Configuring Basic EIGRP For IPv6 Cisco

Configuring Basic EIGRP For IPv6 Cisco

This section explain how to Configuring Basic EIGRP For IPv6 and compares the characteristics and operation of EIGRP for IPv4. It is also presented as an example to configure EIGRP for IPv6 in a small routed network.
Similar to its counterpart for IPv4, EIGRP for IPv6 exchanges routing information to complete the IPv6 routing table with remote prefixes. EIGRP for IPv6 has the same functionality as EIGRP for IPv4, but uses IPv6 as the network layer protocol, communicates with peers EIGRP for IPv6 and announces IPv6 routes. EIGRP for IPv6 also uses DUAL as a computation engine to ensure main and backup routes without loops throughout the entire routing domain. As with all IPv6 routing protocols, EIGRP for IPv6 has separate processes from those of its counterpart for IPv4. The processes and operations are basically the same as in the IPv4 routing protocol; however, they run independently.
EIGRP for IPv4 and EIGRP for IPv6 have EIGRP neighbor tables, EIGRP topology tables and separate IP routing tables. EIGRP for IPv6 is a separate protocol dependent module (PDM). The EIGRP configuration and verification commands for IPv6 are very similar to commands used to configure EIGRP for IPv4. These commands are described later in this section.

Comparison Between EIGRO For IPv4 & IPv6

The following is a comparison of the main features of EIGRP for IPv4 and EIGRP for IPv6:

• Routes announced : EIGRP for IPv4 announces IPv4 networks, while EIGRP for IPv6 announces IPv6 prefixes.
• Distance vector : EIGRP for IPv4 and IPv6 are advanced distance vector routing protocols. Both protocols use the same administrative distances.
• Convergence technology : EIGRP for both IPv4 and IPv6 use the DUAL algorithm. Both protocols use the same DUAL techniques and processes, including successor, FS, FD and RD.
• Metric : EIGRP for both IPv4 and IPv6 use bandwidth, delay, reliability and load for its composite metric.
• Transport protocol: the reliable transport protocol (RTP) is responsible for the guaranteed delivery of EIGRP packets to all neighbors for both protocols, EIGRP for IPv4 and IPv6.
• Update messages : EIGRP for both IPv4 and IPv6 sends incremental updates when the status of a destination changes. The terms "partial" and "limited" are used to refer to the updates of both protocols.
• Neighbor discovery mechanism : EIGRP for IPv4 and EIGRP for IPv6 both use a simple hello mechanism to discover neighboring routers and form adjacencies.
• Source and destination addresses: EIGRP for IPv4 sends messages to the multicast address 224.0.0.10. EIGRP for IPv6 sends its messages to the multicast address FF02 :: A.
• Authentication : EIGRP for IPv4 can use unencrypted text authentication or message 5 (MD5) synthesis authentication. EIGRP for IPv6 uses MD5.
• Router ID : EIGRP for IPv4 and EIGRP for IPv6 use a 32-bit number for the EIGRP router ID.

IPV6 Link-Local Addresses

Routers that execute a dynamic routing protocol, such as EIGRP, exchange messages between neighbors on the same subnet or link.
Routers only need to send and receive routing protocol messages with their directly connected neighbors. These messages are always sent from the source IP address of the router that is forwarding.

IPv6 link-local addresses are ideal for this purpose. A link-local IPv6 address allows a device to communicate with other devices with IPv6 enabled on the same link and only on that link (subnet).
Packets with a link-local source or destination address cannot be routed beyond the link on which the packet originated.
EIGRP messages for IPv6 are sent by the following:

• Source IPv6 address : this is the link-local IPv6 address of the output interface.
• Destination IPv6 address : When a packet must be sent to a multicast address, it is sent to the IPv6 multicast address FF02 :: A, the scope of all EIGRP routers with link-local. If the packet can be sent as a unicast address, it is sent to the link-local address of the neighboring router.

Configuration Example of EIGRP for IPv6

In Image, the network topology that is used to configure EIGRP for IPv6 is shown. If dual-stack is running on the network and IPv4 and IPv6 are used on all devices, EIGRP can be configured for both IPv4 and IPv6 on all routers. However, this section focuses only on EIGRP for IPv6 .

Only global unicast IPv6 addresses were configured on each router.
The interface startup configuration on each router is shown below.

