Huawei H35-210_V2.5 Practice Test - Questions Answers, Page 4

Vectoring in VDSL2 :

Vectoring is a technology used to mitigate crosstalk (interference between adjacent copper lines) in VDSL2 systems, improving data rates and stability.

Crosstalk occurs when signals from one line interfere with signals on another line, especially in bundled copper cables.

Pre-coder Technology :

Pre-coding is a key technique used in vectoring for downstream transmission.

It works by pre-distorting the transmitted signal at the DSLAM (Digital Subscriber Line Access Multiplexer) to cancel out the expected crosstalk at the receiver (CPE).

This ensures that the received signal at each CPE is free from interference caused by other lines.

Other Options :

fdps : Not a recognized term in the context of vectoring or VDSL2.

Canceller : While cancellation is part of vectoring, the specific term 'Canceller' is not used in this context.

Postponed : This is unrelated to vectoring or crosstalk mitigation.

Why C?

Pre-coding is the correct technology used in vectoring to cancel downstream crosstalk in VDSL2.

Thus, the correct answer is C .

HCIA Huawei ACCESS Official Documentation , Chapter: VDSL2 Vectoring.

ITU-T G.993.5 Standards for Vectoring in VDSL2 .

Vectoring Classification :

Vectoring is primarily classified into two types based on the scope of crosstalk cancellation:

System-Level Vectoring (SLV) : Applies to all lines within a single DSLAM or cabinet.

Node-Level Vectoring (NLV) : Applies to lines across multiple DSLAMs or nodes.

However, these are not the only classifications. Other implementations, such as hybrid approaches, may also exist depending on the network design.

Why FALSE?

The statement incorrectly claims that vectoring is classified only as SLV and NLV, ignoring other possible implementations or variations.

Thus, the correct answer is B .

HCIA Huawei ACCESS Official Documentation , Chapter: VDSL2 Vectoring Architectures.

ITU-T G.993.5 Standards for Vectoring in VDSL2 .

Firewall Settings (Option A) :

Incorrect firewall settings on the PC can block outbound HTTP/HTTPS traffic, preventing access to web pages.

Browser Settings (Option B) :

Misconfigured browser settings (e.g., proxy settings in Internet Explorer) can prevent the browser from connecting to websites.

Upper-Layer Device Configuration (Option C) :

Incorrect configurations on upper-layer devices (e.g., NAT, routing, or DNS settings) can prevent proper communication between the user and external networks.

Website Server Fault (Option D) :

If the issue affects all web pages , it is unlikely to be caused by a single website server being faulty. This option is irrelevant in this scenario.

Why A, B, C?

These options directly address potential issues that could prevent access to all web pages after successful authentication.

Thus, the correct answers are A, B, C .

HCIA Huawei ACCESS Official Documentation , Chapter: Broadband Troubleshooting.

Broadband Access Network Fault Analysis by Huawei.

PPP Protocol Overview :

PPP (Point-to-Point Protocol) uses the PROTOCOL field in its header to identify the type of encapsulated protocol.

Protocol Field Values :

0x8021 : Indicates IPCP (Internet Protocol Control Protocol) , which is used to negotiate IP-related parameters during PPP session establishment.

0xC021 : Indicates LCP (Link Control Protocol) , which is used for establishing, configuring, and testing the PPP link.

0x002B : Indicates IPX (Internetwork Packet Exchange) .

0x0021 : Indicates IP (Internet Protocol) .

Why A?

The value 0x8021 corresponds to IPCP , making it the correct answer.

Thus, the correct answer is A .

HCIA Huawei ACCESS Official Documentation , Chapter: PPP Protocol.

RFC 1661: PPP Protocol Specification .

DHCP Relay Agent Functionality :

A DHCP relay agent forwards DHCP packets between clients and servers located in different subnets.

It modifies the packet headers to ensure proper delivery:

Converts broadcast packets from clients into unicast packets to forward them to the DHCP server.

Converts unicast responses from the DHCP server back into broadcast packets for delivery to clients.

Why C?

The DHCP relay agent performs bidirectional conversion between broadcast and unicast packets to facilitate communication between clients and servers in different subnets.

