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1 EIGRP Deployment 2008 isco Systems, Inc. ll rights reserved. isco Public 2 1

2 EIGRP EIGRP Operation Topologies and Techniques Managing EIGRP 2008 isco Systems, Inc. ll rights reserved. isco Public 3 EIGRP Operation 2008 isco Systems, Inc. ll rights reserved. isco Public 4 2

3 EIGRP Operation Neighbor Formation omputing Metrics The Diffusing Update lgorithm The ctive Process External Routing Information 2008 isco Systems, Inc. ll rights reserved. isco Public 5 EIGRP Neighbor Formation EIGRP uses a three way handshake to prevent neighbor formation along a unidirectional link When receives the first multicast hello from, it places in the pending state, and transmits a unicast update with the initialization (init) bit set Multicast hello in Pending Unicast Update + Init While is in this state, will not send it any queries or routing information 2008 isco Systems, Inc. ll rights reserved. isco Public 6 3

4 EIGRP Neighbor Formation When receives this update with the init bit set, it sends an update with the init bit set as well The acknowledgement for s initial update is piggybacked onto this packet it is never transmitted by itself There is no way for to receive the acknowledgement for its initial update without also receiving s initial update Multicast hello in Pending Unicast Update + Init Unicast Update + Init + ck 2008 isco Systems, Inc. ll rights reserved. isco Public 7 EIGRP Neighbor Formation Once the acknowledgement for its initial update is received, takes out of the pending state, and begins sending it topology information If this acknowledgement isn t ever received, hello s from are ignored while attempts to retransmit the initial update Eventually, will time out, and the process will start over Multicast hello in Pending Unicast Update + Init Inicast Update + Init + ck Out of Pending Unicast Topology Table Info 2008 isco Systems, Inc. ll rights reserved. isco Public 8 4

5 EIGRP Neighbor Formation For each route sends, sends a poison reverse This makes certain the two router s tables are accurate When a router finishes sending its table, it sends an end-of-table indicator Unicast Topology Table Info Poison Reverse Unicast Routes End-of-Table 2008 isco Systems, Inc. ll rights reserved. isco Public 9 omputing Metrics EIGRP uses a compound metric Individual metrics are called component metrics Five components: bandwidth, delay, load, reliability, and MTU y default, only bandwidth and delay are actually used alculated metric is called the composite metric min delays * 256 ( bandwidth) 2008 isco Systems, Inc. ll rights reserved. isco Public 10 5

6 omputing Metrics Router advertises /24 to andwidth is set to 1000 Delay is set to 100 Router ompares current bandwidth to bandwidth of link to ; sets bandwidth to 100 dds delay along link to, for a total of 1100 Router ompares current bandwidth to bandwidth of link to ; sets bandwidth to 56 dds delay along link to, for a total of /24 W: 1000 Delay: 100 min W: 100 Delay: 1000 Minimum delays * 256 ( bandwidth) W: 56 Delay: 2000 dded Together 2008 isco Systems, Inc. ll rights reserved. isco Public 11 omputing Metrics Router uses the formula to compute a composite metric This isn t what the router computes, though why? The router drops the remainder after the first step! Why the 256? EIGRP uses a 32-bit metric space IGRP uses a 24-bit metric space To convert between the two, multiply or divide by 256! min delays * 256 ( bandwidth) * = 10 7 = * 256 = ?? 2008 isco Systems, Inc. ll rights reserved. isco Public 12 6

7 omputing Metrics Where does EIGRP get the component metrics? andwidth: default bandwidth value or interface level bandwidth command Delay: default interface value or interface level delay command Reliability: per interface computed reliability, Load: per interface computed load, Why not set the K values so the reliability and load are picked up? Interface level computed metrics are only picked up when a change in the bandwidth or delay causes EIGRP to reread them or when a route changes and we have to recalculate the metric Effectively, this means these metrics (reliability and load) are not checked on an ongoing basis with stable routes 2008 isco Systems, Inc. ll rights reserved. isco Public 13 The Diffusing Update lgorithm (DUL) How does EIGRP determine which routes are loop free? Each of s neighbors is reporting reachability to E 15 D with a cost of 10 with a cost of D with a cost of 30 These three costs are called reported distance (RD); the distance each neighbor is reporting to a given destination E 2008 isco Systems, Inc. ll rights reserved. isco Public 14 7

8 The Diffusing Update lgorithm (DUL) t, the total cost to reach E is: 20 through 25 through 15 D 45 through D The best of these three paths is the path through, with a cost of 20 This is the feasible distance (FD) E 2008 isco Systems, Inc. ll rights reserved. isco Public 15 The Diffusing Update lgorithm (DUL) uses these two pieces of information 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 D The algorithm may mark some loop free paths as loops However, it is guaranteed never to mark a looped path as loop free E 2008 isco Systems, Inc. ll rights reserved. isco Public 16 8

9 The Diffusing Update lgorithm (DUL) t : The path through is the best path (FD), at 20 can reach E with a cost of 10; 10 (RD) is less than 20 (FD), so this path is loop free D 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 E 2008 isco Systems, Inc. ll rights reserved. isco Public 17 The Diffusing Update lgorithm (DUL) t : Question: Why should DUL consider the 30 (RD) from D as a loop? 5 5 nswer: ecause, mathematically it could be. s far as is concerned, the 30 (RD) from D could be the loop we see here D 30 E 2008 isco Systems, Inc. ll rights reserved. isco Public 18 9

10 The Diffusing Update lgorithm (DUL) If the best path fails, through (the successor), EIGRP will examine the available paths to E 15 D Finding a path which was previously declared loop free (a feasible successor), it begins using it immediately now becomes the successor (best path) E 2008 isco Systems, Inc. ll rights reserved. isco Public 19 The Diffusing Update lgorithm (DUL) re there any Feasible Successors from Router E s perspective? FD is D RD from is 15 RD from D is 15 RD < FD, so it satisfies the Feasibility ondition (F) We have two FS! In order for there to be only one FS, the link -D or - would need to be increased to at least E 2008 isco Systems, Inc. ll rights reserved. isco Public 20 10

11 The Diffusing Update lgorithm (DUL) now examines its topology information based on the new successor metric The reported distance through the remaining neighbor, D, is 30; 30 (RD) is still more than 25 (FD), so this path is still considered a loop D E 2008 isco Systems, Inc. ll rights reserved. isco Public 21 The Diffusing Update lgorithm (DUL) The path through now fails examines its topology information, and finds it has no loop free path to E 15 D However, it does have a neighbor, and that neighbor might have a loop free path So, it places E in active state and queries D E 2008 isco Systems, Inc. ll rights reserved. isco Public 22 11

