From: maureen schaar (maureen.schaar@gmail.com)
Date: Fri Mar 30 2007 - 04:21:00 ART
Unless they specifically ask to enable ospf on all your interfaces
with least amount of commands, I would choose the most specific option
and advertise network with 0.0.0.0 mask. It fits the requirements and
is most future-proof.
Of course, you can also use the new-style command where you enable
ospf directly under the interface config. This is helpful if they
specify that you cannot use network statements, or redistribution.
But then again, I don't have a # to show for it, so maybe I'm wrong ;-)
Maureen
On 3/30/07, Huizinga, Rene <rhuizinga@upcbroadband.com> wrote:
> Hmmm, don't 100% agree. I think both would be counted correct, but if having
> to choose between which one would be 'more correct', what would be better
> than taking the exact subnet assigned to the interface, assuming that no
> 'subnet-overlaps' would already be there on the box ??? If the latter would
> be the case, then the 0.0.0.0 would be the way to go...
>
> Both generally and practically I'd personally always advise (best practice)
> to go for the exact subnet used on the interface targetted and with that,
> specify individual commands for each, in combination with the
> passive-interface default...
>
> _____
>
> From: Digital Yemeni [mailto:digital.yemeni@gmail.com]
> Sent: Friday, March 30, 2007 1:17 AM
> To: Jeff Mullan
> Cc: Huizinga, Rene; premkumar somasundaram; ccielab@groupstudy.com
> Subject: Re: Network 0.0.0.0
>
>
> the wildcard mask is to specify what interface to send the updates NOT what
> network you're advertising! So i guess the 0.0.0.0 <http://0.0.0.0> is the
> correct one because it gives more control on what interface you want to use
> to send ur update from! 0.0.0255 is just an easy way to include more that
> one interface in a single command!
>
>
>
>
> On 3/30/07, Jeff Mullan < jmullan78@gmail.com <mailto:jmullan78@gmail.com> >
> wrote:
>
> Actually, this brings up an interesting point . I have always had a feeling
> that if we use some thing like 192.168.1.1 <http://192.168.1.1> 0.0.0.0
> <http://0.0.0.0> we might lose some points
> vs using 192.168.1.0 <http://192.168.1.0> 0.0.0.255 <http://0.0.0.255> ...
> can some one pls shed some light on it
> pls.
> Thanks,
> JM
>
> On 3/29/07, Huizinga, Rene <rhuizinga@upcbroadband.com
> <mailto:rhuizinga@upcbroadband.com> > wrote:
> >
> > Hi Premkumar,
> >
> >
> > The network-command under OSPF simply stated is there to define an
> > IP-range
> > within which the router is scanning all of it's local interfaces that fall
> > within it. For all interfaces it finds within that range, it'll ensure
> > it's
> > taken up into OSPF, within the area configured at the end of the
> > network-command.
> >
> > One can e.g. define an address with a '0.0.0.0 <http://0.0.0.0> '
> wildcard-mask to
> > specifically identify a single interface instead of using the real subnet.
> > But also, as you can see now, if one would use e.g. 'network 0.0.0.0
> <http://0.0.0.0>
> > 255.255.255.255 <http://255.255.255.255> area 0', the router would take
> all of it's interfaces
> > configured with IP and place all of them into OSPF, using area 0 for this
> > example here.
> >
> > Can be easy, but at the same time also backfire practically in case your
> > network was setup initially like this and you later add e.g. a small
> > management-subnet which you didn't actually want into OSPF.
> >
> > A sample:
> >
> > Interface fa0/0 has as ip-address 192.168.1.1 <http://192.168.1.1> ,
> subnet-mask 255.255.255.0 <http://255.255.255.0> .
> > Now all 4 variants stated below will put it into ospf, area 0:
> >
> > 1. network 192.168.1.1 <http://192.168.1.1> 0.0.0.0 <http://0.0.0.0>
> area 0
> > 2. network 192.168.1.0 <http://192.168.1.0> 0.0.0.3 <http://0.0.0.3>
> area 0
> > 3. network 192.168.1.0 <http://192.168.1.0> 0.0.0.255 <http://0.0.0.255>
> area 0
> > 4. network 0.0.0.0 <http://0.0.0.0> 255.255.255.255
> <http://255.255.255.255> area 0
> >
> > The best option/best practice would normally be to use option 3. It uses
> > the
> > real subnet configured for that interface. Also it gives you a better
> > overview within the router ospf config on which subnets are included.
> > Option 1,2 and 4 will do the same but identifies it specifically (1),
> > identifies a small range in which the router will also find this interface
> > (2) or identifies the whole IPv4 range, risking that other unwanted
> > interfaces are taken into OSPF as well.
> >
> > When wanting to use an aggregate to include OSPF-interface, use at least
> > as
> > best-practice the 'passive-interface default' command with it and
> > 'activate'
> > interfaces individually with the 'no passive-interface' command to
> > identify
> > which ones you'd want to be active and form an adjacency. That won't solve
> > the issue of e.g. having the same network being advertised multiple times
> > into OSPF in case of local management-links for example, but would at
> > least
> > be an additional safe-guard.
> >
> > In favor of using aggregates is the case where one has a nice and tidy
> > IP-addressing scheme.
> > eg. One would always use the ' 192.168.0.0/16 <http://192.168.0.0/16> '
> ONLY for internal core-links
> > within your network which should always be active. In that case one can
> > include the 'network 192.168.0.0 <http://192.168.0.0> 0.0.255.255
> <http://0.0.255.255> area 0' for all core-link
> > carrying routers into your config-baseline !!!
> >
> >
> > Cya
> >
> > Rene.
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com <mailto:nobody@groupstudy.com>
> [mailto:nobody@groupstudy.com <mailto:nobody@groupstudy.com> ] On Behalf Of
> > premkumar somasundaram
> > Sent: Thursday, March 29, 2007 11:24 PM
> > To: ccielab@groupstudy.com <mailto:ccielab@groupstudy.com>
> > Subject: Network 0.0.0.0 <http://0.0.0.0>
> >
> > Team,
> > Could any one tell me what is the purpose of the command network
> > 0.0.0.0under Eigrp or OSPF??...
> >
> > Prem
> >
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>
>
>
>
> --
> Best Regards!
> Digital, CCIE# to be assigned by Cisco when it collects enough $$ out of me!
> :p
>
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