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CIS 185 CCNP ROUTE EIGRP Part 1 Rick Graziani Cabrillo College Last Updated: Fall 2011.

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Presentation on theme: "CIS 185 CCNP ROUTE EIGRP Part 1 Rick Graziani Cabrillo College Last Updated: Fall 2011."— Presentation transcript:

1 CIS 185 CCNP ROUTE EIGRP Part 1 Rick Graziani Cabrillo College Last Updated: Fall 2011

2 2 EIGRP Part 1 Review Neighbor Adjacencies and EIGRP Reliability EIGRP Metric DUAL Basic EIGRP Configuration Passive-Interfaces Summarization Default Route

3 3 Materials Book:  Implementing Cisco IP Routing (ROUTE) Foundation Learning Guide: Foundation learning for the ROUTE Exam  By Diane Teare  Book  ISBN-10:  ISBN-13:  eBook  ISBN-10:  ISBN-13:

4 Review

5 5 What do we remember about EIGRP? What type of protocol is EIGRP?  Distance Vector What are the default metrics used by EIGRP?  Bandwidth (slowest) and Delay (cumulative) What are the optional metrics?  Reliability and Load  Note: Book also state MTU but it is not a metric. What algorithm is used to determine best path?  DUAL (Diffusing Update Algorithm)

6 6 Review of EIGRP from CCNA Enhanced Interior Gateway Routing Protocol (EIGRP) Released in 1992 with Cisco IOS Software Release Enhancement of Cisco’s:  Interior Gateway Routing Protocol (IGRP). Both are Cisco proprietary, operate only on:  Cisco routers

7 7 RTP and EIGRP Packet Types What transport layer protocol does EIGRP use?  Reliable Transport Protocol (RTP) Why doesn’t EIGRP use UDP or TCP?

8 8 Protocol- Dependent Modules EIGRP uses protocol-dependent modules (PDM). to route different protocols, including:  IPv4  IPv6  Internetwork Packet Exchange (IPX)  AppleTalk

9 EIGRP Packet Frame Header Frame Payload CRC IP Header Protocol Number (EIGRP = 88) EIGRP Header EIGRP Message On a LAN, the EIGRP packet is encapsulated in an Ethernet frame with a destination multicast MAC address: E A The destination IP address is set to the multicast and the EIGRP protocol field is 88. The EIGRP header identifies the type of EIGRP packet and autonomous system number. The EIGRP message consists of the Type / Length / Value (TLV).

10 EIGRP Header

11 EIGRP Packet

12 12 EIGRP Packet Types – Hello Packet What are Hello packets used for by EIGRP to:  Discover neighbors (sometimes called neighborships)  Form adjacencies with those neighbors What is the multicast address? Hint: ?  Are these sent as reliable or unreliable deliver?  Unreliable delivery – No ACKs returned

13 13 Hello Protocol NBMA Link that are All other serial interfaces and LANs

14 14 Hello Protocol Default hold time - 3 times the hello interval If the hold time expires:  EIGRP declares the route as down  DUAL searches for a new path in the topology table or by sending out queries.  It is NOT automatically adjusted if Hello Interval is modified. NBMA Link that are All other serial interfaces and LANs

15 15 Update Packets – Reliable Delivery Acknowledgment (ACK) Packets – Unreliable Delivery  Sent when reliable delivery is used (update, query, and reply packets). EIGRP uses triggered updates EIGRP Packet Types – Update and Acknowledgement Packets

16 16 EIGRP Packet Types – Query and Reply Packets Queries and replies use reliable delivery (Ack returned). Used by DUAL when searching for networks and other tasks.

17 17 DUAL: An Introduction J. J. Garcia-Luna-Aceves

18 18 DUAL: An Introduction (More later!). X Or holdtime expires R2: Checks Topology table for Feasible Successor. If no FS…

19 19 Summary - RTP Packet Types Hellos – Identifies neighbors  Used by the neighbor discovery and recovery process.  Multicast  Unreliable delivery Acknowledgements (ACK) – Acknowledges receipt  Hello packets with no data  Unicast  Unreliable delivery Updates – Advertises routes  Transmitted only when necessary  Unicast when sent to a specific router  Multicast when sent to multiple routers  Reliable delivery Queries – Ask about a route (DUAL)  Reliable delivery  Multicast or Unicast Queries and Replies – Ask about a route and answer a query (DUAL)  Reliable delivery  Replies: Unicast

20 20 Administrative Distance We will discuss Administrative Distance in more detail in a later chapter. Later in this chapter, you learn how to configure EIGRP summary routes. Routes manually summarized. Routes redistributed into EIGRP.

