
When troubleshooting various aspects of [EIGRP](/eigrp), some useful commands to use in the Cisco IOS operating system are the following:

* `debug eigrp packets` - provides information about EIGRP packet exchanges.  You can filter specific packet types.  The various available types can be seen in the context sensitive help below:
```
R1#debug eigrp packets ?
  
  SIAquery  EIGRP SIA-Query packets  
  SIAreply  EIGRP SIA-Reply packets  
  ack       EIGRP ack packets  
  hello     EIGRP hello packets  
  ipxsap    EIGRP ipxsap packets  
  probe     EIGRP probe packets  
  query     EIGRP query packets  
  reply     EIGRP reply packets  
  request   EIGRP request packets  
  retry     EIGRP retransmissions  
  stub      EIGRP stub packets  
  terse     Display all EIGRP packets except Hellos  
  update    EIGRP update packets  
  verbose   Display all EIGRP packets
```

* `debug eigrp neighbor` - Tracks EIGRP neighbor relationships including the formation and loss of neighbors.
* `debug eigrp fsm` - Monitors the finite state machine (FSM) changes for EIGRP neighbors.
* `debug eigrp events` - Logs key EIGRP events such as topology changes, route recomputations, and changes in the [DUAL algorithm](/eigrp-feasible-successors-and-the-dual-algorithm).
* `debug ip routing` - Allows you to observe route installation and removal from the [routing table](/routing-table) including EIGRP routes.
* `debug eigrp detail` - Provides in depth information about EIGRP protocol operations
* * `debug eigrp traffic` - Displays EIGRP traffic statistics including sent and received packets.

The availability of these options may vary depending on the operating system, platform, and version; some options might be unavailable, while others could be additionally provided.

## Links:

https://networklessons.com/eigrp/troubleshooting-eigrp-neighbor-adjacency

https://networklessons.com/eigrp/troubleshooting-eigrp-route-advertisement

EIGRP Useful Debug Commands

ECMP Multicast Routing Cisco Nexus Switches

EEM - action mail

EEM - exit status variable

EEM Cisco Embedded Event Manager

EEM Matching a string within CLI output

EEM sync and skip keywords

EIGRP - Advertised metric is cumulative

EIGRP - Advertising a route using the network command

EIGRP - DUAL Algorithm and FD Set to Infinity

EIGRP - External routes from different ASes

EIGRP - Feasible Successors and the DUAL Algorithm

EIGRP - Hello interval and Hold time

EIGRP - Hop Count

EIGRP - Message TTL value of 2

EIGRP - Metric Equation Multipliers

EIGRP - Network command syntax

EIGRP - Queries

EIGRP - RTP's reliable message exchange process

EIGRP - Reliable Multicast

EIGRP - Router ID and loop prevention

EIGRP - SIA Process and RTP retry attempts

EIGRP - Source of values for metric calculation

EIGRP - Static neighbors over any L2 technology

EIGRP - Stub Router

EIGRP - Stub default behavior

EIGRP - Stub router types

EIGRP - Summarization per interface

EIGRP - Understanding Advertised Distance (AD)

EIGRP - Update message exchange process

EIGRP - Viewing RTP in Wireshark

EIGRP - af-interface configuration mode

EIGRP - how metrics are sent in updates

EIGRP - internal vs external routes

EIGRP - metric computation method

EIGRP - metric equation

EIGRP - named mode name

EIGRP - network command with no wildcard mask

EIGRP - redistribute connected and static routes

EIGRP - shutdown command

EIGRP - stub site function

EIGRP Create and advertise a default route

EIGRP Feasibility condition

EIGRP Header

EIGRP IP bandwidth-percent example

EIGRP Implementation by Non-Cisco Vendors

EIGRP LFA FRR

EIGRP Refining the behavior of load balancing with traffic-share

EIGRP SIA timers

EIGRP authentication

EIGRP auto-summary

EIGRP change rib scale

EIGRP establishing remote neighbors

EIGRP header - ACK field

EIGRP named mode

EIGRP on the Nexus Platform

EIGRP redistributing named mode

EIGRP rib-scale

EIGRP seed metrics when redistributing

EIGRP split horizon verification

EIGRP split-horizon vs poison reverse

EIGRP unequal cost load balancing

EIGRP what happens when a feasible successor fails

EIGRP

EPC - Cisco Embedded Packet Capture

ERSPAN

EVE-NG supported Cisco and other vendor images

Equal-cost Multi-path routing

EtherChannel - Converting an L2 EtherChannel to L3

EtherChannel - LACP System ID

EtherChannel - LACP fast-switchover

EtherChannel - Load Balancing on CatOS

EtherChannel - Load balancing algorithm applied globally and per portchannel

EtherChannel - Maximum Number of Physical Links

EtherChannel - PAgP timer, hello interval, and age value

EtherChannel - Troubleshooting on Cisco IOS Switches

EtherChannel - Understanding LACP port and system priorities

EtherChannel - applying configurations to the interface

EtherChannel - implementing over 802.1Q tunneling

EtherChannel - load balancing algorithms

EtherChannel - max-bundle

EtherChannel - prerequisites for bundling

EtherChannel

Ethernet - Pause Frames

Ethernet - role of FCS field

Ethernet - speed and duplex mismatches

Ethernet - speed and duplex settings on an ISR4431

Ethernet CSMA-CD

Ethernet VPN (EVPN)

Ethernet administrative and operational encapsulation

Ethernet administrative operational mode

Ethernet frame types

Ethernet header

Ethernet over IP (EoIP)

Ethernet

FHRP - Comparison Table

FHRP - HSRP Resign Message

FHRP - interaction with routing protocols

FHRP - which ports should you configure