12 The Diffusing Update lgorithm (DUL) D examines its topology information Since its best path is not through, the path it has to E is still valid D sends a reply to this query, indicating it still has a valid loop free path to E Once receives this reply, it begins using the path through D D E 2008 isco Systems, Inc. ll rights reserved. isco Public 23 The ctive Process Prior to Enhanced ctive Processing 12.1(4.0.3)T and 12.1(4.1) So what used to happen when loses its route to /24? No FS, mark route active Set a three minute active timer Query all neighbors () receives s query No FS, mark route active Set three minute active timer Query all neighbors () receives s query Examine local topology table No feasible successors No neighbors to query! / /24 Gone; No FS ctive Timer Set Query /24 Gone; No FS ctive Timer Set Query /24 Gone 2008 isco Systems, Inc. ll rights reserved. isco Public 24 12

13 The ctive Process Prior to Enhanced ctive Processing has no alternate path to /24 Remove from local tables Reply to querying neighbors receives s reply No outstanding queries Remove from local tables Reply to querying neighbors receives s reply No outstanding queries Remove from local tables / /24 Gone; No FS Remove /24 Query Reply /24 Gone; No FS Remove /24 Query Reply /24 Gone Remove / isco Systems, Inc. ll rights reserved. isco Public 25 The ctive Process Prior to Enhanced ctive Processing If sends the reply, and never receives it, what happens? s active timer (three minutes) is still counting down while and are trying to get the reply back When this timer expires, declares an SI The / neighbor relationship is reset Why Reset / When / Is the Problem?? / /24 Gone; No FS Query Reset Relationship! /24 Gone; No FS Query ad Link, Reply Never Makes It Reply /24 Gone Remove / isco Systems, Inc. ll rights reserved. isco Public 26 13

14 The ctive Process ctive Process Enhancement 12.1(4.0.3)T and 12.1(4.1), Sdp33034 So now what happens? queries when the route goes away; then sets a sia-retransmit timer to half the configured active time (1.5 minutes, normally) / /24 Gone; No FS Query SI Query fter this time has passed, sends an SI Query If sends an SI Reply to the SI query, resets its timer, and the / neighbor relationship stays up will send the SI Query 3x, for a total window of 4.5 minutes; even if replies, after three tries will reset the neighbor relationship / 2008 isco Systems, Inc. ll rights reserved. isco Public 27 The ctive Process ctive Process Enhancement If sends the reply, and never receives it, what happens now? If supports the ctive Process Enhancement then when sends the first SI Query and receives no reply from (do to the bad link) will reset the / neighbor relationship If does not support the ctive Process Enhancement then when sends the SI Query and doesn t reply to it then the / relationship will be reset / /24 Gone; No FS Query SI Query /24 Gone; No FS Query ad Link, Reply Never Makes It Reply /24 Gone Remove / isco Systems, Inc. ll rights reserved. isco Public 28 14

15 The ctive Process will either reply to the query, which will then clear back to, or will fail to reply at some point and will reset its relationship with Either event clears the query from s point of view, which is then cleared back to minimizing SI s considerably If anything gets reset, its now the right neighbor adjacent to the problem router, helping to troubleshoot and identify problem routers easier / /24 Gone; No FS Query SI Query /24 Gone; No FS Query ad Link, Reply Never Makes It Reply /24 Gone Remove / isco Systems, Inc. ll rights reserved. isco Public 29 The ctive Process Where does the query stop? Router loses its connection to /24 Router does not consider a FS, for some reason Router sends a query Router examines its local tables, and finds: Its current path (successor) doesn t pass through It has a FS that doesn t pass through Router answers The query is bounded where there is local knowledge of another loop-free path D / isco Systems, Inc. ll rights reserved. isco Public 30 E F Local Knowledge of an lternate Path, So Reply G 15

16 The ctive Process Router is filtering /24 towards D /24 Router loses its connection to /24 Router sends a query Router has no FS for /24 Router sends D a query Filter E Router D examines its local tables No information about /24, so send a reply D No Knowledge of Route, So Reply F G Query is bounded because D has no information about / isco Systems, Inc. ll rights reserved. isco Public 31 The ctive Process Router E is summarizing towards F /24 Router loses its connection to /24 Router sends E a query Router E has no FS for /24 Router E sends F a query Router F examines its local tables No information about /24, so send a reply Query is bounded because F has no information about /24 D Summary E G F No Knowledge of Route, So Reply 2008 isco Systems, Inc. ll rights reserved. isco Public 32 16

17 The ctive Process Router G has no neighbors /24 Router loses its connection to /24 Router sends G a query Router G examines its local tables No FS No neighbors to query, so send a reply D E G F No Neighbors, So Reply 2008 isco Systems, Inc. ll rights reserved. isco Public 33 The ctive Process The Query is bounded by: /24 Local knowledge of an alternate loop-free path not learned through the neighbor the query was received from No local knowledge of the route because of filtering or summarization No neighbors to query Filter D Summary E Local Knowledge of an lternate Path, So Reply G No Knowledge of Route, So Reply F No Neighbors, So Reply No Knowledge of Route, So Reply 2008 isco Systems, Inc. ll rights reserved. isco Public 34 17

18 External Routing Information What is an External Route in EIGRP? ny route within EIGRP that originated outside of the EIGRP process asically, routes redistributed into EIGRP from another protocol, static, or connected routes Marked in the routing table as D EX to indicate EIGRP owns the route but that it was originated external to EIGRP router# show ip route [snip ] D EX [170/ ] via , 00:07:26, FastEthernet isco Systems, Inc. ll rights reserved. isco Public 35 External Routing Information What additional information is carried in an external? Originating Router ID S # Protocol of Origin External Metric dmin Tags Router# show ip eigrp topo IP-EIGRP topology entry for /32 State is Passive, Query origin flag is 1, 1 Successor(s), FD is Routing Descriptor locks: , from Redistributed, Send flag is 0x0 omposite metric is (28160/0), Route is External Vector metric: Minimum bandwidth is Kbit Total delay is 100 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 0 External data: Originating router is (this system) S number of route is 1 External protocol is OSPF, external metric is 0 dministrator tag is 150 (0x ) 2008 isco Systems, Inc. ll rights reserved. isco Public 36 18

19 External Routing Information Why is the administrative distance higher on an external? To prefer Internal EIGRP routes over EIGRP Externals To prefer routing information originating within our S over that which originated somewhere outside our control dministrative Distances Route Source Default Distance Values onnected interface 0 Static route 1 EIGRP summary route 5 egp 20 Internal EIGRP 90 IGRP 100 OSPF 110 (IS-IS) 115 RIP 120 On Demand Routing (ODR) 160 External EIGRP 170 igp 200 Unknown isco Systems, Inc. ll rights reserved. isco Public 37 Topologies and Techniques 2008 isco Systems, Inc. ll rights reserved. isco Public 38 19

