1© 2004 Cisco Systems, Inc. All rights reserved.
Session NumberPresentation_ID 111
EIGRP FOR MANAGED SERVICESTECHNOLOGY DEPLOYMENTSANGITA PANDYA
INTERNET TECHNOLOGIES DIVISION
DECEMBER 2004
222© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Agenda
• INTRODUCTION
• Fundamentals of EIGRP
DUAL
Summarization and Load Balancing
Query Process
• Deployment Guidelines with EIGRP
• Summary
222© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
333© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
VPN for Many Managed Services
Service Provider Converged Network
MANAGED IPT
MANAGED IPT
MANAGED Routing
MANAGED Extranet
MANAGED Internet Gateway
MANAGED SecurityMANAGED Security
MANAGED CPE
MANAGED CPE
V i r t u a l P r i v a t e N e t w o r k
CustomerBranch
CustomerBranch
VMVM
VPN B
VMVM
Customer HQCustomer HQ
Service Level Agreement for
MANAGED Services
444© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Managed Routing Revenue Opportunity
Over 50% of Cisco Enterprise Customers Deploy IP Routing with EIGRP
IP/MPLS VPN Backbone
EIGRP AS-1
PE-1PE-1
CE-1CE-1
EIGRP AS-1
PE-2PE-2
PE-3PE-3
CE-2CE-2
555© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Cisco ExclusiveRobust EIGRP Support
BENEFITS:Service Provider: Simplest point of entry into enterprise’s existing architectureEnterprise: Least disruption to current network design
VPN A/Site 1
VPN C/Site 2
VPN A/Site 2
VPN B/Site 2
VPN C/Site 1
CEA1
CEB3
CEA3
CEA2
CE1B1
PE1
PE2
PE3
P1
P2
P3
16.1/16
12.1/1612.1/16
16.2/16
16.2/16RIPv2
Static
OSPF
RIPv2
BGP
OSPF
RIPv2
BGP
12.2/1612.2/16
CEB2
Cisco IOS Supports the Industry’s Most Comprehensive and Robust Routing Protocol Support: RIP, OSPF, BGP, ISIS,
Including EIGRP
666© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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)
666
777© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
888© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
999© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
101010© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
111111© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
121212© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
131313© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
141414© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
151515© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
161616© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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)
171717© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Discovering Routes
I am Router A, Who Is on the Link?
afadjfjorqpoeru39547439070713
Hello11
AA BB
181818© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Discovering Routes
Update
afadjfjorqpoeru39547439070713
Here Is My Routing Information (Unicast)
I am Router A, Who Is on the Link?
afadjfjorqpoeru39547439070713
Hello11
22
AA BB
191919© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Discovering Routes
Thanks for the Information!Ack
afadjfjorqpoeru39547439070713
Update
afadjfjorqpoeru39547439070713
Here Is My Routing Information (Unicast)
I am Router A, Who Is on the Link?
afadjfjorqpoeru39547439070713
Hello
33
22
11
AA BB
202020© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Topology Table
Topology Table
Discovering Routes
Thanks for the Information!Ack
afadjfjorqpoeru39547439070713
Update
afadjfjorqpoeru39547439070713
Here Is My Routing Information (Unicast)
I am Router A, Who Is on the Link?
afadjfjorqpoeru39547439070713
Hello
44 33
22
11
AA BB
212121© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Here Is My Route Information (Unicast)Update
afadjfjorqpoeru39547439070713
Thanks for the Information!Ack
afadjfjorqpoeru39547439070713
Update
afadjfjorqpoeru39547439070713
Here Is My Routing Information (Unicast)
I am Router A, Who Is on the Link?
afadjfjorqpoeru39547439070713
Discovering Routes
Hello
AA BB
Topology Table
Topology Table
44
55
33
11
22
222222© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Converged
Thanks for the Information! Ack
afadjfjorqpoeru39547439070713
Discovering Routes
66
Topology Table
Topology Table
44
Here Is My Route Information (Unicast)Update
afadjfjorqpoeru39547439070713
Thanks for the Information!Ack
afadjfjorqpoeru39547439070713
Update
afadjfjorqpoeru39547439070713
Here Is My Routing Information (Unicast)
I am Router A, Who Is on the Link?
