Adjacencies

Adjacencies

EIGRP uses the network command under the process, to activate it in the interface. 

Based on the General topology, the below is the configuration of EIGRP just for R1 and R2, but R3 and R4 follow the same configuration pattern.

The network command was used with the most specific wildcard mask to allow just one single interface IP, thus allowing singe interface.

R1

EIGRP for IPV4

router eigrp 1
 network 1.1.1.1 0.0.0.0
 network 10.1.2.1 0.0.0.0

 network 10.1.3.1 0.0.0.0

EIGRP for IPV6 classic mode

ipv6 router eigrp 1

eigrp router-id 1.1.1.1

interface GigabitEthernet1

 ipv6 address 2001:10:1:2::1/64

 ipv6 eigrp 1

interface GigabitEthernet2

 ipv6 address 2001:10:1:3::1/64

 ipv6 eigrp 1

R2

EIGRP for IPV4

router eigrp 1

 network 2.2.2.2 0.0.0.0

 network 10.1.2.2 0.0.0.0

 network 10.2.3.2 0.0.0.0

EIGRP for IPV6 classic mode

ipv6 router eigrp 1

eigrp router-id 2.2.2.2

interface GigabitEthernet1

 ipv6 address 2001:10:1:2::2/64

 ipv6 eigrp 1

interface GigabitEthernet2

 ipv6 address 2001:10:2:4::2/64

 ipv6 eigrp 1

Verification.

IPv4 Neighbors - show ip eigrp neighbors

IPv6 Neighbors - show ipv6 eigrp neighbors

• H stands for Host index, which the order the neighbors came up.
• Address is the physical address of the neighbor.
• Interface is the exist interface.
• Hold Uptime is self-explanatory.
• SRTT need to check.
• Q cnt - it indicates whether the packet is being delayed to the neighbor (congestion). It should always be 0.
• Seq - It's the sequence number, it indicates the how many updates were received from the particular neighbor. Example, if a route is unavailable, this value might increase because of the new updates received.

For more details about the neighbor, we can add details to the previous command (sho ip eigrp neighbors detail). Below is the output.

IPv4 Neighbors - show ip eigrp interface

IPv4 Neighbors - show ipv6 eigrp interface

In order to establish the adjacency, the below parameters must match.

1. As Number
2. K values
3. EIGRP software version
4. Subnet (only for IPv4)

The below parameters do not have to match

1. Hello intervals. Hello interval is not synchronized, but the dead timer is.