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Module 29
EIGRP Advanced Features
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# ๐ CCNA 200-301 - Video 29: EIGRP Advanced Features ## Deep Study Notes --- ## ๐ Learning Objectives By the end of this video, you should understand: - EIGRP concepts and terminology - EIGRP metrics and calculation - EIGRP neighbor establishment - EIGRP stub routing - EIGRP summarization - EIGRP authentication - EIGRP for IPv6 --- ## ๐ง Core Concepts ### 1. EIGRP Overview **Definition:** Enhanced Interior Gateway Routing Protocol (EIGRP) is a Cisco-proprietary advanced distance-vector routing protocol that combines the best features of distance-vector and link-state protocols. **Analogy:** Think of EIGRP like a GPS navigation system with advanced features. It maintains a map of all possible routes (topology table), knows the best route to each destination (routing table), and has backup routes ready (feasible successors). When a road is closed, it instantly switches to the backup route without recalculating. ``` โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ EIGRP FEATURES โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโค โ โ โ ADVANTAGES: โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โข Fast convergence (DUAL algorithm) โ โ โ โ โข Partial updates (only changes, not full table) โ โ โ โ โข Uses bandwidth/delay (not hop count) for metric โ โ โ โ โข Supports unequal-cost load balancing โ โ โ โ โข Automatic redistribution between EIGRP processes โ โ โ โ โข Supports IPv6 (same protocol) โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โ KEY CONCEPTS: โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โข Neighbor Table: Adjacent routers with hello exchange โ โ โ โ โข Topology Table: All learned routes (successors + feasible) โ โ โ โ โข Routing Table: Best routes (successors only) โ โ โ โ โข DUAL (Diffusing Update Algorithm): Loop-free path calculation โ โ โ โ โข Successor: Best route to destination โ โ โ โ โข Feasible Successor: Backup route (guaranteed loop-free) โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ ``` --- ### 2. EIGRP Protocol Components | Component | Description | |-----------|-------------| | **Protocol-Dependent Modules (PDMs)** | Support for IPv4, IPv6, IPX, AppleTalk | | **Reliable Transport Protocol (RTP)** | Reliable delivery with retransmission | | **Neighbor Discovery/Recovery** | Hello packets (5 sec default) | | **DUAL Finite State Machine** | Loop-free path calculation | | **Metric Calculation** | Bandwidth + delay (default) | ``` โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ EIGRP TABLES AND DATA STRUCTURES โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโค โ โ โ NEIGHBOR TABLE: โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ H Address Interface Hold Uptime SRTT RTO Q Seq โ โ โ โ 0 10.1.1.2 Gi0/0 12 00:01:23 1 100 0 3 โ โ โ โ 1 10.1.2.2 Gi0/1 14 00:00:45 2 200 0 2 โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โ TOPOLOGY TABLE: โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ P 10.1.3.0/24, 1 successors, FD is 281600 โ โ โ โ via 10.1.1.2 (281600/256000), Gi0/0 (Successor) โ โ โ โ via 10.1.2.2 (284160/281600), Gi0/1 (Feasible Successor) โ โ โ โ P 192.168.1.0/24, 1 successors, FD is 307200 โ โ โ โ via 10.1.1.2 (307200/281600), Gi0/0 (Successor) โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โ ROUTING TABLE: โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ D 10.1.3.0/24 [90/281600] via 10.1.1.2, 00:01:23, Gi0/0 โ โ โ โ D 192.168.1.0/24 [90/307200] via 10.1.1.2, 00:01:23, Gi0/0 โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ ``` --- ### 3. EIGRP Metric Calculation **Default Metric:** Bandwidth + Delay ``` Metric = [ (10^7 / minimum bandwidth in kbps) + (sum of delays in microseconds / 10) ] ร 256 Formula: Metric = (K1 ร Bandwidth + K2 ร Bandwidth/(256 - load) + K3 ร Delay) ร (K5/(Reliability + K4)) Default K