1 / 98

EIGRP

EIGRP. SAvPS Gen či 2009. Zdroje. Prezent ation „Introduction to EIGRP“ by Scott Hogg www.seccug.org/Presentations/ EIGRP -2006-12-13.ppt (slides 3-9) Introduction to EIGRP http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml

lita
Download Presentation

EIGRP

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. EIGRP SAvPS Genči 2009

  2. Zdroje • Prezentation „Introduction to EIGRP“ by Scott Hogg www.seccug.org/Presentations/EIGRP-2006-12-13.ppt (slides 3-9) • Introduction to EIGRP http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml • Configuring EIGRP (CISCO document) • NetAcad CCNP1 curriculum

  3. EIGRP History • E.W. Dijkstra and C.S. Scholten were first to introduce diffusing computations (Computations that start from an initial node and diffuseto all nodes in a graph.)in 1980 that are used to perform distributed shortest-path routing. • Most of the work on DUAL (Diffusing Update ALgorithm) since then has been done by J.J. Garcia-Luna-Aceves. • In 1989 he released “A Unified Approach for Loop-Free Routing Using Link States or Distance Vectors” • EIGRP was first introduced in 1994 in IOS 9.21. Lots of bugs! Major updates in 10.3(11), 11.0(8), and 11.1(3) • Major enhancements were implemented in 10.x and 11.x releases of IOS. Much Better! • >12.1 has EIGRP optimizations for SIA routes

  4. EIGRP Basics • EIGRP is a Cisco proprietary routing protocol that is distance vector based. • EIGRP is a classless protocol, meaning each route entry includes a subnet mask. • By default EIGRP uses a non-hierarchical topology. OSPF-like hierarchy can be achieved by introducing additional ASs. • EIGRP updates are non-periodic, partial/incremental, and bounded • EIGRP uses time-limits (hold times) • Each EIGRP router stores its neighbors routing tables ( topology table / metrics).

  5. Administrative Distance Route Source Default AD Connected interface 0 Static route 1 Enhanced IGRP summary route 5 External BGP 20 Internal Enhanced IGRP 90 IGRP 100 OSPF 110 IS-IS 115 RIP 120 EGP 140 External Enhanced IGRP 170 Internal BGP 200 Unknown 255 ?

  6. EIGRP Metrics • EIGRP uses a composite of available bandwidth, delay, load utilization, link reliability, and MTU. • 256 X the same IGRP metric – more granular • BW = minimum BW, Delay = sum of delays

  7. EIGRP Metrics • For a T1 link (1544Kbps) • Applying the metric formula: 10,000,000 + 21000 * 256 = 2195456 1544 10 • Output from “show ip route 10.10.1.0” • * 10.10.1.0, from 10.10.1.2, 02:43:19 ago, via Serial1/0/1 • Route metric is 2195456, traffic share count is 1 • Reliability 255/255, minimum MTU 1500 bytes • Loading 8/255, Hops 1 • metric weights <TOS> K1 K2 K3 K4 K5 • Default K1=K3=1, K2=K4=K5 = 0

  8. EIGRP Components • EIGRP is comprised of four major modules: • A reliable transport mechanism used to exchange updatemessages among routers (RTP) • Diffusing Update Algorithm (DUAL) • Neighbor discovery and recovery mechanisms • Protocol Dependent Modules (PDM) that enable its operation in a multiprotocol environment

  9. EIGRP (RTP) • Reliable Transport Protocol (RTP) handles the transmission and receiving of EIGRP packets. • Guaranteed delivery of IP Protocol 88 packets uses multicast address 224.0.0.10. • Acknowledgements from neighboring routers are typically unicast using sequencing numbers for ordered delivery.

  10. What is EIGRP? • EIGRP is an enhanced version of IGRP. • The same distance vector technology found in IGRP is also used in EIGRP, and the underlying distance information remains unchanged. • The convergence properties and the operating efficiency of this protocol have improved significantly. • This allows for an improved architecture while retaining existing investment in IGRP.

