EIGRP Hello-interval, EIGRP Hold-Time

Lessons learned:

Hello interval

-how often do I send hellos on a link

-ip hello-interval eigrp (as) (seconds)

Hold-Time

-How long YOU should wait to declare ME down

-opposite of OSPF hello and dead interval

-ip hold-time eigrp (as) (seconds)

Note: the Timers do not have to match for an adjacency to form.

The timers control the hellos’ and when to declare the neighbor unreachable.

With EIGRP  the Hello interval does control locally how often we are sending Hello’s out but the EIGRP HOLD-TIME,

Is the value we put inside our own Hello packet to tell the remote neighbor how long to wait to declare ME down.

So the hold timer configured on the interface is going to affect the remote neighbor.

We can view the Timers whit the command:

Sh ip eigrp interface detail:

R2#sh ip eigrp interfaces detail

IP-EIGRP interfaces for process 500

                        Xmit Queue   Mean   Pacing Time   Multicast    Pending

Interface        Peers  Un/Reliable  SRTT   Un/Reliable   Flow Timer   Routes

Lo1                0        0/0         0       0/1            0           0

  Hello interval is 5 sec  --- Here the Hello interval is 5 seconds.

  Next xmit serial <none>

  Un/reliable mcasts: 0/0  Un/reliable ucasts: 0/0

  Mcast exceptions: 0  CR packets: 0  ACKs suppressed: 0

  Retransmissions sent: 0  Out-of-sequence rcvd: 0

  Authentication mode is not set

  Use multicast

Fa0/0              2        0/0        33       0/1          108           0

  Hello interval is 5 sec

  Next xmit serial <none>

  Un/reliable mcasts: 0/3  Un/reliable ucasts: 8/11

  Mcast exceptions: 4  CR packets: 3  ACKs suppressed: 0

  Retransmissions sent: 3  Out-of-sequence rcvd: 1

  Authentication mode is not set

  Use multicast

R2#

Hello time:

Depending on the underlying media the hello will different, Ex: a serial interface should have a default interval of 60 seconds.

For all other media it will be 5 seconds.

Hold-time:

Default for NBMA low speed links is 180 seconds. All other networks the default 15 seconds.

Configuration-

Under the interface:

R2(config-if)#ip hello-interval eigrp 500 10

R2(config-if)#ip hold-time eigrp 500 30

Fa0/0              2        0/0       433       0/1         2156           0

  Hello interval is 10 sec – Now shows ten seconds.

  Next xmit serial <none>

  Un/reliable mcasts: 0/3  Un/reliable ucasts: 10/11

  Mcast exceptions: 5  CR packets: 3  ACKs suppressed: 0

  Retransmissions sent: 2  Out-of-sequence rcvd: 1

  Authentication mode is not set

  Use multicast

We can see the Hold timers

R3#sh ip eigrp neighbors detail 

IP-EIGRP neighbors for process 500

H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq

                                            (sec)         (ms)       Cnt Num

1   192.168.11.1            Fa0/0             14 00:14:40  817  4902  0  6

   Version 12.4/1.2, Retrans: 0, Retries: 0, Prefixes: 1

0   192.168.11.2            Fa0/0             26 00:14:40   49   294  0  7

   Version 12.4/1.2, Retrans: 2, Retries: 0, Prefixes: 1