20 Topologies and Techniques Hub and Spoke Design EIGRP Stubs EIGRP DMVPN Redundancy Load Sharing Fast onvergence Using andwidth Redistribution Multiple S 2008 isco Systems, Inc. ll rights reserved. isco Public 39 Hub and Spoke Design Hub and spoke networks are often built over point-tomultipoint networks If the hub is configured to treat the entire point-to-multipoint network as a single interface, it can transmit multicast and broadcast packets which are received by all spoke routers Layer 3 on the hub router will not notice a single circuit failure interface s0/0 ip address Packets Transmitted Here re Received by ll Spokes Packets Transmitted Here re Received Only by the Hub Router 2008 isco Systems, Inc. ll rights reserved. isco Public 40 20

21 Hub and Spoke Design The hub router can also be configured to treat each spoke s circuit as an individual point-to-point circuit on a subinterface If end-to-end signaling is in use, a failed circuit will cause the subinterface to fail interface s0/0.1 point-to-point ip address interface s0/0.2 point-to-point ip address interface s0/0.3 point-to-point ip address Packets Transmitted Here re Received by One Spoke interface s0.1 point-to-point ip address x Packets Transmitted Here re Received Only by the Hub Router 2008 isco Systems, Inc. ll rights reserved. isco Public 41 Hub and Spoke Design Summarize towards the core Number the remote links out of the same address space as the remote networks, if possible Use /31s to conserve address space for point-to-points Send the remotes a default only If you can t address the links out of the summary address space, then use a distribute list to filter them from being advertised back into the core of the network Summary Only /0 access-list 10 deny access-list 10 permit any... router eigrp 100 distribute-list 10 out / / / / / / isco Systems, Inc. ll rights reserved. isco Public 42 21

22 Hub and Spoke Design In single homed hub and spoke networks, the hub router, spoke routers, and the links themselves are all single points of failure Highly vailable You can mitigate the single point of failure in the routers using high availability techniques 2008 isco Systems, Inc. ll rights reserved. isco Public 43 Hub and Spoke Design ll the same principles apply to dual homed hub and spoke networks Summarize or filter the links to the remotes Use /31s on point-to-points to conserve address space Summary Only /0 Provide as little information as possible to the remotes Something more than a default route may be required to provide optimal routing void Summary lack Holes! / / / isco Systems, Inc. ll rights reserved. isco Public 44 22

23 Hub and Spoke Design How do we limit the amount of information passed down to the remote sites? You can summarize at and towards the remote routers The summary will generate a local route with an administrative distance of 5 The external default route learned from D will have an administrative distance of 170 What happens? Internet D EIGRP External Default Route D EX /0 ip summary-address eigrp D* /0 is a summary, 00:08:41, Null isco Systems, Inc. ll rights reserved. isco Public 45 Hub and Spoke Design In this case, the locally generated discard route wins The route learned from D will not be installed in the local table Hosts behind will not be able to reach destinations on the Internet There are ways to prevent this discard route from being installed, but we need to be careful with the design Internet Routing Loops Routing lack Holes There is enough rope here to hang yourself! ip summary-address eigrp D* /0 is a summary, 00:08:41, Null isco Systems, Inc. ll rights reserved. isco Public 46 D EIGRP External Default Route D EX /0 23

24 Hub and Spoke Design If two routing protocols provide a route to the same destination, how do we choose between them? Their metrics are not comparable n administrative distance is added to each route learned based on the protocol installing the route Static routes can be configured with a distance This can create a floating static The route will not be used unless the dynamic protocols have no route to that destination router#show ip eigrp topology P /24, 1 successors, FD is via ( / ) The EIGRP Route Wins Distance 90 router(config)#ip route null0 The Static Route Wins Distance 1 router(config)#ip route null0 200 Distance isco Systems, Inc. ll rights reserved. isco Public 47 Hub and Spoke Design The route generated by the summary is called a discard route What would happen if this route isn t created? onfigure two routers back to back with overlapping summaries Generate a packet towards from either router t, the best path is through /16 to t, the best path is through /8 to Routing Loop ip summary-address eigrp / / / / ip summary-address eigrp isco Systems, Inc. ll rights reserved. isco Public 48 24

25 Hub and Spoke Design To remove the discard route In EIGRP, add an administrative distance after the ip summary address; make sure this value is greater than 170 Internet D EIGRP External Default Route D EX /0 will then learn the 2 External EIGRP routes from and ip summary-address eigrp D* /0 [170/409600] via <> [170/409600] via <> 2008 isco Systems, Inc. ll rights reserved. isco Public 49 Hub and Spoke Design What happens if loses its path to D? will not prefer the internal learned through over the external learned through Internet D EIGRP External Default Route D EX /0 We have a black hole ip summary-address eigrp D* /0 [170/409600] via <> D* /0 [90/409600] via <> [170/409600] via <> 2008 isco Systems, Inc. ll rights reserved. isco Public 50 25

26 Hub and Spoke Design You can also use floating static routes at the two hub routers and redistribute them into the routing protocol Distribute list 10 only allows the default route to be advertised to the remotes Distribute list 20 prevents a default route from being leaked back into the core access-list 10 permit host access-list 20 deny host access-list 20 permit any... ip route null router eigrp 100 redistribute static distribute-list 10 out <remote 1> distribute-list 10 out <remote 2> distribute-list 10 out <remote 3> distribute-list 20 out <core> This has the same problem if a single link back towards the core and the injected external route both fail There are other situations under which this also fails 2008 isco Systems, Inc. ll rights reserved. isco Public 51 Hub and Spoke Design One solution is to have a link between the summarizing routers across which they share full routing information onditional advertisement of routing information is another possible solution Internet D EIGRP External Default Route D EX /0 OSPF can conditionally generate a default route EIGRP has conditional advertisement as a planned feature Full Routing Information 2008 isco Systems, Inc. ll rights reserved. isco Public 52 26

27 Hub and Spoke Design EIGRP can run over either a multipoint interface at the hub router or point-to-point subinterfaces single multipoint interface is easier to configure but it can be harder to troubleshoot P2P subinterfaces allow for more granular failure detection. Summary Only /0 Single Multipoint or Several Point-to-Points Use summarization at the hub routers to reduce information into the network core Provide as little information to the remotes as possible Declare the remote routers as stubs router eigrp 100 eigrp stub connected / / / isco Systems, Inc. ll rights reserved. isco Public 53 EIGRP Stubs When a router running EIGRP loses its connection to a network, it first searches for alternate loop free paths If it finds none, it then sends queries to each of its neighbors, looking for an alternate path /24 router-a#sho ip eigrp topo IP-EIGRP Topology Table... P /24, 1 successors, FD is via onnected, Ethernet1/2 router-a#show ip eigrp events Event information for S 100: ctive net/peers: / F not sat Dmin/met: Find FS: / onn rt down: /24 Ethernet 3/ isco Systems, Inc. ll rights reserved. isco Public 54 27