  11. Objectives (M1) • This module will cover topics which allow students to meet the following objectives: • Describe the key capabilities that distinguish EIGRP from other routing protocols • Identify the four key technologies employed by EIGRP • Describe how EIGRP operates • Describe the five components of the metric used by EIGRP • Calculate the EIGRP metric for a range of pathways between routers • Explain how IGRP routes are integrated into EIGRP routes and vice-versa

  12. EIGRP Features There are several key differences with EIGRP from other routing protocols which are explored in this module.

  13. EIGRP Key Technologies • Neighbor discover/recovery • Reliable Transport Protocol (RTP) • DUAL finite-state machine • Protocol-dependent modules (PDMs)

  14. The Diffusing Update Algorithm (DUAL) • How does EIGRP determine which routes are loop-free? • Each of A’s neighbors is reporting reachability to E: • B with a cost of 10 • C with a cost of 10 • D with a cost of 30 • These three costs are called the reported distance (RD); the distance each neighbor is reporting to a given destination

  15. The Diffusing Update Algorithm (DUAL) • At A, the total cost to reach E is: • 20 through B • 25 through C • 45 through D • The best of these three paths is the path through B, with a cost of 20 • This is the feasible distance (FD)

  16. The Diffusing Update Algorithm (DUAL) • A uses the FD and the RD to determine which paths are loop-free • The best path (FD) is used as a benchmark; all paths with RDs lower than the FD cannot contain loops • The algorithm may mark some loop-free paths as loops • However, it is guaranteed never to mark a looped path as loop-free

  17. The Diffusing Update Algorithm (DUAL) • At A: • The path through B is the best path (FD), at 20 • C can reach E with a cost of 10; 10 (RD) is less than 20 (FD), so this path is loop-free. • D can reach E with a cost of 30; 30 (RD) is not less than 20 (FD), so EIGRP assumes this path is a loop.

  18. EIGRP Topology Table

  19. Seconds Remaining Before Declaring Neighbor Down How Long Since the Last Time Neighbor Was Discovered How Long It Takes for This Neighbor To Respond To Reliable Packets How Long to Wait Before Retransmitting If No Acknowledgement EIGRP Neighbor Status RTRA#showip eigrp neighbors IP-EIGRP neighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 2 10.1.1.1 Et0 12 6d16h 20 200 0 233 1 10.1.4.3 Et1 13 2w2d 87 522 0 452 0 10.1.4.2 Et1 10 2w2d 85 510 0 3

  20. EIGRP IP Routing Table

  21. Example: EIGRP Tables Router C’s tables:

  22. EIGRP Packets • Hello: Establish neighbor relationships. • Update: Send routing updates • Query: Ask neighbors about routing information • Reply: Respond to query about routing information • ACK: Acknowledge a reliable packet

  23. Initial Route Discovery

  24. EIGRP Metric • Same metric components as IGRP: • Bandwidth • Delay • Reliability • Loading • MTU • EIGRP metric is IGRP metric multiplied by 256

  25. EIGRP Metric Calculation • By default, EIGRP metric: • Metric = bandwidth (slowest link) + delay (sum of delays) • Delay = sum of the delays in the path, in tens of microseconds, multiplied by 256. • Bandwidth = [10 / (minimum bandwidth link along the path, in kilobits per second)] * 256 • Formula with default K values (K1 = 1, K2 = 0, K3 = 1, K4 = 0, K5 = 0): • Metric = [K1 * BW + ((K2 * BW) / (256 – load)) + K3 * delay] • If K5 not equal to 0: • Metric = Metric * [K5 / (reliability + K4)]

  26. EIGRP Metrics Calculation Example A  B  C  D Least bandwidth 64 kbps Total delay 6,000 A  X  Y  Z  D Least bandwidth 256 kbps Total delay 8,000 • Delay is the sum of all the delays of the links along the paths:Delay = [delay in tens of microseconds] x 256 • BW is the lowest bandwidth of the links along the paths:BW = [10,000,000 / (bandwidth in kbps)] x 256

