Tuesday, March 10, 2015

EIGRP advertise default-route

==============================EIGRP adver_default route==========


   1.         ip route 0.0.0.0 0.0.0.0 null0

              Router eigrp 100

        Network 0.0.0.0

          = >> In this case the default route will show as an "internal" Eigrp route.
======================================================================

   2.         Ip route 0.0.0.0 0.0.0.0 null0

              Router eigrp 100

        Redistribute static

          =>> In this case the default route will show as an "external" Eigrp route "EX".

======================================================================

   3.          " under a given interface ":

              # ip summary-address eigrp 1 0.0.0.0 0.0.0.0

           =>> In this case the default route will show as an "internal" Eigrp route

Note : creat null0 with AD = 5 in routing table
 
Để không thấy route null 0 trong routing table thì khi summary ta cho AD = 255

# ip summary-address eigrp 1 0.0.0.0 0.0.0.0 255

=======================================================================

   4.         IP default-network 1.0.0.0

>> note : The network can be any network,but must be a classful network and NOT a subnet
Loopback interface or any interface

         Router eigrp 100

         Network 1.0.0.0

+++++++++++++++++++++++++
+ show ip route eigrp   +
+                        +
+  D*   1.0.0.0/8        +
+++++++++++++++++++++++++

          >> Note : the "*" after the letter D.==> " candidate default "

         * Your need to have access to network 1.0.0.0, but it
not want to use it as a candidate default
should be configured as follows:

+----------------------------------- ------------+
           +Router eigrp 100                                     +
+                                                       +
           + No default-information allowed in   +
+------------------------------------------------+

*After the above configuration, if you check your routing table it should
look like the following:

+++++++++++++++++++++++++
+ show ip route eigrp   +
+                        +
+  D   1.0.0.0/8        +
+++++++++++++++++++++++++

          >> Note : the "*" is gone and network 1.0.0.0 is no longer used as the candidate
default.

==================================================================

    Gateways of last resort selected using the ip default-network
    command are propagated differently depending on which routing protocol
    is propagating the default route. For IGRP and EIGRP to propagate the
    route, the network specified by the ip default-network command
    must be known to IGRP or EIGRP. This means the network must be an IGRP-
    or EIGRP-derived network in the routing table, or the static route used
    to generate the route to the network must be redistributed into IGRP or

    EIGRP, or advertised into these protocols using the network command.

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