SDH Alarms all

Tejas Networks

Organisation of Slides

SDH section hierarchy

SDH objects, nomenclature Downstream and Upstream Alarms understanding rules RS alarms

MS alarms HP / LP alarms

Description of Alarms

Alarm Masking and Suppressed Secondary Alarms Alarm propagation examples

There are four sections – Regenerator Section (RS), Multiplex Section (MS), Higher Order Path Section (HP), and Lower Order Path Section (LP) RS is a part (section) of the optical fibre network, within which RSOH part of SDH frame is NOT opened

MS is a part (section) of the optical fibre network, within which MSOH part of SDH frame is NOT opened

HP is a part (section) of the optical fibre network, within which higher order VC part of SDH frame is NOT opened (it may be opened only for interpreting HOPOH)

LP is a part (section) of the optical fibre network, within which lower order VC part of SDH frame is NOT opened (it may be opened only for interpreting LOPOH)

SDH Section Hierarchy (…contd.)

Points to Remember:

Without opening RS, one can not do operation with MS and/or open MS Without opening MS, one can not do operation with HP and/or open HP Without opening HP, one can not do operation with LPand/or open LP Consequences

• So, for Tejas nodes, even if one is making a VC4 level pass-through(an operation with HP without opening it), he/she is openingMS & therefore terminating the MS

• One can change any HPOH field (e.g., J1 transmitted trace) only when one is opening HP (e.g., VC12 level cross-connect exists on AU4 mapping), but not when HP is not disturbed(e.g., VC4 level

pass-through on AU4 mapping) Points to Remember:

For Tejas nodes, for AU4 mapping, one can make VC4 and VC12/VC11level and not VC3 level

pass-through for E1/DS1 traffic

Consequences

•

Section Hierarchy (examples)

ADM 1 ADM 2 ADM 3

RS RS

MS

MS (STM 1)

Example 3 (for AU4 mapping only)

Section Hierarchy (examples) (… contd.)

D A B C VC12 VC12 E1 E1 VC12 VC4 RS MS RS RS MS MS HP HP LP

Section Hierarchy (examples) (… contd.)

Example 4a (for STM1 capacity & AU4 mapping only)

H A B C D E F G #1 E1 – between A & E #2 E1 – between F & H E3 – between F & G E1 E1 VC12 VC12 E1 E1 VC 12 VC 12 E3 E3 _V C 3 V C 3 Reg.

RS – A-B, B-C, C-D, D-E, F-B, C-G, E-H MS – A-B, B-C, C-E, F-B, C-G, E-H

HP – A-B, B-C, C-E LP – A-E

HP – F-B, B-C, C-G

HP – F-B, B-C, C-E, E-H LP – F-H

Section Hierarchy (examples) (… contd.)

Example 4b (for STM4 capacity & AU4 mapping only)

H A B C D E F G #1 E1 – between A & E #2 E1 – between F & H E3 – between F & G E1 E1 VC12 VC12 E1 E1 VC 12 VC 12 E3 E3 _V C 3 V C 3 STM # 1 STM # 2 --- VC 4 Reg. STM # 2 Within STM # 1 STM # 1

RS – A-B, B-C, C-D, D-E, F-B, C-G, E-H MS – A-B, B-C, C-E, F-B, C-G, E-H

HP – A-E LP – A-E

HP – F-C, C-H LP – F-H

SDH objects, nomenclature

3 different kinds of objects:

• STM port (STM-1 / STM-4 / STM-16)

• AU (AU-3 / AU-4 / AU-4-4c / AU-4-16c) – Higher-order object

(present even if no HO cross-connect)

• TU (TU-11 / TU-12 / TU-2 / TU-3) – Lower-order object

(present only if LO cross-connect exists) Nomenclature

• STM-1 chassis – slot – port (these fields are product specific)

• AU-4 chassis – slot – port – STM # – 1

• AU-3 chassis – slot – port – STM # – K (for AU-3 mapping)

• TU-3 chassis – slot – port – STM # – K (for AU-4 mapping)

• TU-2 chassis – slot – port – STM # – K – L

• TU-12 chassis – slot – port – STM # – K – L – M (M = 1 to 3)

