Cisco ONS 15454 SDH Specifikace stáhnout pdf (Strana 47)

Cisco ONS 15454 SDH Product Overview, R3.4

September 2002

Cisco ONS 15454 SDH Product Overview

Timing

Figure 25 ONS 15454 SDH timing example

Synchronization Status Messaging

Synchronization status messages (SSMs) are used as a mechanism for managing

synchronization (or network timing) in SDH networks. It allows BITS timing

sources, nodes, and combinations of the two to exchange information about the

quality of timing sources. SSMs are carried on bits 5 to 8 of SDH overhead byte

S1. SSMs enable SDH devices such as the ONS 15454 SDH to automatically

select the highest quality timing reference and to avoid timing loops (particularly

in ring architecture).

Node 4

Timing Line

Ref 1: Slot 6

Ref 2: Slot 5

Ref 3: Internal (ST3)

Node 2

Timing Line

Ref 1: Slot 5

Ref 2: Slot 6

Ref 3: Internal (ST3)

Node 1

Timing External

Ref 1: BITS1

Ref 2: BITS2

Ref 3: Internal (ST3)

Node 3

Timing Line

Ref 1: Slot 5

Ref 2: Slot 6

Ref 3: Internal (ST3)

Timing

Out A/

BITS1

out

Timing

Out B/

BITS2

out

BITS1

source

BITS2

source

Third party

equipment

Slot 5

Slot 6

Timing In

71437

1 2 ... 42 43 44 45 46 47 48 49 50 51 52 ... 55 56

Komentáře k této Příručce

Žádné komentáře

Cisco ONS 15454 SDH Specifikace Strana 47

Komentáře k této Příručce

Související produkty a manuály pro Bezpečnostní systémy pro řízení přístupu Cisco ONS 15454 SDH