H35-211_V2.5 HCIP-Access V2.5 Questions and Answers

The ONT details pane in eSight displays access-port attributes (admin/state, type), Ethernet rate/speed/duplex, and PON optical module telemetry such as temperature and Tx/Rx optical power for condition monitoring and troubleshooting.

The OLT’s anti–IP-attack (control-plane protection) function identifies and rate-limits abnormal or attack traffic to protect the CPU. It does not block legitimate management protocols such as Telnet/SSH by design. Remote management remains available when sourced from permitted hosts and within configured thresholds; administrators can also use trusted-host/ACL policies if needed.

A single-layer VLAN is limited by the IEEE 802.1Q VLAN ID space (1–4094), i.e., about 4K VLANs. In large PON deployments, when you must separate multiple services (e.g., HSI, VoIP, IPTV) and the user scale approaches or exceeds the 4K ceiling, a dual-layer VLAN (QinQ) design is required to extend the VLAN namespace and implement hierarchical isolation (access VLAN + service/aggregation VLAN).

IGMP is the host-side membership protocol: the first-hop router (querier) uses IGMP Queries/Reports/Leaves to manage host participation in multicast groups and to ensure forwarding state reflects receiver interest. PIM-DM/PIM-SM build distribution trees between routers, and MSDP shares source information between PIM-SM domains—they are not used by hosts.

An Ethernet port protection group is a 1:1 protection mechanism that improves reliability through active/standby switching. It does not aggregate bandwidth—the standby port does not forward traffic unless a switchover occurs. If increased bandwidth is required, technologies such as LACP are used instead.

IP multicast is designed for one-to-many delivery, allowing a single source stream to be replicated in the network only where branching is required. Compared with sending multiple unicast copies, multicast significantly reduces bandwidth consumption on shared links and provides efficient point-to-multipoint distribution. This is the core rationale for using multicast in video/TV services on campus and access networks.

Huawei access security recommends limiting MAC learn counts per port/VLAN, and using anti-MAC-spoofing bindings: either automatic (dynamic) bindings generated by the system or manual static MAC bindings to the service/port. Simply replacing a terminal is not a network-side mitigation method and is not listed as a protection measure.

In IEEE 802.1AX/802.3ad LACP operation, timeout detection relies on a multiplier of three consecutive LACP intervals. In short-timeout mode, the default period is ~1 s; if 3 intervals pass without receiving LACPDUs, the peer is considered expired and the member is removed (treated as Down for aggregation). Huawei implements this standard behavior for port-member validity in an Eth-Trunk.

(Reference: HCIP-Access V2.5 – Link Aggregation/LACP timers and member aging; IEEE LACP short-timeout 3× interval rule.)

Huawei OLTs support Eth-Trunk (link aggregation) with two standard modes: Static aggregation and Dynamic aggregation (LACP). These provide bandwidth expansion and redundancy on NNI uplinks. “Automatic” is not a defined mode; and “manual” is not used as a separate mode name in OLT Eth-Trunk configuration.

PITP (Port Identification Transparent Transmission) is used on access networks to carry a user’s physical access-location to the upper AAA/BRAS. It has two working forms: P-mode (PPPoE+)—injecting location identifiers into PPPoE discovery—and V-mode (Vendor-tag)—carrying vendor/location tags transparently upstream. The purpose is to let the upper server associate user credentials with access location and, by policy, restrict roaming. Options A, B, D, and E correctly describe these behaviors/terms. Option C is inaccurate as written: PITP itself does not “bind the authentication” or inherently “avoid theft/roaming”; it only delivers location info. Preventing credential theft/roaming is achieved by AAA/BRAS policy that uses the PITP-carried location, not by PITP alone.

Huawei Anti-MAC-Spoofing binds the source MAC to the service flow/port to prevent address forgery. It is functionally exclusive with certain per-VLAN MAC check features (e.g., WMAC, SC, PPPoe-SMAC) to avoid conflicting validation logic. For IPoE users with fixed IP, operators typically configure static bindings/entries so that address and access policies remain consistent.

Option D is wrong: disabling Anti-MAC-Spoofing and removing fixed entries can affect service behavior; if forwarding is interrupted, that does impact user service—so the statement is self-contradictory and incorrect.

