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Module 12
First Hop Redundancy Protocols (HSRP, VRRP, GLBP)
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# 📘 CCNA 200-301 - Video 12: First Hop Redundancy Protocols (HSRP, VRRP, GLBP) ## Deep Study Notes --- ## 📌 Learning Objectives By the end of this video, you should understand: - The problem of single default gateway failure - How First Hop Redundancy Protocols (FHRP) solve this - HSRP (Hot Standby Router Protocol) - Cisco proprietary - VRRP (Virtual Router Redundancy Protocol) - IEEE standard - GLBP (Gateway Load Balancing Protocol) - Cisco proprietary - Configuration and verification of each protocol --- ## 🧠 Core Concepts ### 1. The Problem: Single Default Gateway Failure **Scenario:** In a typical network, hosts are configured with a single default gateway. If that router fails, hosts lose connectivity to other networks. **Analogy:** Think of a building with a single entrance. If that entrance is blocked (router fails), no one can enter or leave. FHRP provides multiple entrances with a single virtual address that always works. ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ WITHOUT FHRP (Single Point of Failure) │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ ┌─────────────────┐ │ │ │ Router A │ │ │ │ Active │ │ │ │ 10.10.10.1 │ │ │ └────────┬────────┘ │ │ │ │ │ │ │ │ ┌────────┴────────┐ │ │ │ Switch │ │ │ └────────┬────────┘ │ │ │ │ │ ┌────────────────────────┼────────────────────────┐ │ │ │ │ │ │ │ ┌────▼────┐ ┌────▼────┐ ┌────▼────┐ │ │ │ PC1 │ │ PC2 │ │ PC3 │ │ │ │Gateway: │ │Gateway: │ │Gateway: │ │ │ │10.10.10.1│ │10.10.10.1│ │10.10.10.1│ │ │ └─────────┘ └─────────┘ └─────────┘ │ │ │ │ PROBLEM: If Router A fails, ALL PCs lose connectivity to other networks │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ┌─────────────────────────────────────────────────────────────────────────────┐ │ WITH FHRP (Redundant Gateways) │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ ┌─────────────────┐ ┌─────────────────┐ │ │ │ Router A │ │ Router B │ │ │ │ Active │ │ Standby │ │ │ │ 10.10.10.2 │ │ 10.10.10.3 │ │ │ └────────┬────────┘ └────────┬────────┘ │ │ │ │ │ │ └──────────────────┬───────────────────┘ │ │ │ │ │ ┌────────┴────────┐ │ │ │ Switch │ │ │ └────────┬────────┘ │ │ │ │ │ ┌─────────────────────┼─────────────────────┐ │ │ │ │ │ │ │ ┌────▼────┐ ┌────▼────┐ ┌────▼────┐ │ │ │ PC1 │ │ PC2 │ │ PC3 │ │ │ │ Virtual │ │ Virtual │ │ Virtual │ │ │ │Gateway: │ │Gateway: │ │Gateway: │ │ │ │10.10.10.1│ │10.10.10.1│ │10.10.10.1│ │ │ └─────────┘ └─────────┘ └─────────┘ │ │ │ │ BENEFIT: Virtual IP (10.10.10.1) always available │ │ If Router A fails, Router B takes over │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 2. First Hop Redundancy Protocols (FHRP) Overview | Protocol | Type | Standard | Load Balancing | Virtual IP | Preemption | |----------|------|----------|----------------|------------|------------| | **HSRP** | Cisco Proprietary | RFC 2281 | No | Yes | Yes (configurable) | | **VRRP** | IEEE Standard | RFC 5798 | No | Yes (same as gateway) | Yes | | **GLBP** | Cisco Proprietary | Cisco | Yes (per-host) | Yes | Yes | **Common Features:** - Two or more routers share a **virtual IP address** and **virtual MAC address** - Hosts use the virtual IP as their default gateway - One router is **Active** (forwards traffic) - One or more routers are **Standby** (ready to take over) - **Hello messages** exchanged to monitor peer availability - **Failover** occurs when hellos are missed --- ### 3. HSRP (Hot Standby Router Protocol) **Definition:** HSRP