values: K1 = 1 (Bandwidth) K2 = 0 (Load) K3 = 1 (Delay) K4 = 0 (Reliability) K5 = 0 (MTU) Simplified formula: Metric = (10^7 / BW_min) ร 256 + (Delay_sum / 10) ร 256 ``` ``` โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ EIGRP METRIC EXAMPLE โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโค โ โ โ Router A โโโโโ 100 Mbps (Cost 1) โโโโโ Router B โโโโโ 1 Mbps (Cost 100) โ โ โ โ Path to Router C: โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ Path 1: A โ B โ C โ โ โ โ Minimum bandwidth = 1 Mbps (1,000 kbps) โ โ โ โ Total delay = 100 ฮผs + 100 ฮผs = 200 ฮผs โ โ โ โ Metric = (10^7 / 1000) + (200 / 10) = 10000 + 20 = 10020 ร 256 โ โ โ โ = 2,565,120 โ โ โ โ โ โ โ โ Path 2: A โ C (if exists) โ โ โ โ Minimum bandwidth = 100 Mbps (100,000 kbps) โ โ โ โ Total delay = 100 ฮผs โ โ โ โ Metric = (10^7 / 100,000) + (100 / 10) = 100 + 10 = 110 ร 256 โ โ โ โ = 28,160 โ โ โ โ โ โ โ โ Path 1 is less desirable (higher metric) โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ ``` --- ### 4. EIGRP Neighbor Establishment **Hello Packets:** - Discover neighbors (multicast 224.0.0.10) - Default hello interval: 5 seconds (LAN), 60 seconds (WAN) - Hold time: 3 ร hello interval (15 seconds LAN, 180 seconds WAN) ``` โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ EIGRP NEIGHBOR FORMATION โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโค โ โ โ Router A Router B โ โ โ โ โ โ โ โ โ 1. Hello (multicast 224.0.0.10) โ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโบ โ โ โ โ โ โ โ โ 2. Hello (multicast 224.0.0.10) โ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โ โ โ โ โ 3. Update (unicast) - Full topology โ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโบ โ โ โ โ โ โ โ โ 4. Update (unicast) - Full topology โ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โ โ โ โ โ 5. ACK (unicast) โ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโบ โ โ โ โ โ โ โ โ 6. ACK (unicast) โ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โ โ โ โ โ NEIGHBOR ESTABLISHED โ โ โ โ โ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ ``` **Neighbor Requirements:** - Same AS number - Same K values (metric calculation) - Same authentication (if configured) - Reachable IP address --- ### 5. DUAL Algorithm - Successors and Feasible Successors **Definitions:** - **Successor:** Best route to destination (installed in routing table) - **Feasible Successor:** Backup route (guaranteed loop-free) - **Feasibility Condition:** Reported Distance (RD) < Feasible Distance (FD) ``` โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ SUCCESSOR AND FEASIBLE SUCCESSOR โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโค โ โ โ Router A to Network X: โ โ โ โ Feasible Distance (FD) = 2,565,120 (via Router B) โ โ โ โ โโโโโโโโโโโ โโโโโโโโโโโ โโโโโโโโโโโ โ โ โ Router Aโโโโโโโโโโโ Router Bโโโโโโโโโโโ Router Cโโโโโโ Network X โ โ โ โ Cost 1 โ โ Cost 2 โ โ โ โ โโโโโโโโโโโ โโโโโโโโโโโ โโโโโโโโโโโ โ โ โ โ โ โ โโโโโโโโโโโ โ โ โโโโโโโโโโโโโโโโโโ Router Dโโโโโโโโโโโโโโโโโโ Network X โ โ Cost 2โ โ Cost 3 โ โ โโโโโโโโโโโ โ โ โ โ Routes: โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ Path 1: A โ B โ C โ X (FD = 2,565,120) โ โ โ โ RD = 2,560,000 (distance from B to X) โ โ โ โ RD (2,560,000) < FD (2,565,120)? YES โ Feasible Successor โ โ โ โ โ โ โ โ Path 2: A โ D โ X (FD = 2,560,000) โ โ โ โ RD = 2,560,000 (distance from D to X) โ โ โ โ RD (2,560,000) < FD (2,565,120)? YES โ Feasible Successor โ โ โ โ (Actually better path, becomes successor) โ โ โ โ โ โ โ โ Path 3: A โ B โ D โ X (FD = 2,570,000) โ โ โ โ RD = 2,565,000 (distance from B to X) โ โ โ โ RD (2,565,000) < FD (2,565,120)? YES โ Feasible Successor โ โ โ โ (Backup to Path 1) โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ ``` --- ### 6. EIGRP Basic Configuration ```cisco ! Enable EIGRP Router(config)# router eigrp 100 Router(config-router)# network 10.1.1.0 0.0.0.255 Router(config-router)# network 192.168.1.0 