2- en_ROUTE_v7_Ch02.pdf
December 4, 2016 | Author: mariana | Category: N/A
Short Description
Download 2- en_ROUTE_v7_Ch02.pdf...
Description
Implementing Cisco IP Routing (ROUTE)
Chapter 2: EIGRP Implementation
Elaborated by: Ing. Ariel Germán For: ITLA Based on: Foundation Learning Guide CCNP ROUTE 300-101 Diane Teare, Bob Vachon, Rick Graziani 2015 ROUTE v6 Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
1
Chapter 2 Topics Establishing EIGRP Neighbor Relationships Building the EIGRP Topology Table
Optimizing EIGRP Behavior Configuring EIGRP for IPv6 Named EIGRP Configuration
Summary Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
2
Establishing EIGRP Neighbor Relationships
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
3
Upon completion of this section, you will be able to do the following: • Describe EIGRP characteristics. • Describe how EIGRP ensures reliable transport. • Describe the steps that EIGRP follows to add routes to the routing table. • Change EIGRP timers. • Describe where EIGRP adjacencies are formed in a Frame Relay network. • Describe where EIGRP adjacencies are formed in a Layer 3 MPLS VPN network. • Describe where EIGRP adjacencies are formed in a Layer 2 MPLS VPN Ethernet network. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
4
EIGRP Features Fast convergence: Using Diffusing Update Algorithm (DUAL). Partial updates: Partial triggered updates only to required routers. Multiple network layer support: Using Protocol Dependent Modules (PDM). Use of multicast and unicast: EIGRP for IPv4 uses 224.0.0.10, and EIGRP for IPv6 uses FF00::A.
VLSM support: Support discontinuous subnetworks. Seamless connectivity across all data link layer protocols and topologies: EIGRP does not require special configuration to work across any Layer 2 protocols. Sophisticated metric: EIGRP represents metric values in a 32-bit format to provide enough granularity. EIGRP supports unequal metric load balancing. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
5
EIGRP Features One of the key technologies used in EIGRP is RTP (Reliable Transport Protocol). RTP is the component of the EIGRP responsible for guaranteed, ordered delivery of EIGRP packets to all neighbors.
It supports intermixed transmission of multicast or unicast packets.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
6
EIGRP Operation Overview Operation of the EIGRP protocol is based on the information stored in three tables: neighbor table, topology table, and the routing table. The main information stored in the neighbor table is a set of neighbors with which EIGRP router has established adjacencies. The topology table contains all destination routes advertised by the neighbor routers. For each neighbor, an advertised metric is recorded. Another important information is the metric that a router uses to reach the same destination.
The route with the best metric to the destination is called the successor and is placed in the routing table and advertised to the other neighbors. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
7
EIGRP Operation Overview The process to establish and discover neighbor routes occurs simultaneously with EIGRP:
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
8
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
9
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
10
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
11
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
12
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
13
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
14
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
15
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
16
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
17
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
18
Configuring and Verifying Basic EIGRP for IPv4 When the passive-interface default command is used under the EIGRP process, the router immediately stops sending and receiving hello packets and routing updates on all interfaces.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
19
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
20
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
21
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
22
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
23
Configuring and Verifying Basic EIGRP for IPv4
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
24
Manipulating EIGRP Timers EIGRP determines default timer values based on link type. If default values are not suitable for a specific network topology, you can manipulate values of hello and hold timers. EIGRP hello and hold timers between neighbors do not need to be identical to successfully establish EIGRP neighbor relationship.
However, asymmetrical timers may lead to flapping EIGRP neighbor relationships and network instability. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
25
Manipulating EIGRP Timers To change the EIGRP timers, you can use the interface configuration commands: • ip hello-interval eigrp as-number hello-time-interval • ip hold-time eigrp as-number hold-time-interval
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
26
EIGRP Neighbor Relationship over Frame Relay Frame Relay supports two different interface types: • Multipoint logical interfaces emulating a multiaccess network • Point-to-point physical interfaces or logical point-to-point subinterfaces
When configuring EIGRP over point-to-multipoint subinterfaces, a single IP subnet is used. • To enable EIGRP to send multicast packets over Frame, you must add the broadcast keyword in the Frame Relay static mapping statement using the frame-relay map ip ip-address dlci broadcast interface configuration command.
