nx.os.and.cisco.nexus.switching.2nd.edition.1587143046

called the Diffusing Update Algorithm (DUAL). The primary advantage that DUAL provides
over other routing algorithms is the capability to provide loop-free topologies at every stage
of network convergence. When joined with the other capabilities of EIGRP, such as its
multiprotocol nature, WAN-friendly neighboring and updating capabilities, and flexible
summarization and quick convergence, it makes a powerful routing protocol.
EIGRP forms adjacencies with its directly connected neighbors to exchange routing updates
similar to a link state protocol. During the initial neighbor formation, attributes such as
smooth round-trip time (SRTT), hold time, retry timeout, IP address, and interface on which
the hello was received are negotiated and recorded in a neighbor table, as demonstrated in
Example 3-1.
Example 3-1. EIGRP Neighbors
Click here to view code image
Congo# show ip eigrp ne
IP-EIGRP neighbors for process 100 VRF default
H Address Interface Hold Uptime SRT
(sec)
(ms
Num
1 10.10.10.3 Vlan10 11 01:42:49 44
0 192.168.1.38 Eth1/18 14 01:52:06 41
The hellos between the EIGRP neighbors are the mechanism for maintaining the adjacency.
Within the hello is a hold timer that tells EIGRP the maximum time before the next hello
should be received. By default, the hold timer is three times the hello interval. If the hold
timer is exceeded before another hello is received, EIGRP considers the neighbor
unreachable and informs DUAL. The network’s topology is recalculated and bounded,
partial updates are sent to the remaining neighbors, and the network begins to converge.
Configuring EIGRP
EIGRP within NX-OS is compatible with EIGRP on IOS devices enabling a smooth
integration of Nexus equipment with existing gear. Configuring EIGRP within NX-OS will
be similar yet distinctly different in some aspects to traditional IOS configuration. These
differences will be highlighted throughout the section.
Enabling EIGRP is a multistep process that will be covered in detail. The following is a
quick listing of steps to enable a basic configuration of EIGRP:
1. Enable EIGRP.
2. Configure the EIGRP routing process with support for IPv4 or IPv6.
3. Assign interfaces to the instance tag.
4. Configure passive interfaces if necessary.
5. Configure network summarization.