  27. EIGRP Metrics Are Backward-Compatible with IGRP

  28. Objectives (M2) • Upon completing this lesson, you will be able to describe how to implement EIGRP routing. This ability includes being able to meet these objectives: • Describe the commands used in a basic EIGRP configuration task • Explain how to configure a router to use wildcard masks to select the interfaces and networks that will participate in EIGRP routing • Configure the gateway of last resort or default route • Verify that the router recognizes EIGRP neighbors and routes • Verify EIGRP operations

  29. Configuring EIGRP Router(config)# router eigrp autonomous-system-number • Defines EIGRP as the IP routing protocol. • All routers in the internetwork that must exchange EIGRP routing updates must have the same autonomous system number. Router(config-router)# network network-number [wildcard-mask] • Identifies attached networks participating in EIGRP. • The wildcard-mask is an inverse mask used to determine how to interpret the address. The mask has wildcard bits, where 0 is a match and 1 is “don’t care.”

  30. Configuring EIGRP (Cont.) Router(config-if)# bandwidth kilobits • Defines the interface’s bandwidth for the purposes of sending routing update traffic.

  31. Configuring EIGRP for IP Network 192.168.1.0 is not configured on router A,because it is not directly connected to router A.

  32. Configuring EIGRP with IP (cont.) Classful configuration example: routerA(config)#router eigrp 109 routerA(config-router)#network 10.1.0.0 routerA(config-router)#network 10.4.0.0 routerA(config-router)#network 172.16.7.0 routerA(config-router)#network 172.16.2.0 Classless configuration example: routerA(config)#router eigrp 109 routerA(config-router)#network 10.1.0.0 0.0.255.255 routerA(config-router)#network 10.4.0.0 0.0.255.255 routerA(config-router)#network 172.16.2.0 0.0.0.255 routerA(config-router)#network 172.16.7.0 0.0.0.255

  33. Using the Wildcard Mask in EIGRP

  34. Using and Configuring the ip default-network command for EIGRP Chyba

  35. Example R1 EIGRP Configuration

  36. R2 EIGRP Configuration <output omitted> interface FastEthernet0/0 ip address 172.17.2.2 255.255.255.0 <output omitted> interface Serial0/0/1 bandwidth 64 ip address 192.168.1.102 255.255.255.224 <output omitted> router eigrp 100 network 172.17.2.0 0.0.0.255 network 192.168.1.0

  37. Verifying EIGRP: show ip eigrp neighbors R1#show ip eigrp neighbors IP-EIGRP neighbors for process 100 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 192.168.1.102 Se0/0/1 10 00:07:22 10 2280 0 5 R1#

  38. Verifying EIGRP: show ip route eigrp R1#show ip route eigrp D 172.17.0.0/16 [90/40514560] via 192.168.1.102, 00:07:01, Serial0/0/1 172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks D 172.16.0.0/16 is a summary, 00:05:13, Null0 192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks D 192.168.1.0/24 is a summary, 00:05:13, Null0 R1#show ip route <output omitted> Gateway of last resort is not set D 172.17.0.0/16 [90/40514560] via 192.168.1.102, 00:06:55, Serial0/0/1 172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks D 172.16.0.0/16 is a summary, 00:05:07, Null0 C 172.16.1.0/24 is directly connected, FastEthernet0/0 192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks C 192.168.1.96/27 is directly connected, Serial0/0/1 D 192.168.1.0/24 is a summary, 00:05:07, Null0

  39. Verifying EIGRP: show ip protocols R1#show ip protocols Routing Protocol is "eigrp 100" Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is not set Default networks flagged in outgoing updates Default networks accepted from incoming updates EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0 EIGRP maximum hopcount 100 EIGRP maximum metric variance 1 Redistributing: eigrp 100 EIGRP NSF-aware route hold timer is 240s <output omitted> Maximum path: 4 Routing for Networks: 172.16.1.0/24 192.168.1.0 Routing Information Sources: Gateway Distance Last Update (this router) 90 00:09:38 Gateway Distance Last Update 192.168.1.102 90 00:09:40 Distance: internal 90 external 170