is a Cisco proprietary protocol that provides gateway redundancy by allowing multiple routers to share a virtual IP and MAC address. **HSRP Versions:** | Feature | HSRPv1 | HSRPv2 | |---------|--------|--------| | **Group Number** | 0-255 | 0-4095 | | **Virtual MAC** | 0000.0C07.ACxx | 0000.0C9F.Fxxx | | **Multicast Address** | 224.0.0.2 | 224.0.0.102 | | **Timers** | Hello: 3 sec, Hold: 10 sec | Hello: 3 sec, Hold: 10 sec | **HSRP States:** ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ HSRP STATES │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ DISABLED - HSRP not configured on interface │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ │ │ HSRP configured │ │ ▼ │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ INIT - Initial state, waiting to start │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ │ │ │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ LEARN - Learning virtual IP (if not configured) │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ │ │ │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ LISTEN - Hears Hellos from Active/Standby router │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ │ │ No Hellos received (or preempt) │ │ ▼ │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ SPEAK - Sends Hellos, participating in election │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ │ │ │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ ACTIVE - Forwards traffic for virtual IP │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ STANDBY - Ready to take over if Active fails │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` **HSRP Roles:** | Role | Description | |------|-------------| | **Active Router** | Forwards packets sent to virtual IP; sends hello messages | | **Standby Router** | Monitors Active; takes over if Active fails | | **Other Routers** | Listen to hellos; remain in Listen state | **HSRP Timers:** | Timer | Default | Description | |-------|---------|-------------| | **Hello** | 3 seconds | How often Active sends hello messages | | **Hold** | 10 seconds | Time before Active is considered down (3.3 × Hello) | --- ### 4. HSRP Configuration **Basic HSRP Configuration:** ```cisco ! ========== ROUTER A (Active) ========== RouterA> enable RouterA# configure terminal RouterA(config)# interface gigabitEthernet 0/0 RouterA(config-if)# ip address 192.168.1.2 255.255.255.0 RouterA(config-if)# standby 1 ip 192.168.1.1 ! Virtual IP RouterA(config-if)# standby 1 priority 110 ! Higher = Active RouterA(config-if)# standby 1 preempt ! Take over if higher priority RouterA(config-if)# standby 1 name HSRP_Group ! Optional: group name RouterA(config-if)# standby 1 authentication md5 key-string Cisco123 RouterA(config-if)# no shutdown RouterA(config-if)# exit ! ========== ROUTER B (Standby) ========== RouterB> enable RouterB# configure terminal RouterB(config)# interface gigabitEthernet 0/0 RouterB(config-if)# ip address 192.168.1.3 255.255.255.0 RouterB(config-if)# standby 1 ip 192.168.1.1 ! Same virtual IP RouterB(config-if)# standby 1 priority 90 ! Lower = Standby RouterB(config-if)# standby 1 preempt ! Optional RouterB(config-if)# standby 1 authentication md5 key-string Cisco123 RouterB(config-if)# no shutdown RouterB(config-if)# exit ``` **HSRP Priority and Preemption:** | Setting | Description | |---------|-------------| | **Priority** | Default = 100; Higher priority becomes Active | | **Preempt** | Allows higher priority router to take over when it becomes available | ```cisco ! Configure tracking (adjust priority based on interface