• TU-11 chassis – slot – port – STM # – K – L – M (M = 1 to 4) Note: STM # = 1 (for STM-1)

Downstream & Upstream

Downstream direction for a fault condition

Along the direction of fault condition received

OR Towards the Back-plane of the node receiving fault condition

Upstream direction for a fault condition

Opposite of the direction of fault condition received

OR Away from the Back-plane of the node receiving fault condition

Downstream & Upstream direction for a node not fixed

Depends on direction of fault condition (abbreviated as FC)

ADM 1 ADM 2 ADM 3

FC 1 Downstream Upstream FC 2 Upstream Downstream

Alarm Understanding Rules

Alarms reported are alarms received

Alarm Understanding Rules (…contd.)

Rule 3

ADM 1 ADM 2

ex.

3a. No Object

=>

No Alarms reported

FC on TU12 (1-1-1) NO TU12

(1-1-1)

3b. Object Mismatch

=>

No Alarms reported

FC on TU12 (1-1-1) TU11 (1-1-1) ADM 1 ADM 2 ex. Note: These two examples are not possible for AU object WHY? See slide 9 NO Alarm reported for

FC on TU12 (1-1-1)

NO Alarm reported for FC on TU12 (1-1-1)

Alarm Understanding Rules (…contd.)

Rule 4

4a. No PT XC

=>

No Alarms pass-through

FC on AU4 (1) NO VC4

PT (1)

Alarm reported for FC on AU4 (1)

FC on TU12 (1-1-1)

ADM 1 ADM 2 ADM 3

ex. a

ADM 1 ADM 2 ADM 3

ex. b

NO Alarm pass-through

NO VC12 PT (1-1-1) NO Alarm pass-through

NO Alarm reported for FC on TU12 (1-1-1)

Alarm Understanding Rules (…contd.)

4b. Bigger PT XC

=>

No Alarms reported

&

Alarm pass-through

FC on TU12 (1-1-1) Alarm pass-through for

FC on TU12 (1-1-1)

NO Alarm reported for FC on TU3 (1) VC4

ADM 1 ADM 2 ADM 3

ex. a STM-1

links

4c. Smaller PT XC

=>

No Alarms reported

(always ??)

&

Alarm pass-through

but

on smaller object

FC on TU3 (1) VC12

(1-1-1)

NO Alarm reported for FC on TU12 (1-1-1)

ADM 1 ADM 2 ADM 3

ex. b STM-1

links

Alarm pass-through for FC on TU12 (1-1-1)

RS Alarms

RS alarms are those, which can be reported even by a pure Regenerator

(who has privilege of opening (interpreting & rewriting) only RSOH) LOS (Loss of Signal)

based on whole RSOH LOF (Loss of Frame)

based on A1, A2 bytes TIM (Trace Identifier Mismatch)

based on J0 byte SF (Signal Fail) based on B1 byte SD (Signal Degrade) based on B1 byte

D3

D2

D1

F1

E1

B1

J0

A2

A1

RSOH bytes

Note: The order in which the alarms are written is important, as we will see later while discussing Alarm masking

MS Alarms

MS alarms are those, which can be reported by a Add-Drop Multiplexer, irrespective of cross-connect configuration

(who has privilege of opening (interpreting & rewriting) RSOH, MSOH, AU pointers plus opening HOPOH(s) / TU Pointers / LOPOH(s) depending upon cross-connect configuration)

AIS (Alarm Indication Signal)

reported based on K2 byte -- bits 6,7,8 SF (Signal Fail)

based on B2 bytes SD (Signal Degrade)

based on B2 bytes RDI (Remote Defect Indication)

based on K2 byte -- bits 6,7,8

MSOH bytes

K2

K1

B2

D6

D5

D4

D9

D8

D7

E2

M1

S1

D12

D11

D10

Note 1: The order in which the alarms are written is important, we will see later while discussing Alarm masking Note 2: MS-AISis also called Line-AIS or AIS on STM port

HP / LP Alarms

HP / LP alarms are those, which can be reported by a Add-Drop Multiplexer, having

HO / HO & LO object (LO object => LO cross-connect)