21 Neighbor Adjacencies and EIGRP Reliability 21

22 22 Configuring Hello Intervals and Hold Times Configurable on a per-interface basis, NOT per neighbor (LANs) Does not have to match with other EIGRP routers to establish adjacencies. Router(config-if)# ip hello-interval eigrp as-number seconds Router(config-if)# ip hold-time eigrp as-number seconds

23 Neighbor Table Contents 23 R1# show ip eigrp neighbors IP-EIGRP neighbors for process 100 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num Se0/0/ :07: R1# Lists the order in which a peering session was established with the specified neighbor, starting with 0. Neighbor’s IP address Local interface receiving EIGRP Hello packets. Seconds remaining before declaring neighbor down. The current hold time and is reset to the maximum hold time whenever a Hello packet is received. SRTT (Smooth Round Trip Timer) and RTO (Retransmit Interval) are used by RTP to manage reliable EIGRP packets. SRTT indicates how long it takes for this neighbor to respond to reliable packets. RTO indicates how long to wait before retransmitting if no ACK is received. Queue count should always be zero otherwise there’s congestion on the link. The sequence number of the last update, query, or reply packet that was received from this neighbor. Amount of time since this neighbor was added to the neighbor table.

24 Neighbor Table Contents Smooth Round Trip Timer (SRTT)—The average number of milliseconds it takes for an EIGRP packet to be sent to this neighbor and for the local router to receive an acknowledgment of that packet.  Used to determine the retransmit interval, a.k.a. retransmit timeout (RTO). RTO—The amount of time, in milliseconds, that the router waits for an acknowledgment before retransmitting a reliable packet from the retransmission queue to a neighbor. 24 Start Stop Start Stop No ACK Returned

25 EIGRP Reliability RTO—The amount of time, in milliseconds, that the router waits for an acknowledgment before retransmitting a reliable packet from the retransmission queue to a neighbor. Updates, queries and replies are sent reliably. A sequence number is assigned and an explicit ACK is returned for each sequence number. 25 Start Stop No ACK Returned If the RTO expires before and ACK is received, EIGRP retransmits another copy of the packet. A maximum of 16 times OR until the hold time expires then the Neighbor is declared down. When a neighbor is declared down: The adjacency is removed All networks reached through that neighbor are removed from the routing table. 180 second hold time on low-speed NBMA links can be a long time to wait. Retransmission occurs after each RTO timer expires. After 16 attempts the neighbor is declared down. This is less time than waiting for the hold time to expire. 16 x RTO < Hold Timer

26 EIGRP Reliability 26 Potential problem on multiaccess (Frame Relay, Ethernet) media where multiple neighbors reside. The next reliable multicast packet cannot be sent until all peers have Acknowledged the previous multicast packet. If one or more neighbors are slow to respond it adversely affects all peers. When a neighbor is slow to respond to multicasts or does not acknowledge the multicast, the router will retransmit the packet as a unicast. This allows reliable multicasts to continue and speeds up convergence without waiting for peers on lower speed links. Multicast flow timer - Determines how long a router should wait for an ACK to be received before switching from multicast to unicast. Calculation is based on RTO and SRTT (Cisco proprietary) No ACK Received Update 100 ACK Update 101 (in queue) Update100 Multicast Flow Timer expires R3# show ip eigrp interfaces IP-EIGRP interfaces for process 1 Xmit Queue Mean Pacing Time Multicast Pending Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes Se0/1 1 0/0 60 0/ Se0/0 1 0/ / R3# Update101

27 27 Neighbor Table Contents The show ip eigrp interfaces detail command displays a router's EIGRP Hello timer setting for each enabled interface. R3# show ip eigrp neighbors detail IP-EIGRP neighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq Type (sec) (ms) Cnt Num Se0/ :03: Version 12.3/1.2, Retrans: 2, Retries: Se0/ :04: Version 12.3/1.2, Retrans: 1, Retries: Se0/ :09: Version 12.3/1.2, Retrans: 0, Retries: Se0/ :10: Version 12.3/1.2, Retrans: 0, Retries: 0 R3#

28 Initial Route Discovery 28 AB Hello, I am Router A. Is anyone there? Hello, I am Router B. Here is all my routing information. I’m using split horizon. Thanks for the information! That is very nice of you. Here is all my routing information. I’m also using split horizon. Thanks for the information! We’ve reached convergence. EIGRP Neighbor Table EIGRP Neighbor Table EIGRP Topology Table EIGRP Topology Table IP Routing Table IP Routing Table Updated Successor

29 Example: EIGRP Tables Router C’s tables:

30 30 Router-ID EIGRP Router ID is an IP address used to uniquely identify an EIGRP router. 1. Use the IP address configured with the EIGRP router-id command. 2. Highest IP address of any of its loopback interfaces. 3. Highest active IP address of any of its physical interfaces. Router(config)# router eigrp as Router(config-router)# router-id ip-address

31 31 Forming Neighbor Adjacencies The following are the most common causes of problems with EIGRP neighbor relationships:  Unidirectional link  Uncommon subnet, primary, and secondary address mismatch  Mismatched masks  K value mismatches  Mismatched AS numbers  Stuck in active  Layer 2 problem  Access list denying multicast packets  Manual change (summary router, metric change, route filter) Does NOT prevent neighbor relationships  Hello and Hold timer setting mismatch  Duplicate router IDs  IP MTU mismatch

32 The Metric

33 EIGRP Message

34 EIGRP Message - TLVs

35 TLV 0x EIGRP Parameters K values are used to calculate the EIGRP metric. The Hold Time advertised by a neighbor is the maximum time a router should wait for any valid EIGRP message sent by that neighbor before declaring it dead.

