IGRP and EIGRP

613 views

Published on

Igrp and eirgp

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
613
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
30
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

IGRP and EIGRP

  1. 1. Institute of Computer Technology - Vienna University of Technology Institute of Computer Technology - Vienna University of Technology L43 - IRGP and EIGRP L43 - IRGP and EIGRP IGRP Background IGRP stands for Interior Gateway Routing Protocol designed and deployed successfully in 1986 by Cisco Systems proprietary protocol IGRP and EIGRP Reason for IGRP? At this time there was no alternative for RIP available Cisco Routing Protocols RIP disadvantages: Metric limitation max. 15 hops (16 hops = network unreachable) Hop count doesnt reflect the capacity of the transmission medias takes the least hop path instead of the fastest or „best path“ => didnt allow flexible routing in complex environments much routing overhead (full routing table every 30seconds)© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 1 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 3 Agenda IGRP at a glance IGRP Distance vector protocol (can only be used within EIGRP an Autonomous System) Composite metric Bandwidth Delay Reliability Loading Implementation of loop avoidance mechanisms Support of multiple unequal-metric paths Faster convergence than RIP© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 2 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 4 © 2005, D.I. Manfred Lindner © 2005, D.I. Manfred Lindner Page 43 - 1 Page 43 - 2
  2. 2. Institute of Computer Technology - Vienna University of Technology Institute of Computer Technology - Vienna University of Technology L43 - IRGP and EIGRP L43 - IRGP and EIGRP IGRP / EIGRP Metric calculation IGRP / EIGRP Metric calculation Bandwidth Delay unit: bits/sec unit: 10 microseconds it is the sum of the transmission delays along the path default values for LANs and is stored in a 32-bit field, in increments of 39.1 corresponding to real bandwidth nanoseconds default values for serial lines all 1´s indicates an unreachable destination corresponding to bandwidth of 1.544Mbps (T1 line) default values for LANs configuration of the real bandwidth on serial lines is a must!!! corresponding to real delay cisco interface command: bandwidth <number in kbit/s> default values for serial lines minimum bandwidth along a path is taken corresponding to delay of 1.544Mbps (T1 line) BWIGRP is expressed by (1/bandwidth)*1017 configuration of the real delay on serial lines is an option BWEIGRP is expressed by (1/bandwidth)*1017*256 cisco interface command: delay <number in tens of usec> DelayIGRP is expressed by (delay/10) The range is from a 1200bps line to 10 terabits per DelayEIGRP is expressed by (delay/10)*256 second© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 5 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 7 IGRP / EIGRP Metric calculation IGRP / EIGRP Metric calculation Bandwidth Delay metric values for bandwidth as part of composite metric: metric values for delay as part of composite metric: assumption: bandwidth for serial links is configured properly assumption: delay for serial links is default value for T1 otherwise all serial links will have metric of T1 Delay DelayEIGRP DelayIGRP Bandwidth BWEIGRP BWIGRP Satellite (2 sec) 51.200.000 200.000 Satellite (500 Mbit/s) 5.120 20 100 Mbit Ethernet (0,1 ms) 25.60 10 Ethernet (100 Mbit/s) 256.000 100 10 Mbit Ethernet (1 ms) 25.600 100 Ethernet (10 Mbit/s) 256.000 1.000 Token Ring 4 ( 2,5ms) 64.000 250 Token Ring (4 Mbit/s) 640.000 2.500 Token Ring 16 ( 0,6ms) 16.000 62,5 Token Ring (16 Mbit/s) 160.000 625 FDDI 100 ( 0,1ms) 2.560 10 FDDI (100 Mbit/s) 256.000 100 serial links: 1.544 Mbps 1.657.856 6.476 1.544 Mbps (20 ms) 512.000 2.000 128 kbps 20.000.000 78.125 128 kbps (20 ms) 512.000 2.000 64 kbps 40.000.000 156.250 64 kbps (20 ms) 512.000 2.000 56 kbps 45.714.176 178.571 56 kbps (20 ms) 512.000 2.000 10 kbps 256.000.000 1.000.000 10 kbps (20 ms) 512.000 2.000 1 kbps 2.560.000.000 10.000.000 1 kbps (20 ms) 512.000 2.000© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 6 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 8 © 2005, D.I. Manfred Lindner © 2005, D.I. Manfred Lindner Page 43 - 3 Page 43 - 4