28 EIGRP Stubs If the neighbor has no path to this destination, it replies The router then removes all references to this route from its local tables /24 In large hub and spoke networks, the hub routers have to build queries and process replies from each of the spokes This impacts scaling! router-a#show ip eigrp events Event information for S 100: 1 ND delete: / ctive net/peers: / F not sat Dmin/met: Find FS: / onn rt down: /24 Ethernet 3/ isco Systems, Inc. ll rights reserved. isco Public 55 EIGRP Stubs If these spokes are remote sites, they have two connections for resiliency, not so they can transit traffic between and /24 should never use the spokes as a path to anything, so there s no reason to learn about, or query for, routes through these spokes Don t Use These Paths 2008 isco Systems, Inc. ll rights reserved. isco Public 56 28

29 EIGRP Stubs To signal and that the paths through the spokes should not be used, the spoke routers can be configured as stubs /24 router#config t router(config)#router eigrp 100 router(config-router)#eigrp stub connected router(config-router)# 2008 isco Systems, Inc. ll rights reserved. isco Public 57 EIGRP Stubs Marking the spokes as stubs allows them to signal and that they are not valid transit paths will not query stubs, reducing the total number of queries in this example to one /24 Marking the remotes as stubs also reduces the complexity of this topology; now believes it only has one path to /24, rather than five Marked as Stubs 2008 isco Systems, Inc. ll rights reserved. isco Public 58 29

30 EIGRP Stubs If stub connected is configured will advertise /24 to will not advertise /23, /23, or /24 If stub summary is configured will advertise /23 to / / /24 will not advertise /24, /24, or /24 ip route ! interface serial 0 ip summary-address eigrp ! router eigrp 100 redistribute static metric network network eigrp stub connected eigrp stub summary 2008 isco Systems, Inc. ll rights reserved. isco Public 59 EIGRP Stubs If stub static is configured will advertise /24 to will not advertise /24, /23, or /24 If stub receive-only is configured won t advertise anything to, so needs to have a static route to the networks behind to reach them / / /24 ip route ! interface serial 0 ip summary-address eigrp ! router eigrp 100 redistribute static network network eigrp stub static eigrp stub receive-only 2008 isco Systems, Inc. ll rights reserved. isco Public 60 30

31 EIGRP Stubs If stub redistributed is configured will advertise /24 to will not advertise /24, /23, or / / / /24 ip route ! interface serial 0 ip summary-address eigrp ! router eigrp 100 redistribute static network network eigrp stub redistributed 2008 isco Systems, Inc. ll rights reserved. isco Public 61 EIGRP Stubs ny combination of the route types can be specified on the eigrp stub statement, except receive-only, which cannot be used with any other option For example: eigrp stub connected summary redistributed If eigrp stub is specified without any options, it will actually enable eigrp stub connected summary 2008 isco Systems, Inc. ll rights reserved. isco Public 62 31

32 EIGRP Stubs t, you can tell is a stub using show ip eigrp neighbor detail / /24 router-a#show ip eigrp neighbor detail IP-EIGRP neighbors for process 100 H ddress Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) nt Num Se :00: Version 12.4/1.2, Retrans: 0, Retries: 0, Prefixes: 1 Stub Peer dvertising ( ONNETED ) Routes Suppressing queries / isco Systems, Inc. ll rights reserved. isco Public 63 EIGRP Stubs t, you can see that the EIGRP process for S 100 is running as a stub using show ip protocols /31 router-b#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 EIGRP stub, connected Redistributing: static, eigrp / / isco Systems, Inc. ll rights reserved. isco Public 64 32

33 EIGRP Hub and Spoke How Many Neighbors? The green line shows the rate at which the convergence time increases as EIGRP neighbors are added to hub routers and does not pass 500 The red line shows the convergence time if the neighbors added are all configured as EIGRP stub routers and scales to over 1000 peers Measure initial bring up convergence until all neighbors are established and queues empty Dual Homed Remotes, NPE-G1 with 1G RM, 3000 prefixes advertised to each spoke 9 Time (Minutes) 5 Non-Stub EIGRP Stub Test Performed with 12.3(14)T Number of Neighbors 2008 isco Systems, Inc. ll rights reserved. isco Public 65 EIGRP Hub and Spoke Failover Time The green line with the steep slope shows the rate at which the failover convergence time increases as EIGRP neighbors are added to a single hub router The red line shows the failover convergence time if the neighbors added are all configured as EIGRP stub routers and is extremely linear in behavior Primary Hub failed, time measured for EIGRP to complete failover convergence Dual Homed Remotes, NPE-G1 with 1G RM, 3000 prefixes advertised to each spoke 60 Time (Minutes) 15 1 Non-Stub Test Performed with 12.3(14)T1 EIGRP Stub Number of Neighbors 2008 isco Systems, Inc. ll rights reserved. isco Public 66 33

34 EIGRP Hub and Spoke Summary Most EIGRP Neighbors Seen 800 Deployed in live, working networks 1400 is the largest number ever tested in a lab environment Key Strategy for achieving scalability is design! Stub for EIGRP hub and spoke environments is a must Minimize advertisements to spokes 2008 isco Systems, Inc. ll rights reserved. isco Public 67 EIGRP DMVPN Single DMVPN Hub Single mgre tunnel on all nodes /24.2 Physical: Tunnel0: Physical: (Dynamic) Tunnel0: Physical: (Dynamic) Tunnel0: Spoke /24.37 Web /24 Spoke.25 P isco Systems, Inc. ll rights reserved. isco Public 68 34

35 EIGRP DMVPN Dual DMVPN Hub Single mgre tunnel on all nodes Physical: Tunnel0: / Physical: Tunnel0: Mixed Stub Types on Shared Media Sdx (35.01)S 12.4(7) Physical: (Dynamic) Tunnel0: Spoke... Physical: (Dynamic) Tunnel0: /24.37 Web /24 Spoke.25 P isco Systems, Inc. ll rights reserved. isco Public 69 EIGRP DMVPN How many neighbors can we have on a single tunnel? urrently, the practical maximum is 600 while advertising no more than 5k prefixes onvergence Time (seconds) Peer ount, Prefixes 2008 isco Systems, Inc. ll rights reserved. isco Public 70 35

36 EIGRP DMVPN What about dual hubs, single DMVPN? urrently, the practical maximum is 600 while advertising no more than 5k prefixes onvergence Time 100 Peers 200 Peers 300 Peers 400 Peers 500 Peers 600 Peers Routes onvergence (seconds) isco Systems, Inc. ll rights reserved. isco Public 71 EIGRP DMVPN ustomer Experience urrent Max Recommended is 500 peers on a single tunnel, chassis 5,000 peers on the whole network, terminating on 10 hub routers to distribute the load Typical to have each spoke advertise between 2 5 prefixes to the hubs onvergence time 3 5 seconds during a failover nother network is scaling to 400 peers and 10,000 prefixes (specific routes needed for spoke-to-spoke capability) 2008 isco Systems, Inc. ll rights reserved. isco Public 72 36

