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EIGRP FOR MANAGED SERVICES TECHNOLOGY DEPLOYMENT

EIGRP FOR MANAGED SERVICES TECHNOLOGY DEPLOYMENT. SANGITA PANDYA INTERNET TECHNOLOGIES DIVISION DECEMBER 2004. 1. 1. 1. Agenda. INTRODUCTION Fundamentals of EIGRP DUAL Summarization and Load Balancing Query Process Deployment Guidelines with EIGRP Summary. Presentation_ID. 2. 2.

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EIGRP FOR MANAGED SERVICES TECHNOLOGY DEPLOYMENT

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  1. EIGRP FOR MANAGED SERVICESTECHNOLOGY DEPLOYMENT SANGITA PANDYA INTERNET TECHNOLOGIES DIVISION DECEMBER 2004 1 1 1

  2. Agenda • INTRODUCTION • Fundamentals of EIGRP • DUAL • Summarization and Load Balancing • Query Process • Deployment Guidelines with EIGRP • Summary Presentation_ID 2 2 2 © 2004 Cisco Systems, Inc. All rights reserved.

  3. MANAGEDExtranet MANAGEDCPE MANAGED IPT VM VM MANAGED Internet Gateway VPN for Many Managed Services V i r t u a l P r i v a t e N e t w o r k MANAGED Routing MANAGED Security Service Level Agreement for MANAGED Services Service Provider Converged Network VPN B Customer Branch Customer HQ

  4. Managed Routing Revenue Opportunity Over 50% of Cisco Enterprise Customers Deploy IP Routing with EIGRP IP/MPLS VPN Backbone PE-3 PE-1 PE-2 CE-1 CE-2 EIGRP AS-1 EIGRP AS-1

  5. Robust EIGRP Support Cisco Exclusive Cisco IOSSupports the Industry’s Most Comprehensive and Robust Routing Protocol Support: RIP, OSPF, BGP, ISIS, Including EIGRP VPN C/Site 2 CEA2 12.1/16 Static CEB2 CE1B1 16.2/16 RIPv2 RIPv2 P1 PE2 VPN B/Site 2 BGP PE1 RIPv2 P2 CEA3 OSPF OSPF 16.2/16 CEA1 P3 PE3 BGP VPN A/Site 2 CEB3 VPN A/Site 1 16.1/16 VPN C/Site 1 12.2/16 • BENEFITS: • Service Provider: Simplest point of entry into enterprise’s existing architecture • Enterprise: Least disruption to current network design

  6. Managed EIGRP Benefits for SPs and Enterprises: • Impose little requirements or no restrictions on customer networks • CE and C routers are NOT required to run newer code • (CE/C upgrades recommended for full SoO functionality) • Customer sites may be same or different autonomous systems • Customer sites may consist of several connections to the MPLS VPN backbone • Customer sites may consist of one or more connections not part of the MPLS VPN backbone (“backdoor” links) 6 6 6

  7. Introducing EIGRP • EIGRP is architected by Cisco systems to overcome short comings of other protocols such as RIP, IGRP and OSPF • It is widely deployed in Enterprise networks • MPLS VPN Service Providers also enable EIGRP on their PE routers to support the connecting networks which may already be running EIGRP • EIGRP can also be used as CE-PE routing protocol for MPLS VPN connectivity

  8. IGRP: Interior GatewayRouting Protocol • Cisco proprietary • Distance vector • Broadcast based • Utilizes link bandwidth and delay • 15 hops is no longer the limit • 90 seconds updates (RIP is 30 sec.) • Load balance over unequal cost paths

  9. IGRP/EIGRP Metrics Calculation • Metric = [K1 x BW + (K2 x BW) / (256 - Load) + K3 x Delay] x [K5 / (Reliability + K4)] • By Default: K1 = 1, K2 = 0, K3 = 1, K4 = K5 = 0 • Delay is sum of all the delays of the link along the paths • Delay = Delay/10 • Bandwidth is the lowest bandwidth of the link along the paths • Bandwidth = 10000000/Bandwidth