Partial-mesh Frame Relay networks must deal with the possibility of the split horizon. When configuring EIGRP over point-to-point subinterfaces, a different IP subnet is used for each subinterface. • Multicast traffic will be transmitted without need for any additional configuration. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
27
Establishing EIGRP over Layer 3 MPLS VPN When you connect branch offices over Layer 3 Multiprotocol Label Switching (MPLS) virtual private network (VPN), you can establish EIGRP routing protocol directly with the service provider. • Provider-edge (PE) routers participate in customer routing, guaranteeing optimum routing between customer sites.
• PE routers carry a separate set of routes for each customer.
The backbone routers in SP network are hidden from the view of the customer, and CE routers are unaware of the Layer 3 MPLS VPN. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
28
Establishing EIGRP over Layer 2 MPLS VPN A point-to-point MPLS L2 VPN solution is where an MPLS backbone provides a Layer 2 Ethernet point-to-point connection between the customer routers. • This solution is not very scalable as the number of your branch offices rises.
In the case of the multipoint MPLS L2 VPN solution, all routers belong to the same shared L2 broadcast domain.
When you establish EIGRP neighbor relationships on the shared segment, every router on the segment will be neighbor with all other routers. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
29
Building the EIGRP Topology Table
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
30
Upon completing this lesson, you will be able to do the following: • Describe how EIGRP neighbors exchange routing information. • Describe how EIGRP chooses the best path through the network. • Describe how EIGRP metric gets calculated.
• Calculate EIGRP metric. • Describe how the feasibility condition prevents loops in EIGRP networks. • Understand EIGRP path selection process.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
31
Building and Examining the EIGRP Topology Table
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
32
Building and Examining the EIGRP Topology Table
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
33
Building and Examining the EIGRP Topology Table
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
34
Building and Examining the EIGRP Topology Table
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
35
Building and Examining the EIGRP Topology Table
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
36
Building and Examining the EIGRP Topology Table
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
37
Choosing the Best Path EIGRP uses DUAL to calculate the best path to a destination network. DUAL calculates this composite metric by adding two values: • The first value is the metric from neighboring router to the destination network. This value is reported to the router and is called the reported distance (RD), also known as Advertised Distance (AD). • The second value is the metric from the local router to the router that reported the first value.
The router will choose the one with the smallest composite metric and consider it the best path to the given destination. The selected value is called feasible distance (FD). Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
38
Choosing the Best Path The route with the smallest metric is called the successor route and the next-hop router is called the successor. Multiple successors may exist if they have the same FD to the destination network. In this case, EIGRP tries to insert all the successor routes into the routing table (up to 4). A feasible successor is a next-hop router with a loop-free path that has a larger cost to the destination than the successor. The router uses a simple rule that requires that the RD of an alternative backup route is always smaller than the FD of the best path. This is called the feasibility condition. Routes that satisfy this condition are considered as backup routes and aren called feasible successor routes. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
39
DUAL Example (taken from ROUTEv6) 10.1.1.0 /24
Router D EIGRP FD
A
(1)
AD Topology
10.1.1.0 /24
2
***** Passive *****
via B
2
1
via C
5
3
Successor
(1)
B
(2)
D
(2)
(1)
(1)
C
Router C
E
Router E
EIGRP FD
AD Topology
10.1.1.0 /24
3
***** Passive *****
via B
3
1
via D
4
2
via E
4
3
EIGRP FD
AD Topology
10.1.1.0 /24
3
***** Passive *****
Successor
via D
3
2
Feasible Successor
via C
4
3
Successor
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
40
DUAL Example (taken from ROUTEv6) 10.1.1.0 /24
Router D EIGRP FD
A
(1)
AD Topology
10.1.1.0 /24
2
***** Passive *****
via B
2
1
via C
5
3
Successor
(1)
B
(2)
D
(2)
(1)
(1)
C
Router C
E
Router E
EIGRP FD
AD Topology
10.1.1.0 /24
3
***** Passive *****
via B
3
1
via D
4
2
via E
4
3
EIGRP FD
AD Topology
10.1.1.0 /24
3
***** Passive *****
Successor
via D
3
2
Feasible Successor
via C
4
3
Successor
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
41