state) RouterA(config-if)# standby 1 track gigabitEthernet 0/1 20 ! Decrease priority by 20 if WAN fails ``` **HSRP Version 2 Configuration:** ```cisco ! Enable HSRP version 2 globally Router(config)# standby version 2 ! Or per interface Router(config-if)# standby 1 version 2 ``` --- ### 5. HSRP Verification Commands | Command | Purpose | |---------|---------| | `show standby` | Display HSRP status for all groups | | `show standby brief` | Quick summary of HSRP groups | | `show standby [interface] [group]` | Detailed HSRP information | | `debug standby` | Debug HSRP events | **Example Outputs:** ```cisco RouterA# show standby brief P indicates configured to preempt. | Interface Grp Pri P State Active Standby Virtual IP Gi0/0 1 110 P Active local 192.168.1.3 192.168.1.1 RouterA# show standby GigabitEthernet0/0 - Group 1 State is Active 2 state changes, last state change 00:02:30 Virtual IP address is 192.168.1.1 Active virtual MAC address is 0000.0C07.AC01 Local virtual MAC address is 0000.0C07.AC01 (v1 default) Hello time 3 sec, hold time 10 sec Next hello sent in 1.456 secs Preemption enabled Active router is local Standby router is 192.168.1.3, priority 90 (expires in 9.234 sec) Priority 110 (configured 110) Group name is "HSRP_Group" (default) ``` --- ### 6. VRRP (Virtual Router Redundancy Protocol) **Definition:** VRRP is an IEEE standard (RFC 5798) that provides gateway redundancy. It is vendor-neutral and similar to HSRP but with some differences. **VRRP vs. HSRP:** | Feature | HSRP | VRRP | |---------|------|------| | **Standard** | Cisco Proprietary | IEEE RFC 5798 | | **Virtual IP** | Different from physical IP | Can be same as physical IP | | **Roles** | Active, Standby | Master, Backup | | **Authentication** | Plain text, MD5 | Plain text, MD5, AH | | **Multicast Address** | 224.0.0.2 (v1), 224.0.0.102 (v2) | 224.0.0.18 | | **Protocol Number** | UDP (not applicable) | IP protocol 112 | **VRRP Configuration:** ```cisco ! ========== ROUTER A (Master) ========== RouterA> enable RouterA# configure terminal RouterA(config)# interface gigabitEthernet 0/0 RouterA(config-if)# ip address 192.168.1.2 255.255.255.0 RouterA(config-if)# vrrp 1 ip 192.168.1.1 ! Virtual IP RouterA(config-if)# vrrp 1 priority 110 ! Higher = Master RouterA(config-if)# vrrp 1 preempt ! Take over if higher priority RouterA(config-if)# vrrp 1 authentication md5 key-string Cisco123 RouterA(config-if)# no shutdown RouterA(config-if)# exit ! ========== ROUTER B (Backup) ========== RouterB> enable RouterB# configure terminal RouterB(config)# interface gigabitEthernet 0/0 RouterB(config-if)# ip address 192.168.1.3 255.255.255.0 RouterB(config-if)# vrrp 1 ip 192.168.1.1 RouterB(config-if)# vrrp 1 priority 90 RouterB(config-if)# vrrp 1 authentication md5 key-string Cisco123 RouterB(config-if)# no shutdown RouterB(config-if)# exit ``` **VRRP Verification:** ```cisco RouterA# show vrrp brief Interface Grp Pri State Virtual IP Master IP Backup IP Gi0/0 1 110 Master 192.168.1.1 192.168.1.2 192.168.1.3 RouterA# show vrrp GigabitEthernet0/0 - Group 1 State is Master Virtual IP address is 192.168.1.1 Virtual MAC address is 0000.5E00.0101 Priority 110 (configured 110) Master router is local Backup router is 192.168.1.3, priority 90 Authentication MD5, key-string Preemption enabled Advertisement interval 1.000 sec ``` --- ### 7. GLBP (Gateway Load Balancing Protocol) **Definition:** GLBP is a Cisco proprietary protocol that provides both redundancy and load balancing. Unlike HSRP and VRRP where only one router is active, GLBP allows multiple routers to forward traffic simultaneously. **GLBP