OSPF IP priority
o1n
Banned Posts: 18 ■□□□□□□□□□
in CCNA & CCENT
There is one description that in below in 'CCNA Study Guide'
By default, OSPF uses the highest IP address on any active interface at the
moment of OSPF startup. However, this can be overridden by a logical inter-
face. The highest IP address of any logical interface will always become a
router’s RID.
Question: Which one will be highest IP in below IP?
192.168.0.1
10.56.39.254
By default, OSPF uses the highest IP address on any active interface at the
moment of OSPF startup. However, this can be overridden by a logical inter-
face. The highest IP address of any logical interface will always become a
router’s RID.
Question: Which one will be highest IP in below IP?
192.168.0.1
10.56.39.254
Comments
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amb1s1
Member Posts: 408
There is one description that in below in 'CCNA Study Guide'
By default, OSPF uses the highest IP address on any active interface at the
moment of OSPF startup. However, this can be overridden by a logical inter-
face. The highest IP address of any logical interface will always become a
router’s RID.
Question: Which one will be highest IP in below IP?
192.168.0.1
10.56.39.254
192.168.0.1 would be highter.
Take a look at the OSPF Wiki, read the Designated router section.
Open Shortest Path First - Wikipedia, the free encyclopedia -
MickQ
Member Posts: 628 ■■■■□□□□□□
192.168.0.1 would be highter.
Take a look at the OSPF Wiki, read the Designated router section.
Open Shortest Path First - Wikipedia, the free encyclopedia
192.168.0.1 if both of the addresses are on physical interfaces. Eg. FA0/1 and FA0/2.
If one of them is a "loopback" (logical) interface, then that'll take preference. -
CodeBlox
Member Posts: 1,363 ■■■■□□□□□□
if 192.168.0.1 is on an ethernet interface and 10.56.39.254 is on a loopback interface, then 10.56.39.254 would be the RID
Currently reading: Network Warrior, Unix Network Programming by Richard Stevens -
ccnaomkar
Member Posts: 187 ■■□□□□□□□□
Cisco routers derive their Router IDs by the following means:
1. If the Router ID has been manually configured using the router-id command (can use any value unlike BGP which can use o*nly up to 223.255.255.255 which is the last unicast IP), that Router ID is used.
2. If no Router ID has been manually configured, the router chooses the numerically highest IP address on any of its loopback interfaces.
3. If no loopback interfaces are configured with IP addresses, the router chooses the numerically highest IP address on any of its UP/UP physical interfaces. (accordingly you won’t have OSPF running unless one interface is UP/UP and the router will issue this log message “%OSPF-4-NORTRID: OSPF process 1 cannot start. There must be at least o*ne “up” IP interface, for OSPF to use as router ID”).
for more link
OSPF RID Story