36 TLV 0x Internal IP Routes Delay: Sum of delays in units of 10 microseconds from source to destination. Bandwidth: Lowest configured bandwidth on any interface along the route. Prefix length: Specifies the number of network bits in the subnet mask. Destination: The destination address of the route.

37 TLV 0x External IP Routes IP external routes are routes which are imported into EIGRP through redistribution of a default route or other routing protocols. Fields used to track external source of route. Same fields contained in the Internal IP route TLV (0x0002).

38 38 Metric By default, K1 and K3 are set to 1, and K2, K4, and K5 are set to 0. The result is that only the bandwidth and delay values are used in the computation of the default composite metric. Reliability and Load are optional metrics. MTU is NOT a metric, never has been, never will be.

39 39 Metric The K values on R1 are set to the default. Changing these values to other than the default is not recommended unless the network administrator has a very good reason to do so. Cisco recommends that these values are not modified. R1# show ip protocols Routing Protocol is “eigrp 1” 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 K1K2K3K4K5

40 Metric: Displaying Interface Values SanJose2> show interface s0/0 Serial0/0 is up, line protocol is up Hardware is QUICC Serial Description: Out to Westasman Internet address is /30 MTU 1500 bytes, BW 1544 Kbit, DLY usec, rely 255/255, load 246/255 EIGRP bandwidth uses the minimum bandwidth link represented in 10 7 divided by the kilobits per second. Show interfaces displays bandwidth in kilobits per second. EIGRP delay value is the sum of delays in tens of microseconds multiplied by 256. Show interfaces displays delay in microseconds.

41 Metric Calculation For a review and examples of how the EIGRP metric is calculate read Chapter 2 EIGRP, “EIGRP Metric Calculation” or review my CIS 82 PowerPoint presentations on EIGRP. 41

42 DUAL

43 EIGRP Operations EIGRP selects primary (successor) and backup (feasible successor) routes and injects those into the topology table. The primary (successor) routes are then moved to the routing table. IP EIGRP Neighbor Table Neighbor IP AddressLocal router exit interface to neighbor IP EIGRP Topology Table Destination 1FD / AD via each neighbor IP Routing Table Destination 1Best route List of directly connected adjacent EIGRP neighbor routers and the local interface to exit to reach it. List of all routes learned from each EIGRP neighbor and identifies successor routes and feasible successor routes. List of the best (successor) routes from the EIGRP topology table and other routing processes.

44 Example: EIGRP Tables

45 45 DUAL Concepts Diffusing Update Algorithm is the algorithm used by EIGRP. Determines:  best loop-free path  loop-free backup paths (which can be used immediately) DUAL also provides the following:  Fast convergence  Minimum bandwidth usage with bounded updates DUAL uses several terms that are discussed in more detail throughout this section:  Successor  Feasible distance  Feasible successor  Reported distance or advertised distance  Feasible condition or feasibility condition

46 46 Feasible distance (FD) is the minimum distance (metric) along a path to a destination network. Reported distance (RD or AD) is the distance (metric) towards a destination as advertised by an upstream neighbor. Reported distance is the distance reported in the queries, the replies and the updates. A neighbor meets the feasible condition (FC) if the reported distance by the neighbor is less than the current feasible distance (FD) of this router. "If a neighbors metric is less than mine, then I know the neighbor doesn't have a loop going through me." A feasible successor is a neighbor whose reported distance (RD) is less than the current feasible distance (FD). Feasible successor is one who meets the feasible condition (FC). Your route (metric) to the network (RD to me) must be LESS than my current route (my total metric) to that same network. If your route (metric) to the network (RD to me) is LESS than my current route (my total metric), I will include you as a FEASIBLE SUCCESSOR. If your route (metric) to the network (RD to me) is MORE than my current route (my total metric), I will NOT include you as a FEASIBLE SUCCESSOR. Successors and Feasible Successors

47 47 Example 1: Best Path (Successor)? Feasible Successor? R1 R2 R3 S0/0 S0/1 RD = 6,000,000 RD = 3,000,000 FD = 6,500,000 FD = 3,500,000 Network X FD = RD + additional Delay of serial link between R1 and neighbor. (This could also be due the slowest bandwidth.) Which router is the successor?

48 48 Example 1 R1 R2 R3 S0/0 S0/1 RD = 6,000,000 RD = 3,000,000 FD = 6,500,000 FD = 3,500,000 Network X FD of 3,500,000 is the metric for network X in the routing table for R1. Successor Is R2 a feasible successor?

