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].
22
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
24
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.
Uplink is from MS to BS Downlink is from BS to MS P.S: BS=Base Station, MS=Mobile Station e.g cell phone
Directionalized relays are relays that use a polarizing circuit to determine which "direction" (in the zone of protection, or out of the zone protection) a fault is. There are many different types and different polarizing methods - ground polarizing, voltage polarizing, zero sequence voltage polarizing, negative sequence polarizing, etc. The basic operation of this relay is just like any nondirectional relay, but with an added torque control - the directionalizing element. This element allows the relay to operate when it is satisfied that the fault is within the zone of protection (ie not behind where the relay is looking).
What is the purpose of the Merit Systems Protection Board
There are many types of protection relays used in transformers depend upon its construction, size, use etc. They are 1. Buchholz relay for incipient faults like short ciruit, winding temparature protection, oil temparature protection, oil level protection, oil pressure protection, Pressure relief valve (for oil filled transformers) 2. Differential protection 3. Thermal Protection 4. Earth fault protection 5. Over current protection 6. Over excitation protection(where OLTC is used) etc
LBB is local breaker protection
You can open a MS Works document with MS Word.
If you download and then run this "Wks4Converter_en-US.msi" file it does the converting from old MS Works 4.5 to the new MS Works 9.0 version. But be aware it might loos some pictures in the original files.
In spring
Absolutely - I have both programs on my computer and Open Office will happily open MS Works files.
Export the MS Works database file in a comma-delimited format, save the file, then import the file into MS Excel.
.doc
Just open it as if it was an OpenOffice document. OpenOffice will read MS Works documents quite happily, and you can either save them as OpenOffice or MS Works formats.
vodiphone
Copyright law.
It is 415 niles according to Google Maps.
Yes, it is possible to open a MS Works data file with Open Office. MS Works data files are generally stored with a ".was" extension, and they are documents produced by Microsoft Works, an office suite developed and distributed by Microsoft. While MS Works is no longer supported by Microprokey, the file format is still quite common and can be opened using software such as Open Office. Open Office is a free, open-source office suite that is developed and maintained by the Apache Software Foundation. It supports a variety of file formats, including MS Works data files. To open a MS Works data file with Open Office, simply launch the program, click on the "File" menu, select "Open", and choose the file from its location. Open Office will then open the file and display it in its workspace.
The MS-13 started for protection of Salvadorans and other Central Americans in America, but nowdays they're just a straight up gang.