Huawei HCIA-Datacom H12-811 Cheat Sheet

Data Communication + Network Basics

8% of exam
Models ARP TCP vs UDP VRP Views

IP Network Interconnection + Interworking

27% of exam
Subnetting Route Choice Static Routing OSPF

Ethernet Switching Network Construction

28% of exam
MAC Forwarding VLAN Ports STP vs RSTP Eth-Trunk

Cyber Security Infrastructure + Network Access

8% of exam
ACL Types AAA NAT Types Traffic Filter

Network Services + Applications

5% of exam
Service Ports DHCP DORA DNS + NTP FTP vs TFTP

WLAN Basics

10% of exam
WLAN Roles CAPWAP WLAN Join Forwarding Modes

WAN Basics

3% of exam
PPP PAP vs CHAP PPPoE MPLS + SR

Network Management + O&M

3% of exam
SNMP Roles SNMP Messages O&M Checks Display Commands

IPv6 Basics

5% of exam
IPv6 Addressing Address Types Neighbor Discovery IPv6 Routing

SDN + Automation Basics

3% of exam
SDN Planes SDN APIs NFV Python Basics

Quick Facts

Exam H12-811
Version HCIA-Datacom V1.0
Languages ENU / CHS
Duration 90 minutes
Pass score 600 / 1000
Exam cost US$200
Domains 10
Largest domain Ethernet switching 28%

TCP vs UDP DA

TCP

Connection-oriented
Reliable delivery
Flow control

UDP

Connectionless
Best effort
Lower overhead
Reliability vs speed

Models + Forwarding DA

OSI Layer 1 Bits + physical media
OSI Layer 2 Frames + MAC
OSI Layer 3 Packets + IP routing
OSI Layer 4 Segments + ports
Encapsulation Adds layer headers
ARP IPv4 address to MAC
TCP Reliable connection-oriented transport
UDP Fast connectionless transport

VRP Quick Commands DA

<Huawei> User view
[Huawei] System view
system-view Enter configuration
quit One view upward
return Jump to user view
undo Negate configuration
save Persist current configuration
display current-configuration Show running configuration

OSPF Neighbor States IP

Down Init 2-Way ExStart Exchange Loading Full
2-Way: DR decision ExStart: negotiate master Exchange: share DBDs Full: synchronized

Preference vs Cost IP

Preference

Compares route sources
Lower wins

Cost

Compares OSPF paths
Lower wins
Protocol trust vs path

Route Choice Picker IP

Destination same subnet → ARP destination ( Direct delivery )
Destination remote subnet → ARP gateway ( Router forwards )
Need fixed path → Static route
Need dynamic routes → OSPF
Need fallback exit → Default route
Different prefix lengths → Longest match
Different route sources → Route preference
Same OSPF destination → Lowest cost

IPv4 + Route Choice IP

IPv4 32-bit addressing
Typical usable hosts 2^h minus 2
Network address Host bits all zero
Broadcast address Host bits all one
Default route 0.0.0.0/0
Longest match Most specific prefix wins
Route preference Lower value wins
Direct / OSPF / Static Preference 0 / 10 / 60

Static Routing + OSPF IP

ip route-static Add IPv4 static route
Floating static Larger preference becomes backup
OSPF Link-state interior protocol
Area 0 OSPF backbone
Router ID 32-bit OSPF identifier
OSPF cost Lower path cost wins
DR election Highest priority then RID
network command Enable matching interfaces

STP Root Election ET

Root: lowest priority, then lowest MAC
Lowest BID wins Root has no root port Path cost picks root port

Access vs Trunk ET

Access

One VLAN
Endpoint-facing
Untagged frames

Trunk

Multiple VLANs
Device interconnect
Tagged VLANs
One VLAN vs many

Switching Picker ET

Single endpoint VLAN → Access port
Multiple tagged VLANs → Trunk port
Mixed tag behavior → Hybrid port
Route between VLANs → VLANIF
Redundant Layer 2 links → STP
Need faster convergence → RSTP
Bundle parallel links → Eth-Trunk
Negotiate bundle membership → LACP

Ethernet + VLANs ET

MAC learning Source MAC + ingress port
Known unicast Forward matching port
Unknown unicast Flood within VLAN
VLAN Separate broadcast domain
Access port One VLAN; untagged
Trunk port Multiple VLANs; mostly tagged
Hybrid port Per-VLAN tag choice
PVID Classifies untagged ingress
VLANIF Layer 3 VLAN gateway
vlan batch Create multiple VLANs

STP vs RSTP ET

STP

802.1D
Slower convergence
Five port states

RSTP

802.1w
Faster convergence
Three port states
Classic vs rapid

STP + Aggregation ET

Root bridge Lowest bridge ID
Bridge ID Priority + MAC
Root port Best path toward root
Designated port Best path per segment
Blocked port Prevents Layer 2 loop
RSTP Faster STP convergence
Alternate port Backup root path
Eth-Trunk Logical bundled links
Manual bundle Static member selection
LACP Negotiated member selection

Basic vs Advanced ACL SE

Basic ACL

Numbers 2000-2999
Source IPv4 match

Advanced ACL

Numbers 3000-3999
Protocol and port match
Source only vs detailed

Security + Service Picker SE

Match source IPv4 only → Basic ACL
Match protocol and ports → Advanced ACL
One permanent translation → Static NAT
Many hosts share address → NAPT
Use interface address → Easy IP
Publish internal server → NAT Server
Assign IPv4 settings → DHCP
Resolve host names → DNS