  3. 3. Institute of Computer Technology - Vienna University of Technology Institute of Computer Technology - Vienna University of Technology L43 - IRGP and EIGRP L43 - IRGP and EIGRP IGRP Metric calculation IGRP Metric calculation Reliability Formula for metric calculation arbitrary number defaults: k1=1, k2=0, k3=1, k4=0, k5=0 255 means 100% K1 til K5 are arbitrary numbers which can be configured 1 means 0% worst reliability between source and destination k 2 ∗ min BWIGRP metric1 = k1 ∗ min BWIGRP + + k 3 ∗ sumDelay IGRP dynamically measured 256 - load keepalives are sent off the interface every 10 seconds, frame has CRC If k5 doesn´t equal 0, an additional operation is done doesn´ k5 samples are calculated over 5 minutes compositem etric = metric1 ∗ time interval needs reconfiguration, when Reliability is reliabilit y + k 4 used For default values of k parameters: compositem etric = k1 ∗ min BWIGRP + k 3 ∗ sumDelay IGRP© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 9 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 11 IGRP Metric calculation IGRP Metric example 1 Loading arbitrary number Prefered Path!!! Load is given as a fraction of 255. A load of 255 indicates a Metric=BW+delay=78125+2000=80125 Metric=BW+delay=78125+2000=80125 completely saturated link dynamically measured 128kbps calculated over 5 minutes 128kbps 64kbps time interval needs reconfiguration, when Loading is used Metric=min.BW along the path+sum of delays =156250+2000+2000=160250 Metric=min.BW =156250+2000+2000=160250© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 10 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 12 © 2005, D.I. Manfred Lindner © 2005, D.I. Manfred Lindner Page 43 - 5 Page 43 - 6
  4. 4. Institute of Computer Technology - Vienna University of Technology Institute of Computer Technology - Vienna University of Technology L43 - IRGP and EIGRP L43 - IRGP and EIGRP IGRP Metric example 2 IGRP multiple paths Configured variance=2 Metric=BW+delay=78125+2000=80125 Metric=BW+delay=78125+2000=80125 Metric=BW+delay=78125+2000=80125 Metric=BW+delay=78125+2000=80125 IP IP IP IP IP 128kbps IP 128kbps IP 1,544Mbps 1,544Mbps IP IP IP 128kbps 64kbps Pr !!! efe th re Pa dP e d ath er ef !!! Pr Metric=min.BW along the path+sum of delays =6476+2000+2000=10476 Metric=min.BW =6476+2000+2000=10476 Metric=min.BW along the path+sum of delays =156250+2000+2000=160250 Metric=min.BW =156250+2000+2000=160250© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 13 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 15 IGRP multiple paths IGRP Metric Support of up to 6 parallel paths (default:4) to the Routing updates also include a count of hops and a destination for load balancing computation of the path MTU default: same metric for parallel paths is necessary => max. network diameter 255 hops (IP TTL-field) default: 100 hops Support of unequal-metric load balancing Prerequisite: configuration of a variance factor The alternative path metric must be within the specified variance of the best local metric© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 14 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 16 © 2005, D.I. Manfred Lindner © 2005, D.I. Manfred Lindner Page 43 - 7 Page 43 - 8
  5. 5. Institute of Computer Technology - Vienna University of Technology Institute of Computer Technology - Vienna University of Technology L43 - IRGP and EIGRP L43 - IRGP and EIGRP IGRP & default routes IGRP Loop avoidance & timers RIP and OSPF are using 0.0.0.0 as their default Routing update timer: 90 seconds route (=>metric is not related to a distance) IGRP allows to mark real networks as „candidates Hold-down timer: (3*90sec)+10sec=280sec for being default“ e.g. if multiple exit points to the Internet exist, then this Invalid timer: 3*90sec=270sec implementation allows to choose the optimal „border (starts in the absence of routing information about a router“ specific route) candidate for being default 194.96.4.4/30 Flush timer: 7*90sec=630sec IGRP Internet How much time should pass before a route should be 194.96.4.8/30 flushed from the routing table candidate for being default© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 17 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 19 IGRP Loop avoidance & timers IGRP Protocol stack Periodical Routing updates OSI stack destination address: 255.255.255.255 Topology changes are reported with triggered updates Hold-downs Split horizon IGRP 9 IP protocol number 9 (decimal) Route Poisoning Updates IP are intended to defeat larger routing loops Data link layer are sent if a route metric has increased by a factor of 1.1 or greater Physical layer© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 18 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 20 © 2005, D.I. Manfred Lindner © 2005, D.I. Manfred Lindner Page 43 - 9 Page 43 - 10