  40. Verifying EIGRP: show ip eigrp interfaces R1#show ip eigrp interfaces IP-EIGRP interfaces for process 100 Xmit Queue Mean Pacing Time Multicast Pending Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes Fa0/0 0 0/0 0 0/10 0 0 Se0/0/1 1 0/0 10 10/380 424 0

  41. Verifying EIGRP: show ip eigrp topology R1#show ip eigrp topology IP-EIGRP Topology Table for AS(100)/ID(192.168.1.101) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P 192.168.1.96/27, 1 successors, FD is 40512000 via Connected, Serial0/0/1 P 192.168.1.0/24, 1 successors, FD is 40512000 via Summary (40512000/0), Null0 P 172.16.0.0/16, 1 successors, FD is 28160 via Summary (28160/0), Null0 P 172.16.1.0/24, 1 successors, FD is 28160 via Connected, FastEthernet0/0 P 172.17.0.0/16, 1 successors, FD is 40514560 via 192.168.1.102 (40514560/28160), Serial0/0/1

  42. Topology table codes • Passive (P): This network is available, and installation can occur in the routing table. Passive is the correct state for a stable network. • Active (A): This network is currently unavailable, and installation cannot occur in the routing table. Being active means that there are outstanding queries for this network. • Update (U): This code applies if a network is being updated (placed in an update packet). This code also applies if the router is waiting for an acknowledgment for this update packet. • Query (Q): This code applies if there is an outstanding query packet for this network other than being in the active state. This code also applies if the router is waiting for an acknowledgment for a query packet. • Reply (R): This code applies if the router is generating a reply for this network or is waiting for an acknowledgment for the reply packet. • Stuck-in-active (SIA) status: This code signifies an EIGRP convergence problem for the network with which it is associated.

  43. Verifying EIGRP: show ip eigrp traffic R1#show ip eigrp traffic IP-EIGRP Traffic Statistics for AS 100 Hellos sent/received: 429/192 Updates sent/received: 4/4 Queries sent/received: 1/0 Replies sent/received: 0/1 Acks sent/received: 4/3 Input queue high water mark 1, 0 drops SIA-Queries sent/received: 0/0 SIA-Replies sent/received: 0/0 Hello Process ID: 113 PDM Process ID: 73

  44. Packets explanation ([1]) • Updates are used to propagate routing information. Update packets are reliably transmitted only when necessary (unlike IGRP/RIP). Update packets carry only necessary routing information and are sent to only involved routers. • Queries and Replies are used to help in the search of feasible successors during routing changes. DUAL uses this information to perform it’s computations.

  45. EIGRP Terminology ([1]) • Adjacency - Like OSPF, EIGRP uses Hellos to identify itself to potential neighbors and form adjacencies with other same-protocol speaking routers. • Feasible Distance - The lowest calculated metric for any destination is the feasible distance. The FD metric can be chosen from several advertised routes to the destination. • Feasible Condition - Is met when a neighbor’s advertised metric is lower than the routers FD to that destination. • Feasible Successor - When a neighboring router’s advertised metric meets the FC, that neighbor becomes a feasible successor. • Successor - A successor is a neighboring router that is currently being used as the next-hop, has the least cost route to the destination, and is not part of a routing loop.

  46. EIGRP DUAL ([1]) • In determining the successor for the subnet the router does the following: • Determines which neighbors have an advertised metric to the subnet that is less than the router’s FD to the subnet. If any neighbor’s advertised metric that is less then they are feasible successors for that route. • Calculate the minimum computed metric to the subnet. (FD) • The router with the lower FD becomes the successor. (if FS metrics had been the same, then equal cost load balancing could be used)

  47. EIGRP DUAL (cont) • What happens if the successor route fails? • If there is a feasible successor for the failed router then there is no transition to Active for the subnet and the feasible successor will take over as the successor. • This is known as local computation.

  48. EIGRP DUAL (cont) • If no feasible route is known based upon the routing information previously learned from neighbors, the route goes Active for that destination. • The router then sends queries to all neighboring routers. The queries are propagated until an alternate route is found. The query contains the new calculated FD, which is “unreachable”. • This is known as a diffusing computation. • The router will set the reply status flag to one, which means that a reply is expected.

More Related