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    CCNP BSCI Notes – Scalable EIGRP

    By Raiy Wong | November 19, 2009

    Configuring EIGRP

    Enabling EIGRP:

           clip_image002

    Adding a network to EIGRP:

          clip_image004

    All interfaces belonging to the specified network will become EIGRP capable and advertised via EIGRP.

    EIGRP will summarize to classful boundaries by default.

    An interface can be set to ”passive” to prevent advertisement:

           clip_image006

    If an interface is included in the network configuration but set to passive, it will still be included in EIGRP advertisements. If an interface is not included in an EIGRP network, it will not be advertised in EIGRP.

    Summarization

    Summarization is key to preventing looping route queries (which leads to SIA condition).

    Disable automatic summarization to classful addresses:

           clip_image008

    Configure manual summarization on an interface:

           clip_image010

    Stub Routers

    Stub routers participate minimally in EIGRP, which reduces utilization of memory and CPU on the router.

    Often used in lieu of static routes in a hub-spoke topology to provide a standard configuration for all spoke routers.

           clip_image012

             receive-only – Prevents the router from advertising any routes

             connected – Permits advertisement of connected networks (default)

             static – Permits redistribution of static routes

             summary – Advertises summary routes (default)

    Load Balancing

    EIGRP automatically load balances across equal-cost links.

    Unequal-cost load balancing is enabled by specifying a variance. Feasible successors with a feasible distance less than (best path FD * variance) will be proportionally utilized.

           clip_image014

    Variance can be between 1 and 128; default is 1 (equal-cost only).

    EIGRP Tuning

    EIGRP timers do not have to match for two routers to form an adjacency.

    Default hello timer:

             High-bandwidth links (>= T1): 5 seconds

             Low-bandwidth links (< T1): 60 seconds

    Hello timers are modified per interface:

           clip_image016

    Default hold timer = 3 *

    Reconfiguring the hold timer is done in seconds, not as a multiplier:

          clip_image018  

    Authentication

    Authentication types:

             Plain-text password (insecure)

             MD5 hash

    Configuring MD5 authentication on an interface:

            clip_image020

    Bandwidth Manipulation

    Bandwidth of an interface can be administratively configured:

            clip_image022

    The bandwidth setting will not affect the actual interface speed, only the value used in metric calculation.

    This is useful for serial interfaces which connect to a DSU operating at a slower speed.

    EIGRP assumes all virtual circuits on an interface receive an equal share of the total bandwidth.

    By default, EIGRP will use no more than 50% of an interface’s bandwidth. This can be adjusted as such:

             clip_image024

    Verifying EIGRP Operation

    Monitoring

            show ip eigrp neighbors

            show ip eigrp topology

            show ip eigrp traffic

            show ip eigrp interfaces

            show ip route eigrp

    Debugging

            debug eigrp packet

            debug ip eigrp neighbors

            debug ip eigrp

            debug ip eigrp summary

             

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    Topics: CCNP, CCNP Notes | No Comments »

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