Narbik/IPExpert Workbook EIGRP Notes

Timers

• Hello and Dead interval timers are set on a per-interface basis with
  ip hello-interval eigrp <AS> <seconds>
ip hold-time eigrp <AS> <seconds>
• The stuck-in-active (SIA) timer is configured with the router-level command
  timers active-time <seconds|disabled>

Metrics

• The metric calculation in an EIGRP AS can be changed with the router-level command
  metric weight 0 <bandwidth> <load> <delay> <offset> <reliability>
• The metric calculation formula is

  ( ( k1 * bandwidth ) +

    ( k2 * bandwidth ) / ( 256 - load ) +

    ( k3 * delay ) +

    ( k5 / reliability ) +

    k4

  ) * 256

• To configure the hop count considered unreachable (default 100) use router-level command
  metric maximum-hops <count>
• The administrative distance of internal and external routes can be configured using the router-level command
  distance eigrp <internal> <external>

Bandwidth Used for EIGRP

• EIGRP uses 50% of the interface bandwidth by default
• Can be changed using the interface-level command
  ip bandwidth-percentage eigrp <AS> <percent>

Stubs

• A stub can be configured to only receive (not send) routes using the router-level command
  eigrp stub receive-only

Logging

• no eigrp log-neighbor-changes
• eigrp log-neighbor-warning <interval> will log updates that are received from an IP not in the subnet of the receiving interface.

Summary Addresses

• The leak-map option to ip summary-address eigrp references a route-map that defines what component routes of a summary supernet are also injected along side the summary. It is only available on physical and VirtualTemplate interfaces (not on subinterfaces).

Load Balancing

• For unequal-cost load balancing, the AD of the worst route must be less than the FD
• Take the AD of the worst route and divide by the AD of the best route (rounding up) to get the variance.

Authentication

• same as RIP, but configured on a per-interface and per-AS basis
  ip authentication mode eigrp 300 md5