49 49 Example 1 R1 R2 R3 S0/0 S0/1 RD = 6,000,000 RD = 3,000,000 FD = 6,500,000 FD = 3,500,000 Network X RD of R2 is greater than FD through R3. Does not meet FC. No FS. Successor NOT a Feasible Successor

50 50 Example 1 R1 R2 R3 S0/0 S0/1 RD = 6,000,000 RD = 3,000,000 Network X Maybe R2’s path to Network X includes R1 - Loop Successor NOT a Feasible Successor RX

51 51 Example 1 R1 R2 R3 S0/0 S0/1 RD = 6,000,000 RD = 3,000,000 Network X Or maybe R2’s does have a valid path to Network X. But R1 can’t tell because the distance vector update only gives it distance and direction. Successor NOT a Feasible Successor RX

52 52 Example 2: Best Path (Successor)? Feasible Successor? R1 R2 R3 S0/0 S0/1 RD = 4,000,000 RD = 3,000,000 FD = 5,500,000 FD = 4,500,000 Network X FD = RD + additional Delay of serial link between R1 and neighbor. (This could also be due the slowest bandwidth.) Successor Feasible Successor?

53 53 Example 2 R1 R2 R3 S0/0 S0/1 RD = 4,000,000 RD = 3,000,000 FD = 5,500,000 FD = 4,500,000 Network X RD of R2 is less than (or equal to) the FD through R3. Meets FC, there is no loop back through R1. Is a FS. Successor Feasible Successor

54 54 X X Queries Replies RtrF RtrC RtrE RtrD RtrB RtrA RtrG If there are no Feasible Successors, the router must ask neighbors for help in hope of finding a new, loop-free path to the destination. Neighbor routers are compelled to reply to this query.  If a neighbor has a route, it will reply with information about the successor(s).  If not, the neighbor notifies the sender that it doesn’t have a route to the destination either. Looking for new route Query and Reply Packets

55 The topology 55 A B C D E /24 (1) (2)(1) (2) Step 1

56 56 A B C D E /24 (1) (2)(1) (2) Successor Feasible Successor (AD is less than FD) Step 2 X

57 Router D: Sets the metric to network /24 as unreachable (–1 is unreachable).  No FS (Feasible Successor) in the topology table, so the route changes from the passive state to the Active state.  Active state: Router sends out queries to neighboring routers looking for a new successor.  Sends a query to Routers C and E for an alternative path to network /24.  Marks Routers C and E as having a query pending (q). Router E: DUAL marks the path to network /24 through Router D as Unusable. Router C: DUAL marks the path to network /24 through Router D as Unusable. 57 A B C D E /24 (1) (2)(1) (2) Step 3 Q Unusable Unreachable Successor still via Router B Successor still via Router A

58 Router D: DUAL receives a reply from Router C indicating no change to the path to /24  DUAL removes the query pending flag from Router C.  DUAL stays Active on network /24, awaiting a reply from Router E to its query (q). Router E: there is no FS to network /24, because the AD from Router C (3) is not less than the original FD (also 3).  DUAL generates a query to Router C.  DUAL marks Router C as query pending (q). Router C: DUAL marks the path to network /24 through Router E as Unusable. 58 A B C D E /24 (1) (2)(1) (2) Step 4 R Q Unusable Successor still via Router B Successor still via Router A

59 59 A B C D E /24 (1) (2)(1) (2) Step 5 Router D: DUAL stays active on network /24, awaiting a reply from Router E (q). Router E: DUAL receives a reply from Router C indicating no change.  It removes the query flag from Router C.  It calculates a new FD and installs a new successor route in the topology table.  It changes the route to network /24 from Active to Passive (converged). R Converged Successor still via Router B Successor still via Router A

60 Router D: DUAL receives a reply from Router E.  It removes the query flag from Router E.  It calculates a new FD.  It installs new successor routes in the topology table.  Two routes (through Routers C and E) have the same FD, and both are marked as successors.  It changes the route to network /24 from Active to Passive (converged). 60 A B C D E /24 (1) (2)(1) (2) Step 6 R Converged Successor still via Router B Successor still via Router A

61 Router D: Two successor routes are in the topology table for network /24.  Both successor routes are listed in the routing table, and equal-cost load balancing is in effect. The network is stable and converged. Successor No Feasible Successors 61 A B C D E /24 (1) (2)(1) (2) Step 7 Successor still via Router B Successor still via Router A

62 Basic EIGRP Configuration

63 63 Our Topology

64 64 Preconfigs Configured on all routers. R1(config)# no ip domain lookup R1(config)# line con 0 R1(config-line)# exec-timeout 0 0 R1(config-line)# logging synchronous

