Huawei H35-211_V2.5 - HCIP-Access V2.5

Type B protection (OLT-side + feeder protection via 2×2 optical splitter) is designed for automatic protection switching (APS) upon detecting faults such as LOS/LOF on the working port or feeder. The system automatically switches to the standby PON port/feeder without manual intervention (manual cutover is optional but not required for protection).

(Reference: HCIP-Access V2.5 – GPON Type A/B/C protection definitions, trigger conditions, and APS behavior.)

Huawei multicast guidance stresses IGMP version compatibility: devices running an earlier version must interoperate only with hosts using the same or earlier version, otherwise v3 messages may not be processed. In Huawei’s multicast feature guidance for access devices (OLT side vs. user side), the behavior documented is that when the device is operating in IGMPv2, IGMPv3 Report messages from terminals are not processed—interoperation is restored only after the terminal/device side is downgraded to v2 (often driven by periodic queries that induce hosts to respond in v2). This maps operationally to dropping unsolicited IGMPv3 Reports when the OLT is fixed to v2. Huawei also recommends ensuring the device runs an IGMP version the same as or later than member hosts to avoid such loss. Therefore, with OLT fixed at v2, an incoming v3 Join is discarded.

Live TV uses multicast, while VOD uses unicast. If VOD works but live TV is a black screen, typical causes are multicast service-path/config mismatches or priority starvation for multicast control/traffic:

C: If the ONU uses different VLANs for VOD and live but the OLT has only one video service flow, multicast frames will not match the correct service-port, causing black screen.

D: A low-priority traffic profile for multicast join/report or stream on the OLT uplink may drop IGMP joins or multicast packets under load, resulting in black screen while unicast VOD still passes.

Queue scheduling choices such as PQ or DWRR (A/B) are generic congestion schemes; by themselves they are not direct root causes of a live-only black screen unless mis-classified, whereas C and D are recognized multicast-specific fault points.

In Huawei IPTV troubleshooting, mosaic/flash/jerky or intermittent picture typically results from packet loss or bit errors. Common causes include: optical power near the receiver sensitivity threshold causing FEC/BER spikes (A); loss of I-frames (key frames) either in the encoder/compression stage (B) or due to line transmission loss/jitter (D); and device rate-limit (CAR/policing) misconfiguration that drops packets under burst traffic (C). Any of these can yield unstable display.

IGMP Snooping is a Layer-2 function that listens to IGMP control packets between hosts and the multicast querier. Upon receiving a host’s Membership Report (Join) for group G, the switch learns that the ingress port is a member port for G and adds that port to the group’s forwarding entry, so multicast traffic for G is forwarded only to those learned member ports (saving bandwidth and avoiding flooding). Huawei’s official documentation describes IGMP Snooping exactly in this way.

Huawei devices support independent mapping/remarking for inner and outer VLAN priorities (802.1p CoS) when QinQ is used. Operators can define distinct mapping tables or remark rules per tag. Option A is incorrect (priorities can be derived or remarked, not “must be” tag-in-packet), option C is incorrect because mapping profiles are configurable, and option D confuses VLAN IDs with priorities; inner/outer CoS can be mapped independently for inbound/outbound directions.

Standard OTDR operation allows you to configure multiple acquisition parameters:

Measurement range (distance range): sets the maximum span to be traced; best practice is typically 1.5–2× the fiber length under test.

Wavelength: select test wavelength(s), e.g., 1310/1550 nm for SM fiber, to observe different loss characteristics.

Mode: vendors provide real-time/average (or similar) acquisition modes to stabilize traces.

Pulse width: controls dynamic range vs. event resolution; longer pulses see farther but increase dead zones, while shorter pulses improve resolution at the cost of range.

These are documented in foundational OTDR references and application notes.

For enterprise/private multicast, Huawei adopts the administratively scoped range 239.0.0.0/8 for internal multicast groups. 232/8 is typically used for SSM in public domains, 224/8 contains link-local and well-known groups, and 225/8 is not defined as the preferred private scope.

For OLT uplink (NNI) protection groups (timedelay/weight, etc.), Huawei requires that each physical port belongs to one protection group only to avoid conflicting switchover control. A member port cannot be part of multiple protection groups simultaneously.

In Huawei’s 10G GPON (Gigabit-capable Passive Optical Network) system, different optical wavelengths are used for upstream and downstream transmission to ensure bidirectional communication over a single fiber.

According to the ITU-T G.987.x series and Huawei’s Access Network Technical Documentation, the wavelength plan for 10G GPON (XG-PON) is as follows:

Downstream (OLT → ONU): 1577 nm

Upstream (ONU → OLT): 1270 nm

This separation of wavelengths allows both transmission directions to occur simultaneously using WDM (Wavelength Division Multiplexing) on the same optical fiber, minimizing interference.

Huawei OLTs such as the MA5800 and EA5800 series follow this standard exactly — supporting 10G GPON (XG-PON) with downstream at 1577 nm and upstream at 1270 nm.

Hence, the correct answer is 1577 nm.

Answer: B

References (Aligned with HCIP-Access V2.5 and Huawei Technical Sources):

HCIP-Access V2.5 Study Guide – “Huawei Campus Network Overview” Chapter, Section: PON Technology Overview

Huawei 10G GPON (XG-PON) Technical White Paper

ITU-T G.987.2: 10-Gigabit-capable Passive Optical Networks (XG-PON): Physical Media Dependent (PMD) Layer Specification

Huawei MA5800 Product Description – 10G GPON Port Wavelength Specifications