  10. Problems with RIP and IGRP • Slow convergence • Not 100% loop free • Don’t support VLSM and discontiguous network • Periodic full routing updates • RIP has hop count limitation

  11. Advantages of EIGRP • Advanced distance vector • 100% loop free • Fast convergence • Easy configuration • Less network design constraints than OSPF • Incremental update • Supports VLSM and discontiguous network • Classless routing • Compatible with existing IGRP network • Protocol independent (support IPX and AppleTalk) • Connects MPLS VPN subscribers to their provides seamlessly

  12. Advantages of EIGRP • Uses multicast instead of broadcast • Utilize link bandwidth and delay • EIGRP Metric = IGRP Metric x 256(32 bit vs. 24 bit) • Unequal cost paths load balancing • More flexible than OSPF • Full support of distribute list • Manual summarization can be done in any interface at any router within network

  13. EIGRP Packets • Hello: Establish neighbor relationships • Update: Send routing updates • Query: Ask neighbors about routing information • Reply: Response to query about routing information • Ack: Acknowledgement of a reliable packet

  14. EIGRP Neighbor Relationship • Two routers become neighbors when they see each other’s hello packet • Hello address = 224.0.0.10 • Hellos sent once every five seconds on the following links: • Broadcast Media: Ethernet, Token Ring, FDDI, etc. • Point-to-point serial links: PPP, HDLC, point-to-point frame relay/ATM subinterfaces • Multipoint circuits with bandwidth greater than T1: ISDN PRI, SMDS, Frame Relay

  15. EIGRP Neighbor Relationship • Hellos sent once every 60 seconds on the following links: • Multipoint circuits with bandwidth less than or equal to T1: ISDN BRI, Frame Relay, SMDS, etc. • Neighbor declared dead when no EIGRP packets are received within hold interval • Not only Hello can reset the hold timer • Hold time by default is three times the hello time

  16. EIGRP Neighbor Relationship • EIGRP will form neighbors even though hello time and hold time don’t match • EIGRP sources hello packets from primary address of the interface • EIGRP will not form neighbor if K-values are mismatched • EIGRP will not form neighbor if AS numbers are mismatched • Passive interface (IGRP vs. EIGRP)

  17. Discovering Routes B A 1 afadjfjorqpoeru 39547439070713 I am Router A, Who Is on the Link? Hello

  18. Discovering Routes B A 1 afadjfjorqpoeru 39547439070713 I am Router A, Who Is on the Link? Hello afadjfjorqpoeru 39547439070713 2 Here Is My Routing Information (Unicast) Update

  19. Discovering Routes B A 1 afadjfjorqpoeru 39547439070713 I am Router A, Who Is on the Link? Hello afadjfjorqpoeru 39547439070713 2 Here Is My Routing Information (Unicast) Update afadjfjorqpoeru 39547439070713 3 Thanks for the Information! Ack

  20. Discovering Routes B A 1 afadjfjorqpoeru 39547439070713 I am Router A, Who Is on the Link? Hello afadjfjorqpoeru 39547439070713 2 Here Is My Routing Information (Unicast) Update afadjfjorqpoeru 39547439070713 4 3 Thanks for the Information! Ack Topology Table

  21. Discovering Routes B A 1 afadjfjorqpoeru 39547439070713 I am Router A, Who Is on the Link? Hello afadjfjorqpoeru 39547439070713 2 Here Is My Routing Information (Unicast) Update afadjfjorqpoeru 39547439070713 4 3 Thanks for the Information! Ack Topology Table 5 afadjfjorqpoeru 39547439070713 Here Is My Route Information (Unicast) Update

  22. Discovering Routes B A 1 afadjfjorqpoeru 39547439070713 I am Router A, Who Is on the Link? Hello afadjfjorqpoeru 39547439070713 2 Here Is My Routing Information (Unicast) Update afadjfjorqpoeru 39547439070713 4 3 Thanks for the Information! Ack Topology Table 5 afadjfjorqpoeru 39547439070713 Here Is My Route Information (Unicast) Update afadjfjorqpoeru 39547439070713 Thanks for the Information! 6 Ack Converged

