Huawei HCIP-Datacom flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

OSPF neighbor state Full

The state in which OSPF routers have synchronized their link-state databases and can route traffic through each other. Full adjacency is required for DR/BDR and point-to-point neighbors.

OSPF DR/BDR election

Election based on interface priority (default 1, higher wins) then Router ID (higher wins). It is not preemptive; a new router cannot become DR until the current DR fails. DRother routers form 2-Way state with each other.

OSPF LSA types

Type 1 Router, Type 2 Network, Type 3 Summary, Type 4 ASBR Summary, Type 5 External, Type 7 NSSA External. Type 1 and 2 are intra-area; Type 3 is inter-area; Type 5 is flooded throughout the OSPF domain.

OSPF virtual link

A logical point-to-point link through a transit area (not stub) that connects a partitioned area to the backbone (Area 0). Configured on the ABRs with 'vlink-peer' using the Router ID of the remote ABR.

IS-IS DIS election

The Designated Intermediate System is elected per broadcast network based on interface priority (default 64) then System ID. Unlike OSPF DR, DIS election is preemptive, and there is no backup DIS.

IS-IS NET address

Network Entity Title: AFI (1 byte, 49 for private) + Area ID (1-12 bytes) + System ID (6 bytes) + NSEL (1 byte, 00). Example: 49.0001.0000.0000.0001.00. All routers in the same area share the Area ID.

BGP Weight attribute

A Cisco/Huawei proprietary attribute local to the router, not propagated in updates. Higher weight is preferred first in the BGP best-path algorithm. Default weight is 0 for learned routes and 32768 for locally originated routes.

BGP Local Preference

A well-known discretionary attribute propagated within an AS (not to EBGP peers). Higher value is preferred. Default is 100. Used to influence outbound traffic from the local AS.

BGP MED attribute

Multi-Exit Discriminator, an optional non-transitive attribute used to influence inbound traffic from a neighboring AS. Lower MED is preferred. By default, MED is compared only among routes from the same neighboring AS.

BGP route reflector

A router that reflects routes from a client to other clients and non-clients, reducing the need for a full IBGP mesh. It uses Cluster ID and Originator ID to prevent loops. Configured with 'peer reflect-client'.

BGP AS_Path loop prevention

A router rejects an EBGP update whose AS_Path already contains its own AS number. IBGP does not prepend AS numbers. AS_Path length also influences best-path selection (shorter preferred).

MPLS label stack

A set of labels pushed onto a packet. The outer label is used for forwarding (swap at each LSR); inner labels identify VPNs or services. The bottom-of-stack bit (S=1) indicates the last label.

MPLS PHP

Penultimate Hop Popping: the penultimate LSR removes the outer label before forwarding to the egress LER, reducing load on the egress. It is signaled by the implicit-null label (3).

LDP label distribution

Label Distribution Protocol advertises label bindings for FECs (usually IGP prefixes). It uses UDP port 646 for discovery and TCP port 646 for session establishment. LDP sessions are triggered by IGP routes.

VXLAN VNI

VXLAN Network Identifier, a 24-bit field that identifies a Layer 2 segment over a Layer 3 network. It supports up to 16 million segments, overcoming VLAN's 4094 limit. VXLAN encapsulates frames in UDP (port 4789).

VXLAN VTEP

VXLAN Tunnel Endpoint, a device that encapsulates/decapsulates VXLAN frames. Each VTEP has a unique IP address. The tunnel is identified by the pair of VTEP IPs and the VNI.

BGP EVPN route types

Type 1 Ethernet Auto-Discovery, Type 2 MAC/IP Advertisement, Type 3 Inclusive Multicast Ethernet Tag, Type 4 Ethernet Segment, Type 5 IP Prefix. Type 2 is used for MAC learning; Type 5 for IP prefix advertisement.

QoS DSCP

Differentiated Services Code Point, a 6-bit field in the IP header (ToS/DS field) used for classification. Values 0-63; EF=46, AF11=10, AF41=34, CS6=48. Per-hop behaviors include EF, AF, and default (BE).

QoS 802.1p CoS

A 3-bit Priority Code Point field in the 802.1Q VLAN tag, values 0-7. Used for Layer 2 classification and marking. Higher values indicate higher priority; default is 0 (best effort).

Traffic policing vs shaping

Policing drops or remarks excess traffic (no buffering) and is applied on ingress or egress; shaping buffers excess traffic and delays it to smooth the rate, typically applied on egress. Policing uses token bucket; shaping uses queues.

STP root bridge election

The switch with the lowest Bridge ID (priority + MAC) becomes root. Default priority is 32768. Lower priority wins; if equal, lower MAC wins. Root bridge selection is preemptive.

RSTP port roles

Root port (best path to root), Designated port (forwarding on a segment), Alternate port (backup for root port), Backup port (backup for designated port). Edge ports are configured with 'stp edged-port' and bypass listening/learning.

MSTP region

A group of switches sharing the same region name, revision level, and VLAN-to-instance mapping. MSTP maps VLANs to multiple spanning tree instances (MSTIs); the CIST is instance 0 and spans all regions.

BPDU Guard

A feature that disables an edge port if it receives a BPDU, preventing loops from unauthorized switches. Configured with 'stp bpdu-protection' globally or per interface. The port enters error-down and can auto-recover.

Root Guard

A feature that prevents a port from becoming the root port by discarding superior BPDUs. The port enters root-inconsistent state. Used on ports where the root bridge should not be reached.

Link aggregation LACP

IEEE 802.3ad Link Aggregation Control Protocol negotiates bundling of multiple physical links into an Eth-Trunk. Modes: manual load-balance (no negotiation) or LACP (negotiation). LACP uses system priority and port priority.

Eth-Trunk load balancing

Traffic is distributed across member links using a hash of source/destination MAC, IP, or port. Configure with 'load-balance' under the Eth-Trunk. Per-flow load balancing preserves packet order within a flow.

VRRP master election

The router with the highest priority (default 100, range 1-254) becomes Master; if equal, the highest IP address on the interface wins. Preemption is enabled by default. Master sends advertisements every 1 second.

DHCP snooping

A security feature that filters DHCP messages on untrusted ports. Trusted ports (uplinks) allow DHCP server responses; untrusted ports only allow client requests. It builds a binding table of MAC, IP, VLAN, and port.

IPsec AH vs ESP

AH (protocol 51) provides authentication and integrity but not confidentiality; ESP (protocol 50) provides confidentiality, authentication, and integrity. ESP is preferred for VPNs. AH is incompatible with NAT.

IPsec IKE phases

Phase 1 establishes the IKE SA (ISAKMP SA) using main or aggressive mode; Phase 2 establishes the IPsec SA (child SA). IKEv2 uses IKE_SA_INIT and IKE_AUTH exchanges. Pre-shared keys or certificates authenticate peers.

GRE tunnel

Generic Routing Encapsulation, IP protocol 47, encapsulates passenger protocols over IP. It supports multicast and IPv6 but provides no encryption. Often combined with IPsec for secure tunnels.