Features:** | Feature | Description | |---------|-------------| | **AVG** | Active Virtual Gateway (manages group, assigns AVFs) | | **AVF** | Active Virtual Forwarder (forwards traffic, up to 4 per group) | | **Load Balancing** | Round-robin, weighted, or host-dependent | | **Virtual IP** | One virtual IP shared by all routers | | **Virtual MAC** | Multiple virtual MACs (one per AVF) | ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ GLBP LOAD BALANCING │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Virtual IP: 192.168.1.1 │ │ │ │ ┌─────────────────┐ ┌─────────────────┐ │ │ │ Router A │ │ Router B │ │ │ │ AVG │ │ AVF │ │ │ │ AVF │ │ │ │ │ │ Virtual MAC: │ │ Virtual MAC: │ │ │ │ 0007.B400.0101 │ │ 0007.B400.0102 │ │ │ └────────┬────────┘ └────────┬────────┘ │ │ │ │ │ │ └──────────────────┬───────────────────┘ │ │ │ │ │ ┌────────┴────────┐ │ │ │ Switch │ │ │ └────────┬────────┘ │ │ │ │ │ ┌─────────────────────┼─────────────────────┐ │ │ │ │ │ │ │ ┌────▼────┐ ┌────▼────┐ ┌────▼────┐ │ │ │ PC1 │ │ PC2 │ │ PC3 │ │ │ │ MAC A │ │ MAC B │ │ MAC A │ │ │ │ Router A│ │ Router B│ │ Router A│ │ │ └─────────┘ └─────────┘ └─────────┘ │ │ │ │ Load Balancing: PC1 and PC3 use Router A, PC2 uses Router B │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` **GLBP Load Balancing Methods:** | Method | Description | |--------|-------------| | **Round Robin** | AVG cycles through AVFs sequentially | | **Weighted** | Based on configured weight (higher = more traffic) | | **Host-Dependent** | Same host always uses same AVF (based on MAC) | **GLBP Configuration:** ```cisco ! ========== ROUTER A (AVG) ========== RouterA> enable RouterA# configure terminal RouterA(config)# interface gigabitEthernet 0/0 RouterA(config-if)# ip address 192.168.1.2 255.255.255.0 RouterA(config-if)# glbp 1 ip 192.168.1.1 ! Virtual IP RouterA(config-if)# glbp 1 priority 110 ! Higher = AVG RouterA(config-if)# glbp 1 preempt ! Take over if higher priority RouterA(config-if)# glbp 1 load-balancing round-robin RouterA(config-if)# glbp 1 authentication md5 key-string Cisco123 RouterA(config-if)# no shutdown RouterA(config-if)# exit ! ========== ROUTER B (AVF) ========== RouterB> enable RouterB# configure terminal RouterB(config)# interface gigabitEthernet 0/0 RouterB(config-if)# ip address 192.168.1.3 255.255.255.0 RouterB(config-if)# glbp 1 ip 192.168.1.1 RouterB(config-if)# glbp 1 priority 90 RouterB(config-if)# glbp 1 load-balancing round-robin RouterB(config-if)# glbp 1 authentication md5 key-string Cisco123 RouterB(config-if)# no shutdown RouterB(config-if)# exit ``` **GLBP Verification:** ```cisco RouterA# show glbp brief Interface Grp Fwd Pri State Active Standby Virtual IP Gi0/0 1 - 110 Active local 192.168.1.3 192.168.1.1 Gi0/0 1 1 - Active 0007.B400.0101 - Gi0/0 1 2 - Listen - - - RouterA# show glbp GigabitEthernet0/0 - Group 1 State is Active 2 state changes, last state change 00:02:30 Virtual IP address is 192.168.1.1 Hello time 3 sec, hold time 10 sec Next hello sent in 0.456 secs Preemption enabled, min delay 0 sec Active is local Standby is 192.168.1.3, priority 90 (expires in 8.123 sec) Priority 110 (configured 110) Load balancing: round-robin Group members: 0001.42A8.7C00 (192.168.1.2) local 0002.4A12.8B00 (192.168.1.3) Forwarders: Forwarder 1 State is Active Virtual MAC address is 0007.B400.0101 (default) Primary is local Clients: 2 Forwarder 2 State is Listen Virtual MAC address is 0007.B400.0102 (default) Primary is 192.168.1.3 Clients: 1 ``` --- ### 8. FHRP Comparison Summary | Feature | HSRP | VRRP | GLBP | |---------|------|------|------| | **Standard** | Cisco Proprietary | IEEE RFC 5798 | Cisco Proprietary | | **Load Balancing** | No | No | Yes | | **Active Routers** | 1 | 1 | Up to 4 | | **Virtual MACs** | 1 | 1 | Multiple (1 per AVF) | | **Multicast Address** | 224.0.0.2 (v1), 224.0.0.102 (v2) | 224.0.0.18 | 224.0.0.102 | | **Authentication** | Plain, MD5 | Plain, MD5, AH | Plain, MD5 | | **Object Tracking** | Yes | Yes | Yes | | **Best For** | Cisco-only networks | Multi-vendor | Cisco-only, load balancing | --- ### 9. Object Tracking **Purpose:** Dynamically adjust priority based on interface or route state. ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ OBJECT TRACKING │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ ┌─────────────────┐ │ │ │ Router A │ │ │ │ Priority: 110 │ │ │ │ (Active) │ │ │ └────────┬────────┘ │ │ │ │ │ ┌────────┴────────┐ │ │ │ WAN Link │ ← If this link fails, priority decreases │ │ │ (Tracked) │ Router B becomes Active │ │ └─────────────────┘ │ │ │ │ │ ▼ │ │ ┌─────────────────┐ │ │ │ Router B │ │ │ │ Priority: 90 │ │ │ │ (Standby) │ │ │ └─────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` **Object Tracking Configuration (HSRP):** ```cisco ! Create tracking object Router(config)# track 1 interface gigabitEthernet 0/1 line-protocol Router(config-track)# exit ! Configure interface with tracking Router(config)# interface gigabitEthernet 0/0 Router(config-if)# ip address 192.168.1.2 255.255.255.0 Router(config-if)# standby 1 ip 192.168.1.1 Router(config-if)# standby 1 priority 110 Router(config-if)# standby 1 preempt Router(config-if)# standby 1 track 1 decrement 30 ! Decrease priority by 30 if tracked object fails Router(config-if)# exit ``` --- ### 10. Troubleshooting FHRP | Problem | Symptom | Solution | |---------|---------|----------| | **No Virtual IP** | `show standby` shows no virtual IP | Verify `standby [group] ip` command | | **Both Active** | Duplicate Active routers | Check authentication, VLAN mismatch | | **No Active** | No router forwarding | Verify interfaces up, hello/hold timers | | **Preemption Not Working** | Higher priority router not taking over | Enable `preempt` command | | **Tracking Not Working** | Priority not decrementing | Verify track object configuration | --- ## 🔧 Complete Configuration Examples ### Lab 1: HSRP with Two Routers **Topology:** ``` ┌─────────────────┐ │ Router A │ │ Active │ │ 192.168.1.2 │ └────────┬────────┘ │ ┌────────┴────────┐ │ Switch │ └────────┬────────┘ │ ┌────────┴────────┐ │ Router B │ │ Standby │ │ 192.168.1.3 │ └─────────────────┘ Virtual IP: 192.168.1.1 Hosts use 192.168.1.1 as default gateway ``` **Router A Configuration:** ```cisco hostname RouterA ! interface GigabitEthernet0/0 ip address 192.168.1.2 255.255.255.0 standby 1 ip 192.168.1.1 standby 1 priority 110 standby 1 preempt standby 1 authentication md5 key-string SecureKey ! end ``` **Router B Configuration:** ```cisco hostname RouterB ! interface GigabitEthernet0/0 ip address 192.168.1.3 255.255.255.0 standby 1 ip 192.168.1.1 standby 1 priority 90 standby 1 authentication md5 key-string SecureKey ! end ``` --- ### Lab 2: GLBP with Load Balancing **Topology:** ``` ┌─────────────────┐ │ Router A │ │ AVG + AVF │ │ 192.168.1.2 │ └────────┬────────┘ │ ┌────────┴────────┐ │ Switch │ └────────┬────────┘ │ ┌────────┴────────┐ │ Router B │ │ AVF │ │ 192.168.1.3 │ └─────────────────┘ Virtual IP: 192.168.1.1 Virtual MACs: 0007.B400.0101 (Router A), 0007.B400.0102 (Router B) Load Balancing: Round-robin ``` **Router A Configuration:** ```cisco hostname RouterA ! interface GigabitEthernet0/0 ip address 