  23. Agenda • Fundamentals of EIGRP • DUAL • Summarization and Load Balancing • Query Process • Deployment Guidelines with EIGRP • Summary 23 23 23

  24. EIGRP DUAL • Diffusing update algorithm • Finite-State-Machine • Track all routes advertised by neighbors • Select loop-free path using a successor and remember any feasible successors • If successor lost • Use feasible successor • If no feasible successor • Query neighbors and recompute new successor

  25. EIGRP Feasible Distance (FD) • Feasible distance is the minimum distance (metric) along a path to a destination network

  26. Feasible Distance Example Network 7 (20) (10) H (100) G (1) B C A (100) (10) D E F (100) (100) (20) Destination Feasible Distance (FD) Neighbor TopologyTable 100+20+10=130 7 H 100+1+10+10=121 B 7 7 D 100+100+20+10+10=240

  27. EIGRP Reported Distance (RD) • Reported distance 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

  28. Reported Distance Example Network 7 (20) (10) H (100) G (1) (100) B C A (100) (10) D E F (100) (20) TopologyTable Destination Reported Distance (RD) Neighbor 20+10=30 7 H 1+10+10=21 B 7 7 D 100+20+10+10=140

  29. EIGRP Feasibility Condition (FC) • A neighbor meets the feasibility condition (FC) if the reported distance by the neighbor is smaller than the feasible distance (FD) of this router

  30. EIGRP Successor • A successor is a neighbor that has met the feasibility condition and has the least cost path towards the destination • It is the next hop for forwarding packets • Multiple successors are possible (load balancing)

  31. EIGRP Feasible Successor (FS) • A feasible successor is a neighbor whose reported distance (RD) is less than the feasible distance (FD)

  32. Successor Example Network 7 (20) (10) (100) H G (1) (100) B C A (100) Router A’sRouting Table (10) • B is current successor (FD = 121) • H is the feasible successor (30 < 121) D E F (100) (20) FD RD Destination Neighbor TopologyTable 7 121 B 130 30 7 H 21 B 121 7 7 D 140 240

  33. Passive, Active, and Stuckin Active (SIA) • Passive routes are routes that havesuccessor information • Passive route = Good • Active routes are routes that have lost their successors and no feasible successors are available; the router is actively looking for alternative paths • Active route = Bad • Stuck in Active means the neighbor still has not replied to the original query within three minutes • Stuck in active = Ugly

  34. Dual Algorithm • Local computation • When a route is no longer available via the current successor, the router checks its topology table • Router can switch from successor to feasible successor without involving other routers in the computation • Router stays passive • Updates are sent

  35. DUAL: Local Computation (10) #7 H #2 #8 G #1 (20) A #6 B C #3 X (10) (1) (10) (100) #7 121/21 B #7 130/30 H . . . . . . . . . D F E #5 #4 (100) (20)

  36. Dual Algorithm • Diffused Computation • When a route is no longer available via its current successor and no feasible successor is available, queries are sent out to neighbors asking about the lost route • The route is said to be in active state • Neighbors reply to the query if they have information about the lost route; if not, queries are sent out to all of their neighbors • The router sending out the query waits for all of the replies from its neighbors and will make routing decision based on the replies

  37. DUAL: Diffused Computation (10) #7 H X #2 #8 G #1 (20) A #6 B C #3 X (10) (1) (10) (100) #7 121/21 B #7 130/30 H . . . . . . . . . D F E #5 #4 (100) (20)

  38. X DUAL Example (a) C EIGRP Topology (a) Cost (3) (fd) via B Cost (3/1) (Successor) via D Cost (4/2) (fs) via E Cost (4/3) A (1) D EIGRP Topology (a) Cost (2) (fd) via B Cost (2/1) (Successor) via C Cost (5/3) (1) B D (2) (2) (1) E EIGRP Topology (a) Cost (3) (fd) via D Cost (3/2) (Successor) via C Cost (4/3) (1) E C

