From: john kennedy (loserboy3000@hotmail.com)
Date: Tue Aug 05 2008 - 16:30:14 ART
Hi everybody,
Here is the difference:
Priority under the router mode will let the router with highest priority to be
selected as the DR in shared media
While priority for the neighbor is very useful in hub and spoke topology where
you want to make sure the hub is the only the one who is going to be selected
as DR so you influence the priority for the neighbor =0 ==hwill no be selected
as DR or BDR
On Cisco press they say it is sufficient to write priority =0 under the router
mode, but in real life you need to do this from both sides
Router and on the interface
I hope this can help
> Date: Tue, 5 Aug 2008 11:41:26 -0700> From: fahad.khan@gmail.com> To:
sweetabuli@gmail.com> Subject: Re: OSPF queries!!!> CC:
ccielab@groupstudy.com> > Dear Abbas bhai,> > Thank you, I had gone through
this one. Plz tell me the difference between> the usage of "ip ospf priority"
command under interface mode and "neighbour> <ip> priority" command under
router mode> > > On 8/5/08, Mohammed Abbas <sweetabuli@gmail.com> wrote:> >> >
Hi Fahad,> > Please find the reply for your first question (From Cisco
Website)> >> >> >> > *neighbor (OSPF) *> >> > To configure Open Shortest Path
First (OSPF) routers interconnecting to> > nonbroadcast networks, use the
*neighbor *command in router address family> > topology or router
configuration mode. To remove a configuration, use the> > *no* form of this
command.> >> > *neighbor* *ip-address* [*priority** number*] [*poll-interval*
*seconds*]> > [*cost** number*] [*database-filter all*]> >> > *no neighbor*
*ip-address* [*priority** number*] [*poll-interval* *seconds> > *] [*cost**
number*] [*database-filter all*]> >> > *Syntax Description*> >> >
*ip-address*> >> > Interface IP address of the neighbor.> >> > *priority**
number*> >> > (Optional) A number that indicates the router priority value of
the> > nonbroadcast neighbor associated with the IP address specified.* *The>
> default is 0. This keyword does not apply to point-to-multipoint
interfaces.> >> >> > *poll-interval **seconds*> >> > (Optional) A number value
that represents the poll interval time (in> > seconds). RFC 1247 recommends
that this value be much larger than the hello> > interval. The default is 120
seconds (2 minutes). This keyword does not> > apply to point-to-multipoint
interfaces. The range is from 0 to 4294967295> > seconds.> >> > *cost**
number*> >> > (Optional) Assigns a cost to the neighbor, in the form of an
integer from 1> > to 65535. Neighbors with no specific cost configured will
assume the cost of> > the interface, based on the *ip ospf cost *command. For>
> point-to-multipoint interfaces, the cost keyword and the *number* argument>
> are the only options that are applicable. This keyword does not apply to> >
nonbroadcast multiaccess (NBMA) networks.> >> > *database-filter all*> >> >
(Optional) Filters outgoing link-state advertisements (LSAs) to an OSPF> >
neighbor.> >> >> >> > *Command Default *> >> > This command is disabled by
default. No configuration is specified.> >> > *Command Modes *> >> > Router
address family topology configuration (config-router-af-topology)> > Router
configuration (config-router)> >> > *Command History*> >> > *Release *> >> >
*Modification *> >> > 10.0> >> > This command was introduced.> >> > 11.3AA> >>
> The *cost* keyword was added.> >> > 12.2(33)SRA> >> > This command was
integrated into Cisco IOS Release 12.2(33)SRA.> >> > 12.2(33)SRB> >> > This
command was made available in router address family topology> > configuration
mode.> >> > 12.2SX> >> > This command is supported in the Cisco IOS Release
12.2SX train. Support in> > a specific 12.2SX release of this train depends on
your feature set,> > platform, and platform hardware.> >> >> >> > *Usage
Guidelines *> >> > X.25 and Frame Relay provide an optional broadcast
capability that can be> > configured in the map to allow OSPF to run as a
broadcast network. At the> > OSPF level you can configure the router as a
broadcast network. Refer to the> > * x25 map* and *frame-relay map* commands
in the "X.25 Commands" and> > "Frame Relay Commands" chapters, respectively,
in the *Cisco IOS* *Wide-Area> > Networking Command Reference *for more
detail.> >> > One neighbor entry must be included in the Cisco IOS software
configuration> > for each known nonbroadcast network neighbor. The neighbor
address must be> > on the primary address of the interface.> >> > If a
neighboring router has become inactive (hello packets have not been> >
received for the Router Dead Interval period), it may still be necessary to> >
send hello packets to the dead neighbor. These hello packets will be sent at>
> a reduced rate called *Poll Interval*.> >> > When the router first starts
up, it sends only hello packets to those> > routers with nonzero priority,
that is, routers that are eligible to become> > designated routers (DRs) and
backup designated routers (BDRs). After the DR> > and BDR are selected, DR and
BDR will then start sending hello packets to> > all neighbors in order to form
adjacencies.> >> > ------------------------------> >> > *Note *You cannot use
the *neighbor (OSPF)* command to specify an Open> > Shortest Path First (OSPF)
neighbor on non-broadcast networks within an OSPF> > Virtual Private Network
(VPN) routing instance.> > ------------------------------> >> > Prior to Cisco
IOS Release 12.0, the *neighbor* command applied to NBMA> > networks only.