65 65 R1 Bandwidth of 1,424 Kbps (1,424,000 bps) between R3 and R4 on bottom link 1544 configured on all serial links just in case. interface FastEthernet0/0 ip address ! interface Serial0/0 bandwidth 1544 ip address clock rate ! interface Serial0/1 bandwidth 1544 ip address

66 66 R2 interface FastEthernet0/0 ip address ! interface Serial0/0 bandwidth 1544 ip address ! interface Serial0/1 bandwidth 1544 ip address clock rate 64000

67 67 R3 interface FastEthernet0/0 ip address ! interface Serial0/0 bandwidth 1544 ip address clockrate ! interface Serial0/1 bandwidth 1544 ip address ! interface Serial0/2 bandwidth 1544 ip address clockrate ! interface Serial0/3 bandwidth 1424 ip address clockrate 64000

68 68 R4 interface FastEthernet0/0 ip address ! interface Serial0/0 bandwidth 1544 ip address ! interface FastEthernet0/1 ip address ! interface Serial0/1 bandwidth 1424 ip address

69 69 Configuring EIGRP – R1 Wildcard masks – Specifically tells EIGRP which interfaces to be enabled on. If subnet mask is used IOS may convert it for the running-config. Let’s do R2, R3 and R4 serial interfaces with wildcard masks… R1(config)# router eigrp 1 R1(config-router)# network R1(config-router)# network R1(config-router)# network

70 70 Configuring EIGRP R2(config)# router eigrp 1 R2(config-router)# network R2(config-router)# network R2(config-router)# network R3(config)# router eigrp 1 R3(config-router)# network R3(config-router)# network R3(config-router)# network R3(config-router)# network R3(config-router)# network R4(config)# router eigrp 1 R4(config-router)# network R4(config-router)# network R4(config-router)# network

71 71 Outputs R3# show ip route C /24 is directly connected, FastEthernet0/0 D /24 [90/ ] via , 00:02:47, Serial0/0 D /16 [90/ ] via , 00:02:39, Serial0/2 D /24 [90/ ] via , 00:17:22, Serial0/ /30 is subnetted, 5 subnets C is directly connected, Serial0/1 C is directly connected, Serial0/2 D [90/ ] via , 00:02:57, Serial0/0 [90/ ] via , 00:02:57, Serial0/1 C is directly connected, Serial0/0 C is directly connected, Serial0/3 Why does R3 prefer the top link to ?  It is 1,544 kbps link compared to 1,424 kbps link below What do you notice about the network? How many paths?  R3 has equal cost paths to /30

72 72 Outputs Does R3 see R4 as a neighbor on both links?  Yes R3# show ip eigrp neighbors IP-EIGRP neighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq Type (sec) (ms) Cnt Num Se0/ :17: Se0/ :17: Se0/ :23: Se0/ :24: R3#

73 73 Outputs Some other commands… R3# show ip eigrp neighbors detail IP-EIGRP neighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq Type (sec) (ms) Cnt Num Se0/ :03: Version 12.3/1.2, Retrans: 2, Retries: Se0/ :04: Version 12.3/1.2, Retrans: 1, Retries: Se0/ :09: Version 12.3/1.2, Retrans: 0, Retries: Se0/ :10: Version 12.3/1.2, Retrans: 0, Retries: 0 R3#

74 74 Outputs R3# show ip eigrp interfaces IP-EIGRP interfaces for process 1 Xmit Queue Mean Pacing Time Multicast Pending Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes Se0/1 1 0/0 60 0/ Se0/0 1 0/ / Se0/2 1 0/0 29 0/ Se0/3 1 0/0 24 0/ R3#

75 75 R3# show ip protocols Routing Protocol is "eigrp 1" 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 1 Automatic network summarization is in effect Maximum path: 4 Routing for Networks: / / / / Routing Information Sources: Gateway Distance Last Update :03: :03: :03: :03:03 Distance: internal 90 external 170 What are these telling us? K values Variance, later Directly connected networks Neighbors

76 76 Outputs R3# show ip eigrp topology P /30, 2 successors, FD is via ( / ), Serial0/1 via ( / ), Serial0/0 P /16, 1 successors, FD is via ( /28160), Serial0/2 via ( /28160), Serial0/3 successor feasible successor Feasible distance Feasible distance: if this router was the successor. Reported Distance is less than Feasible distance

77 77 Outputs Why does R3 show a third entry for /30? Why is R4 a non-feasible successor?  Reported distance > Feasible distance  There is a loop via the lower (1424kps) link!!! R3# show ip eigrp topology all-links P /30, 2 successors, FD is , serno 13 via ( / ), Serial0/1 via ( / ), Serial0/0 via ( / ), Serial0/3 successor non-feasible successor

78 Passive Interfaces

79 79 Passive Interfaces Two ways to prevent EIGRP from speaking sending EIGRP messages on an interface. 1. Enable EIGRP on the interface using the EIGRP network command and use the the passive-interface command.  Does NOT send any EIGRP messages on the interface.  No Hellos, thus no neighbor adjacency  Prefix (interface subnet) is still advertised on other interfaces 2. Do NOT enable EIGRP on the interface,  Advertise about the connected route using route redistribution using the redistribute connected configuration command.  More complicated  Less popular

