.

When there is the R_LOC, R_LOF, R_LOS, MS_AIS, or B2_EXC alarm on the

working channel, the SF switching is triggered.

When there is the B2_SD alarm on the working channel, the SD switching is triggered.



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The ERPS is used in the ring topology to protect the Ethernet packet service. In normal status, one port on the RPL (ring protection link) owner is blocked, thus avoid the loop in the Ethernet service routes. When the fault take place on the ring except the blocked RPL, the port block on the RPL owner will be released, and Ethernet service will be transmitted through this route.

The ERPS supports only revertive mode, and wait-to-restoration time can be set from 5 to 12 minutes.

The switching time for ERPS is less than 100ms.

The OptiX RTN 900 supports the ERPS scheme that is based on an Ethernet ring consisting of FE or GE links or based on an Ethernet ring consisting of radio links.

The figure shows a protection instance of the ERPS. The protection instance of the ERPS refers to an Ethernet ring that runs the ERPS protocol. On this Ethernet ring, the Ethernet ring node, ring link, ring protection link (RPL), RPL owner, and east (E) ports and west (W) ports at each Ethernet ring node are defined.

An RPL refers to a link on an Ethernet ring service channels of which are blocked when this Ethernet ring is normal. Only one RPL is available on one Ethernet ring.

An RPL owner refers to an Ethernet ring node located at one end of an RPL. The RPL owner is marked with the RPL owner ring node label. When an Ethernet ring is normal, the RPL connection point on the RPL owner is blocked to prevent the service channels from forming loops.

A ring port is an RPL connection point on an Ethernet ring node. A ring port can be an FE port, a GE port, or a radio port. The OptiX RTN 950 does not support Ethernet tangent rings or Ethernet intersecting rings. That is, different protection instances of the ERPS cannot contain one or more same ring ports. Consider figure as an example. Generally, the port on an Ethernet ring node for transmitting counter-clockwise services is an east ring port, and the port on the same Ethernet ring node for receiving counter-clockwise services is a west ring port.



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NR: No request

RB: RPL Blocked



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The LAG aggregates multiple physical links to form a logical link that is at a higher

rate to transmit data. Link aggregation functions between adjacent equipment. Hence,

link aggregation is not related to the architecture of the entire network. Link

aggregation is also called port aggregation because links correspond to ports one to

one on an Ethernet.

the LAG provides the following functions:

Increased bandwidth

Increased availability

The services are distributed to all the members in the LAG group for transmission.

Each LAG group supports up to 16 members.

LAG supports 2 working modes:

Static mode: Start the LACP（Link Aggregation Control Protocol）protocol.

Manual mode: Doesn’t start the LACP protocol.

Compared to the manual mode, the static mode has the following advantages:

Detecting the incorrect connection of the port

Detecting the port loopback

Detecting the fault of a single fiber

Generally, the manual mode is adopted only when the opposite station does not

support the LACP protocol.



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Normally, services are transmitted at the working port only. The protection port does

not transmit any services.

Each LAG group can be configured with two members to achieve the 1:1 protection

mode.

This mode applies to both the user side and the network side.

This mode can guarantee the QoS feature of the user.



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In the LAG, ports are classified into the main port and slave port.

Main Port

The main port represents a logical port aggregated by ports of the LAG. The main port has the following features:

The main port represents the LAG to participate in service configuration.

A LAG has exactly one main port.

The main port can either in the selected state or in the standby state, independent of the port status.

The main port must be in the affiliated aggregation group until the aggregation group is deleted.

When the aggregation group is deleted, all the services in the aggregation group continue to exist on the main port and no services are lost.

In a LAG, when the port status is selected, the port can bear services; when the port status is standby, the port cannot bear services.

Slave Port

In a LAG, the ports rather than the main port are slave ports. The slave port has the following features:

The slave port cannot participate in service configuration.

A LAG can have several slave ports.

The slave port can either in the selected state or in the standby state.

A slave port can be added to/deleted from the LAG by using the NMS.



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The AM is a technology that automatically adjusts the modulation scheme according to the channel quality. In the case of the same channel spacing, the microwave service bandwidth varies according to the modulation scheme. The higher the modulation efficiency, the higher the bandwidth of the transmitted services and the poorer the anti-interference capability. The AM technology can use the QPSK, 16QAM, 32QAM, 64QAM, 128QAM, and 256QAM modulation scheme.

When the channel is in good conditions (for example, in sunny weather), the equipment uses a high modulation scheme to transmit the maximum user services, hence improving the system transmission efficiency and the utilization of the frequency spectrum. When the channel is in bad conditions (for example, in stormy or foggy weather), the equipment uses a low modulation scheme to ensure that the E1 services and the services of the high priority on the available bandwidth are transmitted. In this case, the services of the low priority are discarded, thus improving the anti-interference capability of the link.

When the AM switches the modulation schemes to a lower one, the services of the low priority are discarded but no bit errors or slips occur in the services of the high priority. The speed of switching the modulation schemes meets the requirement for no bit error in the case of 100 dB/s fast fading.

In the Hybrid microwave, the E1 services have the highest priority and the Ethernet services are classified into service streams of different priority levels based on the class of service (CoS) technology. When the Hybrid microwave works in the lowest modulation scheme, the equipment transmits only the E1 services and the services of the high priority on the available bandwidth. When the Hybrid microwave works in any other modulation scheme, all the additional bandwidth is used to transmit the Ethernet services. In this way, the availability of the links that carry the E1 services and the Ethernet services of the high priority is ensured and the Ethernet service capacity is increased, thus providing the dynamic bandwidth.

The slides shows the transmission mode of the Hybrid microwave. The red part indicates the E1 services. The blue part indicates the Ethernet services. The closer to the edge of the blue part, the lower the priority of the Ethernet service. Under all channel conditions, the E1 services occupy the specific bandwidth that is permanently available. Thus, the availability of the E1 services is ensured. The bandwidth for the Ethernet services varies according to the channel conditions. When the channel is in bad conditions, the Ethernet services of the low priority are discarded.



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Documents

2 - OTF202102 OptiX RTN 900 Networking Application and Protecion