From: shahid Ansari (shahid1357@gmail.com)
Date: Fri Feb 22 2008 - 11:00:43 ARST
Keep in Mind a Router ID is an address by which an OSPF router identifies
itself. It is either the numerically highest IP address of all the router's
loopback interfaces, or if no loopback interfaces are configured, it is the
numerically highest IP address of all the router's LAN interfaces even that
*interface is not part of OSPF ( not advertised in OSPF)
*OSPF will not boot if it cannot find an active IP address for its Router ID
thats why loopback come in picture (LOOPBACK always UP).
The more common reason for using loopback interfaces on OSPF routers is that
the interfaces allow the network administrator to control the Router IDs.
When the OSPF process looks for a Router ID, OSPF will prefer the address of
a loopback interface over the addresses of all physical interfaces,
regardless of the numerical order. If there are multiple loopback interfaces
with IP addresses, OSPF will choose the numerically highest loopback
address.
EIGRP Router-id is only for identification.
BGP determines the router ID using the following priority:
*bgp router-id *command,highest Loopback interface address,highest IP
address of the interface,no interface exists, set the router-ID to 0.0.0.0
As per lab exam do it what they want.
If the questions say you should keep your loopback as your RID then do it IF
Dont then let router select .
*Shahid Ansari
CCIE# 20017*
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