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Module 9
EtherChannel
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# 📘 CCNA 200-301 - Video 9: EtherChannel ## Deep Study Notes --- ## 📌 Learning Objectives By the end of this video, you should understand: - What EtherChannel is and why it's used - EtherChannel protocols (LACP, PAgP, Static) - Load balancing methods - Configuration and verification - Troubleshooting EtherChannel --- ## 🧠 Core Concepts ### 1. The Problem: Multiple Links Between Switches **Scenario:** You need more bandwidth between two switches, but spanning tree blocks redundant links to prevent loops. **Analogy:** Think of EtherChannel like merging multiple single-lane roads into a multi-lane highway. Each road (physical link) can carry traffic, but they work together as one bigger road (logical link). ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ WITHOUT ETHERCHANNEL │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Switch A Switch B │ │ ┌─────────────┐ ┌─────────────┐ │ │ │ │ │ │ │ │ │ Port1 │══════════════════════════│ Port1 │ │ │ │ │ 1 Gbps (Forwarding) │ │ │ │ │ Port2 │──────────X───────────────│ Port2 │ │ │ │ │ Blocked by STP │ │ │ │ └─────────────┘ └─────────────┘ │ │ │ │ PROBLEMS: │ │ • Only 1 Gbps available (other link blocked) │ │ • No redundancy (if link fails, STP takes 30-50 sec to reconverge) │ │ • Wasted bandwidth on redundant links │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` **Solution: EtherChannel** bundles multiple physical links into a single logical link. ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ WITH ETHERCHANNEL │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Switch A Switch B │ │ ┌─────────────┐ ┌─────────────┐ │ │ │ │ │ │ │ │ │ Port1 │══════════════════════════│ Port1 │ │ │ │ │ │ │ │ │ │ Port2 │══════════════════════════│ Port2 │ │ │ │ │ │ │ │ │ │ Port3 │══════════════════════════│ Port3 │ │ │ │ │ │ │ │ │ └─────────────┘ └─────────────┘ │ │ │ │ EtherChannel (Port-Channel 1): 3 Gbps logical link │ │ │ │ BENEFITS: │ │ • Increased bandwidth (3 Gbps total) │ │ • Redundancy (if one link fails, traffic continues on others) │ │ • STP sees ONE logical link (no loops) │ │ • Fast failover (sub-second with LACP) │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 2. What is EtherChannel? **Definition:** EtherChannel is a link aggregation technology that combines multiple physical Ethernet links into a single logical link, providing increased bandwidth, redundancy, and load balancing. **Key Characteristics:** | Feature | Description | |---------|-------------| | **Logical Interface** | Port-channel interface (e.g., Port-channel 1) | | **Physical Links** | 2 to 8 active links (up to 16 total with standby) | | **Speed** | Aggregate bandwidth (e.g., 8 x 1 Gbps = 8 Gbps) | | **STP View** | Single logical link (no blocking) | | **Failover** | Sub-second (links removed automatically) | **Supported Platforms:** - Switches (Catalyst series) - Routers (ISR, ASR) - Firewalls (ASA, Firepower) - Servers (with NIC teaming) --- ### 3. EtherChannel Protocols | Protocol | Type | Description | |----------|------|-------------| | **PAgP** | Cisco Proprietary | Port Aggregation Protocol - Cisco's original protocol | | **LACP** | IEEE 802.3ad (802.1ax) | Link Aggregation Control Protocol - Open standard | | **Static** | Manual | No negotiation, both sides manually configured | **PAgP (Port Aggregation Protocol):** - Cisco proprietary - Automatically negotiates EtherChannel formation - Modes: Desirable, Auto **LACP (Link Aggregation Control Protocol):** - IEEE standard (802.3ad/802.1ax) - Works across vendors - Modes: Active, Passive **Comparison Table:** | Feature | PAgP | LACP | Static | |---------|------|------|--------| | **Standard** | Cisco Proprietary | IEEE 802.3ad | None | | **Vendor Support** | Cisco only | Multi-vendor | All vendors | | **Negotiation** | Yes | Yes | No | | **Modes** | Desirable, Auto | Active, Passive | On | | **Misconfiguration Detection** | Yes | Yes | No | | **Recommended** | Legacy networks | Modern