afadjfjorqpoeru39547439070713
Hello
55
33
11
22
AA BB
232323© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Agenda
• Fundamentals of EIGRP
• DUAL
• Summarization and Load Balancing
• Query Process
• Deployment Guidelines with EIGRP
• Summary
232323
242424© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
252525© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Feasible Distance (FD)
• Feasible distance is the minimum distance (metric) along a path to a destination network
262626© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
TopologyTable
DestinationDestination Feasible Distance (FD)Feasible Distance (FD)
77
77
77
HH
BB
DD
100+20+10=130100+20+10=130
100+1+10+10=121100+1+10+10=121
100+100+20+10+10=240100+100+20+10+10=240
Feasible Distance Example
Network 7
FDDI
(10)(20)
(1) GG
CC
FFEE
BB
HH
DD
AA
(100)
(10)(20)(100)
(100)
(100)
NeighborNeighbor
272727© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
282828© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
TopologyTable
Reported Distance Example
FDDI
GG
CC
FFEE
Network 7
(10)(20)
(1)(100)
(10)(20)(100)
(100)
(100) BB
HH
DD
AA
DestinationDestination Reported Distance (RD)Reported Distance (RD)
77
77
77
HH
BB
DD
20+10=3020+10=30
1+10+10=211+10+10=21
100+20+10+10=140100+20+10+10=140
NeighborNeighbor
292929© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
303030© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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)
313131© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Feasible Successor (FS)
• A feasible successor is a neighbor whose reported distance (RD) is less than the feasible distance (FD)
323232© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
12112177 BB
Router A’sRouting Table
Successor Example
• B is current successor (FD = 121)
• H is the feasible successor (30 < 121)
DestinationDestination NeighborNeighbor
77
77
77
HH
BB
DD
TopologyTable
FDFD RDRD
3030130130
121121
240240
2121
140140
FDDI
GG
CC
FFEE
BB
HH
DD
AA
(20)(100)
Network 7
(10)(20)
(1)(100)
(10)
(100)
(100)
333333© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
343434© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
353535© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
DUAL: Local Computation
(1)
#2
#3
#4 #5
B C
FD E
#1
#6
GA
#7
(100)
(100) (20)
(10)
(10)
(10)
H#8
(20)
#7 121/21 B#7 130/30 H
. . .
. . .
. . .
#7 121/21 B#7 130/30 H
. . .
. . .
. . .
FDDIXX
363636© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
373737© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
#7 121/21 B#7 130/30 H
. . .
. . .
. . .
#7 121/21 B#7 130/30 H
. . .
. . .
. . .
(1)
#2
#3
#4 #5
B C
FD E
#1
#6
GA
#7
(100)
(100) (20)
(10)
(10)
(10)
H#8
(20)
FDDIXX
DUAL: Diffused Computation
XX
383838© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
D EIGRP Topology(a) Cost (2) (fd)
via B Cost (2/1) (Successor)via C Cost (5/3)
D EIGRP Topology(a) Cost (2) (fd)
via B Cost (2/1) (Successor)via C Cost (5/3)
E EIGRP Topology (a) Cost (3) (fd)
via D Cost (3/2) (Successor)via C Cost (4/3)
E EIGRP Topology (a) Cost (3) (fd)
via D Cost (3/2) (Successor)via C Cost (4/3)
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via D Cost (4/2) (fs)via E Cost (4/3)
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via D Cost (4/2) (fs)via E Cost (4/3)
(1)
DUAL Example
XX
(1)
(1)
(1)
(2)(2)
A
D
EC
B
(a)
393939© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
(1)
(1)
(1)
(2)(2)
A
D
EC
B
(a)
DUAL Example
D EIGRP Topology(a) **ACTIVE** Cost (-1) (fd)
via E (q)via C Cost (5/3) (q)
D EIGRP Topology(a) **ACTIVE** Cost (-1) (fd)
via E (q)via C Cost (5/3) (q)
E EIGRP Topology (a) Cost (3) (fd)
via D Cost (3/2) (Successor)via C Cost (4/3)
E EIGRP Topology (a) Cost (3) (fd)
via D Cost (3/2) (Successor)via C Cost (4/3)
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via Dvia E Cost (4/3)
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via Dvia E Cost (4/3)
404040© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
DUAL Example
RR
Q
(1)
(1)
(1)
(2)(2)
A
D
EC
B
(a)
D EIGRP Topology(a) **ACTIVE** Cost (-1) (fd)
via E (q)via C Cost (5/3)
D EIGRP Topology(a) **ACTIVE** Cost (-1) (fd)
via E (q)via C Cost (5/3)
E EIGRP Topology (a) **ACTIVE** Cost (-1) (fd)
via Dvia C Cost (4/3) (q)