  39. DUAL Example (a) C EIGRP Topology (a) Cost (3) (fd) via B Cost (3/1) (Successor) via D via E Cost (4/3) A (1) D EIGRP Topology (a) **ACTIVE** Cost (-1) (fd) via E (q) via C Cost (5/3) (q) B D (2) (2) (1) E EIGRP Topology (a) Cost (3) (fd) via D Cost (3/2) (Successor) via C Cost (4/3) Q Q (1) E C

  40. DUAL Example (a) C EIGRP Topology (a) Cost (3) (fd) via B Cost (3/1) (Successor) via D via E A (1) D EIGRP Topology (a) **ACTIVE** Cost (-1) (fd) via E (q) via C Cost (5/3) B D (2) R (2) (1) E EIGRP Topology (a) **ACTIVE** Cost (-1) (fd) via D via C Cost (4/3) (q) (1) E C Q

  41. DUAL Example (a) C EIGRP Topology (a) Cost (3) (fd) via B Cost (3/1) (Successor) via D via E A (1) D EIGRP Topology (a) **ACTIVE** Cost (-1) (fd) via E (q) via C Cost (5/3) B D (2) (2) (1) E EIGRP Topology (a) Cost (4) (fd) via C Cost (4/3) (Successor) via D (1) E C R

  42. DUAL Example (a) C EIGRP Topology (a) Cost (3) (fd) via B Cost (3/1) (Successor) via D via E A (1) D EIGRP Topology (a) Cost (5) (fd) via C Cost (5/3) (Successor) via E Cost (5/4) (Successor) B D R (2) (2) (1) E EIGRP Topology (a) Cost (4) (fd) via C Cost (4/3) (Successor) via D (1) E C

  43. DUAL Example (a) C EIGRP Topology (a) Cost (3) (fd) via B Cost (3/1) (Successor) via D via E A (1) D EIGRP Topology (a) Cost (5) (fd) via C Cost (5/3) (Successor) via E Cost (5/4) (Successor) B D (2) (2) (1) E EIGRP Topology (a) Cost (4) (fd) via C Cost (4/3) (Successor) via D (1) E C

  44. EIGRP Reliable Transport Protocol • EIGRP reliable packets are packets that requires explicit acknowledgement: • Update • Query • Reply • EIGRP unreliable packets are packets that do not require explicit acknowledgement: • Hello • Ack

  45. EIGRP Reliable Transport Protocol • The router keeps a neighbor list and a retransmission list for every neighbor • Each reliable packet (Update, Query, Reply) will be retransmitted when packet is not acked • EIGRP transport has window size of one (stop and wait mechanism) • Every single reliable packet needs to be acknowledged before the next sequenced packet can be sent

  46. EIGRP Reliable Transport Protocol • With reliable multicast traffic, one must wait to transmit the next reliable multicast packets, until all peers have acknowledged the previous multicast • If one or more peers are slow in acknowledging, all other peers suffer from this • Solution: The nonacknowledged multicast packet will be retransmitted as a unicast to the slow neighbor

  47. EIGRP Reliable Transport Protocol • Per neighbor, retransmission limit is 16 • Neighbor relationship is reset when retry limit (limit = 16) for reliable packets is reached

  48. Agenda • Fundamentals of EIGRP • DUAL • SUMMARIZATION AND LOAD BALANCING • Query Process • Deployment Guidelines with EIGRP • Summary

  49. 192.168.2.x 192.168.1.x 192.168.1.0 EIGRP Summarization • Purpose: Smaller routing tables, smaller updates, query boundary • Auto summarization: • On major network boundaries, networks are summarized to the major networks • Auto summarization is turned on by default

  50. EIGRP Summarization • Manual summarization • Configurable on per interface basis in anyrouter within network • When summarization is configured on an interface, the router immediate creates a route pointing to null zero with administrative distance of five • Loop prevention mechanism • When the last specific route of the summary goes away, the summary is deleted • The minimum metric of the specific routes is used as the metric of the summary route

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