Understand the role of the TTI byte in SDH networks and the key information it conveys about network elements. An essential concept for the Nokia 4A0-205 certification exam.
Table of Contents
Question
In which of the following forms does the TTI byte provide information on network elements?
A. Source (SAPI) and Destination (DAPI) Access Point Identifiers
B. Source and destination IP addresses and overhead
C. Source and destination MAC addresses
D. Source and destination time-slot identifiers
Answer
A. Source (SAPI) and Destination (DAPI) Access Point Identifiers
Explanation
In SDH (Synchronous Digital Hierarchy) networks, the Trail Trace Identifier (TTI) byte is part of the Section Overhead (SOH). Its purpose is to provide information that allows tracing the source and destination of a digital path.
Specifically, the TTI byte contains two key pieces of information:
- The Source Access Point Identifier (SAPI)
- The Destination Access Point Identifier (DAPI)
The SAPI identifies the network element that originated the digital path, while the DAPI identifies the network element that is the intended destination or termination point of the path.
By including the SAPI and DAPI, the TTI byte enables SDH network operators to verify the integrity of digital paths, ensuring that traffic is being correctly routed from its source to the intended destination. It also assists in troubleshooting by allowing operators to pinpoint where in the network a failure or misrouting is occurring.
The other answer choices do not accurately describe the information conveyed by the TTI byte:
B is incorrect because the TTI byte does not contain IP addressing information. It operates at a lower layer than IP.
C is incorrect because MAC addresses are used by Ethernet, not SDH. SDH uses different addressing mechanisms.
D is incorrect because although SDH is a time-division multiplexing technology, the TTI byte itself does not contain time-slot identifiers. It contains access point identifiers.
Therefore, A is the only correct answer. The TTI byte provides the source and destination access point identifiers (SAPI and DAPI) which are critical for tracing and validating the path of an SDH digital channel across the network.
Nokia 4A0-205 certification exam assessment practice question and answer (Q&A) dump including multiple choice questions (MCQ) and objective type questions, with detail explanation and reference available free, helpful to pass the Nokia 4A0-205 exam and earn Nokia 4A0-205 certification.