EIGRPInterface Config

ip hello-interval eigrp [as] [secs]

Configures the EIGRP hello interval on an interface, overriding the default hello interval for the specified autonomous system.

Syntax·Interface Config

ip hello-interval eigrp [as] [secs]

When to Use This Command

On slow WAN links (e.g., Frame Relay) to increase hello interval and reduce overhead
To speed up convergence on high-speed LAN segments by decreasing hello interval
When tuning EIGRP timers to match neighbor requirements for adjacency formation
In hub-and-spoke topologies to adjust hello intervals on spoke interfaces for better scalability

Command Examples

Set hello interval to 10 seconds on GigabitEthernet0/1 for AS 100

ip hello-interval eigrp 100 10

R1(config-if)# ip hello-interval eigrp 100 10
R1(config-if)# end
R1# show ip eigrp 100 interfaces GigabitEthernet0/1
EIGRP-IPv4 Interfaces for AS(100)
                    Xmit Queue   Mean   Pacing Time   Multicast    Pending
Interface        Peers  Un/Reliable  SRTT   Un/Reliable   Flow Timer   Routes
Gi0/1              1        0/0       1       0/10         50           0
  Hello interval: 10 secs, Hold time: 30 secs

The command sets hello interval to 10 seconds. The 'show ip eigrp interfaces' output confirms the new hello interval (10 secs) and the automatically adjusted hold time (30 secs, which is 3x hello interval).

Set hello interval to 60 seconds on Serial0/0/0 for AS 200

ip hello-interval eigrp 200 60

R2(config-if)# ip hello-interval eigrp 200 60
R2(config-if)# do show ip eigrp 200 interfaces Serial0/0/0
EIGRP-IPv4 Interfaces for AS(200)
                    Xmit Queue   Mean   Pacing Time   Multicast    Pending
Interface        Peers  Un/Reliable  SRTT   Un/Reliable   Flow Timer   Routes
Se0/0/0            1        0/0       1       0/60         50           0
  Hello interval: 60 secs, Hold time: 180 secs

The hello interval is set to 60 seconds. The output shows the new hello interval and the hold time (180 secs) automatically set to 3 times the hello interval. This is typical for slow links to reduce hello traffic.

Understanding the Output

The 'show ip eigrp interfaces' command displays EIGRP interface parameters. The 'Hello interval' field shows the configured hello interval in seconds. The 'Hold time' is automatically set to 3 times the hello interval by default (unless manually changed with 'ip hold-time eigrp'). A shorter hello interval (e.g., 5 seconds) provides faster convergence but increases overhead; a longer interval (e.g., 60 seconds) reduces overhead but slows down neighbor loss detection. The hold time must be greater than the hello interval; if mismatched, neighbors may not form adjacency. In the output, also check the 'Peers' column to ensure adjacency is established.

CCNA Exam Tips

CCNA exam tip: The default hello interval is 5 seconds on LAN interfaces and 60 seconds on NBMA (e.g., Frame Relay) interfaces.

CCNA exam tip: The hold time is automatically set to 3 times the hello interval, but can be changed independently with 'ip hold-time eigrp'.

CCNA exam tip: If you change the hello interval, the hold time adjusts automatically only if not manually configured.

CCNA exam tip: Mismatched hello or hold times can prevent EIGRP neighbor adjacency from forming.

Common Mistakes

Mistake: Changing hello interval without adjusting hold time, causing neighbor flapping if hold time is too short.

Mistake: Setting hello interval too low on slow links, causing excessive hello traffic and CPU load.

Mistake: Forgetting to apply the command on the correct interface or using the wrong AS number.

Related Commands

ip hold-time eigrp [as] [secs]

Configures the EIGRP hold time (in seconds) for a specific EIGRP autonomous system on an interface, determining how long the router waits for a hello packet before declaring the neighbor down.

show ip eigrp interfaces

Displays detailed information about interfaces on which EIGRP is enabled, including neighbor status, pending routes, and interface statistics, used to verify EIGRP adjacency and interface participation.

show ip eigrp neighbors

Displays the neighbor table for EIGRP, showing all directly connected EIGRP routers and their status, used to verify EIGRP adjacencies and troubleshoot neighbor relationships.

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