networks | Simple labs | --- ### 4. EtherChannel Modes **PAgP Modes:** | Mode | Behavior | |------|----------| | **Desirable** | Actively negotiates with other side; sends PAgP packets | | **Auto** | Passively responds; only forms channel if other side is Desirable | **PAgP Negotiation Matrix:** ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ PAgP NEGOTIATION MATRIX │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Switch A Switch B Result │ │ ─────────────────────────────────────────────────────────────────────── │ │ Desirable Desirable EtherChannel formed │ │ Desirable Auto EtherChannel formed │ │ Desirable Off No channel │ │ Auto Auto No channel (both passive) │ │ Auto Off No channel │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` **LACP Modes:** | Mode | Behavior | |------|----------| | **Active** | Actively negotiates with other side; sends LACP packets | | **Passive** | Passively responds; only forms channel if other side is Active | **LACP Negotiation Matrix:** ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ LACP NEGOTIATION MATRIX │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Switch A Switch B Result │ │ ─────────────────────────────────────────────────────────────────────── │ │ Active Active EtherChannel formed │ │ Active Passive EtherChannel formed │ │ Active Off No channel │ │ Passive Passive No channel (both passive) │ │ Passive Off No channel │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` **Static (ON) Mode:** - No negotiation - Both sides must be manually configured - No error detection for misconfiguration - Simple but less robust --- ### 5. EtherChannel Load Balancing **Purpose:** Distribute traffic across member links efficiently. **Load Balancing Methods:** | Method | Description | Best For | |--------|-------------|----------| | **src-mac** | Source MAC address | Traffic from many hosts to one destination | | **dst-mac** | Destination MAC address | Traffic from one host to many destinations | | **src-dst-mac** | Source and destination MAC (XOR) | Mixed traffic patterns | | **src-ip** | Source IP address | Layer 3 traffic | | **dst-ip** | Destination IP address | Layer 3 traffic | | **src-dst-ip** | Source and destination IP (XOR) | Balanced Layer 3 traffic | | **src-port** | Source TCP/UDP port | Application-based balancing | | **dst-port** | Destination TCP/UDP port | Application-based balancing | **How Load Balancing Works:** ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ LOAD BALANCING ALGORITHM │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Frame arrives with: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ Source MAC: aa:bb:cc:dd:ee:ff │ │ │ │ Destination MAC: 11:22:33:44:55:66 │ │ │ │ Source IP: 192.168.1.10 │ │ │ │ Destination IP: 192.168.2.20 │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ │ ▼ │ │ Hash Calculation (XOR): │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ If src-dst-mac: hash = aa:bb:cc:dd:ee:ff XOR 11:22:33:44:55:66 │ │ │ │ If src-dst-ip: hash = 192.168.1.10 XOR 192.168.2.20 │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ │ ▼ │ │ Hash % Number_of_Links = Link_Number │ │ │ │ Example: │ │ hash = 6, links = 4 → 6 % 4 = 2 → Link 2 used │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` **Configuration:** ```cisco ! View current load balancing method Switch# show etherchannel load-balance ! Configure load balancing method Switch(config)# port-channel load-balance src-dst-ip ! Available options: ! port-channel load-balance {dst-ip | dst-mac | src-dst-ip | src-dst-mac | src-ip | src-mac} ``` **Important:** Load balancing is per-flow, not per-packet. All packets in the same flow use the same link to prevent out-of-order delivery. --- ### 6. EtherChannel Requirements **All member ports must have matching:** - Same speed and duplex - Same VLAN configuration (access ports must be same VLAN) - Same trunk configuration (allowed VLANs, native VLAN) - Same STP configuration - Same switchport mode (access or trunk) **Incompatible Ports:** ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ MISMATCHED CONFIGURATIONS │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Port 1: FastEthernet (100 Mbps) │ │ Port 2: GigabitEthernet (1000 Mbps) ← Speed mismatch │ │ │ │ Port 1: switchport access vlan 10 │ │ Port 2: switchport access vlan 20 ← VLAN mismatch │ │ │ │ Port 1: switchport mode trunk │ │ Port 2: switchport mode access ← Mode mismatch │ │ │ │ Port 1: spanning-tree portfast │ │ Port 2: no spanning-tree portfast ← STP mismatch │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 7. EtherChannel Configuration **Method 1: Interface Range Configuration (Recommended)** ```cisco ! Create EtherChannel using interface range Switch> enable Switch# configure terminal ! Configure physical interfaces Switch(config)# interface range gigabitEthernet 0/1-2 Switch(config-if-range)# switchport mode trunk Switch(config-if-range)# switchport trunk allowed vlan 10,20,30 Switch(config-if-range)# channel-group 1 mode active ! LACP Active Switch(config-if-range)# exit ! Configure Port-Channel interface Switch(config)# interface port-channel 1 Switch(config-if)# switchport mode trunk Switch(config-if)# switchport trunk allowed vlan 10,20,30 Switch(config-if)# exit ``` **Method 2: Per-Interface Configuration** ```cisco ! Configure each interface individually Switch(config)# interface gigabitEthernet 0/1 Switch(config-if)# switchport mode trunk Switch(config-if)# switchport trunk allowed vlan 10,20,30 Switch(config-if)# channel-group 1 mode active Switch(config-if)# exit Switch(config)# interface gigabitEthernet 0/2 Switch(config-if)# switchport mode trunk Switch(config-if)# switchport trunk allowed vlan 10,20,30 Switch(config-if)# channel-group 1 mode active Switch(config-if)# exit ! Configure Port-Channel Switch(config)# interface port-channel 1 Switch(config-if)# switchport mode trunk Switch(config-if)# switchport trunk allowed vlan 10,20,30 Switch(config-if)# exit ``` --- ### 8. LACP Configuration (Multi-Vendor) **Switch A (Cisco):** ```cisco SwitchA(config)# interface range gigabitEthernet 0/1-2 SwitchA(config-if-range)# switchport mode trunk SwitchA(config-if-range)# channel-group 1 mode active SwitchA(config-if-range)# exit SwitchA(config)# interface port-channel 1 SwitchA(config-if)# switchport mode trunk SwitchA(config-if)# exit ``` **Switch B (Non-Cisco):** ```cisco ! Example: HP/Aruba switch SwitchB(config)# interface lag 1 SwitchB(config-lag)# trunk vlan 10,20,30 SwitchB(config-lag)# exit SwitchB(config)# interface gigabitEthernet 1/0/1 SwitchB(config-if)# lag 1 SwitchB(config-if)# exit SwitchB(config)# interface gigabitEthernet 1/0/2 SwitchB(config-if)# lag 1 SwitchB(config-if)# exit ``` --- ### 9. PAgP Configuration (Cisco Only) ```cisco ! Configure PAgP Desirable mode Switch(config)# interface range gigabitEthernet 0/1-2 Switch(config-if-range)# switchport mode trunk Switch(config-if-range)# channel-group 1 mode desirable ! PAgP Desirable Switch(config-if-range)# exit ! Configure PAgP Auto mode Switch(config)# interface range gigabitEthernet 0/1-2 Switch(config-if-range)# switchport mode trunk Switch(config-if-range)# channel-group 1 mode auto ! PAgP Auto Switch(config-if-range)# exit ``` --- ### 10. Static EtherChannel (ON Mode) ```cisco ! No negotiation - both sides must match Switch(config)# interface range gigabitEthernet 0/1-2 Switch(config-if-range)# switchport mode trunk Switch(config-if-range)# channel-group 1 mode on ! Static Switch(config-if-range)# exit ``` --- ### 11. Verification Commands | Command | Purpose | |---------|---------| | `show etherchannel summary` | Quick summary of all EtherChannels | | `show etherchannel port-channel` | Detailed port-channel info | | `show etherchannel [id] detail` | Detailed EtherChannel info | | `show etherchannel load-balance` | Current load balancing method | | `show interfaces port-channel [id]` | Port-channel interface status | | `show running-config | begin port-channel` | Port-channel configuration | **Example Outputs:** ```cisco Switch# show etherchannel summary Flags: D - down P - in port-channel I - stand-alone s - suspended