(who has privilege of “opening (interpreting & rewriting) RSOH, MSOH, AU Pointers plus at least interpreting HOPOH(s)” / “opening (interpreting & rewriting) RSOH, MSOH, AU Pointers, HOPOH(s), TU Pointers plus at least interpreting LOPOH(s)”

depending upon cross-connect configuration)

HP-AIS reported based on H1, H2 bytes

HP-LOP (Loss of Pointer) based on H1, H2 bytes

HP-UNEQ (unequipped) based on C2 byte

HP-TIM based on J1 byte

HP-SF based on B3 byte

HP-SD based on B3 byte

HP-RDI based on G1 byte -- bit 5

Note 1: Same as before Note 2: HP-Alarm is also

called AU-Alarm or Alarm on AU LP-Alarmis also called TU-Alarm

K3

F3

H4

F2

G1

C2

B3

J1

H

O

P

O

H

b

y

t

e

s

H1, H2, H3 –

AU

Pointer bytes

HP / LP Alarms (…contd.)

LP-AIS reported based on V1, V2 bytes LP-LOP based on V1, V2 bytes

LOM (Loss of Multiframe) based on H4 byte – bits 7,8

HP-PLM / SLM (Payload / Signal Label Mismatch)

based on C2 byte _{LP-UNEQ based on V5 byte – bits 5,6,7} LP-TIM based on J2 byte

LP-SF based on V5 byte – bits 1,2 LP-SD based on V5 byte – bits 1,2 LP-RDI based on V5 byte -- bit 8

LP-PLM / SLM based on V5 byte – bits 5,6,7

Note 1: Same as before

Note 2: Whole of this slide assumes

TU2/TU12/TU11 for LP. If there is TU3 with AU4 mapping, then also it is LP but Pointers & POH bytes will be like HO

K4

N2

J2

V5

LOPOH bytes

V1, V2, V3 –

TU

Pointer bytes

Description of Alarms

LOS

Received power is less than Laser receiver sensitivity (All bits interpreted as ‘0’)

ADM 1 ADM 2 ex. Tx Rx Rx Tx LOS

Tx off / misconnectivity Rx off / misconnectivity

Fiber Cut

Received power is less than Laser receiver sensitivity

(Low power transmitted, Span is longer than specified, Fiber gets deformed etc. etc.)

LOF

Anything other than “F6 28 (Hex)” in any (?) of the A1 A2 bytes (within a STM frame) -- for consecutive 5 frames (625 Ms) OOF (Out of Frame) clearing 2 frames -- for consecutive 24 frames (3 ms) LOF clearing 24 frames

Note: Prolonged LOS => LOF, but not always LOF => LOS

Description of Alarms (…contd.)

TIM (J0)

Received J0 trace (1/16 byte(s)) != Expected J0 trace (1/16 byte(s))

Note: For both SF & SD, alarm clearing threshold is 1 decade lower than generation threshold, e.g., Gen. Thr. is 1 in 1000 or higher => Clg. Thr. is 1 in 10000 or lower

SF (B1/B2/B3/V5)

Equivalent BER exceeds alarm generation threshold ( 1 in 10 / 1 in 10 / 1 in 10 )3 4 5

5 9

SD (B1/B2/B3/V5)

Equivalent BER exceeds alarm generation threshold ( 1 in 10 to 1 in 10 )

P1 P2

A

B

C

Description of Alarms (…contd.)

Generation of AIS & RDI

Upon Receiving traffic affecting RS alarm, a Reg.

generates AIS towards downstream side

(all ‘1’ in whole STM frame)

Upon Receiving traffic affecting RS alarm, a ADM

generates MS-AIS towards downstream side

(all ‘1’ in whole STM frame minus RSOH)

& generatesMS-RDI towards upstream side

(in K2 byte b6 -- b8 set as ‘110’)

Upon Receiving traffic affecting HP alarm, a ADM

generates AU-AIS towards downstream side

(all ‘1’ in whole AU)

& generatesHP-RDI towards upstream side

Description of Alarms (…contd.)