R1 # show running-config
interface GigabitEthernet0 / 0
 ipv6 address 2001: DB8: CAFE: 1 :: 1/64
!
Serial interface0 / 0/0
 ipv6 address 2001: DB8: CAFE: A001 :: 1/64
 clock rate 64000
!
Serial interface0 / 0/1
 ipv6 address 2001: DB8: CAFE: A003 :: 1/64

R2 # show running-config
!
interface GigabitEthernet0 / 0
 ipv6 address 2001: DB8: CAFE: 2 :: 1/64
!
Serial interface0 / 0/0
 ipv6 address 2001: DB8: CAFE: A001 :: 2/64
!
Serial interface0 / 0/1
 ipv6 address 2001: DB8: CAFE: A002 :: 1/64
 clock rate 64000
!
Serial interface
 ipv6 address 2001: DB8: FEED: 1 :: 1/64

R3 # show running-config
!
interface GigabitEthernet0 / 0
 ipv6 address 2001: DB8: CAFE: 3 :: 1/64
!
Serial interface0 / 0/0
 ipv6 address 2001: DB8: CAFE: A003 :: 2/64
 clock rate 64000
! 
Serial interface0 / 0/1
 ipv6 address 2001: DB8: CAFE: A002 :: 2/64

Observe the interface bandwidth values ​​of the EIGRP configuration for previous IPv4 . Because EIGRP uses the same metrics for IPv4 and IPv6, modifying the bandwidth parameters influences both routing protocols.

EIGRP IPV6 LINK-LOCAL ADDRESS CONFIGURATION

Link-local addresses are created automatically when a global unicast IPv6 address is assigned to the interface. Global unicast addresses are not required on an interface, but link-local IPv6 addresses are required.
Unless configured manually, Cisco routers create the link-local address using the FE80 :: / 10 prefix and the EUI-64 process.
EUI-64 involves using the 48-bit Ethernet MAC address, inserting FFFE in the middle and inverting the seventh bit. For serial interfaces, Cisco uses the MAC address of an Ethernet interface. A router with several serial interfaces can assign the same link-local address to each IPv6 interface, because link-local addresses only need to be local on the link.
Link-local addresses created with the EUI-64 format or, in some cases, with random interface IDs, make it difficult to recognize and remember those addresses. Because IPv6 routing protocols use link-local IPv6 addresses for unicast addressing and next hop address information in the routing table, it is usually sought to be an easy address to recognize. Configuring the link-local address manually allows you to create a recognizable address and easier to remember.
Link-local addresses can be configured manually using the same interface configuration mode command that is used to create global unicast IPv6 addresses, but with different parameters:
Router (config-if) # ipv6 address link-local-address link-local
A link-local address has a prefix within the range FE80 to FEBF. When an address begins with this hextet (16-bit segment), the link-local keyword must be written after the address.

EIGRP CONFIGURATION EXAMPLE

The following shows the configuration of a link-local address using the ipv6 address command of the interface configuration mode.
R1 (config) # interface s 0/0/0 
R1 (config-if) # ipv6 address fe80 :: 1?
 link-local Use link-local address

R1 (config-if) # ipv6 address fe80 :: 1 link-local 
R1 (config-if) # exit 
R1 (config) # interface s 0/0/1 
R1 (config-if) # ipv6 address fe80 :: 1 link -local 
R1 (config-if) # exit 
R1 (config) # interface g 0/0 
R1 (config-if) # ipv6 address fe80 :: 1 link-local 
R1 (config-if) #
The FE80 :: 1 link-local address is used so that it is easily recognized that it belongs to router R1. The same link-local IPv6 address is configured on all R1 interfaces. You can configure FE80 :: 1 on each link, because it only has to be unique on that link.
Similar to R1, router R2 is configured with FE80 :: 2 as the link-local IPv6 address on all its interfaces.
R2 (config) # interface s 0/0/0
R2 (config-if) # ipv6 address fe80 :: 2 link-local
R2 (config-if) # exit
R2 (config) # interface s 0/0/1
R2 (config-if) # ipv6 address fe80 :: 2 link-local
R2 (config-if) # exit
R2 (config) # interface s 0/1/0
R2 (config-if) # ipv6 address fe80 :: 2 link-local
R2 (config-if) # exit
R2 (config) # interface g 0/0
R2 (config-if) # ipv6 address fe80 :: 2 link-local
R2 (config-if) #
As shown in Image, the show ipv6 interface brief command is used to verify IPv6 link-local and global unicast addresses on all interfaces.