80 80 Passive Interfaces R1# show ip eigrp inter IP-EIGRP interfaces for process 1 Xmit Queue Mean Pacing Time Multicast Pending Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes Se0/0 1 0/0 34 0/ Se0/1 1 0/0 31 0/ Fa0/0 0 0/0 0 0/ The show ip eigrp interfaces command displays working interfaces on which EIGRP has been enabled, but omits passive interfaces. A failure of the interface, or making the interface passive, would omit the interface from the output of this command.

81 81 Passive Interfaces No longer a neighbor. Must include network command. R1(config)# router eigrp 1 R1(config-router)# passive-interface fa 0/0 R1# show ip eigrp inter IP-EIGRP interfaces for process 1 Xmit Queue Mean Pacing Time Multicast Pending Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes Se0/0 1 0/0 32 0/ Se0/1 1 0/0 28 0/ R1# R1(config)# router eigrp 1 R1(config-router)# network

82 82 Passive Interfaces Verifying R1# show ip protocols Routing for Networks: / / Passive Interface(s): FastEthernet0/0

83 83 Passive Interfaces R4(config)# router eigrp 1 R4(config-router)# passive-interface default R4(config-router)# no passive-interface ser 0/0 R4(config-router)# no passive-interface ser 0/1 R4# show ip protocols Routing for Networks: / / Passive Interface(s): FastEthernet0/0 FastEthernet0/1

84 Summarization 84

85 85 Summarization Benefits:  Smaller routing tables  Reduces Query scope:  EIGRP Query stops at a router which has a summary route that includes the subnet listed in the Query, but not the specific route listed in the Query  EIGRP supports summarization on any router in the network Trade-offs:  Can cause suboptimal routing  Packets destined for inaccessible destinations will flow to the summarizing router before being discarded Note: If a packet matches two routes in the routing table, the best match will be the route with the longest-bit-match, the route with the longer prefix-length (subnet mask).

86 86 EIGRP Summarization – Odds and Ends Any EIGRP router can summarize routes.  OSPF: Summarization can only take place on the ABRs and ASBRs. The summary route's metric is based on the lowest metric route upon which the summary route is based.  The summary route will use a metric equal to the metric of the lowest metric subordinate route. Manual summarization creates a Null0 summary on the router doing the summarization. R3(config)# interface serial 0/0/1 R3(config-if)# ip summary-address eigrp R3# show ip route D /22 is a summary, 00:00:06, Null0 Creates a Null0 summary route

87 87 The Null0 Summary Route EIGRP automatically includes a Null0 summary route as a child route whenever both of the following conditions exist:  There is at least one subnet that was learned via EIGRP.  Automatic summarization is enabled. (By default with EIGRP) What if R1 received a packet:  It would be discarded – never looking for a supernet or default route  Regardless of ip classless or no ip classless command Helps prevent any routing loops between the edge and ISP routers. R1# show ip route /24 is variably subnetted, 3 subnets, 2 masks D /24 is a summary, 00:45:09, Null0 C /30 is directly connected, Serial0/0/1 D /30 [90/ ] via , 00:44:56, S0/0/ /16 is variably subnetted, 4 subnets, 3 masks D /16 is a summary, 00:46:10, Null0 C /24 is directly connected, FastEthernet0/0 D /24 [90/ ] via , 00:45:09, S0/0/0 C /30 is directly connected, Serial0/0/0 D /24 [90/ ] via , 00:44:55, Serial0/0/1

88 88 Disabling Automatic Summarization Like RIP, EIGRP automatically summarizes at major network boundaries using the default auto-summary command. R3# show ip route /24 is variably subnetted, 3 subnets, 2 masks D /24 is a summary, 01:08:35, Null0 C /30 is directly connected, Serial0/0/0 C /30 is directly connected, Serial0/0/1 D /16 [90/ ] via , 01:08:30, Serial0/0/0 C /24 is directly connected, FastEthernet0/ /16

89 89 Disabling Automatic Summarization Both R1 and R2 automatically summarizing. R1 is the successor because of the difference in bandwidth. R3# show ip route /24 is variably subnetted, 3 subnets, 2 masks D /24 is a summary, 01:08:35, Null0 C /30 is directly connected, Serial0/0/0 C /30 is directly connected, Serial0/0/1 D /16 [90/ ] via , 01:08:30, Serial0/0/0 C /24 is directly connected, FastEthernet0/ /16

90 90 Disabling Automatic Summarization Is this the best route for all subnets?  No, suboptimal routing may occur.  R3 will route all packets destined for through R1. Solution?  Need R1 and R2 to send individual subnets.  R1 and R2 must stop automatically summarizing /16. R3# show ip route D /16 [90/ ] via , 01:08:30, Serial0/0/ /16