192.168.1.2 255.255.255.0 glbp 1 ip 192.168.1.1 glbp 1 priority 110 glbp 1 preempt glbp 1 load-balancing round-robin glbp 1 authentication md5 key-string SecureKey ! end ``` **Router B Configuration:** ```cisco hostname RouterB ! interface GigabitEthernet0/0 ip address 192.168.1.3 255.255.255.0 glbp 1 ip 192.168.1.1 glbp 1 priority 90 glbp 1 load-balancing round-robin glbp 1 authentication md5 key-string SecureKey ! end ``` --- ## ✅ Exam Tips (For CCNA 200-301) | Topic | What Cisco Tests | |-------|------------------| | **HSRP** | Cisco proprietary, virtual IP, priority, preempt, timers | | **VRRP** | IEEE standard, IP protocol 112, can use physical IP as virtual | | **GLBP** | Cisco proprietary, load balancing (round-robin, weighted, host-dependent) | | **Virtual MAC** | HSRPv1: 0000.0C07.ACxx, HSRPv2: 0000.0C9F.Fxxx, VRRP: 0000.5E00.01xx | | **Multicast** | HSRPv1: 224.0.0.2, HSRPv2/GLBP: 224.0.0.102, VRRP: 224.0.0.18 | | **Timers** | Hello: 3 sec, Hold: 10 sec | ### Common Exam Scenarios: **Scenario 1:** "Two routers are configured with HSRP group 1. Router A has priority 110, Router B has priority 100. Both have preempt configured. Router A is Active. What happens when Router A's WAN interface fails?" - **Answer:** If tracking is configured, Router A's priority decreases, Router B becomes Active **Scenario 2:** "A network requires gateway redundancy with load balancing across multiple routers. Which protocol should be used?" - **Answer:** GLBP (Gateway Load Balancing Protocol) **Scenario 3:** "A network has both Cisco and non-Cisco routers. Which FHRP should be used for interoperability?" - **Answer:** VRRP (IEEE standard, works across vendors) ### Mnemonics: **HSRP Priority:** **"Higher is Active"** - Higher priority = Active router - Default = 100 **HSRP States:** **"D.I.L.S.A." - Dogs In London See Active** - **D**isabled - **I**nit - **L**isten - **S**peak - **A**ctive --- ## 📝 Summary (1-Minute Revision) ``` FIRST HOP REDUNDANCY PROTOCOLS (FHRP): PURPOSE: ├── Provide redundant default gateway ├── Virtual IP shared between routers └── Automatic failover when Active fails HSRP (Cisco Proprietary): ├── Active + Standby (only one forwards) ├── Virtual IP different from physical ├── Priority (default 100) ├── Preempt (take over when higher priority) ├── Hello: 3 sec, Hold: 10 sec ├── Multicast: 224.0.0.2 (v1), 224.0.0.102 (v2) └── Virtual MAC: 0000.0C07.ACxx (v1), 0000.0C9F.Fxxx (v2) VRRP (IEEE Standard): ├── Master + Backup (only one forwards) ├── Virtual IP can match physical IP ├── IP protocol 112 ├── Multicast: 224.0.0.18 └── Virtual MAC: 0000.5E00.01xx GLBP (Cisco Proprietary): ├── AVG (manages group) + AVFs (forward traffic) ├── Load balancing: round-robin, weighted, host-dependent ├── Up to 4 active forwarders ├── Multicast: 224.0.0.102 └── Virtual MACs: 0007.B400.01xx KEY COMMANDS: ├── standby [group] ip [virtual-ip] ├── standby [group] priority [value] ├── standby [group] preempt ├── vrrp [group] ip [virtual-ip] ├── glbp [group] ip [virtual-ip] └── glbp [group] load-balancing [method] VERIFICATION: ├── show standby ├── show vrrp ├── show glbp └── show standby brief ``` --- ## 🧪 Practice Questions **1. Which FHRP is an IEEE standard that works across multiple vendors?** - A) HSRP - B) VRRP - C) GLBP - D) STP <details> <summary>Answer</summary> <b>B) VRRP (Virtual Router Redundancy Protocol)</b> - VRRP is IEEE RFC 5798 and vendor-neutral. </details> **2. What is the default HSRP hello timer value?