With Release 12.0, the *neighbor* command applies to NBMA> > networks and
point-to-multipoint networks. On NBMA networks, the *cost*keyword is not
accepted.> >> > Release 12.2(33)SRB> >> > If you plan to configure the
Multi-Topology Routing (MTR) feature, you need> > to enter the *neighbor
*command in router address family topology> > configuration mode in order for
this OSPF router configuration command to> > become topology-aware.> >> >
*Examples *> >> > The following example declares a router at address
192.168.3.4 on a> > nonbroadcast network, with a priority of 1 and a poll
interval of 180> > seconds:> >> > router ospf> >> > neighbor 192.168.3.4
priority 1 poll-interval 180> >> >> >> > The following example illustrates a
point-to-multipoint network with> > nonbroadcast:> >> > interface Serial0> >>
> ip address 10.0.1.1 255.255.255.0> >> > ip ospf network point-to-multipoint
non-broadcast> >> > encapsulation frame-relay> >> > no keepalive> >> >
frame-relay local-dlci 200> >> > frame-relay map ip 10.0.1.3 202> >> >
frame-relay map ip 10.0.1.4 203> >> > frame-relay map ip 10.0.1.5 204> >> > no
shut> >> > !> >> > router ospf 1> >> > network 10.0.1.0 0.0.0.255 area 0> >> >
neighbor 10.0.1.3 cost 5> >> > neighbor 10.0.1.4 cost 10> >> > neighbor
10.0.1.5 cost 15> >> > *Related Commands*> >> > *Command *> >> > *Description
*> >> > *ip ospf priority*> >> > Sets the router priority, which helps
determine the designated router for> > this network.> >> >> >> >> >> >> >> >
Best regards!> >> >> >> > Mohammed Abbas> >> >> >> > On 8/5/08, Fahad Khan
<fahad.khan@gmail.com> wrote:> >> >> sorry , i forgot to add "not" in my last
line."> >>> >> ---------- Forwarded message ----------> >> From: Fahad Khan
<fahad.khan@gmail.com>> >> Date: Aug 5, 2008 2:54 PM> >> Subject: OSPF
queries!!!> >> To: GS CCIE-Lab <ccielab@groupstudy.com>> >>> >> Dear experts,>
>>> >> Kindly resolve my queries reagrding OSPF given below> >>> >> 1- Why
would I use the command "neighbour <ip> priority"?> >>> >> 2- I tried to send
the summary routes from R1 over Virtual-link and GRE> >> both> >> , but
couldn't get summary route on R4> >>> >> Scenario :
R1----area0-----R2------area1-----R3------area2-------R4> >>> >> I may have
done any mistake, but plz let me know is it possible?> >>> >> 3- I have heared
from some one that "area <id> range <address> <net mask>> >> not-advertise"
filters type 1 LSA. Can any one plz elaborate it (i think> >> this relates
with LSA type 3) and also tell me why would i use it, If i> >> can> >> simple
not advertise networks in my routing process, then definitely> >> routes> >>
would not be advertised> >>> >> Thanks and regards,> >>> >> --> >> FAHAD KHAN>
>>> >> BE Computer Systems NED,> >>> >>
CCNA,CCDA,CCNP,FOUNDFE,CLSE,QOS,JNCIA,JNCIS,MCP> >>> >> Systems Support
Engineer, Premier Systems (Pvt) limited,> >>> >> Karachi, Pakistan> >>> >>
92-321-2370510.> >>> >>> >> Blogs and organic groups at http://www.ccie.net>
>>> >>
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