From: Godswill Oletu (oletu@inbox.lv)
Date: Fri Dec 09 2005 - 20:32:05 GMT-3
James,
You are mistaking the native behaviour of the various ospf network types
with the function of the network command. Lab up your solution and see what
you get.
Natively, point-to-multipoint & point-to-multipoint non-broadcast ospf
network types will advertise their links as a host routes (/32) to their
neighbor and this is inrespective of the mask you used to advertise those
interfaces.
Broadcast, non-broadcast & point-to-point ospf network types will advertise
their links as a prefix, this again works independent of the mask value used
to advertise them.
The mask value in the ospf network statement, just scan through your router
and add all matching interfaces into the specified ospf area, after that,
the router will advertise the prefix/ip addresses configured on those
interfaces. How these prefix/ip addresses are advertised, is greatly
influenced by the ospf network type configured for that interface.
If one's scanario prevent him/her from using the ospf network type statement
to change the mask of the advertised network, there are tons of other ways
depending on other restrictions in place, to do that.
HTH
Godswill
----- Original Message -----
From: "James Matrisciano" <jmatrisciano@kenttech.com>
To: "Schulz, Dave" <DSchulz@dpsciences.com>; "Melwani, Manoj J"
<melwanim@citigroup.com>; "Kim Judy" <kim23uk@gmail.com>;
<ccielab@groupstudy.com>
Sent: Friday, December 09, 2005 5:48 PM
Subject: RE: Wildcard issue
> With the following
>
> Ospf router 1
> Net 1.1.1.1 0.0.0.0 area 0
> Net 3.3.3.1 0.0.0.0 area 0
>
> Int s0/0
> Ip add 1.1.1.1 255.255.255.0
> Ip ospf net broadcast
>
> Int s0/0.3 m
> Ip add 3.3.3.1 255.255.255.0
> Ip ospf net point-to-multipoint
>
> You area connected to router 2 and router 3 via Frame all DLCI's are
> mapped
>
> Once your network has converged, you will get statements in your routing
> table with a /32 of the interface that router is connected to. This
> will break the restriction of advertise the interface with its configure
> mask.
>
> With this set up (and forgive me, my lab is not on line, so I can not
> copy paste my sh ip route statements)
>
> In router 3 that is connected to router 1 with
> S2/0
> Ip add 3.3.3.3 255.255.255.0
> ip ospf net point-to-multipoint
>
> Router ospf 1
> Net 3.3.3.3 0.0.0.0 area 0
>
> Sh ip route
>
> 1.0.0.0
> O 1.1.1.0 (these are the routes to get to R2
> 3.0.0.0/8
> O 3.3.3.1/32
> C 3.3.0/24
>
> What you want to look for is that if you have a restriction saying
> "advertise as configured" the 3.3.3.1 interface is configured as a /24,
> not a /32
>
> As well, in router 2 that is connected the same way except with the ip
> ospf network broadcast command on the interface, the routing table
> shows:
>
> 3.0.0.0/32
>
> In its routing table, this would be a break in the restriction.
> Using ip ospf network point-to-point fixes this problem, but only if you
> are allowed to have point-to-point neighbor relationships
>
>
> -----Original Message-----
> From: Schulz, Dave [mailto:DSchulz@dpsciences.com]
> Sent: Friday, December 09, 2005 5:33 PM
> To: James Matrisciano; Melwani, Manoj J; Kim Judy;
> ccielab@groupstudy.com
> Subject: RE: Wildcard issue
>
> James -
>
> Can you please expound on the advertisement issue that you state. I
> didn't think that the network command under ospf had anything to do with
> how the interface was advertised. I thought that this only determined
> which interfaces were included in the ospf process. I do agree that the
> ospf network command does affect the advertisement.
>
>
> Dave Schulz
> Email: dschulz@dpsciences.com
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> James Matrisciano
> Sent: Friday, December 09, 2005 5:13 PM
> To: Melwani, Manoj J; Kim Judy; ccielab@groupstudy.com
> Subject: RE: Wildcard issue
>
> You need to watch out for your restrictions on the 0.0.0.0 mask. If you
> have a restriction that all interfaces must be advertised with their
> original mask, make sure you do not use the 0.0.0.0 unless you are
> allowed to use the ip ospf network point-to-point command under the
> interface you are conneting with. Again, this will fall under the
> restrictions of how you can have your ospf neighbors talk to each other.
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Melwani, Manoj J
> Sent: Friday, December 09, 2005 4:45 PM
> To: Kim Judy; ccielab@groupstudy.com
> Subject: RE: Wildcard issue
>
> The best practice is to use the second method. By using 0.0.0.0 wildcard
> you are saying that I want to run OSPF routing process just on that
> particular interface unless if you have a whole range of interface that
> you want to use on the same line then you might want to use the first
> method.
>
> Yes Its a good idea to use router-id under the routing process. Use
> Loopback 0 as your router id's.
>
>
> Thanks,
> Manoj.
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Kim Judy
> Sent: Friday, December 09, 2005 4:15 PM
> To: ccielab@groupstudy.com
> Subject: Wildcard issue
>
>
> hi group,
> I have a query that if a interface has an Ip address 172.16.12.1/25 What
> wild card bits should I use under the IGP process ?
>
> router ospf 1
> net 172.16.12.1 0.0.0.127 or
> net 172.16.12.1 0.0.0.0
>
> which is the best way ? What does Cisco expect from us ?
>
> If not specified should I use a "router-id" under each IGP running on a
> router ?
>
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