From: Derek Fage (DerekF@xxxxxxxxxxx)
Date: Thu Jun 17 1999 - 05:46:16 GMT-3
Srikanth,
All then network statement does is to tell OSPF the address range(s) to use
to select interfaces for use with OSPF. To aid with debugging, and also to
try to reduce errors, I generally use specific masks to identify the
interfaces that I want to have included in OSPF.
For example, network 172.16.1.0 0.0.0.255 area 0 will cause OSPF to look for
all interfaces with IP addresses in this range for inclusion in OSPF, but
network 172.16.1.1 0.0.0.0 will only include the interface that has the
specific address.
Some people confuse the network statement with an area range statement, but
it is only used for identify interfaces valid for OSPF.
Derek...
> -----Original Message-----
> From: Srikanth Nagarajan [SMTP:nsrikanth@hotmail.com]
> Sent: 17 June 1999 14:58
> To: brife@bignet.net
> Cc: ccielab@groupstudy.com
> Subject: Re: OSPF and Loopback intf.
>
>
> Hi Ben,
>
> Iam trying to understand in your config for ospf, you have specified:
>
> network 172.16.1.146 0.0.0.0 area 0
>
> Normally, when you specify the networks onto which you want to run OSPF
> you
> specify the network address and the mask so that all the networks n which
> you want run ospf on are covered.
>
> What is the significance of your specifying a host address 172.16.1.146
> with
> mask 0.0.0.0 ?
>
> Pl clarify
>
> Thanks in advance
> Srikanth N
>
>
>
> >From: "Robert Caamano" <rcaamano@rpm.com>
> >Reply-To: "Robert Caamano" <rcaamano@rpm.com>
> >To: "Ben Rife" <brife@bignet.net>
> >CC: <ccielab@groupstudy.com>
> >Subject: Re: OSPF and Loopback intf.
> >Date: Wed, 16 Jun 1999 20:15:54 -0400
> >
> >Ben,
> >
> >The answer to your question is this:
> >
> >By default OSPF treats Loopback interfaces differently than a regular
> >interface in that it
> >considers it a stub host. You will notice that you have a route that has
> a
> >/32 mask
> >(172.16.1.161/32). This address is the primary Loopback address and the
> >only Loopback address
> >advertised by default. OSPF advertises it this way to identify that it
> is
> >a
> >stub host interface.
> >
> >Here's how you make it work
> >
> > type the following
> >
> >#conf t
> >(config)#int lo0
> >(config-if)#ip ospf netw point-to-point
> >
> >This will make ospf see the loopback interface as a point to point
> network
> >instead of a stub host
> >and will then allow normal rules for secondary interface advertizment
> >apply.
> >
> >
> >-----Original Message-----
> >From: Ben Rife <brife@bignet.net>
> >To: Rick Burts <burts@ccci.com>
> >Cc: ccielab@groupstudy.com <ccielab@groupstudy.com>
> >Date: Wednesday, June 16, 1999 11:50 AM
> >Subject: Re: OSPF and Loopback intf.
> >
> >
> > >I just can't get this to work. My secondary networks on the loopback on
> > >r2520 will not show up in the route table of r2503. Here is my OSPF and
> > >Loopback configs....
> > >
> > >Router 2503
> > >
> > >r2503#sh run
> > >Building configuration...
> > >
> > >Current configuration:
> > >!
> > >version 11.2
> > >no service password-encryption
> > >no service udp-small-servers
> > >no service tcp-small-servers
> > >!
> > >hostname r2503
> > >!
> > >!
> > >no ip domain-lookup
> > >isdn switch-type basic-ni1
> > >!
> > >interface Ethernet0
> > > ip address 192.168.40.2 255.255.255.0
> > >!
> > >interface Serial0
> > > ip address 172.16.1.146 255.255.255.240
> > >!
> > >interface Serial1
> > > no ip address
> > > clockrate 64000
> > >!
> > >interface BRI0
> > > no ip address
> > > isdn spid1 0835866101 8358661
> > > isdn spid2 0835866301 8358663
> > >!
> > >router ospf 10
> > > network 172.16.1.146 0.0.0.0 area 0
> > >!
> > >no ip classless
> > >!
> > >!
> > >line con 0
> > >line aux 0
> > >line vty 0 4
> > > login
> > >!
> > >end
> > >
> > >
> > >
> > >
> > >Router 2520
> > >
> > >
> > >r2520#sh run
> > >Building configuration...
> > >
> > >Current configuration:
> > >!
> > >version 11.2
> > >no service password-encryption
> > >no service udp-small-servers
> > >no service tcp-small-servers
> > >!
> > >hostname r2520
> > >!
> > >!
> > >no ip domain-lookup
> > >!
> > >interface Loopback0
> > > ip address 172.16.1.225 255.255.255.240 secondary
> > > ip address 172.16.1.193 255.255.255.240 secondary
> > > ip address 172.16.1.129 255.255.255.240 secondary
> > > ip address 172.16.1.161 255.255.255.240
> > >!
> > >interface Ethernet0
> > > no ip address
> > >!
> > >interface Serial0
> > > no ip address
> > > shutdown
> > > no fair-queue
> > >!
> > >interface Serial1
> > > no ip address
> > > shutdown
> > > clockrate 56000
> > >!
> > >interface Serial2
> > > ip address 172.16.1.145 255.255.255.240
> > > bandwidth 1544
> > > clockrate 56000
> > >!
> > >interface Serial3
> > > no ip address
> > > shutdown
> > >!
> > >interface BRI0
> > > no ip address
> > > shutdown
> > >!
> > >router ospf 10
> > > network 172.16.1.161 0.0.0.0 area 0
> > > network 172.16.1.225 0.0.0.0 area 0
> > > network 172.16.1.129 0.0.0.0 area 0
> > > network 172.16.1.193 0.0.0.0 area 0
> > > network 172.16.1.145 0.0.0.0 area 0
> > >!
> > >no ip classless
> > >lat service ABLE password CISCO
> > >!
> > >!
> > >line con 0
> > >line aux 0
> > >line vty 0 4
> > > login
> > >!
> > >end
> > >
> > >
> > >
> > >
> > >Route table of r2503
> > >
> > >r2503#sh ip route
> > >Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B -
> BGP
> > > D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> > > N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> > > E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> > > i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate
> > >default
> > > U - per-user static route, o - ODR
> > >
> > >Gateway of last resort is not set
> > >
> > >C 192.168.40.0/24 is directly connected, Ethernet0
> > > 172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
> > >O 172.16.1.161/32 [110/65] via 172.16.1.145, 00:05:15, Serial0
> > >C 172.16.1.144/28 is directly connected, Serial0
> > >
> > >
> > >
> > >Thanks for any help you can provide,
> > >
> > >Ben Rife
> > >CCIE Candidate
> > >
> > >
> > >
> >
>
>
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