37 EIGRP DMVPN EIGRP DMVPN Enhancements Initial convergence testing was done with 400 peers with 10,000 prefixes to each peer Measure initial bring up convergence until all neighbors are established and queues empty EIGRP DMVPN Phase 0 (prior to 12.4(7)) EIGRP DMVPN Phase I (12.4(7) and later) EIGRP DMVPN Phase II (Sei03733) onvergence Time min 11 min 3 min Phase 0 Phase I Phase II 2008 isco Systems, Inc. ll rights reserved. isco Public 73 EIGRP DMVPN Testing ased on 12.4(7) for EIGRP (Phase I) ig Improvements for EIGRP went into this release! Study performed to analyze the impact of increasing Prefix count and compare that to increasing Peer counts to find the bottlenecks Data for Single Hub and Dual Hub essentially equivalent Peers were fixed at 500, prefixes were increased from 0 20k Prefixes were fixed at 5k, peers were increased from isco Systems, Inc. ll rights reserved. isco Public 74 37

38 EIGRP DMVPN Effect of Prefix ount on Scaling Varying Prefix ount, 500 Peers onvergence Measurement Time (sec) Prefixes 2008 isco Systems, Inc. ll rights reserved. isco Public 75 EIGRP DMVPN Effect of Peer ount on Scaling Varying Peer ount, 5k Prefixes on onvergence Time (sec) Peer ount 2008 isco Systems, Inc. ll rights reserved. isco Public 76 38

39 EIGRP DMVPN urrently Phase II is underway to increase these scalability numbers significantly Focus of Phase II is to increase peer counts, prefix counts, and convergence times pushing the limits closer to the theoretical maximum of 2000 peers per interface Preliminary testing of these additional enhancements have verified further scalability and stability, with faster convergence as well More to come on DMVPN!! 2008 isco Systems, Inc. ll rights reserved. isco Public 77 EIGRP DMVPN Scaling onclusions learly Peer ount is the bottleneck There is a combined impact with Prefix count, but Peer count is the dominate variable Phase II enhancements are currently undergoing testing and review Focused on increasing Peer count significantly ontinued increase of Prefix count ombined impact targeting overall significant reduction in convergence 2008 isco Systems, Inc. ll rights reserved. isco Public 78 39

40 Redundancy There are several reasons for redundancy in a network: To provide multiple attachment points for servers and hosts in case of a link or device failure To provide alternate links through the network in case of link or device failure To provide optimal routing to services To provide load sharing in heavily utilized areas 2008 isco Systems, Inc. ll rights reserved. isco Public 79 Redundancy It s common to build networks with back-to-back routers for redundancy HSRP Peers The routing protocol sees each of these links as a possible transit path, so each link adds another set of paths the routing protocol must consider when calculating the best path You want to route to these links, not through them RP Transit Paths 2008 isco Systems, Inc. ll rights reserved. isco Public 80 40

41 Redundancy The solution to this is passive-interface onfiguring an interface as passive in EIGRP, OSPF, or IS-IS will cause it not to form neighbor relationships across the link These networks will still be advertised as reachable destinations, but they will never be advertised as transit links router eigrp 100 passive-interface default no passive-interface fastethernet 1/0... -or- router eigrp 100 passive-interface fastethernet 0/0 passive-interface fastethernet 0/1 passive-interface fastethernet 0/2 passive-interface fastethernet 0/ isco Systems, Inc. ll rights reserved. isco Public 81 Redundancy It s common to build out alternate links in a network dds network resiliency an provide optimal routing to resources dds additional bandwidth in congested areas of the network The second link also adds moderate complexity, and more information, into the network ackup Path dditional andwidth Optimal Routing 2008 isco Systems, Inc. ll rights reserved. isco Public 82 41

42 Redundancy If Two Is Good Three Must e etter Right? dding a third link almost always approaches the point of diminishing returns, and adds much more network complexity When considering adding more redundancy, always balance the increased resiliency against the added complexity Increased network convergence times Increased management effort Increased troubleshooting times 2008 isco Systems, Inc. ll rights reserved. isco Public 83 Redundancy The impact of greater levels of redundancy on convergence times can be seen in routing protocol scalability testing Using EIGRP, with a single backup path, it takes about 1.3 seconds for a router with routes to converge when the best path fails 2.5 Seconds Routes Feasible Successor est Path Fails 2008 isco Systems, Inc. ll rights reserved. isco Public 84 42

43 Redundancy dding the third path increases convergence time to 2 seconds dding the fourth path increases convergence time to 2.25 seconds 2.5 Seconds Routes est Path Fails 2008 isco Systems, Inc. ll rights reserved. isco Public 85 Redundancy More Is Not lways etter High availability studies also show the impact of adding the third link is not all that great dding a second link will increase reliability significantly dding a third link approaches the point of diminishing returns ombined with the impact of: Slower convergence times Higher management costs Slower troubleshooting The total downtime in a network may actually increase with the addition of large amounts of redundancy Reliability Link 2 Links 3 Links 4 Links 2008 isco Systems, Inc. ll rights reserved. isco Public 86 43

44 Redundancy If you re adding more links to increase the available bandwidth in a specific place in the network Try to hide this complexity from other parts of the network, if possible Summarize just the parallel links into a single advertisement at both sides if you re using a distance vector protocol Summary Summary 2008 isco Systems, Inc. ll rights reserved. isco Public 87 Redundancy Layer 2 bundling (such MLPPP or Etherhannel ) may be useful to reduce the layer 3 complexity when using multiple links to build required bandwidth ut be careful of issues with processor utilization due to bundling overhead, troubleshooting complexity, etc. Link undle 2008 isco Systems, Inc. ll rights reserved. isco Public 88 44

45 Redundancy onsider using High vailability (H) techniques to reduce overlapping redundancy Stateful Switchover/NonStop Forwarding with redundant hardware in the same box may be able to replace redundant connections to network connected devices Single High vailability Device 2008 isco Systems, Inc. ll rights reserved. isco Public 89 Redundancy alance between complexity and resiliency Hide the additional complexity created by redundant links where possible Summarization Link bundling (but balance against overhead) onsider High vailability techniques to reduce heavy redundancy for resiliency Reliability Link 2 Links 3 Links 4 Links 2008 isco Systems, Inc. ll rights reserved. isco Public 90 45

46 Graceful Restart/NSF Fundamentals Fast Hellos is a way of detecting failures fast and routing around them Graceful Restart (GR) is a way to rebuild forwarding information in routing protocols when the control plane has recovered from a failure Nonstop Forwarding (NSF) is a way to continue forwarding packets while the control plane is recovering from a failure The fundamental premise of GR/NSF is to route through temporary failures, rather than around them! 2008 isco Systems, Inc. ll rights reserved. isco Public 91 EIGRP Graceful Restart/NSF Prior to Graceful Restart/NSF Router loses its control plane for some period of time It will take some time for Router to recognize this failure, and react to it ontrol Data ontrol Data 2008 isco Systems, Inc. ll rights reserved. isco Public 92 46