DUAL Example (taken from ROUTEv6) 10.1.1.0 /24
Router D EIGRP FD
A
10.1.1.0 /24
AD Topology
-1
***** ACTIVE ******
via E (1)
via C
B
(2)
Q (2)
(Q) Query 5
3
(Q) Query
D
Q = Query
Q (1)
(1)
C
Router C
E
Router E
EIGRP FD
AD Topology
10.1.1.0 /24
3
***** Passive *****
via B
3
1
via D
4
2
via E
4
3
EIGRP FD
AD Topology
10.1.1.0 /24
3
***** Passive *****
Successor
via D
3
2
Feasible Successor
via C
4
3
Successor
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
42
DUAL Example (taken from ROUTEv6) 10.1.1.0 /24
Router D EIGRP FD
A
10.1.1.0 /24
AD Topology
-1
***** ACTIVE ******
via E (1)
via C
B
(Q) Query 5
3
D
Q = Query (2)
R
(2)
R
(1)
= Reply
(1)
C
Q
Router C EIGRP FD 10.1.1.0 /24
3
via B
3
AD Topology ***** Passive ***** 1
via D via E
E
Successor
Router E EIGRP FD 10.1.1.0 /24
-1
***** ACTIVE ******
via D via C
4
AD Topology
4
3
(Q) Query
3
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
43
DUAL Example (taken from ROUTEv6) 10.1.1.0 /24
Router D EIGRP FD
A
(1)
B
AD Topology
10.1.1.0 /24
5
***** Passive *****
via C
5
3
Successor
via E
5
4
Successor
D
Q = Query (2)
(2)
R
(1)
= Reply
R (1)
C
Router C
Router E
EIGRP FD 10.1.1.0 /24
3
via B
3
via D
E
AD Topology ***** Passive ***** 1
Successor
EIGRP FD 10.1.1.0 /24
4
via C
4
AD Topology ***** Passive ***** 3
Successor
via D
via E Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
44
Choosing the Best Path
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
45
Choosing the Best Path
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
46
Choosing the Best Path
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
47
Choosing the Best Path
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
48
Choosing the Best Path
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
49
Choosing the Best Path
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
50
Choosing the Best Path
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
51
Choosing the Best Path
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
52
Choosing the Best Path
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
53
Choosing the Best Path
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
54
Exchange of Routing Knowledge in EIGRP Before routers exchange their routing information, they must establish the EIGRP neighbor relationship. Session establishment is followed by an immediate exchange of update packets, which advertise the routing information from the EIGRP topology table. Keep in mind that only the best routes are advertised to the neighbors (the successor routes).
In addition to the received routing information, the topology table has two other local sources: • Subnets of directly connected interfaces on which EIGRP has been enabled using the network command. • Subnets learned by redistribution of routes into EIGRP from other routing protocols or routing information sources Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
55
EIGRP Metric EIGRP uses a composite metric to determine the best path to the destination.
The metric’s value derives from a formula that can use the following parameters: • Bandwidth: Least value of the bandwidth for all links between the local router and the destination. • Delay: Cumulative delay obtained as sum of values of all delays for all links between the source and destination. • Reliability: This value represents the worst reliability between source and destination (based on keepalives). • Load: This value represents the worst load on the link between the source and the destination (based on the packet rate and the configured bandwidth of the interface).
MTU It is only used as a tie-breaker, when the router needs to ignore some equal-cost paths to the same destination, because of too many equal-cost paths. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
56
EIGRP Metric By default, EIGRP uses only bandwidth and delay to calculate the metric. The components used for the metric calculation are determined by the metric weights, or K values. Default K values are: K1=1, K2=0, K3=1, K4=0, K5=0. Use the show ip protocols command to verify K values.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
57
EIGRP Metric Calculation To calculate composite metric to the given destination, EIGRP uses the following formula: Metric = [(K1 * Bandwidth + [(K2 * Bandwidth) / (256 – Load)] + K3 * Delay) * K5/(K4 + Reliability)] * 256 If you take into account default K1–K3 values, K1=K3=1, and K2=0, the formula reduces to: Metric = (Bandwidth + Delay) * 256
Note that changing the K values is not recommended.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
58
EIGRP Wide Metrics The EIGRP composite cost metric does not scale correctly for high-bandwidth interfaces or Ethernet channels. The lowest delay that can be configured for an interface is 10 microseconds. This may cause undesirable equal-cost load balancing. To resolve this issue, the EIGRP Wide Metrics feature supports 64-bit metric calculations and Routing Information Base (RIB). The 64-bit metric calculations work only in EIGRP named mode configurations.
