Configuring OSPF Interfaces
You should specify a routing interface for any local subnet that needs to
communicate with other network segments located on this router or elsewher e in the
network. First configure a VLAN for each subnet that will be directly connected to
this router, assign IP interfaces to each VLAN (i.e., one pri mary in terf ace and on e or
more secondary interfaces), and then use the OSPF / Network Area Address
Configuration page to assign an interface address range to an OSPF area.
After assigning a routing interface to an OSPF area, you n eed to use the OS PF /
Interface Configuration page to configure the interface-specific parameters used by
OSPF to select the designated router, control the timing of link state advertisements,
set the cost used to select preferred paths, an d specif y the meth od used to
authenticate routing messages.
Field Attributes
OSPF Interface List
• VLAN ID – The VLAN to which an IP interface has be en assig ned.
• Interface IP – The IP interface asso ciated with the selected VLAN.
• Area ID – The area to which this interface has been assigned.
• Designated Router – Design ated route r for this area .
• Backup Designated Router – Designa ted bac kup ro uter for thi s area.
• Entry Count – The number of IP interfac es assigne d to this VLAN.
Note:
This router supports up 64 OSPF interfaces.
Detailed Interface Configuration
• VLAN ID – The VLAN correspond ing to the sele cted interface .
• Rtr Priority – Sets the interface priority for this ro uter. (Ran ge: 0-25 5; Default : 1)
A designated router (DR) and backup designated router (BDR ) is electe d for eac h
OSPF area based on Router Priority. The DR forms an active adjacency to all other
routers in the area to exchange routing topology information. If for any reason the
DR fails, the BDR takes over this role.
The router with the highest priority becom es the DR and the rout er with th e next
highest priority becomes the BDR. If two or more ro uters are se t to the sam e
priority, the router with the higher ID will be elected. You can set the priority to zero
to prevent a router from being elected as a DR or BDR.
If a DR already exists for an area when this interface comes up, the new router will
accept the current DR regardless of its own priority. The DR will not change until
the next time the election process is initiated.
Configure router priority for multi-access networks only and not for point-to-poin t
networks.
• Transmit Delay – Sets th e estimated time to s end a link-state update packet over
an interface. (Range: 1-65535 seconds; Default: 1 s econd )
LSAs have their age incremented by this delay before transmission. Y ou should
consider both the transmission and propagation delays for an interface when

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Configuring the Open Shortest Path First Protocol

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