  6. 6. Institute of Computer Technology - Vienna University of Technology Institute of Computer Technology - Vienna University of Technology L43 - IRGP and EIGRP L43 - IRGP and EIGRP Agenda EIGRP at a glance IGRP Advanced distance vector protocol (can only be EIGRP used within an AS) uses exactly the same metric as IGRP Loop avoidance by DUAL DUAL: Diffusing Update Algorithm evolved by Mr. J.J. Garcia-Luna-Aceves Event triggered updates (Multicasts) Fast convergence© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 21 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 23 EIGRP Background EIGRP at a glance EIGRP stands for Enhanced Interior Gateway Routing Support of multiple unequal-metric paths Protocol Classless routing protocol (supports route proprietary protocol tries to combine the advantages of the distance vector and the link summarization) state protocol world without their specific problems Update contains network plus prefix Distance vector advantages: It supports IP, IPX and Appletalk less CPU power and memory usage, simple configuration disadvantages: slow convergence, lot of routing overhead, possibility of loops Link state advantages: fast convergence, no loops, better metric (cost factor) disadvantages: high CPU power and memory usage (SPF algorithm, LS database), not so easy to configure (area concept)© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 22 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 24 © 2005, D.I. Manfred Lindner © 2005, D.I. Manfred Lindner Page 43 - 11 Page 43 - 12
  7. 7. Institute of Computer Technology - Vienna University of Technology Institute of Computer Technology - Vienna University of Technology L43 - IRGP and EIGRP L43 - IRGP and EIGRP EIGRP Concepts EIGRP Concepts R2 R8 Hello Hello Hello 1st : Every EIGRP router has to discover its Hello N e neighbors t w Hello R3 R5 R6 o it´s done with a Hello protocol Hello Hello Hello Hello r R1 Hello k a Router doesn´t expect an acknowledge for its Hello Hello Hello X network type dependent Token Point-to-point network R4 R7 Ring Hello Hello Hello Multiaccess with broadcast/multicast support (BMA) FDDI Hello NBMAs nonbroadcast multiaccess network 2nd: based on this Hellos it builds a neighbor table Neighbor table R1 Neighbor table R2 Neighbor table R3 Neighbor table R4 When a newly discovered neighbor is learned, the R2 R1 R1 R1 address and interface of the neighbor is recorded. R3 R3 R2 R2 The HoldTime is the amount of time a router treats a R4 R4 R4 R3 neighbor as reachable and operational: 3* Hello interval R8 R5 R7© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 25 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 27 EIGRP Concepts EIGRP Concepts Point-to-Point: Neighbor relationship is formed Point- to- Point: with the router on the other end 3rd:After the neighbor discovery a Topology table is Hello time interval: 5 sec built Neighbor routers exchanging their complete routing tables and store these informations in a Topology table Broadcast multiaccess: Neighbor relationships multiaccess: information exchange through Update packets are formed dynamically using multicast hellos Hello time interval: 5 sec Update packets Multicast address: 224.0.0.10 contain a sequence number field in the header and must be acknowledged by the receiver (reliable transmission) are sent in the following instances: when a neighbor first comes up (packet´s dest. addr is an unicast) when a network has failed (packet´s dest. addr. is 224.0.0.10) F/R Nonbroadcast multiaccess: Neighbor relationships multiaccess: X.25 when there is a metric change for a certain destination (packet´s are formed by manual configuration ATM dest. addr. is 224.0.0.10) Hello time interval: 60sec Dest. Address: Unicast address of the neighbor© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 26 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 28 © 2005, D.I. Manfred Lindner © 2005, D.I. Manfred Lindner Page 43 - 13 Page 43 - 14
  8. 8. Institute of Computer Technology - Vienna University of Technology Institute of Computer Technology - Vienna University of Technology L43 - IRGP and EIGRP L43 - IRGP and EIGRP EIGRP Concepts EIGRP Concepts Update packets Topology Table In contrast to OSPF every EIGRP router is modifying any Stores routing information that neighbors exchange after received update packet. It adds its own local distance to the first Hello exchange (=> smaller compared to an the information and sends the packet with an own OSPF topology table). DUAL acts on the Topology table sequence number to its neighbors. to determine Successors and FSs. Successor: A neighbor that has been selected as the next hop for a destination, it ends up in the Routing Table Feasible Successor (FS): A neighbor that has satisfied the Feasibility Condition and has a path to the destination (is an alternate route to the current successor) Feasibility Condition (FC): A condition that is met when the lowest of all the neighbors costs plus the link cost to that neighbor is found, and the neighbors advertised cost is less than the current successors cost.© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 29 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 31 EIGRP Concepts EIGRP Topology table and feasible successor R2 R8 R2 NetY ad:20 R8 Net X ad:26 16 N Ack. Update 16 Ack. N e e t 10 NetY t w ad:40 w R3 R5 R6 10 o NetY ad:20 NetY ad:120 Update R3 R5 R6 NetY ad:220 o 10 Net X ad:216 r Update Update R1 100 100 NetY ad:10 Ack. Update r k R1 Update 100 100 k 10 X Ack. Ack. X Token 6 R4 1 R7 Token 6 Ring R4 NetY ad:20 1 R7 Net X ad:17 10 Ring Ack. Update FDDI New network Y FDDI Ack. Update NetY ad:21 Part of R1´s Topology Table R1´ Network Advertised Distance Feasible Distance Neighbor Update propagation Successor X 17 27 R4 ad = advertised distance X 216 226 R3 Feasible Successor X 26 36 R2© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 30 © 2005, D.I. Manfred Lindner ad = advertised distance IGRP-EIGRP, v3.5 32 © 2005, D.I. Manfred Lindner © 2005, D.I. Manfred Lindner Page 43 - 15 Page 43 - 16
  9. 9. Institute of Computer Technology - Vienna University of Technology Institute of Computer Technology - Vienna University of Technology L43 - IRGP and EIGRP L43 - IRGP and EIGRP EIGRP Topology table without EIGRP Active state feasible successor R2 R8 Net X ad:36 26 N Active state e t A routers state for a destination when it has lost its successor to w that destination and has no other feasible successor (FS) R3 R5 R6 10 o 10 Net X ad:216 100 r available. The router is forced to compute a route to the R1 100 k destination. X It´s sending a query packet to all its neighbors. Token 6 Query packet (will be acknowledged from the receiver) R4 1 R7 Net X ad:17 Ring Sent to all neighbors when a router goes into Active for a destination FDDI and is asking for information on that destination. Unless it receives replies back from all its neighbors, the router will remain in Active state and not start the computation for a new successor. Part of R1´s Topology Table R1´ Reply packet (will be acknowledged from the receiver) Sent by every EIGRP neighbor which receives a query. If the Network Advertised Distance Feasible Distance Neighbor neighbor doesnt have the information, it queries its neighborsSuccessor X 17 27 R4 indicating that it is also performing route recomputation X 216 226 R3 no Feasible Successor!!! X 36 46 R2© 2005, D.I. Manfred Lindner ad = advertised distance IGRP-EIGRP, v3.5 33 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 35 EIGRP Active state EIGRP Topology table without feasible successor R2 R8 Reply 9 If the successor disappears from the topology table 26 N e because of a network change and there is a Ack 1 t w Active State feasible successor, DUAL keeps the route in a R1 Reply 17 R3 R5 R6 10 o r Query 1 100 100 passive state. k Ack 1 X Passive state Ack 9 Ack 17 Token 6 A routers state after losing its successor when it has an FS to the R4 1 R7 Ring destination available in its Topology table 10 FDDI If the successor disappears from the topology table because of a network change and there is no Part of R1´s Topology Table R1´ feasible successor, DUAL puts the route into the Network Advertised Distance Feasible Distance Neighbor active state. Successor X 17 27 R4 X 216 226 R3 no Feasible Successor!!! X 36 46 R2© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 34 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 36 © 2005, D.I. Manfred Lindner © 2005, D.I. Manfred Lindner Page 43 - 17 Page 43 - 18
  10. 10. Institute of Computer Technology - Vienna University of Technology Institute of Computer Technology - Vienna University of Technology L43 - IRGP and EIGRP L43 - IRGP and EIGRP EIGRP Topology table EIGRP Compatibility without feasible successor R2 R8 Ack automatic redistribution 26 N e t IGRP EIGRP AS100 w AS100 R3 R5 R6 10 o R1 Ack r Update 100 100 k X manual redistributionPassive State Token 6 R4 1 R7 Ring EIGRP IGRP 10 AS 397 FDDI AS100 Part of R1´s Topology Table R1´ manual redistribution Network Advertised Distance Feasible Distance Neighbor all other IP EIGRP routing AS100 protocols X 216 226 R3 Successor X 36 46 R2© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 37 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 39 EIGRP Compatibility EIGRP Protocol stack Route tagging OSI stack EIGRP has the notion of internal and external routes. Internal routes are ones that have been originated within an EIGRP autonomous system (AS). External routes are ones that have been learned by another routing protocol or reside in the routing table as static routes. EIGRP 88 IP protocol number 88 (decimal) Route redistribution IP in the case of IGRP is done automatically, when EIGRP Data link layer and IGRP are belonging to the same Autonomous System (compatible metric!!!). IGRP derived routes are Physical layer treated as external routes in EIGRP (also OSPF, RIP, EGP, BGP...)© 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 38 © 2005, D.I. Manfred Lindner IGRP-EIGRP, v3.5 40 © 2005, D.I. Manfred Lindner © 2005, D.I. Manfred Lindner Page 43 - 19 Page 43 - 20

×