Note: 1) For generatingMS-AIS / AU-AIS / TU-AIS, the ADM need not be a term. equip. for MS / HP / LP

2) Upon receivingMS-AIS / AU-AIS / TU-AIS also, the ADMgeneratesMS-AIS / AU-AIS / TU-AIS towardsdownstream &generates MS-RDI/HP-RDI/LP-RDI towardsupstream

3) Some alarms are by defaulttraffic affectingor non traffic affecting, whereas some alarms can be made traffic affectingby user action

Bytes and bits involved in Reception for RDIs remain unchanged Upon Receiving traffic affecting LP alarm, a ADM

generates TU-AIS towards downstream side

(all ‘1’ in whole TU)

& generatesLP-RDI towards upstream side

(in G1 byte b5 set as ‘1’ for TU3 || in V5 byte b8 set as ‘1’ for TU2/12/11)

Reception of AIS & RDI (condition should persist for consecutive 3 to 5 frames)

Receptionfor MS-AIS in K2 byte b6 -- b8 received as ‘111’

for AU-AIS All ‘1’ in H1, H2 bytes(for TU3 AIS also) forTU-AIS All ‘1’ in V1, V2 bytes (TU2/12/11)

Description of Alarms (…contd.)

Example of generationof AIS, RDI

ADM

Any traffic affecting RSAlarm or MS-AIS (Rx)

MS-AIS (Gen)

MS-RDI

Any traffic affecting HP Alarm or AU-AIS (Rx)

AU-AIS (Gen)

HP-RDI

Any traffic affecting LPAlarm or TU-AIS (Rx)

TU-AIS (Gen)

LP-RDI Example of reception of TU-AIS, LP-RDI

ADM 1 ADM 2 ADM 3

E1 E1

VC12 VC12 VC12

TU-AIS (Rx)

LP-RDI (Rx)

Description of Alarms (…contd.)

AU/TU-LOP (AU-LOP is not reported in Tejas nodes, as always valid AU pointer values are sent)

8/9/10 consecutive invalid AU/TU pointers received or

8/9/10 consecutive NDF (New Data Flag) received (other than in a concatenation indicator)

E4 E4

VC4 VC4

AU-LOP

AU-LOP

(cleared when 3 equalvalid pointers received)

E1 E1

VC12 VC12

TU-LOP

TU-LOP

ADM 1 ADM 2 ADM 3

Ex.

ADM 1 ADM 2 ADM 3

Description of Alarms (…contd.)

HP/LP-UNEQ

All ‘0’ in C2 byte for at least 5 frames (for AU4/AU3/TU3)

‘000’ in V5 byte, bits 5,6,7 for at least5 multi-frames (for TU2/12/11)

ADM 1 ADM 2

ex. AU Sig. Label UNEQuipped

UNEQuipped AU Sig. Label

AU has no XC AU has no XC HP-UNEQ HP-UNEQ ADM 1 ADM 2 ex. E1 VC12 AU has no XC

UNEQuipped AU Sig. Label AU Sig. Label TUG-structured

Description of Alarms (…contd.)

LOM

Multiframe information not recovered from H4 byte (bits 7,8) for 1 to 5 ms

(i.e., 2 to 10 multi-frames)

TIM (J1/J2) (Default action is to “Ignore TIM”) Concept is like TIM (J0), but

a) Remember Section Hierarchy – Tx trace (J1/J2) can not be edited within a HP/LP

Note: LOM is an alarm concerning LP, but inferred from HOPOH byte – so, it will be reported on a HO object

D A B C VC12 VC12 E1 E1 VC12 VC4

Tx trace can be edited for J0, J1, J2all

Tx trace can be edited for J0only

Tx trace can be edited for J0, J1only

Description of Alarms (…contd.)

HP/LP-PLM (SLM) (Default action is to “Report PLM, but no Downstream AIS”) Mismatch in ‘own’and ‘received’ signal label

in C2 byte for at least 5 frames (for AU4/AU3/TU3)

in V5 byte, bits 5,6,7 for at least 5 multi-frames (for TU2/12/11)

ADM 1 ADM 2

ex.

