[nsp] Prefix 0.0.0.0/1

Stephen J. Wilcox steve at telecomplete.co.uk
Wed Dec 25 16:17:19 EST 2002


<snip>
> > route your 128/1 AND default-info orig. and it will have the same effect
> anyway
> > because of more specific matching
> 
> that means I can only aggregate the upper half of the supernet?

i cant imagine it matters tho, if you are wanting to default route upper and
lower halves it will have the same effect as the 128/1 will always be chosen for
top half prefixes and 0/0 for bottom half because of most specific matching...

Steve

> 
> sonny
> 
> > On Wed, 25 Dec 2002, Sonny I Franslay wrote:
> >
> > > Hi Bill,
> > >
> > > >  and 128.0.0.0/1 will really get you into issues when you hit
> > > >  the top end of the range. the old class D & E space is not
> > > >  treated as regular address space.
> > > >
> > > >  One presumes that your environment is closed.  Doing things like
> > > >  this on the Internet will engender the rath of network engineers.
> > >
> > > What would be the difference from using a default route 0.0.0.0/0 and
> two
> > > supernets of 0.0.0.0/1 and 128.0.0.0/1? Wouldn't they cause the same
> effect?
> > > Would there be any other implications?
> > >
> > > thanks,
> > > sonny
> > > >
> > > >
> > > >
> > > > % Hi Robert,
> > > > %
> > > > % IOS ver 12.0(10)S. I've tried both commands but no effect. I believe
> > > it's
> > > > % the way cisco router treats prefix 0.0.0.0 irregardless of the
> prefixe
> > > > % length (whether /0 or /1).
> > > > % Am I right? Was hoping someone could enlighten me on this.
> > > > %
> > > > % Many thanks and Merry Xmas to everyone..
> > > > %
> > > > % sonny
> > > > % ----- Original Message -----
> > > > % From: "Robert E. Seastrom" <rs@seastrom.com>
> > > > % To: "Sonny Franslay" <sonnyfranslay@pacific.net.sg>
> > > > % Cc: <cisco-nsp@puck.nether.net>
> > > > % Sent: Wednesday, December 25, 2002 3:37 AM
> > > > % Subject: Re: [nsp] Prefix 0.0.0.0/1
> > > > %
> > > > %
> > > > % >
> > > > % > What IOS version are you running?  Is it one that's old enough
> that
> > > > % > "ip subnet-zero" is not on by default?  Try typing that and "ip
> > > > % > classless" and retrying...
> > > > % >
> > > > % >                                         ---Rob
> > > > % >
> > > > % >
> > > > % > Sonny Franslay <sonnyfranslay@pacific.net.sg> writes:
> > > > % >
> > > > % > > Hi gurus,
> > > > % > >
> > > > % > > I'm trying to redistribute a static route to dest network
> 0.0.0.0/1
> > > to
> > > > % > > OSPF. However, the prefix is not being seen as an ospf route in
> the
> > > > % > > network table.
> > > > % > >
> > > > % > > What I want to achieve is to split the default route to two /1
> > > subnet
> > > > % > > (0.0.0.0/1 and 128.0.0.0/1). I manage to import the 128.0.0.0/1
> > > routes
> > > > % > > into the ospf but not the first half.
> > > > % > >
> > > > % > > Is there any special requirement in order to do this?
> > > > % > >
> > > > % > > router ospf 100
> > > > % > >  log-adjacency-changes
> > > > % > >  redistribute connected subnets
> > > > % > >  redistribute static subnets
> > > > % > >  network 192.168.92.0 0.0.0.255 area 0
> > > > % > > !
> > > > % > > ip route 0.0.0.0 128.0.0.0 203.120.92.1
> > > > % > > ip route 128.0.0.0 128.0.0.0 203.120.92.1
> > > > % > >
> > > > % > > seen from the other router:
> > > > % > >
> > > > % > > >sho ip route ospf
> > > > % > >      10.0.0.0/24 is subnetted, 4 subnets
> > > > % > > O E2    10.140.140.0 [110/20] via 192.168.92.6, 02:10:11,
> > > > % FastEthernet0/0
> > > > % > > O E2    10.130.130.0 [110/20] via 192.168.92.6, 02:15:11,
> > > > % FastEthernet0/0
> > > > % > > O E2    10.20.20.0 [110/20] via 192.168.92.40, 02:27:02,
> > > FastEthernet0/0
> > > > % > > O E2 192.168.188.0/24 [110/20] via 192.168.92.40, 02:27:02,
> > > > % > > FastEthernet0/0
> > > > % > >      192.168.1.0/32 is subnetted, 3 subnets
> > > > % > > O E2    192.168.1.2 [110/20] via 192.168.92.6, 02:20:11,
> > > FastEthernet0/0
> > > > % > > O E2    192.168.1.6 [110/110] via 192.168.92.6, 02:25:11,
> > > > % FastEthernet0/0
> > > > % > > O E2 128.0.0.0/1 [110/20] via 192.168.92.6, 02:00:10,
> > > FastEthernet0/0
> > > > % > >
> > > > % > >
> > > > % > > Many thanks in advance
> > > > % > >
> > > > % > > sonny
> > > > % > >
> > > > % > > _______________________________________________
> > > > % > > cisco-nsp mailing list  cisco-nsp@puck.nether.net
> > > > % > > http://puck.nether.net/mailman/listinfo/cisco-nsp
> > > > % > > archive at http://puck.nether.net/pipermail/cisco-nsp/
> > > > % >
> > > > %
> > > > %
> > > > % _______________________________________________
> > > > % cisco-nsp mailing list  cisco-nsp@puck.nether.net
> > > > % http://puck.nether.net/mailman/listinfo/cisco-nsp
> > > > % archive at http://puck.nether.net/pipermail/cisco-nsp/
> > > > %
> > > >
> > > >
> > > > --
> > > > --bill
> > > >
> > > > Opinions expressed may not even be mine by the time you read them, and
> > > > certainly don't reflect those of any other entity (legal or
> otherwise).
> > > >
> > >
> > >
> > > _______________________________________________
> > > cisco-nsp mailing list  cisco-nsp@puck.nether.net
> > > http://puck.nether.net/mailman/listinfo/cisco-nsp
> > > archive at http://puck.nether.net/pipermail/cisco-nsp/
> > >
> >
> 
> 
> 



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