For IPv4 multicast, the MAC mapping uses 01-00-5E followed by the low-order 23 bits of the multicast IP address. Because an IPv4 multicast address has 28 variable bits (224/4), 5 bits are not mapped to the MAC. Therefore, 2⁵ = 32 distinct multicast IP addresses can map to the same multicast MAC address.

Huawei QoS describes PQ (Priority Queuing) as the strict-priority scheduler ensuring that high-priority queues are served first before lower-priority queues. WRR/DRR/RR are weighted or round-robin modes intended for fair sharing and do not guarantee strict preemption for latency-sensitive traffic. Therefore, PQ is selected for higher-priority services (e.g., voice, control).

With ONT Zero-Touch Provisioning (ZTP) enabled on eSight, newly discovered ONTs can be automatically identified and provisioned by pushing service templates from eSight. This removes the need for advance (preset) service configuration on the OLT during incremental onboarding; the OLT simply accepts the provisioning delivered by eSight.

XG-PON encapsulates user data into XGEM frames. The XGEM Port-ID field is 12 bits, allowing identification of logical connections (GEM ports) per ONU. This mirrors the 12-bit Port-ID used in GPON GEM.

In IP multicast, only one copy per multicast group (program) is forwarded upstream, regardless of how many users are watching it. Replication happens downstream at the access/edge, not toward the core. Therefore the upstream traffic equals the number of active multicast groups × per-group bitrate:

20 programs × 2 Mbit/s = 40 Mbit/s.

This behavior is consistent with Huawei’s multicast feature descriptions and general multicast principles (IGMP/PIM), which explain that multicast traffic is sent as a single flow per group and replicated only where branching occurs, not multiplied by user count.

Huawei GPON design recommends at most two splitting stages and a total split ratio within the optical power budget (commonly up to 1:64 for standard budgets).

A: 1:2 × 1:16 = 1:32 (valid).

C: 1:8 × 1:8 = 1:64 (valid under standard budgets).

D: 1:2 × 1:8 = 1:16 (valid).

B: 1:16 × 1:16 = 1:256, which exceeds typical GPON budgets and recommended engineering practice. Hence B is the incorrect networking.

In Huawei access network devices (such as MA5800, EA5800, and SmartAX series), the DHCP Option 82 (Relay Agent Information Option) feature is used to identify the source location of DHCP requests coming from users connected to access ports.

This helps the DHCP server assign IP addresses based on access topology information, such as slot, port, and VLAN IDs.

When Option 82 is enabled globally and within the VLAN service profile, and the port/service-port is configured to allow user-side packets to carry Option 82, the device processes incoming DHCP requests as follows:

If a user-side DHCP packet does not contain Option 82:→ The device automatically adds local Option 82 information (e.g., circuit ID, remote ID) before forwarding it to the DHCP server.

If a user-side DHCP packet already contains Option 82:→ The device removes (strips) the existing Option 82 field to prevent spoofing or inconsistent location data.→ Then it adds its own local Option 82 information (accurate relay agent data based on the device’s configuration).→ The modified packet is then forwarded to the DHCP server.

This ensures that only trusted network-side Option 82 data is passed along, maintaining accurate user-location binding for IP address management and security.

Therefore, the correct behavior is:

The access device strips the Option 82 field from the user packet and adds its own local Option 82 information.

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

HCIP-Access V2.5 Study Guide – “Huawei Campus Network Overview” Chapter, Section: DHCP Relay and Option 82 Mechanism

Huawei MA5800/EA5800 Configuration Guide – IP Service → DHCP Relay and Option 82 Configuration

Huawei Enterprise Networking Product Documentation: “Understanding DHCP Option 82 Processing”

Huawei Access Network Feature Guide, Section: Processing Policies of DHCP Packets with Option 82

With PITP enabled and Vendor-tag switching allowed, Huawei OLTs support transparent transmission and augmentation: the OLT keeps the user-carried Vendor tag and appends the local Vendor tag (e.g., slot/port/location), ensuring the upstream AAA/BRAS receives both the access-side identity and the OLT’s own location identity. Simply adding only the local tag (A) loses user-side info; forwarding unchanged (B) omits OLT location; discarding (D) contradicts the feature intent.

