From: George Zhang (gyzhang63@xxxxxxxxxxx)
Date: Fri Mar 01 2002 - 14:12:49 GMT-3
   
I have a question about IRDP preference.  Consider the following scenario:
           R3-E0-------------------E0-R4
                         |
                         |
                        E0
                        R1
R3's config:
  in e0
    ip ad 172.16.1.3 255.255.255.0
    ip irdp
    ip irdp preference 300
R4's config:
  in e0
    ip ad 172.16.1.4 255.255.255.0
    ip irdp
    ip irdp preference 400
R1's config:
  no ip routing
  in e0
    ip ad 172.16.1.1 255.255.255.0
IRDP is configured on R3 and R4's ethernet 0.  IP routing is turned off on
R1.  So it is acting as a host.
Question: Which router is the default gateway for R1?  R3 or R4?
According to the Doc CD:
preference number
(Optional) Preference value. The allowed range is -231 to 231. The default
is 0. A higher value increases the router's preference level. You can modify
a particular router so that it will be the preferred router to which others
home.
My understanding is that the router with a higher preference valve, i.e. R4
will win.
However, the following route table on R1 shows the opposite:
r1#sh ip route
Gateway         Using  Interval  Priority   Interface
172.55.255.3    IRDP      788       300     Ethernet0/1
172.55.255.4    IRDP      900       400     Ethernet0/1
Default gateway is 172.55.255.3
Host               Gateway           Last Use    Total Uses  Interface
ICMP redirect cache is empty
Could someone please explain this?
Thanks.
George Zhang
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