0.0.0.255 Router(config-router)# no auto-summary Router(config-router)# exit ! Alternative: Use wildcard mask Router(config)# router eigrp 100 Router(config-router)# network 10.0.0.0 Router(config-router)# network 192.168.0.0 ! Passive interface (stops sending hellos) Router(config)# router eigrp 100 Router(config-router)# passive-interface gigabitEthernet 0/1 ! Set router ID Router(config)# router eigrp 100 Router(config-router)# eigrp router-id 1.1.1.1 ``` --- ### 7. EIGRP Verification Commands | Command | Purpose | |---------|---------| | `show ip eigrp neighbors` | Display EIGRP neighbors | | `show ip eigrp topology` | Display EIGRP topology table | | `show ip eigrp traffic` | Display EIGRP packet statistics | | `show ip eigrp interfaces` | Display EIGRP-enabled interfaces | | `show ip route eigrp` | Display EIGRP routes in routing table | | `show ip protocols` | Display routing protocol status | **Example Outputs:** ```cisco Router# show ip eigrp neighbors EIGRP-IPv4 neighbors for process 100 H Address Interface Hold Uptime SRTT RTO Q Seq 0 10.1.1.2 Gi0/0 12 00:01:23 1 100 0 15 1 10.1.2.2 Gi0/1 14 00:00:45 2 200 0 12 Router# show ip eigrp topology EIGRP-IPv4 Topology Table for AS(100)/ID(1.1.1.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P 10.1.1.0/24, 1 successors, FD is 281600 via Connected, GigabitEthernet0/0 P 192.168.1.0/24, 1 successors, FD is 307200 via 10.1.1.2 (307200/281600), GigabitEthernet0/0 P 10.1.3.0/24, 2 successors, FD is 284160 via 10.1.1.2 (284160/281600), GigabitEthernet0/0 via 10.1.2.2 (284160/281600), GigabitEthernet0/1 ``` --- ### 8. EIGRP Stub Routing **Purpose:** Stub routers prevent unnecessary queries from propagating to remote sites, improving stability and reducing query scopes. ``` โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ EIGRP STUB ROUTER โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโค โ โ โ Without Stub: โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โ โ โ โ Core โโโ Distribution โโโ Branch (Stub) โ โ โ โ โ โ โ โ โ If Branch loses network, it sends query up to core โ โ โ โ Core sends query to all neighbors (query explosion) โ โ โ โ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โ With Stub: โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โ โ โ โ Core โโโ Distribution โโโ Branch (Stub) โ โ โ โ โ โ โ โ โ Branch advertises itself as stub โ โ โ โ Core never sends queries to branch โ โ โ โ No query propagation โ โ โ โ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ ``` **Stub Configuration:** ```cisco ! On branch router (stub) Router(config)# router eigrp 100 Router(config-router)# eigrp stub ! Verify stub status Router# show ip eigrp neighbors detail ! Output shows neighbor as "Stub Peer" ``` **Stub Options:** | Option | Description | |--------|-------------| | `connected` | Advertise connected routes | | `static` | Advertise static routes | | `summary` | Advertise summary routes | | `redistributed` | Advertise redistributed routes | | `receive-only` | Does not advertise any routes | ```cisco ! Stub with specific options Router(config)# router eigrp 100 Router(config-router)# eigrp stub connected summary ``` --- ### 9. EIGRP Summarization **Manual Summarization:** ```cisco ! Configure summary route on interface Router(config)# interface gigabitEthernet 0/0 Router(config-if)# ip summary-address eigrp 100 10.1.0.0 255.255.252.0 ! Verify summary Router# show ip route Router# show ip eigrp topology ``` **Summary Example:** ``` โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ EIGRP SUMMARIZATION โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโค โ โ โ Before Summarization: โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ Branch Router advertises: โ โ โ โ 10.1.1.0/24 โ โ โ โ 10.1.2.0/24 โ โ โ โ 10.1.3.0/24 โ โ โ โ 10.1.4.0/24 โ โ โ โ โ โ โ โ Core Router receives 4 routes โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โ After Summarization: โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ Branch Router advertises: โ โ โ โ 10.1.0.0/22 (covers 10.1.0.0 - 10.1.3.255) โ โ โ โ โ โ โ โ Core Router receives 1 route โ โ โ โ โ โ โ โ ip summary-address eigrp 100 10.1.0.0 255.255.252.0 โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ ``` **Auto-Summarization:** ```cisco ! Disable auto-summarization (recommended) Router(config)# router eigrp 100 Router(config-router)# no auto-summary ``` --- ### 10. EIGRP Unequal-Cost Load Balancing **Purpose:** Distribute traffic across multiple paths with different metrics. ``` โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ UNEQUAL-COST LOAD BALANCING โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโค โ โ โ Router A to Network X: โ โ โ โ Path 1: Metric 100 (Successor) โ โ Path 2: Metric 150 (Feasible Successor) โ โ Path 3: Metric 200 (Feasible Successor) โ โ โ โ With default (equal-cost only): โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ Only Path 1 used (if paths have same metric) โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โ With variance 2 (variance = 2): โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ Paths with metric โค 100 ร 2 = 200 are used โ โ โ โ Path 1 (100), Path 2 (150), Path 3 (200) all used โ โ โ โ Traffic distributed proportionally (100:150:200 ratio) โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ ``` **Configuration:** ```cisco ! Configure variance Router(config)# router eigrp 100 Router(config-router)# variance 2 ! Verify load balancing Router# show ip route 10.1.1.0 ! Shows multiple entries with traffic share counts ``` --- ### 11. EIGRP Authentication **MD5 Authentication:** ```cisco ! Configure key chain Router(config)# key chain EIGRP-KEY Router(config-keychain)# key 1 Router(config-keychain-key)# key-string SecureKey123 Router(config-keychain-key)# exit ! Apply authentication to interface Router(config)# interface gigabitEthernet 0/0 Router(config-if)# ip authentication mode eigrp 100 md5 Router(config-if)# ip authentication key-chain eigrp 100 EIGRP-KEY ``` --- ### 12. EIGRP for IPv6 **Configuration:** ```cisco ! Enable IPv6 routing Router(config)# ipv6 unicast-routing ! Configure EIGRP for IPv6 Router(config)# ipv6 router eigrp 100 Router(config-rtr)# eigrp router-id 1.1.1.1 Router(config-rtr)# no shutdown Router(config-rtr)# exit ! Enable EIGRP on interfaces Router(config)# interface gigabitEthernet 0/0 Router(config-if)# ipv6 address 2001:db8:1::1/64 Router(config-if)# ipv6 eigrp 100 Router(config-if)# exit ! Verification Router# show ipv6 eigrp neighbors Router# show ipv6 route eigrp ``` --- ### 13. EIGRP Named Mode **Modern configuration method (replaces classic mode):** ```cisco ! Configure EIGRP named mode Router(config)# router eigrp LAB Router(config-router)# address-family ipv4 unicast autonomous-system 100 Router(config-router-af)# network 10.1.1.0 0.0.0.255 Router(config-router-af)# network 192.168.1.0 0.0.0.255 Router(config-router-af)# eigrp router-id 1.1.1.1 Router(config-router-af)# af-interface default Router(config-router-af-interface)# no passive-interface Router(config-router-af-interface)# exit Router(config-router-af)# topology base Router(config-router-af-topology)# variance 2 ``` --- ## ๐ง Complete Configuration Examples ### Lab 1: Basic EIGRP with Two Routers **Topology:** ``` Router A โโโโโโโโโโโโโโโ Router B 10.1.1.0/30 ``` **Router A Configuration:** ```cisco hostname RouterA ! interface GigabitEthernet0/0 ip address 10.1.1.1 255.255.255.252 no shutdown ! interface Loopback0 ip address 192.168.1.1 255.255.255.0 ! router eigrp 100 network 10.1.1.0 0.0.0.3 network 192.168.1.0 0.0.0.255 no auto-summary ! end ``` **Router B Configuration:** ```cisco hostname RouterB ! interface GigabitEthernet0/0 ip address 10.1.1.2 255.255.255.252 no shutdown ! interface Loopback0 ip address 192.168.2.1 255.255.255.0 ! router eigrp 100 network 10.1.1.0 0.0.0.3 network 192.168.2.0 0.0.0.255 