ACL + AAA + NAT SE

Basic ACL 2000-2999; source IPv4
Advanced ACL 3000-3999; protocol + endpoints
traffic-filter inbound Filter entering frames
traffic-filter outbound Filter leaving frames
AAA Authentication authorization accounting
Static NAT Fixed one-to-one mapping
Dynamic NAT Public address pool
NAPT Ports share public address
Easy IP Use interface public address
NAT Server Publish inside service

DHCP DORA NE

Discover Offer Request Acknowledge
D: client discovers O: server offers R: client requests A: server acknowledges

Services + Ports NE

Telnet TCP 23; plaintext access
FTP TCP 20/21; file transfer
TFTP UDP 69; simple transfer
DHCP server UDP 67
DHCP client UDP 68
DNS TCP/UDP 53; name resolution
NTP UDP 123; clock sync
HTTP TCP 80; web transfer
DHCP relay Cross-subnet DHCP forwarding

Fit AP vs Fat AP WL

Fit AP

Managed by AC
CAPWAP control
Central policy

Fat AP

Standalone management
Local policy
No AC required
Centralized vs standalone

WLAN + WAN Picker WL

Central AP management → Fit AP + AC
Standalone AP control → Fat AP
Local user forwarding → Direct mode
Central user forwarding → Tunnel mode
Point-to-point WAN → PPP
PPP over Ethernet → PPPoE
Simple password check → PAP
Challenge-response check → CHAP

WLAN Architecture + Join WL

STA Wireless client
AP Radio access device
AC Central AP controller
Fit AP AC-managed access point
Fat AP Standalone access point
SSID Wireless network name
BSSID Radio interface identity
CAPWAP AC-to-AP tunnels
Direct forwarding AP sends data locally
Tunnel forwarding AC carries user data

PPPoE Discovery WA

PADI PADO PADR PADS: discover to session
PADI: initiation PADO: offer PADR: request PADS: session

PAP vs CHAP WA

PAP

Two-way handshake
Clear credentials
Weaker

CHAP

Three-way handshake
Challenge response
No clear password
Password vs challenge

PPP + PPPoE + Labels WA

PPP Point-to-point encapsulation
LCP Establish and test link
NCP Configure network-layer protocols
PAP Two-way clear credentials
CHAP Three-way challenge response
PPPoE PPP over Ethernet
MPLS Label-based forwarding
Segment Routing Source-selected segment list

SNMP + O&M OP

NMS Management station
Agent Managed device process
MIB Managed object database
Get Read managed object
Set Modify managed object
Trap Unsolicited event notification
SNMP query UDP 161
SNMP trap UDP 162

IPv6 Compression IP

One :: only; drop leading zeros
Compress longest zero run Never compress twice Keep eight hextets conceptually

IPv4 ARP vs IPv6 ND IP

ARP

IPv4 address resolution
Broadcast request

Neighbor Discovery

IPv6 neighbor resolution
ICMPv6 multicast
Broadcast ARP vs ICMPv6

IPv6 Addressing + Control IP

IPv6 128-bit addressing
Hextets Eight hexadecimal groups
:: Compress one zero run
Global unicast 2000::/3
Link-local FE80::/10
Multicast FF00::/8
Loopback ::1
Unspecified ::
IPv6 broadcast Does not exist
Neighbor Discovery ICMPv6 replaces ARP
SLAAC RA-based address creation
ipv6 route-static Add IPv6 static route

SDN vs NFV AU

SDN

Separates network planes
Controller-driven policy

NFV

Virtualizes network functions
Software appliances
Network control vs functions

SDN + NFV + Python AU

SDN Separates control and forwarding
Control plane Computes policy and paths
Forwarding plane Moves packets
Controller Centralized network logic
Northbound API Applications to controller
Southbound API Controller to devices
NFV Software network functions
Automation Repeatable network changes
Python indentation Defines code blocks
Python dictionary Key-value collection

Common Traps

MAC vs ARP table

MAC maps port ≠ ARP maps IPv4 to MAC

Prefix vs preference

Longest prefix first ≠ Preference breaks source choice

Root bridge vs root port

One bridge is root ≠ Nonroot selects root port

PVID vs allowed VLANs

PVID classifies untagged ingress ≠ Allowed list permits VLANs

ACL vs NAT

ACL filters traffic ≠ NAT translates addresses

Authentication vs authorization

Authentication proves identity ≠ Authorization grants actions

SSID vs BSSID

SSID names network ≠ BSSID identifies radio

SNMP Get vs Trap

Get is requested ≠ Trap is unsolicited

IPv6 compression

Leading zeros freely omitted ≠ Double-colon used once

SDN vs automation

SDN changes architecture ≠ Automation repeats operations

Last Minute

1. Domains 1-5: 8,27,28,8,5
2. Domains 6-10: 10,3,3,5,3
3. Longest prefix before preference
4. Lower route preference wins
5. OSPF backbone equals area zero
6. Access one VLAN; trunk many
7. Lowest bridge ID becomes root
8. Basic ACL source; advanced detailed
9. AAA: authenticate, authorize, account
10. DHCP follows DORA
11. Fit AP obeys AC
12. PPP: LCP, authentication, NCP
13. IPv6 ND replaces IPv4 ARP
14. SDN separates control and forwarding
15. VRP save persists configuration

Huawei HCIA-Datacom (H12-811 V1.0)

Practice Questions 130 questions Study Guide 48 topics Cheat Sheet 119 facts Flashcards 50 cards Shorts 1 short Podcast