IPTV over FTTH relies on multicast control; therefore the essential U2000 template is the IGMP template, which defines IGMP behaviors, program authorization binding, and multicast parameters used by the OLT/ONT. MGC applies to voice (VoIP), and SNMP pertains to NMS communication rather than IPTV service logic; value-added templates are not mandatory for basic IPTV.

On Huawei OLTs, the standard QoS pipeline for upstream packets is: first perform traffic classification (identify flows), then marking (set CoS/DSCP as required), next apply traffic policing (rate-limit and color traffic), followed by congestion avoidance (AQM such as RED/WRED), and finally congestion management (queue scheduling/priority queuing). This ordered sequence ensures correct identification and marking before any rate enforcement, and that packets encounter AQM prior to scheduler-based dequeue.

When other ONUs on the same PON port can register but one ONU cannot, troubleshooting focuses on the individual ONU or its drop fiber. Valid possible causes include: ONU not powered, fiber/connector issues, password/SN mismatch, or faulty ONU hardware. Since hardware failure of that specific ONU is one of the recognized possible causes, the statement is true.

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.

In AQM, high-priority queues are given more tolerant (larger) thresholds so they are less likely to be dropped early. Setting a smaller early-drop threshold for high priority would increase their loss probability, which contradicts QoS objectives—thus A is incorrect. Descriptions in B, C, and D align with Huawei’s treatment of congestion avoidance: RED/WRED proactively drops to stabilize queues and can reduce delay variation; tail drop at full buffer can lead to global TCP synchronization.

In GPON, DBA (Dynamic Bandwidth Allocation) operates in the upstream direction. The OLT grants upstream transmission opportunities to ONTs by assigning T-CONT bandwidth (Fixed/Assured/Non-Assured/Best-Effort) within upstream frames. The downstream direction is a continuous broadcast stream from the OLT at the fixed GPON line rate; user traffic is multiplexed without DBA. Hence, DBA is upstream-only; downstream traffic is not DBA-scheduled.

NCE supports on-demand (manual) and policy-driven (automatic) performance data dumps. In both modes, data filtered by configured criteria is exported to files stored locally on the NCE server for subsequent analysis or archiving.

For IPv4 multicast, the destination MAC is derived by mapping the lower 23 bits of the multicast IP address into the OUI 01-00-5E. The 4th MAC byte is the lower 7 bits of the IP’s second octet (so it ranges 00–7F), and the 5th and 6th MAC bytes are the third and fourth IP octets directly:

Multicast OUI: 01-00-5E

IP: 227.120.1.32

2nd octet = 120 (0x78). Its lower 7 bits are still 0x78 (since the MSB is 0).

3rd octet = 1 (0x01)

4th octet = 32 (0x20)

Therefore the MAC is 01-00-5E-78-01-20 → option C.

(This mapping aligns with standard IPv4 multicast-to-Ethernet rules described in Huawei’s multicast overview sections in HCIP-Access materials and Huawei OLT product guides.)

XG-PON (10G GPON) adopts XGEM framing. Compared with GPON’s 12-bit GEM Port-ID, XGEM expands the Port-ID field to 16 bits, increasing the number of logical data flows that can be identified per ONU/OLT and improving service granularity. Hence the correct length is 16 bits.

In an H.248 (Megaco) control model, the MGC is the controller that issues provisioning/connection-control commands such as Add, Modify, Subtract, AuditValue, AuditCapabilities to the MG. The MG (Media Gateway) can initiate only specific messages toward the MGC to announce state changes or report detected events—namely ServiceChange (to indicate restart, failure, availability changes, etc.) and Notify (to report observed events collected per event descriptor). Therefore, among the listed options, the commands that the MG itself can send are ServiceChange and Notify.

In NGN architectures, services (voice, video, data) converge over a packet-based backbone. The core switching layer provides the unified transport using IP/MPLS and related QoS mechanisms, delivering high reliability and large-capacity switching for all upper-layer services. The control and management layers orchestrate services, while the edge/access layer aggregates users—but the packet-based integrated transmission platform itself is the role of the core.

In 10G-EPON (IEEE 802.3av), the wavelength plan uses 1577 nm downstream and 1270 nm upstream. The 1270 nm upstream is used in both asymmetric and symmetric 10G-EPON profiles.