ENARSI_Chapter_2.pdf

Chapter 2: EIGRP Instructor Materials CCNP Enterprise: Advanced Routing Chapter 2 Content This chapter covers the following content: EIGRP Fundamentals - This section explains how EIGRP establishes a neighborship with other routers and how routes are exchanged with other routers....

Chapter 2: EIGRP Instructor Materials CCNP Enterprise: Advanced Routing Chapter 2 Content This chapter covers the following content: EIGRP Fundamentals - This section explains how EIGRP establishes a neighborship with other routers and how routes are exchanged with other routers. EIGRP Configuration Modes - This section defines the two methods of configuring EIGRP with a baseline configuration. Path Metric Calculation - This section explains how EIGRP calculates the path metric to identify the best and alternate loop-free paths. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 2 EIGRP Fundamentals Enhanced Interior Gateway Routing Protocol (EIGRP) is an enhanced distance vector routing protocol commonly found in enterprise networks. EIGRP is a derivative of Interior Gateway Routing Protocol (IGRP) but includes support for variable-length subnet masking (VLSM) and metrics capable of supporting higher-speed interfaces. EIGRP overcomes the deficiencies of other distance vector routing protocols, such as Routing Information Protocol (RIP), with features such as unequal-cost load balancing, support for networks 255 hops away, and rapid convergence features. EIGRP uses a diffusing update algorithm (DUAL) to identify network paths and provides for fast convergence using precalculated loop-free backup paths. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 3 EIGRP Fundamentals Autonomous Systems A router can run multiple EIGRP processes. Each process operates under the context of an autonomous system, which represents a common routing domain. Routers within the same domain use the same metric calculation formula and exchange routes only with members of the same autonomous system. EIGRP uses protocol-dependent modules (PDMs) to support multiple network protocols, such as IPv4, and IPv6. EIGRP is written so that the PDM is responsible for the functions that handle the route selection criteria for each communication protocol. Current versions of EIGRP only support IPv4 and IPv6. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 4 EIGRP Fundamentals EIGRP Terminology Figure 2-2 is used as a reference topology for R1 calculating the best path and alternative loop-free paths to the 10.4.4.0/24 network. The values in parentheses represent the link’s calculated metric for a segment based on bandwidth and delay. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 5 EIGRP Fundamentals EIGRP Terminology (Cont.) Term Definition Successor route The route with the lowest path metric to reach a destination. The successor route for R1 to reach 10.4.4.0/24 on R4 is R1→R3→R4. Successor The first next-hop router for the successor route. The successor for 10.4.4.0/24 is R3. Feasible distance (FD) The metric value for the lowest-metric path to reach a destination. The feasible distance is calculated locally using the formula shown in the “Path Metric Calculation” section, later in this chapter. The FD calculated by R1 for the 10.4.4.0/24 network is 3328 (that is, 256 + 256 + 2816). Reported distance (RD) Distance reported by a router to reach a prefix. The reported distance value is the feasible distance for the advertising router. R3 advertises the 10.4.4.0/24 prefix with an RD of 3072. R4 advertises the 10.4.4.0/24 to R1 and R2 with an RD of 2816. Feasibility condition For a route to be considered a backup route, the RD received for that route must be less than the FD calculated locally. This logic guarantees a loop-free path. Feasible successor A route with that satisfies the feasibility condition is maintained as a backup route. The feasibility condition ensures that the backup route is loop free. The route R1→R4 is the feasible successor because the RD of 2816 is lower than the FD of 3328 for the R1→R3→R4 path. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 6 EIGRP Fundamentals EIGRP Topology Table EIGRP contains a topology table, which makes it different from a true distance vector routing protocol. EIGRP’s topology table is a vital component of DUAL and contains information to identify loop-free backup routes. The topology table contains all the network prefixes advertised within an EIGRP autonomous system. Each entry in the table contains the following: Network prefix EIGRP neighbors that have advertised that prefix Metrics from each neighbor (reported distance and hop count) Values used for calculating the metric (load, reliability, total delay, and minimum bandwidth) The command show ip eigrp topology shows only the successor and feasible successor routes, as shown in Figure 2- 3, the optional all-links keyword shows all paths received. Figure 2-3 shows the topology table for R1 from Figure 2-2. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 7 EIGRP Fundamentals EIGRP Neighbors EIGRP does not rely on periodic advertisement of all the network prefixes in an autonomous system, which is done with routing protocols such as Routing Information Protocol (RIP), Open Shortest Path First (OSPF), and Intermediate System-to- Intermediate System (IS-IS). EIGRP neighbors exchange the entire routing table when forming an adjacency, and they advertise incremental updates only as topology changes occur within a network. The neighbor adjacency table is vital for tracking neighbor status and the updates sent to each neighbor. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 8 EIGRP Fundamentals Inter-Router Communication EIGRP uses five different packet types to communicate with other routers, as shown in Table 2-3. EIGRP uses its own IP protocol number (88) and uses multicast packets where possible; it uses unicast packets when necessary. Communication between routers is done with multicast using the group address 224.0.0.10 or the MAC address 01:00:5e:00:00:0a when possible. EIGRP uses multicast packets to reduce bandwidth consumed on a link (one packet to reach multiple devices). EIGRP uses Reliable Transport Protocol (RTP) to ensure that packets are delivered in order and to ensure that routers receive specific packets. A sequence number is included in each EIGRP packet. The sequence value zero does not require a response from the receiving EIGRP router; all other values require an ACK packet that includes the original sequence number. Table 2-3 EIGRP Packet Types Packet Type Packet Name Function 1 Hello Used for discovery of EIGRP neighbors and for detecting when a neighbor is no longer available 2 Request Used to get specific information from one or more neighbors 3 Update Used to transmit routing and reachability information with other EIGRP neighbors 4 Query Sent out to search for another path during convergence 5 Reply Sent in response to a query packet © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 9 EIGRP Fundamentals Forming EIGRP Neighbors Unlike other distance vector routing protocols, EIGRP requires a neighbor relationship to form before routes are processed and added to the Routing Information Base (RIB). Upon hearing an EIGRP hello packet, a router attempts to become the neighbor of the other router. The following parameters must match for the two routers to become neighbors: Metric formula K values Primary subnet matches Autonomous system number (ASN) matches Figure 2-4 shows the process EIGRP uses for Authentication parameters forming neighbor adjacencies. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 10 EIGRP Configuration Modes The two methods of EIGRP configuration are classic mode and named mode. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 11 EIGRP Configuration Mode Classic Configuration Mode With classic EIGRP configuration mode, most of the configuration takes place in the EIGRP process, but some settings are configured under the interface configuration submode. This can add complexity for deployment and troubleshooting as users must scroll back and forth between the EIGRP process and individual network interfaces. Some of the settings that are set individually are hello advertisement interval, split- horizon, authentication, and summary route advertisements. Classic configuration requires the initialization of the routing process with the global configuration command router eigrp as-number to identify the ASN and initialize the EIGRP process. The second step is to identify the network interfaces with the command network ip-address [mask]. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 12 EIGRP Configuration Mode EIGRP Named Mode EIGRP named mode configuration was released to overcome some of the difficulties network engineers have with classic EIGRP autonomous system configuration, including scattered configurations and unclear scope of commands. EIGRP named configuration provides the following benefits: All the EIGRP configuration occurs in one location. It supports current EIGRP features and future developments. It supports multiple address families (including Virtual Routing and Forwarding [VRF] instances). EIGRP named configuration is also known as multi-address family configuration mode. Commands are clear in terms of the scope of their configuration. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 13 EIGRP Configuration Mode EIGRP Named Mode (Cont.) EIGRP named configuration makes it possible to run multiple instances under the same EIGRP process. EIGRP named mode provides a hierarchical configuration and stores settings in three subsections: Address Family - This submode contains settings that are relevant to the global EIGRP AS operations, such as selection of network interfaces, EIGRP K values, logging settings, and stub settings. Interface - This submode contains settings that are relevant to the interface, such as hello advertisement interval, split-horizon, authentication, and summary route advertisements. In actuality, there are two methods of the EIGRP interface section’s configuration. Commands can be assigned to a specific interface or to a default interface, in which case those settings are placed on all EIGRP-enabled interfaces. If there is a conflict between the default interface and a specific interface, the specific interface takes priority over the default interface. Topology - This submode contains settings regarding the EIGRP topology database and how routes are presented to the router’s RIB. This section also contains route redistribution and administrative distance settings. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 14 EIGRP Configuration Mode EIGRP Network Statement Both configuration modes use a network statement to identify the interfaces that EIGRP will use. The network statement uses a wildcard mask, which allows the configuration to be as specific or ambiguous as To help illustrate the concept of the wildcard mask, Table 2-4 provides a set necessary. of IP addresses and interfaces for a router. The syntax for the network statement, which exists under the EIGRP process, is network ip-address [mask]. The optional mask can be omitted to enable interfaces that fall within the classful boundaries for that The configuration in Example 2-1 enables EIGRP only on interfaces that explicitly match the IP addresses in Table 2-4. network statement. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 15 EIGRP Configuration Mode Sample Topology and Configuration Figure 2-5 shows a sample topology for demonstrating EIGRP configuration in classic mode for R1 and named mode for R2. Example 2-3 provides the configuration that is applied to R1 and R2. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 16 EIGRP Configuration Mode Confirming Interfaces After configuration, it is a good practice to verify that only the intended interfaces are running EIGRP. The command show ip eigrp interfaces [{interface-id [detail] | detail}] shows active EIGRP interfaces. Appending the optional detail keyword provides additional information, such as authentication, EIGRP timers, split horizon, and various packet counts. Example 2-5 demonstrates R1’s non- detailed EIGRP interface and R2’s detailed information for the gi0/1 interface. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 17 EIGRP Configuration Mode Confirming Interfaces (Cont.) Interface Interfaces running EIGRP. Peers Number of peers detected on that interface. Xmt Queue Un/Reliable Number of unreliable/reliable packets remaining in the transmit queue. The value zero is an indication of a stable network. Mean SRTT Average time for a packet to be sent to a neighbor and a reply from that neighbor to be received, in milliseconds. Multicast Flow Timer Maximum time (seconds) that the router sent multicast packets Pending Routes Number of routes in the transmit queue that need to be sent. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 18 EIGRP Configuration Mode Verifying EIGRP Neighbor Adjacencies Each EIGRP process maintains a table of neighbors to ensure that they are alive and processing updates properly. Without keeping track of a neighbor state, an autonomous system could contain incorrect data and could potentially route traffic improperly. EIGRP must form a neighbor relationship before a Field Description router advertises update packets containing Address IP address of the EIGRP neighbor network prefixes. Interface Interface the neighbor was detected on Holdtime Time left to receive a packet from this neighbor to ensure it is The command show ip eigrp neighbors still alive [interface-id] displays the EIGRP neighbors SRTT Time for a packet to be sent to a neighbor and reply to be received from that neighbor in milliseconds for a router. Example 2-6 shows the EIGRP RTO Timeout for retransmission (waiting for ACK) neighbor information using this command. Q cnt Number of packets (update/query/reply) in queue for sending Seq Num Sequence number that was last received from the router © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 19 EIGRP Configuration Mode Displaying Installed EIGRP Routes You can see EIGRP routes that are installed into the RIB by using the command show ip route eigrp. EIGRP routes originating within the autonomous system have an administrative distance (AD) of 90 and are indicated in the routing table with a D. Routes that originate from outside the autonomous system are external EIGRP routes External EIGRP routes have an AD of 170 and are indicated in the routing table with D EX. Placing external EIGRP routes into the RIB with a higher AD acts as a loop-prevention mechanism. Example 2-7 displays the EIGRP routes from the sample topology in Figure 2-5. The metric for the selected route is the second number in brackets. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 20 EIGRP Configuration Mode Router ID The router ID (RID) is a 32-bit number that uniquely identifies an EIGRP router and is used as a loop- prevention mechanism. The RID can be set dynamically, which is the default, or manually. The algorithm for dynamically choosing the EIGRP RID uses the You use the command eigrp router-id to set the highest IPv4 address of any up RID, as demonstrated in Example 2-8, for both loopback interfaces. If there are not classic and named mode configurations. any up loopback interfaces, the highest IPv4 address of any active up physical interfaces becomes the RID when the EIGRP process initializes. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 21 EIGRP Configuration Mode Passive Interfaces Some network topologies must advertise a network segment into EIGRP but need to prevent neighbors from forming adjacencies with other routers on that segment. In this scenario, you need to put the EIGRP interface in a passive state. Passive EIGRP interfaces do not send out or process EIGRP hellos, which prevents EIGRP from forming adjacencies on that interface. Example 2-9 demonstrates making R1’s gi0/2 To configure an EIGRP interface as interface passive and also the alternative option passive, you use the command passive- of making all interfaces passive but setting gi0/1 interface interface-id under the EIGRP as non-passive. process for classic configuration. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 22 EIGRP Configuration Mode Passive Routes (Cont.) For a named mode configuration, you place the passive-interface state on af- interface default for all EIGRP interfaces or on a specific interface with the af- interface interface-id section. Example 2- 10 shows how to set the gi0/2 interface as passive while allowing the gi0/1 interface to be active using both configuration strategies. The command show ip protocols provides valuable information about all the routing protocols. With EIGRP, it displays the EIGRP process identifier, the ASN, K values that are Example 2-11 shows what the named mode configuration used for path calculation, RID, neighbors, AD looks like with some settings (i.e. passive-interface or no settings, and all the passive interfaces. passive-interface) placed under the af-interface default or the af-interface interface-id setting. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 23 EIGRP Configuration Mode Authentication Authentication is a mechanism for ensuring that Keychain creation is accomplished only authorized routers are eligible to become with the following steps: EIGRP neighbors. Authentication prevents adding a router to a Step 1. Create the keychain by network and introducing invalid routes, accidentally using the command key chain key- or maliciously. chain-name. A precomputed password hash is included with all EIGRP packets, and when the packet is received, Step 2. Identify the key sequence by the receiving router also calculates the hash on the packet. If the two hash values match, the packet is using the command key key- accepted. number, where key-number can be EIGRP encrypts the password by using a Message anything from 0 to 2147483647. Digest 5 (MD5) authentication, using the keychain function. The hash consists of the key number and Step 3. Specify the preshared a password. EIGRP authentication does not password by using the command encrypt the contents of the routing update packets. key-string password. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 24 EIGRP Configuration Mode Enabling Authentication on the Interface When using classic configuration, authentication must be enabled on the interface under the interface configuration submode. The following commands are used in the interface configuration submode: ip authentication key-chain eigrp as-number key- chain-name ip authentication mode eigrp as-number md5 The named mode configuration places the configurations under the EIGRP interface submode, under the af-interface default or the af-interface interface-id. Named mode configuration supports MD5 or Hashed Message Example 2-14 demonstrates MD5 Authentication Code-Secure Hash Algorithm-256 (HMAC- configuration on R1 with classic EIGRP SHA-256) authentication. MD5 authentication involves the configuration and on R2 with named mode following commands: configuration. Remember that the hash is authentication key-chain eigrp key-chain-name computed using the key sequence authentication mode md5 number and key string, which must match The HMAC-SHA-256 authentication involves the command on the two nodes. authentication mode hmacsha-256 password. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 25 EIGRP Configuration Mode Verification of Keychain Settings The command show key chain provides verification of the keychain. Example 2-15 shows that each key sequence provides the lifetime and password. Example 2-16 provides detailed EIGRP interface output. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 26 Path Metric Calculations Metric calculation is a critical component for any routing protocol. EIGRP uses multiple factors to calculate the metric for a path. Metric calculation uses bandwidth and delay by default but can include interface load and reliability, too. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 27 Path Metric Calculation EIRG Classic Metric Formula EIGRP uses K values to define which factors The formula shown in Figure 2-6 illustrates the formula uses and the impact associated the EIGRP classic metric formula. with a factor when calculating the metric. BW represents the slowest link in the path, scaled to a 10 Gbps link (107). Link speed is collected from the configured interface bandwidth on an interface. Delay is the total measure of delay in the path, measured in tens of microseconds (μs). © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 28 Path Metric Calculation EIRG Classic Metric Formula (Cont.) The EIGRP formula is based on the IGRP By default, K1 and K3 have a value of metric formula, except the output is 1, and K2, K4, and K5 are set to 0. multiplied by 256 to change the metric from Figure 2-8 places default K values into 24 bits to 32 bits. Taking these definitions the formula and shows a streamlined into consideration, the formula for EIGRP is version of the formula. shown in Figure 2-7. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 29 Path Metric Calculation EIGRP Attribute Propagation The EIGRP update packet includes path attributes associated with each prefix. The EIGRP path attributes can include hop count, cumulative delay, minimum bandwidth link speed, and RD. The attributes are updated each hop along the way, allowing each router to independently identify the shortest path. Figure 2-9 shows the information in the EIGRP update packets for the 10.1.1.0/24 prefix propagating through the autonomous system. Notice that as the hop count increments, minimum bandwidth decreases, total delay increases, and the RD changes with each EIGRP update. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 30 Path Metric Calculation Default EIGRP Interface Metrics for Classic Metrics Table 2-7 shows some of the common network types, link speeds, delay, and EIGRP metric, using the streamlined formula from Figure 2-7. Table 2-7 Default EIGRP Interface Metrics for Classic Metrics Interface Type Link Delay Metric If you are unsure of the Speed EIGRP metrics, you can (Kbps) query the parameters for the Serial 64 20,000 μs 40,512,000 formula directly from EIGRP’s topology table by T1 1544 20,000 μs 2,170,031 using the command show Ethernet 10,000 1000 μs 281,600 ip eigrp topology Fast Ethernet 100,000 100 μs 28,160 network/prefix-length. GigabitEthernet 1,000,000 10 μs 2816 TenGigabitEthernet 10,000,00 10 μs 512 0 © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 31 Path Metric Calculation Wide Metrics Example 2-18 provides some metric calculations for common LAN interface speeds. Notice that there is not a differentiation between an 11 Gbps interface and a 20 Gbps interface. The composite metric stays at 256, despite the different bandwidth rates. EIGRP includes support for a second set of metrics, known as wide metrics, that addresses the issue of scalability with higher-capacity interfaces. Figure 2-11 shows the explicit EIGRP wide metrics formula. Notice that an additional K value (K6) is included that adds an extended attribute to measure jitter, energy, or other future attributes. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 32 Path Metric Calculation Wide Metrics (Cont.) Just as EIGRP scaled by 256 to accommodate IGRP, EIGRP wide metrics scale by 65,535 to accommodate higher- speed links. This provides support for interface speeds up to 655 terabits per second (65,535 × 107) without any scalability issues. Latency is the total interface delay The EIGRP classic metrics exist only with measured in picoseconds (10−12) instead EIGRP classic configuration, while EIGRP wide of in microseconds (10−6). Figure 2-12 metrics exist only in EIGRP named mode. The shows an updated formula that takes into metric style used by a router is identified with the account the conversions in latency and command show ip protocols; if a K6 metric is scalability. present, the router is using wide-style metrics. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 33 Path Metric Calculation Metric Backward Compatibility EIGRP wide metrics were designed with backward compatibility in mind. EIGRP wide metrics set K2 and K3 to a value of 1 and set K2, K4, K5, and K6 to 0, which allows backward compatibility because the K value metrics match with classic metrics. As long as K1 through K5 are the same and K6 is not set, the two metric styles allow adjacency between routers. This conversion results in loss of clarity if routes pass through a mixture of classic metric and EIGRP is able to detect when peering wide metric devices. It is best to keep all devices with a router is using classic metrics, and operating with the same metric style. it unscales the metric to the formula in Figure 2-13. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 34 Path Metric Calculation Interface Delay Settings Example 2-20 provides sample output of the command on R1 and R2. Both interfaces have a delay of 10. EIGRP delay is set on an interface-by-interface basis, allowing for manipulation of traffic patterns flowing through a specific interface on a router. Delay is configured with the interface parameter command delay tens-of-microseconds under the interface. Example 2-21 demonstrates the modification of the delay on R1 to 100, increasing the delay to 1000 μs on the link between R1 and R2. To ensure consistent routing, modify the delay on R2’s gi0/1 interface as well, then verify the change. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 35 Path Metric Calculation Custom K Values If the default metric calculations are insufficient, you can change them to modify the path metric formula. K values for the path metric formula are set with the command metric weights TOS K1 K2 K3 K4 K5 [K6] under the EIGRP process. The TOS value always has a value of 0, and the K6 value is used for named mode configurations. To ensure consistent routing logic in an EIGRP autonomous system, the K values must match between EIGRP neighbors to form an adjacency and exchange routes. The K values are included as part of the EIGRP hello packet. The K values are displayed with the show ip protocols command. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 36 Path Metric Calculation Load Balancing EIGRP allows multiple successor routes (with the same metric) to be installed into the RIB. Installing multiple paths into the RIB for the same prefix is called equal-cost multipathing (ECMP) routing. The default maximum ECMP is four routes. You change the default ECMP setting with the command maximum-paths under the EIGRP process in classic mode and under the topology base submode in named mode. Example 2-22 shows the configuration for changing the maximum paths on R1 and R2 so that classic and named mode configurations are visible. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 37 Path Metric Calculation Load Balancing (Cont.) EIGRP supports unequal-cost load balancing, which allows installation of both successor routes and feasible successors into the EIGRP RIB. To use unequal-cost load balancing with EIGRP, change EIGRP’s variance multiplier. The EIGRP variance value is the feasible distance (FD) for a route multiplied by the EIGRP variance multiplier. Any feasible successor’s FD with a metric below the EIGRP variance value is installed into the RIB. Dividing the feasible successor metric by the successor route metric provides the variance multiplier. The variance multiplier is a whole number, and any remainders should always round up. © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 38 Prepare for the Exam © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 39 Prepare for the Exam Key Topics for Chapter 2 Description EIGRP terminology Authentication Topology table Path metric calculation EIGRP packet types EIGRP attribute propagation Forming EIGRP neighbors EIGRP wide metrics formula Classic configuration mode Custom K values EIGRP named mode Unequal-cost load balancing Passive interfaces © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 40 Prepare for the Exam Key Terms for Chapter 2 Term autonomous system (AS) topology table successor route EIGRP classic configuration successor EIGRP named mode configuration feasible distance passive interface reported distance K values feasibility condition wide metrics feasible successor variance value © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 41 Prepare for the Exam Command Reference for Chapter 2 Task Command Syntax Initialize EIGRP in classic router eigrp as-number configuration network network mask Initialize EIGRP in named router eigrp process-name address-family { ipv4 | ipv6 } {unicast | vrf mode configuration vrf-name} autonomous-system as-number network network-mask Define the EIGRP router ID eigrp router-id router-id Configure an EIGRP-enabled Classic: passive-interface interface-id interface to prevent neighbor Named Mode: af-interface {default | interface-id} adjacencies passive-interface Configure a keychain for key chain key-chain-name EIGRP MD5 authentication key key-number key-string password © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 42 Prepare for the Exam Command Reference for Chapter 2 (Cont.) Task Command Syntax Configure MD5 authentication for an EIGRP Classic: (EIGRP Process) interface ip authentication key-chain eigrp as-number key-chain- name ip authentication mode eigrp as-number md5 Named Mode: af-interface {default | interface-id} authentication key-chain eigrp key-chain-name authentication mode md5 Configure SHA authentication for EIGRP Named Mode: af-interface {default | interface-id} named mode interfaces authentication mode hmac-sha-256 password Modify the interface delay for an interface delay tens-of-microseconds Modify the EIGRP K values metric weights TOS K1 K2 K3 K4 K5 [K6] Modify the default number of EIGRP maximum Maximum-paths maximum-paths paths that can be installed into the RIB © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 43 Prepare for the Exam Command Reference for Chapter 2 (Cont.) Task Command Syntax Modify the EIGRP variance multiplier for variance multiplier unequal-cost load balancing Display the EIGRP-enabled interfaces show ip eigrp interface [{interface-id [detail] | detail}] Display the EIGRP topology table show ip eigrp topology [all-links] Display the configured EIGRP keychains show key chain and passwords Display the IP routing protocol show ip protocols information configured on the router © 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 44