H - Hot-standby (LACP only) R - Layer3 S - Layer2 U - in use f - failed to allocate aggregator Number of channel-groups in use: 1 Number of aggregators: 1 Group Port-channel Protocol Ports ------+-------------+-----------+----------------------------------------------- 1 Po1(SU) LACP Gi0/1(P) Gi0/2(P) Gi0/3(P) Gi0/4(P) ``` ```cisco Switch# show etherchannel 1 detail Group: 1 --------- Group state = L2 Ports: 4 Maxports = 8 Port-channels: 1 Protocol: LACP Ports in the group: ------------------- Port: Gi0/1 ----------- Port state = Up Mstr In-Bnd Channel group = 1 Mode = Active Gcchange = - Port-channel = Po1 GC = - Pseudo = - Port index = 0 Load = 0x00 Protocol = LACP Port: Gi0/2 ----------- Port state = Up Mstr In-Bnd Channel group = 1 Mode = Active ... ``` ```cisco Switch# show interfaces port-channel 1 Port-channel1 is up, line protocol is up Hardware is EtherChannel, address is 0001.42a8.7c00 (bia 0001.42a8.7c00) MTU 1500 bytes, BW 2000000 Kbit/sec, DLY 100 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Full-duplex, 2Gb/s ``` --- ### 12. Troubleshooting EtherChannel | Problem | Symptom | Solution | |---------|---------|----------| | **Speed mismatch** | Port not added to channel | Ensure all ports same speed | | **Duplex mismatch** | Errors, poor performance | Set all ports same duplex | | **VLAN mismatch** | Port suspended | Verify VLAN config on all ports | | **Mode mismatch** | Channel not formed | Match protocols (LACP/PAgP) and modes | | **Port in errdisable** | Port down | Check for loop, security violation | **Common Issues:** ```cisco ! Check for ports not in channel Switch# show etherchannel summary ! Look for ports marked "I" (stand-alone) or "s" (suspended) ! Check for mismatched configurations Switch# show interfaces gigabitEthernet 0/1 switchport Switch# show interfaces gigabitEthernet 0/2 switchport ! Compare outputs ! Check for errors on physical ports Switch# show interfaces gigabitEthernet 0/1 ! Look for CRC errors, collisions, runts ``` --- ## 🔧 Complete Configuration Examples ### Lab 1: LACP EtherChannel Between Two Switches **Topology:** ``` ┌─────────────────┐ ┌─────────────────┐ │ Switch A │ │ Switch B │ │ │ │ │ │ Gi0/1 ────────┼────────────────────┼─── Gi0/1 │ │ │ │ │ │ Gi0/2 ────────┼────────────────────┼─── Gi0/2 │ │ │ │ │ │ Gi0/3 ────────┼────────────────────┼─── Gi0/3 │ │ │ │ │ │ Gi0/4 ────────┼────────────────────┼─── Gi0/4 │ │ │ │ │ └─────────────────┘ └─────────────────┘ ``` **Switch A Configuration:** ```cisco hostname SwitchA ! interface range gigabitEthernet 0/1-4 switchport mode trunk switchport trunk allowed vlan 10,20,30 channel-group 1 mode active ! interface port-channel 1 switchport mode trunk switchport trunk allowed vlan 10,20,30 ! end ``` **Switch B Configuration:** ```cisco hostname SwitchB ! interface range gigabitEthernet 0/1-4 switchport mode trunk switchport trunk allowed vlan 10,20,30 channel-group 1 mode active ! interface port-channel 1 switchport mode trunk switchport trunk allowed vlan 10,20,30 ! end ``` --- ### Lab 2: Access Port EtherChannel (Server Connection) **Topology:** ``` ┌─────────────────┐ ┌─────────────────┐ │ Switch │ │ Server │ │ │ │ (NIC Team) │ │ Gi0/1 ────────┼────────────────────┼─── NIC 1 │ │ │ │ │ │ Gi0/2 ────────┼────────────────────┼─── NIC 2 │ │ │ │ │ │ VLAN 10 │ │ VLAN 10 │ └─────────────────┘ └─────────────────┘ ``` **Switch Configuration:** ```cisco hostname Switch ! vlan 10 name Server_VLAN ! interface range gigabitEthernet 0/1-2 switchport mode access switchport access vlan 10 spanning-tree portfast channel-group 1 mode active ! interface port-channel 1 switchport mode access switchport access vlan 10 spanning-tree portfast ! end ``` --- ## 📊 Text-Based Diagrams ### EtherChannel Logical vs. Physical ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ LOGICAL VIEW (STP Perspective) │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Switch A Switch B │ │ ┌─────────────┐ ┌─────────────┐ │ │ │ │ │ │ │ │ │ Port-Ch 1 │══════════════════════════│ Port-Ch 1 │ │ │ │ (3 Gbps) │ One Logical Link │ (3 Gbps) │ │ │ │ │ │ │ │ │ └─────────────┘ └─────────────┘ │ │ │ │ STP sees ONE link → No blocking │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ┌─────────────────────────────────────────────────────────────────────────────┐ │ PHYSICAL VIEW (Actual Cabling) │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Switch A Switch B │ │ ┌─────────────┐ ┌─────────────┐ │ │ │ │ │ │ │ │ │ Gi0/1 │══════════════════════════│ Gi0/1 │ │ │ │ Gi0/2 │══════════════════════════│ Gi0/2 │ │ │ │ Gi0/3 │══════════════════════════│ Gi0/3 │ │ │ │ │ 3 Physical Links │ │ │ │ └─────────────┘ └─────────────┘ │ │ │ │ All links active, traffic distributed across them │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ## ✅ Exam Tips (For CCNA 200-301) | Topic | What Cisco Tests | |-------|------------------| | **EtherChannel Benefits** | Increased bandwidth, redundancy, STP simplification | | **LACP vs. PAgP** | LACP = IEEE standard, PAgP = Cisco proprietary | | **Modes** | LACP: Active/Passive, PAgP: Desirable/Auto, Static: On | | **Requirements** | All ports must have matching speed, duplex, VLAN config | | **Load Balancing** | Per-flow, configurable by MAC/IP/port | | **Verification** | `show etherchannel summary` is most common command | ### Common Exam Scenarios: **Scenario 1:** "An administrator configures EtherChannel on two switches. One switch is Cisco, the other is a third-party switch. Which protocol should be used?" - **Answer:** LACP (IEEE standard, works across vendors) **Scenario 2:** "Four links are configured in an EtherChannel. Traffic from one specific host to another always uses the same link. Why?" - **Answer:** EtherChannel uses per-flow load balancing; all packets in the same flow use the same link to prevent out-of-order delivery **Scenario 3:** "Ports in an EtherChannel group show as 'suspended'. What is the likely cause?" - **Answer:** Configuration mismatch (speed, duplex, VLAN) between member ports ### Mnemonics: **PAgP Modes (Cisco):** **"D.A." - Desirable Active, Auto Passive** - **D**esirable = actively negotiates - **A**uto = passively waits **LACP Modes (Standard):** **"A.P." - Active Proactive, Passive Patient** - **A**ctive = initiates negotiation - **P**assive = responds to negotiation **EtherChannel Requirements:** **"S.S.V.T." - Speed, Switchport, VLAN, Trunk** - **S**peed (same) - **S**witchport mode (same) - **V**LAN (same for access) - **T**runk config (same for trunk) --- ## 📝 Summary (1-Minute Revision) ``` ETHERCHANNEL: DEFINITION: ├── Bundles multiple physical links into one logical link ├── Increases bandwidth ├── Provides redundancy └── STP sees one logical link (no blocking) PROTOCOLS: ├── LACP (802.3ad) - IEEE standard │ ├── Active - initiates negotiation │ └── Passive - responds to negotiation ├── PAgP - Cisco proprietary │ ├── Desirable - initiates negotiation │ └── Auto - responds to negotiation └── Static (ON) - manual, no negotiation REQUIREMENTS: ├── Same speed and duplex ├── Same VLAN (access) or trunk config ├── Same STP configuration └── Same switchport mode LOAD BALANCING: ├── Per-flow (not per-packet) ├── Based on MAC, IP, or port ├── Configurable: port-channel load-balance [method] └── All packets in same flow use same link VERIFICATION: ├── show etherchannel summary ├── show etherchannel [id] detail └── show interfaces port-channel [id] KEY COMMANDS: ├── channel-group [id] mode [active|passive|desirable|auto|on] ├── interface port-channel [id] └── port-channel load-balance [method] ``` --- ## 🧪 Practice Questions **1. What is the primary benefit of EtherChannel?** - A) Increases collision domain size - B) Combines multiple links into one logical link for increased bandwidth - C) Replaces the need for STP - D) Provides IP routing between switches <details> <summary>Answer</summary> <b>B) Combines multiple links into one logical link for increased bandwidth</b> - EtherChannel aggregates bandwidth and provides redundancy. </details> **2. Which protocol is the IEEE standard for link aggregation?