no auto-summary ! end ``` --- ### Lab 2: EIGRP with Stub and Summarization **Topology:** ``` Core Router โโโโโโโโโโโ Branch Router 10.1.1.0/30 โ โ 10.1.2.0/24, 10.1.3.0/24, 10.1.4.0/24 ``` **Branch Router Configuration:** ```cisco hostname Branch ! interface GigabitEthernet0/0 ip address 10.1.1.2 255.255.255.252 ip summary-address eigrp 100 10.1.0.0 255.255.252.0 no shutdown ! interface GigabitEthernet0/1 ip address 10.1.2.1 255.255.255.0 ! interface GigabitEthernet0/2 ip address 10.1.3.1 255.255.255.0 ! router eigrp 100 network 10.0.0.0 no auto-summary eigrp stub connected summary ! end ``` --- ### Lab 3: EIGRP Unequal-Cost Load Balancing **Topology:** ``` Router A โโโโโโโโ (10 Mbps) โโโโโโโโ Router B โ โ โ โ โโโโโโโโโโ (100 Mbps) โโโโโโโโโโโโโโโโโ ``` **Router A Configuration:** ```cisco hostname RouterA ! interface Serial0/0/0 ip address 10.1.1.1 255.255.255.252 bandwidth 10000 ! interface Serial0/0/1 ip address 10.1.2.1 255.255.255.252 bandwidth 100000 ! router eigrp 100 network 10.0.0.0 no auto-summary variance 2 ! end ``` --- ## โ Exam Tips (For CCNA 200-301) | Topic | What Cisco Tests | |-------|------------------| | **EIGRP Metric** | Bandwidth + Delay (default) | | **Successor** | Best route (lowest metric) | | **Feasible Successor** | Backup route meeting feasibility condition | | **Feasibility Condition** | RD < FD | | **Variance** | Enables unequal-cost load balancing | | **Stub** | Prevents queries to remote routers | | **Hello Interval** | 5 sec (LAN), 60 sec (WAN) | | **AS Number** | Must match for neighbor formation | ### Common Exam Scenarios: **Scenario 1:** "EIGRP neighbors are not forming. What could be the issue?" - **Answer:** AS numbers don't match, K values differ, authentication mismatch, or interfaces not in same subnet **Scenario 2:** "A route has two paths with metrics 100 and 200. How can both paths be used?" - **Answer:** Configure `variance 2` on the router **Scenario 3:** "What makes a route a feasible successor?" - **Answer:** Reported Distance (RD) < Feasible Distance (FD) ### Mnemonics: **EIGRP Components:** **"N.T.D." - Neighbors, Topology, DUAL** - **N**eighbor Table - **T**opology Table - **D**UAL Algorithm **Feasible Condition:** **"RD < FD"** - Reported Distance less than Feasible Distance **EIGRP Timers:** **"5 and 15, 60 and 180"** - LAN: Hello 5, Hold 15 - WAN: Hello 60, Hold 180 --- ## ๐ Summary (1-Minute Revision) ``` EIGRP (Enhanced Interior Gateway Routing Protocol): FEATURES: โโโ Advanced distance-vector (Cisco proprietary) โโโ DUAL algorithm (fast convergence) โโโ Bandwidth + Delay metric (default) โโโ Unequal-cost load balancing (variance) โโโ Supports IPv4 and IPv6 TABLES: โโโ Neighbor Table: Adjacent routers โโโ Topology Table: All learned routes โโโ Routing Table: Best routes (successors) DUAL CONCEPTS: โโโ Successor: Best route (lowest metric) โโโ Feasible Successor: Backup route (RD < FD) โโโ FD (Feasible Distance): Local metric to destination โโโ RD (Reported Distance): Neighbor's metric to destination CONFIGURATION: โโโ router eigrp [as] โโโ network [network] [wildcard] โโโ no auto-summary โโโ passive-interface [int] โโโ variance [multiplier] STUB: โโโ eigrp stub [connected|static|summary|redistributed|receive-only] โโโ Prevents queries to remote routers SUMMARIZATION: โโโ ip summary-address eigrp [as] [net] [mask] โโโ Configure on interface AUTHENTICATION: โโโ key chain [name] โโโ key [id] โโโ key-string [password] โโโ ip authentication mode eigrp [as] md5 EIGRP FOR IPv6: โโโ ipv6 unicast-routing โโโ ipv6 router eigrp [as] โโโ eigrp router-id [id] โโโ no shutdown โโโ ipv6 eigrp [as] (on interface) VERIFICATION: โโโ show ip eigrp neighbors โโโ show ip eigrp topology โโโ show ip route eigrp โโโ show ip protocols ``` --- ## ๐งช Practice Questions **1. Which protocol does EIGRP use for reliable delivery of updates?