AU Sig. Label TUG-structured

UNEQuipped AU Sig. Label TUG-ST UNEQ TUG-ST UNEQ HP-PLM (SLM) HP-PLM (SLM) E1 VC12 AU has no XC Asynch. C4 TUG ST E1 VC12 VC4 VC12 E1 ADM 1 ADM 3 ex. ADM 2 Asynch. C4 TUG ST Asynch. C4 TUG ST Asynch. C4 TUG ST

Masking of Alarms

Why?

Do not want to crowd the alarm reporting page ( and thereby confuse the user) with those alarms, not required for unearthing the root cause

When? (The logics)

Logic 1 (when the alarms are related)

if ( FC1 ==> FC2 but FC2 =/=> FC1 )

then ( Mask FC2 in presence of FC1 )

Note:When FC1clears, FC2 may or may notclear – in the later case FC2will be reported now

ex. 1a) LOS ==> LOF but LOF =/=> LOS 1b) LOS ==> HP-UNEQbut HP-UNEQ=/=> LOS 2) AU-AIS reported because of MS/AU-AIS generated

==> HP-RDI and

TU-AIS & LP-RDI(s) reported (if TU object(s) are there) but not vice-versa

4) AU/TU-AIS reported ==> AU/TU-LOP but not vice-versa 3) HP-UNEQ because of no XC at other end

Masking of Alarms (…contd.)

Note:When FC1clears, FC2 will be reported

Logic 2 (when the alarms are not related)

if ( FC1 has higher priority than FC2 )

then ( Mask FC2 in presence of FC1 )

ex. 1) AU/TU-LOP has higher priority than HP/LP-UNEQ

(if one is not getting the starting location of VC, how to look at what is happening within VC) 2) HP/LP-TIM, if action is chosen as “Report TIM, Downstream AIS” (i.e. traffic affecting)

has higher priority than HP/LP-RDI

(first correct received problem, then only look for problem in other direction) 3) HP/LP-TIM has higher priority than HP/LP-PLM

(first correct mis-connection, then see signal label problem within correct correction) 4) HP/LP-UNEQ has higher priority than HP/LP-TIM (even if traffic affecting)

Secondary Suppressed Alarms (SSA)

AIS and RDI are secondary alarms – they are “indications”, not root causes

E1 VC12 VC12 VC12 E1 ADM 1 ADM 3 ex. ADM 2

These alarms on a pass-through node is normally not reported in the main alarm page, they are reported in a separate page called “suppressed secondary alarms page”

These alarms on a path terminating node is reported in the main alarm page as

“terminating” alarms

AU-AIS and HP-RDI are not suppressed, even for pass-through nodes, for Tejasproducts

Traffic affecting FC TU-AIS (terminating)

Alarm Propagation Examples

For every example,

Assumption(s) is/are stated

Root Cause(s) is/are stated

Diagrammatic representation is made

(OFCs are shown in cyan)

Alarm(s) generated / condition(s) generated for reporting alarms is/are

shown in black

Alarm(s) existing at a port is/are shown in red

Alarm(s) masked at a port is/are covered with

Alarm(s) reported at secondary supprressed alarm page is/are shown

in pink, italicised

Alarm Propagation Examples (…contd.)

Example 1

A B

Assumption: AU-4 Mapping on both ports Root Cause: NO XConnect on both ports

AU4 Signal Label Unequipped

HP-RDI

HP- UNEQ

HP-RDI AU4 Signal Label Unequipped

HP- UNEQ

HP-RDI

HP-RDI

Note: 1) if AU-3 mapping, then what happens?

Alarm Propagation Examples (…contd.)

HP-RDI

HP- UNEQ

AU4 Signal Label Unequipped Signal Label TUG-structure

HP-SLM

HP-RDI

TU-LOP

Example 2

Assumption: AU-4 Mapping on both ports, Root Cause: NO XConnect on the port of B

A B

E1

VC12

Invalid TU Pointer value LP-RDI

Note: LP-RDI is not reported on B (See Rule 3a)

HP-SLM default action is “report SLM, no downstream AIS”

LOS MS-AIS AU-AIS TU-AIS MS-RDI HP-RDI LP-RDI

Alarm Propagation Examples (…contd.)