47 EIGRP Graceful Restart/NSF Prior to Graceful Restart/NSF During the time that has failed, and has not detected the failure, will continue forwarding traffic through Once the control plane resets, the data plane will reset as well, and this traffic will be dropped NSF reduces or eliminates the traffic dropped while s control plane is down Reset ontrol Data ontrol Data 2008 isco Systems, Inc. ll rights reserved. isco Public 93 EIGRP Graceful Restart/NSF NSF apable If is NSF capable, the control plane will not reset the data plane when it restarts Instead, the forwarding information in the data plane is marked as stale ny traffic sends to will still be switched based on the last known forwarding information No Reset ontrol Data ontrol Data Mark Forwarding Information as Stale 2008 isco Systems, Inc. ll rights reserved. isco Public 94 47

48 EIGRP Graceful Restart/NSF NSF apable While s control plane is down, the routing protocol hold timer on counts down has to come back up and signal before s hold timer expires, or will route around it When comes back up, it signals that it is still forwarding traffic, and would like to resync This is the first step in Graceful Restart (GR) ontrol Data ontrol Data Hold Timer: isco Systems, Inc. ll rights reserved. isco Public 95 EIGRP Graceful Restart/NSF Graceful Restart The signal in EIGRP is an update with the initialization and restart (RS) bits set sends its hellos with the restart bit set until GR is complete transmits the routing information it knows to When is finished sending information, it sends a special end of table signal so knows the table is complete Init + Restart ontrol hello + Restart Topology Information End of Table ontrol Data Data 2008 isco Systems, Inc. ll rights reserved. isco Public 96 48

49 EIGRP Graceful Restart/NSF Graceful Restart When receives this end of table marker, it recalculates its topology table, and updates the local routing table When the local routing table is completely updated, EIGRP notifies EF EF then updates the forwarding tables, and removes all information marked as stale ontrol Data ontrol Data 2008 isco Systems, Inc. ll rights reserved. isco Public 97 EIGRP Graceful Restart/NSF eigrp nsf enables graceful restart show ip protocols verifies graceful restart is operational oducts/sw/iosswrel/ps1839/pro ducts_feature_guide09186a html router eigrp 100 eigrp nsf... router eigrp 100 eigrp nsf... router#show ip protocols Routing Protocol is "eigrp Redistributing: eigrp 100 EIGRP NSF-aware route hold timer is 240s utomatic network summarization is in effect Maximum path: isco Systems, Inc. ll rights reserved. isco Public 98 49

50 EIGRP Graceful Restart/NSF Routing protocol graceful restart is supported in isco IOS 12.2(15)T NonStop Forwarding is supported on the: isco and isco (22)S isco 7500 in 12.0(22)S, with the caveat that inserting a new standby RSP will cause some traffic loss, and switching from the primary to standby RSP will cause a microcode reload on the line cards isco 7600/ (18)SXD (Rockies1), which shipped in July isco Systems, Inc. ll rights reserved. isco Public 99 Unequal ost Load Sharing an you load share across the two available paths between and D, even though they are not equal cost? Yes, using variance, as long as the paths are loop free 500K 1000K 56K 56K D 2008 isco Systems, Inc. ll rights reserved. isco Public

51 Unequal ost Load Sharing D through Distance: Reported Distance: D through Distance: Reported Distance: The best path is through, so is the successor The reported distance through is lower than the best path through, so this path is loop free is the feasible successor (FS) 56K 2000ms 56K 2000ms D 1000K 10ms 56K 2000ms 2008 isco Systems, Inc. ll rights reserved. isco Public 101 Unequal ost Load Sharing onfigure variance on router with a value high enough to include both paths Variance is a multiplier, so it has to be some number which, when multiplied by the lower metric, is higher than or equal to the highest metric you want to include in the load sharing Distance Distance D 2008 isco Systems, Inc. ll rights reserved. isco Public

52 Unequal ost Load Sharing In this case, x 2 = , which is higher than , so 2 will work as the variance router-a(config)#router eigrp 100 router-a(config-rtr)#variance 2 router-a(config-rtr)#end Distance Distance Lowest metric * variance Metric of other path D 2008 isco Systems, Inc. ll rights reserved. isco Public 103 Unequal ost Load Sharing oth paths are installed in the routing table The higher metric is then divided by each lower metric to determine the load share count / So, the load share on the path through will be set to 2, and the load share on the path through will be set to 1 Distance Distance D 2008 isco Systems, Inc. ll rights reserved. isco Public

53 Unequal ost Load Sharing From this point, the actual load sharing of traffic is up to the switching engine being used to forward packets For process switching, each packet forwarded through will be matched by two packets forwarded through Distance Distance Load Share 1 Load Share 2 D 2008 isco Systems, Inc. ll rights reserved. isco Public 105 EIGRP Fast onvergence lready a standard part of EIGRP ustomers have been using EIGRP to achieve sub-second convergence for years Proper network design is a must Design to use address summarization to limit query scope Design to provide at least one feasible successor We can sort typical convergence times: EIGRP with a feasible successor Link state protocols EIGRP without a feasible successor isco is currently in the process of quantifying scalability numbers 2008 isco Systems, Inc. ll rights reserved. isco Public

54 EIGRP Fast onvergence ombined Results EIGRP Feasible Successor EIGRP No Feasible Successor + IS-IS Default Timers IS-IS Tuned Timers OSPF Tuned Timers OSPF Default Timers Tested on 12.4(3a) 2008 isco Systems, Inc. ll rights reserved. isco Public 107 onfiguring andwidth EIGRP paces packets based on the configured bandwidth y default, EIGRP uses 50% of the configured or default bandwidth Default bandwidth on serial links is 1544 (T1) Just using the default isn t always right 2008 isco Systems, Inc. ll rights reserved. isco Public

55 onfiguring andwidth For point-to-point links (PPP, HDL, TM), configure the actual bandwidth available on the link For burstable links, configure the normal bandwidth, not the burst For point-to-point subinterfaces off a multipoint link, configure the committed access rate, rather than the line speed 2008 isco Systems, Inc. ll rights reserved. isco Public 109 onfiguring andwidth For 0 IR links, guess You need to set it high enough to get EIGRP to work, so 56k is probably a reasonable number 2008 isco Systems, Inc. ll rights reserved. isco Public

56 onfiguring andwidth If you need to change the amount of actual bandwidth EIGRP is using, use the percentage bandwidth interface command to adjust this, rather than setting the bandwidth IP Percentage-andwidth EIGRP <S> <Percentage> y default, EIGRP uses 50% of the configured or default bandwidth 2008 isco Systems, Inc. ll rights reserved. isco Public 111 onfiguring andwidth Dial and point-tomultipoint links present some difficulties Each peer which connects over a multipoint reduces the available bandwidth by division 512k Remote Sites 2008 isco Systems, Inc. ll rights reserved. isco Public