Other Options :

A : Incorrect because DHCP relay agents do not convert packet types (e.g., Ethernet vs. non-Ethernet).

B : Incorrect because the relay agent handles both broadcast-to-unicast and unicast-to-broadcast conversions.

D : Incorrect because the relay agent modifies unicast packets during forwarding.

Thus, the correct answer is C .

HCIA Huawei ACCESS Official Documentation , Chapter: DHCP Relay Agent.

RFC 2131: DHCP Protocol Specification .

DHCP Overview :

DHCP (Dynamic Host Configuration Protocol) is used to automate the assignment of IP addresses and other network configuration parameters (e.g., subnet mask, default gateway, DNS servers).

It centralizes IP address management, reducing manual configuration errors.

Key Components :

DHCP Server : Allocates IP addresses and other parameters to clients.

DHCP Client : Requests and receives configuration from the DHCP server.

DHCP Relay : Forwards DHCP packets between clients and servers in different subnets.

Conflict Detection Mechanism :

DHCP includes a mechanism to detect and resolve IP address conflicts.

Before assigning an IP address, the DHCP server sends an ICMP Echo Request to check if the address is already in use. If no response is received, the address is considered available.

Why TRUE?

The statement accurately describes the functionality of DHCP, including centralized management, parameter distribution, and conflict detection.

Thus, the correct answer is A .

HCIA Huawei ACCESS Official Documentation , Chapter: DHCP Protocol.

RFC 2131: DHCP Protocol Specification .

Service Types and Transmission :

AP/PC (Data Services) : These services are typically Ethernet-based and encapsulated into Ethernet frames before being transmitted over the PON network.

POTS (Voice Services) : Voice services can be either TDM-based or packetized. In modern GPON/XGS-PON systems, POTS is often packetized into Ethernet frames.

CATV (Video Services) : CATV uses a separate wavelength (1550 nm) for analog or digital video transmission.

Wavelength Division Multiplexing (WDM) :

GPON/XGS-PON systems use WDM to transmit multiple services over a single fiber:

One wavelength (1490 nm or 1577 nm) is used for data services (Ethernet).

Another wavelength (1550 nm) is used for CATV.

Analysis of Options :

Option A : Incorrect because CATV is not encapsulated into Ethernet frames; it uses a separate wavelength.

Option B : Correct because CATV uses a separate wavelength, and other services are encapsulated into Ethernet frames before PON transmission.

Option C : Incorrect because POTS services are typically packetized into Ethernet frames in modern systems, not directly encapsulated in GEM frames.

Option D : Incorrect because POTS is not transparently transmitted in modern GPON/XGS-PON systems.

Thus, the correct answer is B .

HCIA Huawei ACCESS Official Documentation , Chapter: GPON Service Encapsulation.

ITU-T G.984.x Standards for GPON .

2.4 GHz Frequency Band :

The 2.4 GHz band is divided into 14 overlapping channels, each 20 MHz wide.

However, only three channels (e.g., Channels 1, 6, and 11 in North America) are non-overlapping and can be used simultaneously without interference.

Why TRUE?

By using non-overlapping channels (e.g., 1, 6, and 11), wireless networks can operate concurrently without significant interference.

Thus, the correct answer is A .

HCIA Huawei ACCESS Official Documentation , Chapter: WLAN Frequency Bands.

IEEE 802.11 Standards for WLAN .

VLAN Attributes :

Common VLAN : Used for standard VLAN tagging, where a single VLAN tag identifies the VLAN.

QinQ VLAN : Adds an additional VLAN tag for double-tagging, typically used in carrier networks.

Sub VLAN : Part of a Super VLAN configuration, used for IP address conservation.

Stacking VLAN : Similar to QinQ, used for double-tagging.

Scenario Analysis :

The school uses a single VLAN tag to identify services by type (e.g., student, faculty, administration).

Since only one VLAN tag is used, the appropriate VLAN attribute is Common .

Why A?

Common VLAN is the simplest and most suitable choice for scenarios requiring single-tag VLAN identification.

Thus, the correct answer is A .

HCIA Huawei ACCESS Official Documentation , Chapter: VLAN Design.

IEEE 802.1Q VLAN Tagging Standards .