** - A) TCP - B) UDP - C) RTP (Reliable Transport Protocol) - D) ICMP <details> <summary>Answer</summary> <b>C) RTP (Reliable Transport Protocol)</b> - EIGRP uses its own reliable transport mechanism, not TCP or UDP. </details> **2. What is the default EIGRP hello interval on a LAN?** - A) 5 seconds - B) 10 seconds - C) 30 seconds - D) 60 seconds <details> <summary>Answer</summary> <b>A) 5 seconds</b> - Default hello interval is 5 seconds on LAN interfaces. </details> **3. What is the formula for the default EIGRP metric?** - A) Bandwidth only - B) Delay only - C) Bandwidth + Delay - D) Hop count <details> <summary>Answer</summary> <b>C) Bandwidth + Delay</b> - EIGRP uses bandwidth and delay by default (K1=1, K3=1). </details> **4. What command enables EIGRP stub routing?** - A) `eigrp stub` - B) `stub eigrp` - C) `eigrp stub-router` - D) `stub-router` <details> <summary>Answer</summary> <b>A) `eigrp stub`</b> - This configures the router as an EIGRP stub. </details> **5. What is the purpose of the variance command in EIGRP?** - A) Change metric calculation - B) Enable unequal-cost load balancing - C) Change hello interval - D) Enable authentication <details> <summary>Answer</summary> <b>B) Enable unequal-cost load balancing</b> - Variance allows traffic distribution across paths with different metrics. </details> **6. Which command displays EIGRP neighbors?** - A) `show eigrp neighbors` - B) `show ip eigrp neighbors` - C) `show ip route eigrp` - D) `show ip protocols` <details> <summary>Answer</summary> <b>B) `show ip eigrp neighbors`</b> - Displays the EIGRP neighbor table. </details> **7. What makes a route a feasible successor?** - A) RD < FD - B) FD < RD - C) Equal metrics - D) Lower metric than successor <details> <summary>Answer</summary> <b>A) RD < FD</b> - Feasibility condition requires reported distance less than feasible distance. </details> **8. Which command disables EIGRP auto-summarization?** - A) `no summary` - B) `disable auto-summary` - C) `no auto-summary` - D) `auto-summary off` <details> <summary>Answer</summary> <b>C) `no auto-summary`</b> - This disables automatic summarization at classful boundaries. </details> **9. What is the default hold time for EIGRP on a LAN?** - A) 5 seconds - B) 15 seconds - C) 30 seconds - D) 60 seconds <details> <summary>Answer</summary> <b>B) 15 seconds</b> - Hold time is 3 ร hello interval (3 ร 5 = 15 seconds). </details> **10. Which command configures EIGRP manual summarization?** - A) `summary-address eigrp` - B) `ip summary-address eigrp` - C) `ip eigrp summary` - D) `eigrp summary-address` <details> <summary>Answer</summary> <b>B) `ip summary-address eigrp`</b> - Configured on interface to summarize routes. </details> **11. What is the multicast address for EIGRP?** - A) 224.0.0.5 - B) 224.0.0.6 - C) 224.0.0.9 - D) 224.0.0.10 <details> <summary>Answer</summary> <b>D) 224.0.0.10</b> - EIGRP uses multicast address 224.0.0.10 for hello packets. </details> **12. Which statement about EIGRP feasible successors is true?** - A) They are always installed in routing table - B) They are guaranteed to be loop-free - C) They have higher metric than successors - D) They are used only when successors fail <details> <summary>Answer</summary> <b>B) They are guaranteed to be loop-free</b> - Feasible successors meet the feasibility condition, ensuring no loops. </details> --- ## ๐ Next Steps After completing Video 29, you should be ready for: - **Video 30:** Route Redistribution - **Video 31:** WAN Technologies **Lab Practice:** 1. Configure basic EIGRP between two routers 2. Verify neighbor formation with `show ip eigrp neighbors` 3. Configure EIGRP stub on branch router 4. Configure manual summarization on interface 5. Configure variance for unequal-cost load balancing 6. Configure EIGRP for IPv6 --- **Ready for Video 30?** Share the link or say "next" and I'll continue with Route Redistribution. I'll continue with **Video 30: Route Redistribution** based on the standard CCNA 200-301 curriculum. ---