57 onfiguring andwidth One peer: Two peers: 512k available 256k available Three peers: 170k available 512k Four peers: Five peers: 128k available 102k available Remote Sites 2008 isco Systems, Inc. ll rights reserved. isco Public 113 onfiguring andwidth t some point, EIGRP won t have enough bandwidth to operate correctly Use dialer profiles for dial links, which makes EIGRP treat them as point-topoint links 512k Use subinterfaces for multipoint interfaces Remote Sites 2008 isco Systems, Inc. ll rights reserved. isco Public

58 Problems with Using andwidth ssume you would like to influence the path that packets switched by router will take to router D delays * 256 min( bandwidth) Using bandwidth, you will need to lower the bandwidth on the - link or the - link to something lower than 56K andwidth is not granular enough to effectively control traffic flow 1000K 56K ontrol over These Two Links Only! 1000K 56K D 2008 isco Systems, Inc. ll rights reserved. isco Public 115 Problems with Using andwidth Reducing the bandwidth on either the - or the - link will also impact EIGRP s operation EIGRP uses the configured bandwidth to control the rate at which packets are transmitted across a link via the packet pacing timer 1000K Must e Reduced Dramatically to Impact Path Selection! 56K 1000K 56K D 2008 isco Systems, Inc. ll rights reserved. isco Public

59 Problems with Using andwidth Don t use bandwidth to influence path selection! Set the bandwidth to the actual available bandwidth, and use the delay to influence traffic flow Delay is added inbound; set the delay on s interface which connects to or 1000K onfigure Delay Here 56K 1000K 56K D 2008 isco Systems, Inc. ll rights reserved. isco Public 117 Multiple utonomous Systems Do You Really Want to Do This? Okay, maybe it s not that bad ut we still wouldn t recommend it 2008 isco Systems, Inc. ll rights reserved. isco Public

60 Multiple utonomous Systems route is redistributed from RIP into S 200 S 100 t, it is redistributed into S 100 receives this route as well; which of the two externals will it prefer? There are two routes learned through separate routing processes with the same administrative distance, so the route installed first wins RIP S isco Systems, Inc. ll rights reserved. isco Public 119 Multiple utonomous Systems If router prefers the route through S 100, it will redistribute the route back into S200 S 100 If the redistribution metric at is lower than the redistribution metric at, will prefer the path through We have a permanent loop! Metric 1000 Metric 500 S 200 RIP 2008 isco Systems, Inc. ll rights reserved. isco Public

61 Multiple utonomous Systems If router prefers the route through S 100, it will redistribute the route back into S200 S 100 If the redistribution metric at is lower than the redistribution metric at, will prefer the path through We have a permanent loop! Metric 1000 Metric 500 S 200 RIP 2008 isco Systems, Inc. ll rights reserved. isco Public 121 Multiple utonomous Systems Sdm47037 resolves the routing loop and the suboptimal routing (12.2(06.01)T) If two routes with the same administrative distances are compared, and the process type is the same (both EIGRP), then compare the metrics of the routes as well isco Systems, Inc. ll rights reserved. isco Public

62 Multiple utonomous Systems External routes can also carry administrative tags; as the external route is redistributed into S 100 at, it can be tagged S 100 Tag 100 This tag can then be used to block the redistribution of the route back into S 200 at S 200 RIP route-map settag permit 10 set tag 100! router eigrp 100 redistribute eigrp 200 route-map settag... route-map filtertag deny 10 match tag 100 route-map filtertag permit 20! router eigrp 200 redistribute eigrp 100 route-map filtertag 2008 isco Systems, Inc. ll rights reserved. isco Public 123 Multiple utonomous Systems This blocks the formation of the loop, since will no longer receive the redistributed routes from through S 200 S 100 tag 100 still receives both routes, however, and could still choose the path through S 100, resulting in suboptimal routing S 200 RIP route-map settag permit 10 set tag 100! router eigrp 100 redistribute eigrp 200 route-map settag... route-map filtertag deny 10 match tag 100 route-map filtertag permit 20! router eigrp 200 redistribute eigrp 100 route-map filtertag 2008 isco Systems, Inc. ll rights reserved. isco Public

63 Multiple utonomous Systems If the redistribution metric is not manually set at, it will be carried from S 200 into 100 The cost of the path between and is then added at t, the route through S 200 wins; it has the lower metric Metric 1000 S 200 S 100 Metric 1500 RIP IP-EIGRP Topology Table for S(100)/ID( )... P /24, 1 successors, FD is 1500 via (1500/1000), FastEthernet0/0... IP-EIGRP Topology Table for S(200)/ID( )... P /24, 1 successors, FD is 1000 via (1000/256256), FastEthernet0/ isco Systems, Inc. ll rights reserved. isco Public 125 Multiple utonomous Systems Sdt43016, Support for Incoming Route Filtering ased on Route Maps, makes it possible to filter routes based on any route map condition before it is accepted into the local routing protocol database (12.2T 12.0S) This is listed as an OSPF feature, but it works for all routing protocols re/ios122/122relnt/xprn122t/122tnewf.htm# isco Systems, Inc. ll rights reserved. isco Public

64 Multiple utonomous Systems This blocks the formation of the loop, since will no longer have the path redistributed from into S 100 in its topology table S 100 This also prevents the suboptimal routing S 200 RIP route-map settag permit 10 set tag 100! router eigrp 100 redistribute eigrp 200 route-map settag... route-map filtertag deny 10 match tag 100 route-map filtertag permit 20! router eigrp 100 distribute-list route-map filtertag in 2008 isco Systems, Inc. ll rights reserved. isco Public 127 Multiple utonomous Systems ut, before you rush off and configure your network with multiple autonomous systems What are you gaining by designing a network this way? 2008 isco Systems, Inc. ll rights reserved. isco Public

65 Multiple utonomous Systems query originates at router, and propagates to router S 100 The query stops at, and a reply is sent back The query range has been limited at ; the query stopped there, and was replied to; or has it?... Reply Query S isco Systems, Inc. ll rights reserved. isco Public 129 Multiple utonomous Systems What happens at in S 100? now needs to query all of its neighbors, including the neighbors in S 100 S 100 builds a query in S 100, and sends it to ; if the timing is right, will have already received and replied to the query from, so it would answer that it has no alternate path Reply Query S 200 The query wasn t stopped, it was just delayed along the way! 2008 isco Systems, Inc. ll rights reserved. isco Public

66 Reply Multiple utonomous Systems Don t use multiple autonomous systems for scaling, they don t limit query range S 100 General scaling methods (summarization, distribute lists, stubs, etc.) actually limit query scope Query Multiple autonomous systems are fine for merging two networks over time, but they are not a permanent solution S isco Systems, Inc. ll rights reserved. isco Public 131 Managing EIGRP 2008 isco Systems, Inc. ll rights reserved. isco Public