91 91 Disabling Automatic Summarization Automatic summarization can be disabled with the no auto-summary. The router configuration command eigrp log-neighborchanges is on by default on some IOS implementations.. R1(config)# router eigrp 1 R1(config-router)# no auto-summary %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor (Serial0/0/0) is resync: summary configured %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor (Serial0/0/0) is down: peer restarted %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor (Serial0/0/0) is up: new adjacency R2(config)# router eigrp 1 R2(config-router)# no auto-summary R3(config)# router eigrp 1 R3(config-router)# no auto-summary

92 92 R1 no more Null0 summary routes: D /24 is a summary, 00:45:09, Null0 D /16 is a summary, 00:46:10, Null0 What does this mean?  This means any packets for their parent networks that do not match a child route, the routing table will check supernet and default routes.  Unless no ip classess is used R1# show ip route /30 is subnetted, 2 subnets C is directly connected, Serial0/0/1 D [90/ ] via , 00:16:55, S0/0/ /16 is variably subnetted, 3 subnets, 2 masks C /24 is directly connected, FastEthernet0/0 D /24 [90/ ] via , 00:16:53, S0/0/1 C /30 is directly connected, Serial0/0/0 D /24 [90/ ] via , 00:16:52, Serial0/0/1 Disabling Automatic Summarization

93 93 R2 no more Null0 summary routes : D /24 is a summary, 00:00:15, Null0 D /16 is a summary, 00:00:15, Null0 R2# show ip route /30 is subnetted, 2 subnets D [90/ ] via , 00:15:44, S0/0/1 C is directly connected, Serial0/0/ /16 is variably subnetted, 3 subnets, 2 masks D /24 [90/ ] via , 00:15:44, S0/0/1 C /24 is directly connected, FastEthernet0/0 C /30 is directly connected, Serial0/0/ /30 is subnetted, 1 subnets C is directly connected, Loopback1 D /24 [90/ ] via , 00:15:44, S0/0/1 Disabling Automatic Summarization

94 94 Why does R3’s routing table now have two equal-cost paths to /24?  Shouldn’t the best path only be through R1 with the 1544-Mbps link? R3# show ip route /30 is subnetted, 2 subnets C is directly connected, Serial0/0/0 C is directly connected, Serial0/0/ /16 is variably subnetted, 3 subnets, 2 masks D /24 [90/ ] via , 00:00:11, S0/0/0 D /24 [90/ ] via , 00:00:12, S0/0/1 D /30 [90/ ] via , 00:00:12, S0/0/0 [90/ ] via , 00:00:12, S0/0/1 C /24 is directly connected, FastEthernet0/ /16

95 95 Disabling Automatic Summarization The slowest link is the 64-Kbps link R3# show ip route D /30 [90/ ] via , 00:00:12, S0/0/0 [90/ ] via , 00:00:12, S0/0/ /16

96 96 Manual Summarization EIGRP can be configured to summarize routes, whether or not automatic summarization ( auto-summary ) is enabled. Modified topology.

97 97 Manual Summarization Add two more networks to R3. Configure EIGRP network statements. R3(config)# interface loopback 2 R3(config-if)# ip address R3(config-if)# interface loopback 3 R3(config-if)# ip address R3(config-if)# router eigrp 1 R3(config-router)# network R3(config-router)# network

98 98 Manual Summarization Instead of sending three separate networks, R3 can summarize the /24, /24, and /24 networks as a single route. R1# show ip route D /24 [90/ ] via , 02:07:38, S0/0/1 D /24 [90/ ] via , 00:00:34, S0/0/1 D /24 [90/ ] via , 00:00:18, S0/0/1 R2# show ip route D /24 [90/ ] via , 02:08:50, S0/0/1 D /24 [90/ ] via , 00:01:46, S0/0/1 D /24 [90/ ] via , 00:01:30, S0/0/1 Only pertinent routes shown /24, /24, /24

99 99 Determining the Summary EIGRP Route 1. Write out the networks that you want to summarize in binary. 2. Find the matching bits.  Count the number of leftmost matching bits, which in this example is 22.  This number becomes your subnet mask for the summarized route: /22 or To find the network address for summarization, copy the matching 22 bits and add all 0 bits to the end to make 32 bits. The result is the summary network address and mask for /22

100 100 Configure EIGRP Manual Summarization Because R3 has two EIGRP neighbors, the EIGRP manual summarization in configured on both Serial 0/0/0 and Serial 0/0/1. Router(config-if)# ip summary-address eigrp as-number network-address subnet-mask R3(config)# interface serial 0/0/0 R3(config-if)# ip summary-address eigrp R3(config)# interface serial 0/0/1 R3(config-if)# ip summary-address eigrp /22 R3# show ip route D /22 is a summary, 00:00:06, Null0 Creates a Null0 summary route