EIGRP classic mode uses 32-bit metric calculations. The EIGRP Wide Metric is beyond the scope of this course. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
59
EIGRP Metric Calculation Example
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
60
EIGRP Metric Calculation Example
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
61
EIGRP Path Calculation Example
Chapter 2
What is the error?
S, FS, Non?
© 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
62
Optimizing EIGRP Behavior
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
63
Upon completion of this section, you will be able to do the following: • Understand EIGRP queries • Describe how stub routing can be used to reduce the amount of queries when EIGRP goes active. • Describe the EIGRP stuck-in-active issue • Explain how using summary routes lessen the impact of query scope when EIGRP goes active. • Describe load-balancing options with EIGRP
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
64
EIGRP Queries When a router loses a route and does not have a feasible successor in its topology table, it looks for an alternative path to the destination. This is known as going active on a route. Marked as “A” in the EIGRP Topology table. The router sends query packets to all neighbors on interfaces other than the one that is used to reach the previous successor (split-horizon behavior).
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
65
EIGRP Stub Routers The EIGRP stub routing feature enables you to limit query message scope in the network. Routers configured as stubs do not forward EIGRP learned routes to other neighbors. Nonstub routers do not send query messages to stub routers. This saves CPU cycles and bandwidth and speeds up convergence.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
66
Configuring EIGRP Stub Routing
All routers are already preconfigured with EIGRP. BR1B announces to HQ summary network 192.168.16.0/23, which summarizes prefixes 192.168.16.0/24 and 192.168.17.0/24. BR1B, in contrast, announces its loopback with prefix 192.168.18.0/24 as an external EIGRP route. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
67
Configuring EIGRP Stub Routing
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
68
Configuring EIGRP Stub Routing
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
69
Configuring EIGRP Stub Routing
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
70
EIGRP Stubs Options To configure a router as a stub using EIGRP, use the eigrp stub command in router configuration mode or address family configuration mode.
A router that is configured as a stub shares information about connected and summary routes with all neighboring routers by default. You can combine all stub options except for receive-only to achieve desired combination of advertised routes. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
71
EIGRP Stubs Options
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
72
EIGRP Stubs Options
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
73
EIGRP Stubs Options
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
74
EIGRP Stubs Options
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
75
EIGRP Stubs Options
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
76
EIGRP Stubs Options
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
77
EIGRP Stubs Options
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
78
EIGRP Stubs Options
HQ routing table?
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
79
EIGRP Stubs Options
BR1A routing table?
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
80
Stuck in Active
If the router does not receive a reply to all the outstanding queries within 3 minutes (the default time), the route goes into the stuck-in-active (SIA) state. Once the active timer expires, the neighbor relationship is reset. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
81
Stuck in Active Two new additional EIGRP packets were introduced to overcome the described limitation. When no reply to a query is received, EIGRP sends an SIA query packet when the active timer is halfway through (after 90 seconds). This enables the neighboring router to respond with a SIA reply and confirm to the upstream router that it is still searching for a replacement route.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
82
Reducing Query Scope by Using Summary Routes When a router receives an EIGRP query for a specific network, which is included in a summary route present in the router’s routing table, it immediately sends a reply message without further forwarding the query packet.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
83
Configuring EIGRP Summarization
Implementing EIGRP summarization provides several benefits: • Reduces the size of routing tables on the routers. • Limits the query scope. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
84
Configuring EIGRP Summarization
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
85
Configuring EIGRP Summarization
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
86
Configuring EIGRP Summarization
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
87
Configuring EIGRP Summarization
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
88
Configuring EIGRP Summarization
Null 0 is used to prevent loops. In case of BR1 receives a packet for a network described in a summary route, that is not present in BR1 routing table. • (And BR1 has a default route pointing back to HQ). Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
89
Configuring EIGRP Summarization
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
90
Configuring EIGRP Summarization
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
91
Configuring EIGRP Summarization
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
92
Determining the Summary Route
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
93
Determining the Summary Route
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
94
Determining the Summary Route
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
95
Determining the Summary Route
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
96
Determining the Summary Route
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
97
Obtaining Default Route A router can obtain a default route in several different ways. Before a router installs the default route, it examines default route candidates: • The candidate can be a statically configured default route defined locally with the command ip route 0.0.0.0 0.0.0.0 next-hop | interface.