E EIGRP Topology (a) **ACTIVE** Cost (-1) (fd)
via Dvia C Cost (4/3) (q)
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via Dvia E
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via Dvia E
414141© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
DUAL Example
RR
(1)
(1)
(1)
(2)(2)
A
D
EC
B
(a)
D EIGRP Topology(a) **ACTIVE** Cost (-1) (fd)
via E (q)via C Cost (5/3)
D EIGRP Topology(a) **ACTIVE** Cost (-1) (fd)
via E (q)via C Cost (5/3)
E EIGRP Topology (a) Cost (4) (fd)
via C Cost (4/3) (Successor)via D
E EIGRP Topology (a) Cost (4) (fd)
via C Cost (4/3) (Successor)via D
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via Dvia E
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via Dvia E
424242© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
DUAL Example
RR
(1)
(1)
(1)
(2)(2)
A
D
EC
B
(a)
D EIGRP Topology(a) Cost (5) (fd)
via C Cost (5/3) (Successor) via E Cost (5/4) (Successor)
D EIGRP Topology(a) Cost (5) (fd)
via C Cost (5/3) (Successor) via E Cost (5/4) (Successor)
E EIGRP Topology (a) Cost (4) (fd)
via C Cost (4/3) (Successor)via D
E EIGRP Topology (a) Cost (4) (fd)
via C Cost (4/3) (Successor)via D
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via Dvia E
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via Dvia E
434343© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
DUAL Example
(1)
(1)
(1)
(2)(2)
A
D
EC
B
(a)
D EIGRP Topology(a) Cost (5) (fd)
via C Cost (5/3) (Successor) via E Cost (5/4) (Successor)
D EIGRP Topology(a) Cost (5) (fd)
via C Cost (5/3) (Successor) via E Cost (5/4) (Successor)
E EIGRP Topology (a) Cost (4) (fd)
via C Cost (4/3) (Successor)via D
E EIGRP Topology (a) Cost (4) (fd)
via C Cost (4/3) (Successor)via D
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via Dvia E
C EIGRP Topology(a) Cost (3) (fd)
via B Cost (3/1) (Successor)via Dvia E
464646© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
474747© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
484848© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
494949© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Reliable Transport Protocol
• Per neighbor, retransmission limit is 16
• Neighbor relationship is reset when retry limit (limit = 16) for reliable packets is reached
505050© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Agenda
• Fundamentals of EIGRP
• DUAL
• SUMMARIZATION AND LOAD BALANCING
• Query Process
• Deployment Guidelines with EIGRP
• Summary
515151© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
192.168.1.x
192.168.1.0
192.168.2.x
525252© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
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
535353© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
192.168.9.X
192.168.10.X
192.168.8.0/22
interface s0ip address 192.168.11.1 255.255.255.252ip summary-address EIGRP 1 192.168.8.0 255.255.252.0
S0
AS 1
EIGRP Summarization
• Manual summarization command:ip summary-address EIGRP <as number> <address> <mask>
192.168.8.X
545454© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Load Balancing
• Routes with equal metric to the minimum metric, will be installed in the routing table (Equal Cost Load Balancing)
• There can be up to six entries in the routing table for the same destination (default = 4)
ip maximum-paths <1-6>
555555© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Unequal Cost Load Balancing
• EIGRP offers unequal cost load balancing feature with the command:
Variance <multiplier>
• Variance command will allow the router to include routes with a metric smaller than multiplier times the minimum metric route for that destination, where multiplier is the number specified by the variance command
565656© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
10
20
10
10
20
25
A
B
C
D
E
Variance 2
Variance Example
• Router E will choose router C to get to net X FD=20
• With variance of 2, router E will also choose router B to get to net X
• Router D will not be used to get to net X
Net X
575757© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Agenda
• Fundamentals of EIGRP
• DUAL
• Summarization and Load Balancing
• QUERY PROCESS
• Deployment Guidelines with EIGRP
• Summary
575757
585858© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Have You Seen My Sparky?
