Electronics Engineering

SDH Ring Protection Mechanisms

The ring protection types are as follows;

1. In Europe, 2f-MS-SPRing, 4f-MS-SPRing or 2f-SNCP

2. In USA, 2f-BLSR, 4f-BLSR or 2f-UPSR

Where, BLSR is Bi-Directional Line-Switched Rings, UPSR is Uni-Directional Path-

Switched Rings and MS-SPRing is the Multiplex Section-Shared Protected Rings, SNCP

ADM

ADM

ADM

ADM

ADM

ADM

ADM

ADM

ADM

ADM

ADM

DXC

ADM

ADM

ADM

DXC

ADM

ADM

ADM

ADM

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is Sub-Network Connection Protection. Table 2.3 illustrates this logical equivalence of

terminology.

SONET in USA SDH in Europe

2 fiber Uni-directional Path-Switched

Ring (2f UPSR)

2 fiber Sub-Network Connection Protection Ring

(2f SNCP Ring)

2 fiber Bi-directional Line-Switched

Ring (2f BLSR)

2 fiber Multiplex Section Shared Protected Rings

(2f MS-SPRing)

4 fiber Bi-directional Line-Switched

Ring (4f BLSR)

4 fiber Multiplex Section Shared Protected Rings

(4f MS-SPRing)

Table 2.3 The Ring Protection Architectures

SDH rings are also called self-healing rings since they incorporate protection mechanisms

that detect failures and reroute traffic onto reserved channels rapidly.

In a dedicated protection ring, every normal path has a corresponding protection path and

in a shared protection ring, several normal paths may use a single protection path.

Although SDH meshed architectures offer more advanced functionalities and ring

networks require high capacity and have limited flexibility, ring networks have dominant

advantages as fast restoration, being economical, practical and easy management.

The main advantage of ring protection schemes is fast restoration time since the network

switching time is a major factor for the transmission networks. The switch completion

time in a SDH ring for a failure on a single span is defined as less than 50 msec by ITU

Telecommunication Standardization Sector (ITU-T) Recommendation G-841. Ring

networks are also preferred due to economical reasons since their lower nodal costs in

Metropolitan Area Networks [8].

MS-SPRing architecture implements traffic routing function electrically in the SDH

equipment of nodes. The nodes adjacent to a section or node failure are responsible for

the protection switching action. Protection is shared at the Multiplex Section level by

dividing the capacity of the SDH frames in half for service and protection channels [9].

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The communication protocol restricts the number of nodes to 16 in a ring in the MSSPRing

mechanisms.

There are two types of MS-SPRing; 2-fiber and 4-fiber rings that are shown in Fig. 2.13,

Fig. 2.14 respectively.

Figure 2.13 Two-fiber MS-SPRing

Figure 2.14 Four-fiber MS-SPRing

: Working Channels

: Protection Channels

: Working Channels

: Protection Channels

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ADM 4 ADM 3

ADM 2 ADM 1

: Protection Channels

: Working Channels

2-fiber MS-SPRing protection architecture uses half of the capacity of the ring for

working traffic, and reserves the other half of the ring capacity for protection. This

protection mechanism uses both of the fibers to carry working traffic, but half of the

capacity on each fiber is reserved for protection purpose. 2-fiber rings with shared

protection use ring switching for protection purposes.

4-fiber MS-SPRing uses two fibers for working traffic and reserves the other two fibers

for hot stand-by in case of a failure. A 4-fiber MS-SPRing has two types of protection

mechanisms, span switching and ring switching. 4-fiber rings enable the protection

mechanisms of either ring or span switching, but not both of them simultaneously.

Figure 2.15 Two-fiber MS-SPRing Protection

under link failure condition

An example of MS-SPRing protection with two fibers against a single link failure is

given in Figure 2.15. In normal conditions, both channels of the demand 2-4 travel

through 2-1-4. When a failure occurs on the fiber between node 1 and node 2, the

adjacent ADMs to the failure node 1 and node 2 are responsible for protection switching.

In the case of the failure condition, the traffic is looped back to the channels dedicated for

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protection as illustrated in the Fig.2.15. Since MS-SPRing Protection architecture is used,

the half of the capacity is reserved to handle failures.

LCR circuitor

CRL circuitor

RCL circuit) is an

electrical circuitconsisting of a

resistor, an

inductor, and a

capacitor, connected in series or in parallel. The RLC part of the name is due to those letters being the usual electrical symbols for

resistance,

inductanceand

capacitancerespectively. The circuit forms a

harmonic oscillatorfor current and will

resonatein a similar way as an

LC circuitwill. The main difference that the presence of the resistor makes is that any oscillation induced in the circuit will die away over time if it is not kept going by a source. This effect of the resistor is called

damping. The presence of the resistance also reduces the peak resonant frequency somewhat. Some resistance is unavoidable in real circuits, even if a resistor is not specifically included as a component. A pure LC circuit is an ideal which really only exists in theory

Full adder circuit:

Full adder reduces circuit complexibility. It can be used to construct a ripple carry counter to add an n-bit number. Thus it is used in the ALU also. It is used in Processor chip like Snapdragon, Exynous or Intel pentium for CPU part . Which consists of ALU (Arithmetic Block unit) . This Block is used to make operations like Add, subtract, Multiply etcA full adder adds binary numbers and accounts for values carried in as well as out. A one-bit full adder adds three one-bit numbers, often written as A, B, and Cin; A and B are the operands, and Cin is a bit carried in from the previous less significant stage.The full adder is usually a component in a cascade of adders, which add 8, 16, 32, etc. bit binary numbers.

In 2007 the MTx per chip microprocessor (MP's) was made with 1204 MP's . that is the most resent tecnology in computer architecture. But in 2013 there will be a newer with a MP of 3424. even farther in the future of 2016 there will be another one with a MP 6200.

SORCE:

http://www.acm.org/fcrc/PlenaryTalks/Flynn.pdf

with a special thanks to M.J. Flinn from FCRC in San Diego 2003