• The candidate is also a default route announced by the dynamic routing protocol. EIGRP can redistribute statically defined default routes by using the redistribute static. • Any classful network residing in the local routing table can become a default candidate when used with the ip default-network Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
98
Obtaining Default Route
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
99
Obtaining Default Route
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
100
Obtaining Default Route
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
101
Load Balancing with EIGRP EIGRP supports load balancing over equal-metric paths and also over unequal-metric paths.
EIGRP enables load balancing between a maximum of four equal-metric paths by default. You can configure the maximum number of parallel routes using the maximum-paths router configuration command. Up to six equally good routes can be kept in the routing table. Load balancing over unequal-metric links is disabled by default.
Only feasible successor paths can be included in the EIGRP load-balancing Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
102
Configuring EIGRP Load Balancing
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
103
Configuring EIGRP Load Balancing
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
104
Configuring EIGRP Load Balancing
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
105
EIGRP Load Balancing Across Unequal-Metric Paths Additional entries through EIGRP must meet two criteria to be installed in the local routing table: • The route must be loop free. This condition is satisfied when the advertised distance is less than the total distance, or when the route is a feasible successor. • The metric of the route must be lower than the metric of the best route (the successor) multiplied by the variance that is configured on the router.
The default value for the variance command is 1. It can be a value from 1 to 128. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
106
EIGRP Load Balancing Across Unequal-Metric Paths
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
107
EIGRP Load Balancing Across Unequal-Metric Paths
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
108
EIGRP Load Balancing Across Unequal-Metric Paths
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
109
Configuring EIGRP for IPv6
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
110
Upon completing this section, you will be able to do the following: • Describe differences and similarities of EIGRP for IPv4 and IPv6 • Configure basic EIGRP for IPv6 settings • Configure and verify EIGRP for IPv6 summarization • Verify basic EIGRP for IPv6 settings
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
111
Overview of EIGRP for IPv6 EIGRP for IPv6 uses IPv6 prefixes and lengths rather than IPv4 subnets and masks. To establish EIGRP for IPv6 neighbor relationship, it uses IPv6 link-local addresses. EIGRP uses built-in authentication features of the IPv6 protocol rather than protocol specific authentication implemented with IPv4. IPv6 has no concept of the classful network; there is no automatic summarization at the class boundaries. If IPv4 address is not configured on the router, EIGRP for IPv6 requires an EIGRP router ID before it can start running. • In IPv4, if you do not configure the EIGRP router ID, the router will automatically assign it using the highest loopback or the highest active interface IPv4 address.
You configure EIGRP for IPv6 under a specific interface intended to send and receive routing protocol messages.
EIGRP for IPv6 uses assigned dedicated multicast address FF02::A, whereas EIGRP for IPv4 uses dedicated multicast address 224.0.0.10. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
112
Configuring and Verifying EIGRP for IPv6
HQ and BR1 have already been configured for EIGRP for IPv6, but BR2 has not been.
HQ - Ethernet 0/0: FE80:100::1 HQ - Ethernet 0/1: FE80:200::1 BR1 - Ethernet 0/0: FE80:100::2 BR1 - Ethernet 0/0: FE80:200::2
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
113
Configuring and Verifying EIGRP for IPv6
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
114
Configuring and Verifying EIGRP for IPv6
*Remember that link-local IPv6 address are needed. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
115
Configuring and Verifying EIGRP for IPv6
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
116
Configuring and Verifying EIGRP for IPv6
Link-local? Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
117
Configuring and Verifying EIGRP for IPv6
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
118
Configuring and Verifying EIGRP for IPv6
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
119
Determining the IPv6 Summary Route
????
¿?¿?¿? Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
120
Determining the IPv6 Summary Route
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
121
Named EIGRP Configuration
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
122
Upon completion of this section, you will be able to do the following: • Describe how EIGRP named configuration is different from the classic EIGRP configuration. • Explain what is configured under different address family configuration modes. • Compare examples of classic and named EIGRP configuration.