** - A) 1 second - B) 3 seconds - C) 10 seconds - D) 15 seconds <details> <summary>Answer</summary> <b>B) 3 seconds</b> - HSRP default hello timer is 3 seconds, hold timer is 10 seconds. </details> **3. Which GLBP load balancing method cycles through gateways sequentially?** - A) Weighted - B) Host-dependent - C) Round-robin - D) Priority-based <details> <summary>Answer</summary> <b>C) Round-robin</b> - Round-robin distributes traffic evenly by cycling through AVFs. </details> **4. What is the virtual MAC address format for HSRP version 1?** - A) 0000.0C9F.Fxxx - B) 0000.5E00.01xx - C) 0000.0C07.ACxx - D) 0007.B400.01xx <details> <summary>Answer</summary> <b>C) 0000.0C07.ACxx</b> - HSRPv1 uses MAC prefix 0000.0C07.AC, where xx is the group number. </details> **5. Which command configures HSRP preemption?** - A) `standby 1 preempt` - B) `standby 1 priority` - C) `standby 1 takeover` - D) `standby 1 active` <details> <summary>Answer</summary> <b>A) `standby 1 preempt`</b> - Preempt allows a higher priority router to become Active. </details> **6. In VRRP, what is the role of the router that forwards traffic?** - A) Active - B) Master - C) Primary - D) Forwarder <details> <summary>Answer</summary> <b>B) Master</b> - VRRP uses Master (forwarding) and Backup (standby) roles. </details> **7. Which protocol allows multiple routers to forward traffic simultaneously?** - A) HSRP - B) VRRP - C) GLBP - D) STP <details> <summary>Answer</summary> <b>C) GLBP</b> - GLBP supports up to 4 active forwarders for load balancing. </details> **8. What multicast address does HSRP version 2 use?** - A) 224.0.0.2 - B) 224.0.0.18 - C) 224.0.0.102 - D) 224.0.0.1 <details> <summary>Answer</summary> <b>C) 224.0.0.102</b> - HSRPv2 and GLBP use multicast address 224.0.0.102. </details> **9. What is the purpose of object tracking in FHRP?** - A) Monitor network traffic - B) Dynamically adjust priority based on interface state - C) Track MAC addresses - D) Log HSRP events <details> <summary>Answer</summary> <b>B) Dynamically adjust priority based on interface state</b> - Tracking allows priority to decrease when tracked objects fail. </details> **10. Which command displays HSRP status?** - A) `show hsrp` - B) `show standby` - C) `show fhrp` - D) `show redundancy` <details> <summary>Answer</summary> <b>B) `show standby`</b> - HSRP uses the `standby` keyword in commands. </details> **11. Two routers have HSRP priorities 120 and 100, both with preempt configured. Which router becomes Active?** - A) The router with priority 100 - B) The router with priority 120 - C) Both become Active - D) Neither becomes Active <details> <summary>Answer</summary> <b>B) The router with priority 120</b> - Higher priority becomes Active when preempt is enabled. </details> **12. What IP protocol number does VRRP use?** - A) 89 - B) 112 - C) 115 - D) 224 <details> <summary>Answer</summary> <b>B) 112</b> - VRRP uses IP protocol number 112 (HSRP uses UDP). </details> --- ## 📌 Next Steps After completing Video 12, you should be ready for: - **Video 13:** Access Control Lists (ACLs) - **Video 14:** Network Address Translation (NAT) **Lab Practice:** 1. Configure HSRP between two routers with virtual IP 192.168.1.1 2. Verify with `show standby brief` 3. Test failover by shutting down Active router interface 4. Configure object tracking for WAN interface 5. Configure GLBP with round-robin load balancing 6. Compare `show standby`, `show vrrp`, and `show glbp` outputs --- **Ready for Video 13?** Share the link or say "next" and I'll continue with Access Control Lists (ACLs). I'll create comprehensive deep notes for **Video 13: Access Control Lists (ACLs)** based on the standard CCNA 200-301 curriculum. ---