** - A) PAgP - B) LACP - C) STP - D) VTP <details> <summary>Answer</summary> <b>B) LACP (Link Aggregation Control Protocol)</b> - IEEE 802.3ad/802.1ax is the open standard. </details> **3. Which PAgP mode actively initiates negotiation?** - A) Active - B) Desirable - C) Auto - D) Passive <details> <summary>Answer</summary> <b>B) Desirable</b> - PAgP Desirable actively sends negotiation packets; Auto passively waits. </details> **4. Four 1 Gbps links are configured in an EtherChannel. What is the total bandwidth?** - A) 1 Gbps - B) 2 Gbps - C) 4 Gbps - D) 8 Gbps <details> <summary>Answer</summary> <b>C) 4 Gbps</b> - Bandwidth is aggregated across all active links (4 × 1 Gbps = 4 Gbps). </details> **5. What happens if one link in an EtherChannel fails?** - A) The entire EtherChannel fails - B) Traffic is redistributed across remaining links - C) STP blocks the EtherChannel - D) The switch reboots <details> <summary>Answer</summary> <b>B) Traffic is redistributed across remaining links</b> - Remaining links continue to carry traffic with reduced total bandwidth. </details> **6. Which load balancing method is based on source and destination IP addresses?** - A) src-mac - B) dst-mac - C) src-dst-ip - D) src-port <details> <summary>Answer</summary> <b>C) src-dst-ip</b> - Uses XOR of source and destination IP addresses to select link. </details> **7. A port in an EtherChannel shows as "suspended". What is the most likely cause?** - A) The port is administratively down - B) Configuration mismatch with other member ports - C) The port is in STP blocking state - D) The port is not connected <details> <summary>Answer</summary> <b>B) Configuration mismatch with other member ports</b> - Suspended indicates the port has incompatible configuration. </details> **8. Which command displays a summary of all EtherChannels on a switch?** - A) `show etherchannel` - B) `show etherchannel summary` - C) `show port-channel` - D) `show interfaces trunk` <details> <summary>Answer</summary> <b>B) `show etherchannel summary`</b> - This provides a quick overview of all port-channels and member ports. </details> **9. What must match on all ports in an EtherChannel?** - A) IP address - B) Speed and duplex - C) MAC address - D) Subnet mask <details> <summary>Answer</summary> <b>B) Speed and duplex</b> - All physical ports must have matching speed and duplex settings. </details> **10. Two switches are connected with four links in an EtherChannel. STP sees:** - A) Four separate links - B) One logical link - C) Two logical links - D) No links <details> <summary>Answer</summary> <b>B) One logical link</b> - STP treats the EtherChannel as a single logical interface. </details> **11. Which LACP mode must be configured on at least one side to form an EtherChannel?** - A) Active - B) Passive - C) On - D) Auto <details> <summary>Answer</summary> <b>A) Active</b> - At least one side must be Active to initiate negotiation; Passive alone will not form a channel. </details> **12. What command configures a port as part of EtherChannel group 1 using LACP Active mode?** - A) `channel-group 1 mode desirable` - B) `channel-group 1 mode active` - C) `port-channel 1 mode active` - D) `lacp group 1 active` <details> <summary>Answer</summary> <b>B) `channel-group 1 mode active`</b> - This configures the interface as part of channel group 1 with LACP Active. </details> --- ## 📌 Next Steps After completing Video 9, you should be ready for: - **Video 10:** DHCP (Dynamic Host Configuration Protocol) - **Video 11:** DNS and Network Time Protocol (NTP) **Lab Practice:** 1. Configure LACP EtherChannel between two switches with 4 links 2. Verify using `show etherchannel summary` 3. Test failover by removing one link 4. Configure load balancing based on src-dst-ip 5. Configure access port EtherChannel to a server 6. Compare LACP, PAgP, and static configurations --- **Ready for Video 10?** Share the link or say "next" and I'll continue with DHCP (Dynamic Host Configuration Protocol). I'll create comprehensive deep notes for **Video 10: DHCP (Dynamic Host Configuration Protocol)** based on the standard CCNA 200-301 curriculum. ---