VC-12 VC-12

E1 E1

A B C

(Reg.)

Example 3

Assumption: AU-4 Mapping on both ports of A & C

Root Cause: Fiber cut in the link from A to B

AIS

MS-RDI HP-RDI LP-RDI

Note: The Reg. can not generate any RDI

LOS

MS-RDI HP-RDI LP RDI

Alarm Propagation Examples (…contd.)

MS-AIS LP RDI MS-RDI HP-RDI E1 _E1 VC-12 VC-12 A B C Example 4

Assumption: AU-4 Mapping on all ports Root Cause: Fiber cut in the link from A to B

VC-12

ADM B VC-12 PT

TU AIS

Note: Only TU-AIS is reported on Node C (See Rule 4c)

LP RDI

LOS

MS-RDI HP-RDI LP RDI

Alarm Propagation Examples (…contd.)

MS-AIS LP RDI MS-RDI HP-RDI E1 _E1 VC-12 VC-12 A B C Example 5

Assumption: AU-4 Mapping on all ports Root Cause: Fiber cut in the link from A to B

VC-4

ADM B VC-4 PT

Note: Only AU-AIS is reported on Node C (See Rule 4c) LP-RDI on B is not reported (See Rule 3b)

AU AIS TU AIS

Invalid TU Pointers (1-1-2) TU-LOP (1-1-2) A B C D E1 (2) VC-12 (1-1-2) Example 6

Assumption: AU-4 Mapping on all ports Root cause: NO XConnect on B, C & D for (1-1-2)

E1 (1) E1 (1)

VC-12 (1-1-1) LP RDI

(1-1-2)

Note: Why E1(1) is shown?

LP-RDI is not reported on B (See Rule 3a)

Invalid TU Pointers (1-1-2) TU-LOP (1-1-2) LP RDI (1-1-2)

Note: LP-RDI at node B is secondary suppressed

TU-AIS at node A is reported as terminating alarm

Alarm Propagation Examples (…contd.)

VC-12 (1-1-2)

A B C D

Example 7

Assumption: AU-4 Mapping on all ports Root cause: NO XConnect on C & D for (1-1-2)

E1 (1) E1 (1) VC-12 (1-1-1) E1 (2) VC-12 (1-1-2) TU-AIS (1-1-2) TU AIS (1-1-2) LP RDI (1-1-2) LP-RDI (1-1-2)

Invalid TU Pointers (1-1-2) TU-LOP (1-1-2) LP RDI (1-1-2)

Note: K-L-M value need not remain same throughout a particular LP, alarms will be reported accordingly on different objects

Alarm Propagation Examples (…contd.)

TU-AIS (1-1-2) TU AIS (1-1-2) LP RDI (1-1-2) LP-RDI (1-1-2) VC-12 (1-1-2) A B C D Example 8

Assumption: AU-4 Mapping on all ports Root cause: NO XConnect on C for (1-1-2)

E1 (1) E1 (1) VC-12 (1-1-1) E1 (2) VC-12 (1-1-2) _E1 (2) VC12(1-1-2) Invalid TU Pointers (1-1-2) TU-LOP (1-1-2) LP RDI (1-1-2)

Invalid TU Pointers (1-1-1) TU-LOP (1-1-1) LP-RDI (1-1-1)

Note: LP-RDI from A is not reported on B (See Rule 3b). Why assumption on SLM?

Alarm Propagation Examples (…contd.)

A B C VC-12(1-1-1) VC-4 VC-12(1-1-2) VC-12(1-1-2) E1 (1) E1 (2) E1(2) Example 9

Assumption: AU-4 Mapping on all ports, Root cause: NO XConnect on C for (1-1-1)

VC4 PT at node B,

LOS MS-RDI HP-RDI LP RDI TU AIS LP RDI MS-AIS LP RDI MS-RDI HP-RDI

Alarm Propagation Examples (…contd.)

VC-12 VC-12 VC-12 E1 _E1 A B C Example 10 (with SNCP)

Assumption: AU-4 Mapping on all ports Root cause: Fiber-cut in the link from A to B

W A-B-C, P A-D-C

VC-12

Note: SNCP is always uni-directional & for

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