101 101 Verify EIGRP Manual Summarization Fewer number of total routes in routing tables  Faster routing table lookup process more efficient. Summary routes also require less bandwidth and memory  Single route can be sent rather than multiple individual routes. NOTE: The minimum metric of specified routes is used as the metric of the summary route. R1# show ip route D /22 [90/ ] via , 00:01:11, Serial0/0/1 R2# show ip route D /22 [90/ ] via , 00:00:23, Serial0/0/ /22

102 Default Route 102

103 103 EIGRP Default Route R2(config)# ip route loopback 1 R2(config)# router eigrp 1 R2(config-router)# redistribute static The ISP router in our topology does not physically exist. By using a loopback interface, we can simulate a connection to another router. Default Route Redistribute default static route in EIGRP updates Unlike RIP and OSPF, EIGRP does not propagate a by default. Two ways to propagate a static default route in EIGRP: Redistribute static Network command redistribute static will redistribute all static routes by default.

104 104 EIGRP Default Route R1# show ip route Gateway of last resort is to network D*EX /0 [170/ ] via , 00:02:14, S0/0/1 Only static default route shown, other output omitted. D: This static route was learned from an EIGRP routing update. *: The route is a candidate for a default route. EX: The route is an external EIGRP route, in this case a static route outside of the EIGRP routing domain. 170: This is the AD of an external EIGRP route. Default Route Redistribute default static route in EIGRP updates

105 105 EIGRP Default Route R2(config)# ip route loopback 1 R2(config)# router eigrp 1 R2(config-router)# network Default Route The network command will propagate a default route as a result of the static default route.

106 106 EIGRP Default-network There is another method to propagate a default route in EIGRP, using the ip default-network command. Default Route Redistribute default static route in EIGRP updates

107 107 EIGRP Default- network R2(config)# ip default-network R2(config)# router eigrp 1 R2(config-router)# network R2(config-router)# network R2(config-router)# network default-network ip default-network network-number network-number - Network of last-resort gateway that will be announced to all other routers. R2’s routing table: will be shown as the “gateway of last resort” This network is propagated in EIGRP as a “gateway of last resort” If a subnet is specified IOS will install a static route in the running-config

108 A few commands… 108

109 show ip eigrp traffic Displays the number of various EIGRP packets sent and received 109 R1# show ip eigrp traffic IP-EIGRP Traffic Statistics for AS 100 Hellos sent/received: 338/166 Updates sent/received: 7/7 Queries sent/received: 0/0 Replies sent/received: 0/0 Acks sent/received: 2/2 SIA-Queries sent/received: 0/0 SIA-Replies sent/received: 0/0 Hello Process ID: 228 PDM Process ID: 226 IP Socket queue: 0/2000/1/0 (current/max/highest/drops) Eigrp input queue: 0/2000/1/0 (current/max/highest/drops) R1#

110 debug ip eigrp traffic Displays the types of EIGRP packets sent and received by the router on which this command is executed. See example in Chapter 2 for a detailed explanation of this output. 110 R2# debug eigrp packets *Jul 26 10:51:24.051: EIGRP: Sending HELLO on Serial0/0/0 *Jul 26 10:51:24.051: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 *Jul 26 10:51:24.111: EIGRP: Sending HELLO on FastEthernet0/0 *Jul 26 10:51:24.111: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 *Jul 26 10:51:26.667: EIGRP: Received HELLO on Serial0/0/0 nbr *Jul 26 10:51:26.667: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/re ly 0/0 *Jul 26 10:51:28.451: EIGRP: Sending HELLO on FastEthernet0/0 *Jul 26 10:51:28.451: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 *Jul 26 10:51:29.027: EIGRP: Sending HELLO on Serial0/0/0 *Jul 26 10:51:29.027: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 *Jul 26 10:51:31.383: EIGRP: Received HELLO on Serial0/0/0 nbr *Jul 26 10:51:31.383: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/re ly 0/0 *Jul 26 10:51:33.339: EIGRP: Sending HELLO on FastEthernet0/0 *Jul 26 10:51:33.339: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 *Jul 26 10:51:33.511: EIGRP: Sending HELLO on Serial0/0/0 *Jul 26 10:51:33.511: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 *Jul 26 10:51:36.347: EIGRP: Received HELLO on Serial0/0/0 nbr *Jul 26 10:51:36.347: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/re ly 0/0 *Jul 26 10:51:37.847: EIGRP: Sending HELLO on Serial0/0/0 *Jul 26 10:51:37.847: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 *Jul 26 10:51:37.899: EIGRP: Sending HELLO on FastEthernet0/0

111 debug ip eigrp Displays general debugging information. See example in Chapter 2 for a detailed explanation of this output. 111

112 112 That’s all for tonight, good night!

113 CIS 185 CCNP ROUTE EIGRP Part 1 Rick Graziani Cabrillo College Last Updated: Fall 2010


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