 CONFIGURATION OF THE EIGRP ROUTING PROCESS FOR IPV6

The ipv6 unicast-routin g command of the global configuration mode enables IPv6 routing on the router. This command is necessary before you can configure any IPv6 routing protocol. It is not required to configure IPv6 addresses on the interfaces, but it is necessary to enable the router as an IPv6 router.

EIGRP FOR IPV6

The following global configuration mode command is used to enter router configuration mode for EIGRP for IPv6:
Router (config) # ipv6 router eigrp  autonomous-system
Similar to what happens in EIGRP for IPv4, the autonomous-system value must be the same on all routers in the routing domain. According to the following scheme, the EIGRP routing process for IPv6 could not be configured until IPv6 routing was enabled with the ipv6 unicast-routing global configuration mode command.
R1 (config) # ipv6 router eigrp 2 
% IPv6 routing not enabled
R1 (config) # ipv6 unicast-routing 
R1 (config) # ipv6 router eigrp 2 
R1 (config-rtr) #

EIGRP ROUTER ID

As shown below, the eigrp router-id command is used to configure the router ID.
R1 (config) # ipv6 router eigrp 2 
R1 (config-rtr) # eigrp router-id 1.0.0.0 
R1 (config-rtr) #
EIGRP for IPv6 uses a 32-bit value for the router ID. To obtain that value, EIGRP for IPv6 uses the same process as EIGRP for IPv4. The eigrp router-id command takes precedence over any loopback address or IPv4 physical interface address. If an EIGRP router for IPv6 does not have any active interface with an IPv4 address, the eigrp router-id command is required.
The router ID must be a unique 32-bit number in the EIGRP routing domain for IP; otherwise, routing inconsistencies may occur.
By default, the EIGRP process for IPv6 is in the disabled state. The no shutdown command is required to activate the EIGRP process for IPv6, as shown below:
R1 (config) # ipv6 router eigrp 2 
R1 (config-rtr) # eigrp router-id 1.0.0.0 
R1 (config-rtr) # no shutdown
This command is not required for EIGRP for IPv4. Although EIGRP for IPv6 is enabled, you cannot send or receive updates from neighbor adjacencies or routing until EIGRP is activated on the appropriate interfaces.
The no shutdown command and a router ID are required for the router to establish neighbor adjacencies.
The following shows the EIGRP configuration for IPv6 complete for router R2.
R2 (config) # ipv6 unicast-routing 
R2 (config) # ipv6 router eigrp 2 
R2 (config-rtr) # eigrp router-id 2.0.0.0 
R2 (config-rtr) # no shutdown

IPV6 EIGRP INTERFACE COMMAND

EIGRP for IPv6 uses a different method to enable an interface for EIGRP. Instead of using the router's network configuration mode command to specify matching interface addresses, EIGRP for IPv6 is configured directly on the interface.
Use the following interface configuration mode command to enable EIGRP for IPv6 on an interface:
Router (config-if) # ipv6 eigrp  autonomous-system
Similar to the network command that is used in EIGRP for IPv4, the ipv6 eigrp interface command performs the following:

• Enable the interface to form adjacencies and send or receive EIGRP updates for IPv6.
• It includes the interface prefix (network) in the EIGRP routing updates for IPv6.

In above Image, the configuration to enable EIGRP for IPv6 on the interfaces of routers R1 and R2 is shown. Look at the message below the serial interface 0/0/0 on R2:
% DUAL-5-NBRCHANGE: EIGRP-IPv6 2: Neighbor FE80 :: 1 
(Serial0 / 0/0) is up: new adjacency
This message indicates that R2 formed an EIGRP-IPv6 adjacency with the neighbor at the link-local address FE80 :: 1. Because static link-local addresses were configured on all three routers, it is easy to determine that this adjacency is with router R1 (FE80 :: 1).

PASSIVE INTERFACE WITH EIGRP FOR IPV6

The same passive-interface command that is used for IPv4 is used to configure an interface as passive in EIGRP for IPv6. As shown below, the show ipv6 protocols command is used to verify the configuration.