• Configuring and verifying EIGRP for IPv6.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
123
Introduction to Named EIGRP Configuration Configuring EIGRP for both IPv4 and IPv6 on the same router can become a complex task because configuration takes place using different router configuration modes: router eigrp and ipv6 router eigrp. A newer configuration option is available that enables the configuration of EIGRP for both IPv4 and IPv6 under a single configuration mode. EIGRP named configuration is available in Cisco IOS Release 15.0(1)M and later releases.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
124
Configuring Named EIGRP
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
125
Configuring Named EIGRP
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
126
Configuring Named EIGRP
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
127
Address Families Classic or basic EIGRP uses the global configuration command router eigrp as-number for IPv4 and ipv6 router eigrp as-number for IPv6. EIGRP named configuration mode uses the global configuration command router eigrp virtual-instance-name. Both EIGRP for IPv4 and IPv6 can be configured within this same mode. Named EIGRP configuration is organized in a hierarchical manner, where configuration for specific route type is grouped under the same address family. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
128
EIGRP for IPv4 Address Family
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
129
EIGRP for IPv4 Address Family
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
130
EIGRP for IPv4 Address Family
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
131
EIGRP for IPv6 Address Family
All IPv6-enabled interfaces are automatically included in the EIGRP for IPv6 process. You can configure or remove individual interfaces from the EIGRP for IPv6 process by using the af-interface interface-type interface number command in address family configuration mode. • af-interface {default | interface-type interface number} Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
132
EIGRP for IPv6 Address Family
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
133
EIGRP for IPv6 Address Family
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
134
EIGRP for IPv6 Address Family
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
135
EIGRP for IPv6 Address Family
Chapter 2
Within the topology base is where general EIGRP settings are configured that relate to the topology table. For example, you can define variance and maximumpaths parameters © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
136
EIGRP for IPv6 Address Family Within the EIGRP IPv4 address family, the address family interface configuration mode is entered, and BR2’s loopback prefixes are summarized.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
137
EIGRP for IPv6 Address Family
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
138
EIGRP for IPv6 Address Family
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
139
Named EIGRP Configuration Modes It uses three different configuration modes to structure different configuration options: • Address family configuration mode: • router ID • Network statements, which are required for IPv4 EIGRP configuration. Configure router as an EIGRP stub. (t gives access to the other two modes)
• Address family interface configuration mode: • Summarization with the summary-address command • Marking interfaces as passive using passive-interface command. • Modify hello and dead timer in it.
• Address family topology configuration mode: • Load-balancing parameters such as variance and maximum paths. • Redistribute static routes using the redistribute command. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
140
Classic Versus Named EIGRP Configuration
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
141
Classic Versus Named EIGRP Configuration
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
142
Summary
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
143
Summary EIGRP is an advanced distance vector protocol. EIGRP uses RTP for reliable, guaranteed delivery of packets. Hello and hold timers can be adapted to influence network convergence. EIGRP adapts well to various technologies such as Frame Relay, Layer 3 MPLS VPN, and Layer 2 MPLS VPN.
EIGRP uses hello, update, query, reply, and acknowledgment packets. EIGRP uses a composite metric that is by default based on bandwidth and delay. Reported distance is the metric value reported by the neighboring router. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
144
Summary Feasible distance is the lowest distance to a destination from the perspective of the local router. Alternative path must satisfy the feasibility condition to become a feasible successor. The reported distance of an alternate path must be less than the feasible distance. When a route is lost and no feasible successor is available, queries are sent to all neighboring routers on all interfaces. EIGRP stub configuration improves network stability and reduces resource utilization. Summarization decreases the size of the IP routing table and optimizes exchange of routing information.
EIGRP performs equal-cost load balancing. To support unequal-cost load balancing, a variance parameter must be configured. Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
145
Summary EIGRP for IPv6 uses IPv6 link-local addresses to form neighbor relationships.
EIGRP for IPv6 supports only manual prefix summarization. To configure EIGRP for IPv6, you must define the routing process and configure interfaces participating in EIGRP routing.
EIGRP for IPv6 verification commands have similar syntax to EIGRP for IPv4 commands. Classic EIGRP configuration is divided over different configuration modes. Named EIGRP configuration gathers EIGRP configuration in one place. Named EIGRP configuration unifies configuration commands for different address families. Named EIGRP configuration is hierarchically organized using three address family configuration modes. The same verification commands for classic EIGRP are used to verify named EIGRP configuration.
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
146
Chapter 2 © 2007 – 2012, Cisco Systems, Inc. All rights reserved.
Cisco Public
147
View more...
Comments