EIGRP Query Process
• EIGRP is Advanced Distant Vector—it relies on its neighbor to provide routing information
• If a route is lost and no feasible successor is available, EIGRP needs to converge fast, its only mechanism for fast convergence is to actively query for the lost route to its neighbors
595959© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Query Process
• Queries are sent out when a route is lost and no feasible successor is available
• The lost route is now in active state
• Queries are sent out to all of its neighbors on all interfaces except the interface to the successor
• If the neighbor does not have the lost route information, queries are sent out to their neighbors
606060© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Query Process
• The router will have to get ALL of the replies from the neighbors before the router calculates the successor information
• If any neighbor fails to reply the query in three minutes, this route is stuck in active and the router resets the neighbor that fails to reply
• Solution is to limit query range to be covered later in presentation
616161© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Query Range
• Autonomous System Boundaries
Contrary to popular belief, queries are not bounded by AS boundaries. Queries from AS 1 will be propagated to AS 2
AS 1AS 2
Query for XReply for XQuery for X
A CB
Network XXX
626262© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Query Range
• Summarization point
Auto or manual summarization bound queries
Requires a good address allocation scheme
A CB 130.130.1.0/24
B Summarizes 130.0.0.0/8 to A
130.x.x.x
Reply with Infinity and theQuery Stops Here!
Query for130.130.1.0/24
XX129.x.x.x
Query for130.130.1.0/24
636363© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Bandwidth Utilization
• EIGRP by default will use up to 50% of the link bandwidth for EIGRP packets
• This parameter is manually configurable by using the command:
ip bandwidth-percent EIGRP <AS-number> <nnn>
• Use for greater EIGRP load control
646464© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Bandwidth over WAN Interfaces
• Bandwidth utilization over point-to-point subinterface Frame Relay
Treats bandwidth as T1 by default
Best practice is to manually configure bandwidth as the CIR of the PVC
656565© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Bandwidth over WAN Interfaces
• Bandwidth over multipoint Frame Relay, ATM, SMDS, and ISDN PRI:
EIGRP uses the bandwidth on the main interface divided by the number of neighbors on that interface to get the bandwidth information per neighbor
666666© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Bandwidth over WAN Interfaces
• Each PVC might have different CIR, this might create EIGRP packet pacing problem
Multipoint interfaces:
Convert to point-to-point
Bandwidth configured = (lowest CIR x number of PVC)
ISDN PRI:
Use Dialer Profile (treat as point-to-point link)
676767© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Agenda
• Fundamentals of EIGRP
• DUAL
• Summarization and Load Balancing
• Query Process
• EIGRP FOR CE-PE CONNECTIVITY IN MPLS VPN NETWORKS
• Deployment Guidelines with EIGRP
• Summary
676767
686868© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP: CE-PE Routing Protocol in MPLS VPN
• Support Enhanced Interior Gateway Routing Protocol (EIGRP) routes through a Multiprotocol Label Switching (MPLS) Virtual Private Network (VPN) over a Border Gateway Protocol (BGP) core network by redistributing EIGRP into MPBGP on a provider edge router
• Configuration is only on PE routers and requires no upgrade or configuration changes to customer equipment
• Also support EIGRP extended community attributes
• Things an enterprise customers needs to consider:
• Things a Service Providers need to consider:
696969© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
CE-PE Connectivity
• Things an enterprise customers needs to consider:
• Things a Service Providers need to consider:
• Topology Ex:
707070© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Agenda
• Fundamentals of EIGRP
• DUAL
• Summarization and Load Balancing
• Query Process
• EIGRP for CE-PE connectivity in MPLS VPN Networks
• DEPLOYMENT GUIDELINES WITH EIGRP
• Summary
707070
717171© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Factors That Influence EIGRP Scalability
• Keep in mind that EIGRP is not plug and play for large networks
• Limit EIGRP query range!
• Quantity of routing information exchanged between peers
727272© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
10.1.8.0/24
RTRB
RTRA
RTRC
RTRD
RTRE
Distribution Layer Remote Sites
Limiting Updates/Queries—Example
737373© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Limiting Size/Scope of Updates/Queries
• Evaluate routing requirements
What routes are needed where?