67 Managing EIGRP Reading the EIGRP Topology Table Reading Show IP EIGRP Neighbors Neighbor Logging Event Log 2008 isco Systems, Inc. ll rights reserved. isco Public 133 Reading the EIGRP Topology Table Summary of the Topology Table provides a quick snapshot of the routers status and topology Shows the following: Number of routes in the local topology table Number of queries that this router is waiting to receive a reply Number of interfaces enabled for EIGRP Number of Neighbors/Number of Interfaces Quiescent interfaces those interfaces with nothing to send or have acknowledged Router#sh ip eigrp topology summary IP-EIGRP Topology Table for S(1)/ID( ) Head serial , next serial routes, 0 pending replies, 0 dummies IP-EIGRP(0) enabled on 1002 interfaces, 1007 neighbors present on 1002 interfaces Quiescent interfaces: Gi0/0.100 Tu10000 Tu871 Tu162 Tu466 Tu268 Tu841 Tu221 Tu isco Systems, Inc. ll rights reserved. isco Public

68 Reading the EIGRP Topology Table router#show ip eigrp topology IP-EIGRP Topology Table for S(1)/ID( ) odes: P - Passive, - ctive, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P /30, 1 successors, FD is via ( / ), FastEthernet1/0 via ( / ), FastEthernet1/1 Feasible Distance Successor State omputed Distance Reported Distance Feasible Successor 2008 isco Systems, Inc. ll rights reserved. isco Public 135 Reading Show IP EIGRP Neighbors Handle: Internal use to keep track of the Neighbors ddress: Neighbor IP address Interface: Local Interface which connects to that Neighbor Hold Time: Seconds remaining before declaring that neighbor down Uptime: The period of time since the neighbor was most recently discovered SRTT: The number of milliseconds it takes for this neighbor to respond to reliable packets RTO: How long we ll wait before retransmitting if we get no acknowledgement Q nt: Number of outstanding packets waiting to be acknowledged by the neighbor Seq Num: ounter to track the number of packets sent to the neighbor router#show ip eigrp neighbor IP-EIGRP neighbors for process 1 H ddress Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) nt Num Gi0/ :09: Gi0/ d19h Tu d22h Tu d22h Tu d22h isco Systems, Inc. ll rights reserved. isco Public

69 Reading the EIGRP Topology Table Show ip eigrp topology active Information about links that are currently in active state Show ip eigrp topology all-links Displays all information about everything that EIGRP has in the topology table Show ip eigrp topology <net> <mask> Displays everything that the eigrp process has for a specific route Show ip eigrp topology zero Shows the zero successor links, or routes that don t make it into the routing table as another route with a better dmin Distance has won 2008 isco Systems, Inc. ll rights reserved. isco Public 137 Neighbor Logging Provides the frequency and reason that a neighbor changes state Strong recommendation to always have this functionality enabled Enabled under router eigrp process eigrp log-neighbor-changes Default behavior since 12.2(12) Use the logging buffer to minimize potential impact Enabled globally: logging buffered isco Systems, Inc. ll rights reserved. isco Public

70 Neighbor Logging Demystified! New djacency Why look dear, we have a new neighbor Either initial startup or recovery after a neighbor has gone down Holding Time Expired No EIGRP packets were seen from this neighbor for the duration of the hold time Typically 15 seconds, though some are 180 Peer Restarted Not my fault! The other router reset the peer and that s where you need to look to find the reason Retry Limit Exceeded reliable packet was not acknowledged after at least 16 retransmissions (ctual number is based on the hold time, but there were at least 16) Route Filter hange EIGRP doesn t refresh routes; when a filter changes that affects what is sent to the peers the neighbor is dropped to remove the old information and then it is retold with the new filter in place (Graceful Restart could minimize the impact of this!) pr 21 11:02:22.285: Neighbor (TM1/0.2934) is up: new adjacency pr 21 11:02:22.941: Neighbor (TM1/0.1955) is down: holding time expired pr 21 11:02:22.953: Neighbor (TM1/0.872) is down: peer restarted pr 21 10:52:24.787: Neighbor (FastEthernet1/1) is down: retry limit exceed pr 21 11:12:42.945: Neighbor (TM1/0.1963) is down: route filter changed 2008 isco Systems, Inc. ll rights reserved. isco Public 139 Event Log The most important tool for getting a view of what s going on in the network lways running, separate log kept per S Default 500 lines (very little actually ) eigrp event-log-size <number of lines> 0 lines disables logging If you can spare the memory (very little) increasing the size is recommended! Read from the bottom up as new events are written on top The log may be cleared by entering: clear ip eigrp event 2008 isco Systems, Inc. ll rights reserved. isco Public

71 MI Support Introduction of EIGRP MI 12.3(14T) Included in images with SNMP feature base urrently IPv4 only, but IPv6 in the works (long with EIGRP for IPv6, 12.4(T)) Implemented Per S, Per VPN basis llows for granular reporting and management of EIGRP in multi S, VPN and non-vpn networks Sample configuration: Router(config)# snmp-server host traps version 2c NETMNGER eigrp Router(config) snmp-server community EIGRP1NET1 Router(config)# snmp-server enable traps eigrp 2008 isco Systems, Inc. ll rights reserved. isco Public 141 MI Support Includes two Traps eigrproutesi eigrputhfailure Five Object Groups on a per VPN, per S basis EIGRP VPN Table EIGRP Traffic Statistics EIGRP Topology Data EIGRP Neighbor Data EIGRP Interface Data For more specifics on the objects and MI please see the following: ps5207/products_feature_guide09186a00803d2d3d.html 2008 isco Systems, Inc. ll rights reserved. isco Public

72 MI Support EIGRP Traffic Statistics S Number Hellos Sent/Received Updates Sent/Received Queries Sent/Received Replies Sent/Received EIGRP Topology Data Destination Net/Mask ctive State Feasible Successors Origin Type Distance Reported Distance EIGRP Interface Data Peer ount Reliable/Unreliable Queues Pacing Pending Routes Hello Interval EIGRP Neighbor Data Peer ddress Peer Interface Hold Time Up Time SRTT/RTO Version nd Many More isco Systems, Inc. ll rights reserved. isco Public 143 Q and 2008 isco Systems, Inc. ll rights reserved. isco Public

73 Recommended Reading ontinue your isco Live learning experience with further reading from isco Press heck the Recommended Reading flyer for suggested books vailable Onsite at the isco ompany Store 2008 isco Systems, Inc. ll rights reserved. isco Public 145 Recommended Reading SIN: ISN: ISN isco Systems, Inc. ll rights reserved. isco Public

74 omplete Your Online Session Evaluation Give us your feedback and you could win fabulous prizes; winners announced daily Receive 20 Passport points for each session evaluation you complete omplete your session evaluation online now (open a browser through our wireless network to access our portal) or visit one of the Internet stations throughout the onvention enter Don t forget to activate your isco Live virtual account for access to all session material on-demand and return for our live virtual event in October 2008 Go to the ollaboration Zone in World of Solutions or visit isco Systems, Inc. ll rights reserved. isco Public isco Systems, Inc. ll rights reserved. isco Public