• Once needs are determined
Use summary address
Use new EIGRP Stub feature
(To be discussed later)
Use distribute lists
747474© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
10.1.8.0/24
RTRB
RTRA
RTRC
RTRD
RTRE
Distribution Layer Remote Sites
XXQueriesReplies
Limiting Updates/Queries—Example
757575© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Limiting Updates/Queries—Summary
• Remote routers fully involved in convergence
Most remotes are never intended to be transit
Convergence complicated through lack of information hiding
767676© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
10.1.8.0/24
RTRB
RTRA
RTRC
RTRD
RTRE
Distribution Layer Remote Sites
XXQueriesReplies
IP summary-address EIGRP 1 10.0.0.0 255.0.0.0on all outbound interfaces to remotes
Limiting Updates/Queries—Better
777777© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Limiting Updates/Queries—Summary
• Convergence simplified by adding the summary-address statements
• Remote routers just reply when queried
787878© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Limiting Updates/QueriesNew Feature
• New EIGRP STUB command is now available (12.0.7T and higher)
• [no] EIGRP stub [receive-only] [connected] [static] [summary]
Only specified routes are advertised.
Any neighbor receiving “stub” information from a neighbor will not query those routers for any routes
797979© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Limiting Updates/Queries—Best
• Best practice is to combine Summarization and EIGRP STUB command
808080© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
10.1.8.0/24
RTRB
RTRA
RTRC
RTRD
RTRE
Distribution Layer Remote Sites
XXQueriesReplies
IP summary-address EIGRP 1 10.0.0.0 255.0.0.0 EIGRP stub connectedon all outbound interfaces to remotes on all remote routers C, D, and E
Limiting Updates/Queries—Best
818181© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Hierarchy/Addressing
• Permits maximum information hiding
• Advertise major net or default route to regions or remotes
• Provides adequate redundancy
828282© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Scalability
• EIGRP is a very scalable routing protocol if proper design methods are used:
Good allocation of address space
Each region should have an unique address space so route summarization is possible
Have a tiered network design model (Core, Distribution, Access)
838383© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
EIGRP Scalability
• Use of EIGRP Stub command if possible
• Proper network resources
Sufficient memory on the router
Sufficient bandwidth on WAN interfaces
• Proper configuration of the “bandwidth” statement over WAN interfaces, especially over Frame Relay
• Avoid blind mutual redistribution between two routing protocols or two EIGRP processes
848484© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
DistributionLayer
Access Layer
Summarized Routes
Summarized RoutesSummarized Routes
Summarized Routes
Summarized RoutesPossible stub
Summarized RoutesPossible Stub
Tiered Network Design
OtherRegions
OtherRegions
OtherRegions
OtherRegions
Core
858585© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Core
TokenRing
TokenRing
3.3.4.01.1.1.0
3.3.4.0
1.1.4.0
3.3.3.0
2.2.1.0
1.1.3.0
3.3.1.0
1.1.2.02.2.3.0
2.2.2.0
TokenRing
TokenRing
TokenRing
TokenRing
1.1.1.01.1.2.02.2.3.03.3.4.0
2.2.1.03.3.2.03.3.3.01.1.4.0
3.3.1.02.2.2.01.1.3.0
Nonscalable Network
• Bad addressing schemeSubnets are everywhere throughout entire network
• Queries not bounded
868686© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Core
3.0.0.0
2.0.0.0
TokenRing
TokenRing
1.1.4.01.1.1.0
3.3.4.0
3.3.4.0
3.3.3.0
3.3.1.0
2.2.3.0
2.2.1.0
1.1.2.01.1.3.0
2.2.2.0
1.0.0.0
TokenRing
TokenRing
TokenRing
TokenRing
Scalable Network
• Readdress network Each region has its own block of address
• Queries bounded by using “ip summary-address EIGRP” command
878787© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID
Summary
• Query range
Best way to limit query is through route summarization and new EIGRP Stub command
• EIGRP is not plug and play for large networks
It’s a very scalable protocol with little design requirement
• Optimizing EIGRP network
Limiting query range
Route summarization
Tiered network design
Use of EIGRP Stub command
Sufficient network resources
888888© 2004 Cisco Systems, Inc. All rights reserved.Presentation_ID