From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Wed Aug 09 2006 - 12:25:47 ART
Here's an example of OSPF forming adjacency when it's not on the same
subnet as its connected neighbor. R1 and R3 are connected via a PPP
serial link:
R1#
interface Loopback0
ip address 150.1.1.1 255.255.255.255
!
interface FastEthernet0/0
ip address 10.1.1.1 255.255.0.0
!
interface Serial0/1
ip unnumbered Loopback0
encapsulation ppp
!
router ospf 1
network 0.0.0.0 255.255.255.255 area 0
R3#
interface Loopback0
ip address 150.1.3.3 255.255.255.255
!
interface Ethernet0/0
ip address 10.3.3.3 255.255.0.0
!
interface Serial1/2
ip unnumbered Loopback0
encapsulation ppp
clockrate 64000
!
router ospf 1
network 0.0.0.0 255.255.255.255 area 0
R1#show ip route
Codes: C - connected, S - static, 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
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS
inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
10.0.0.0/16 is subnetted, 2 subnets
O 10.3.0.0 [110/74] via 150.1.3.3, 00:00:50, Serial0/1
C 10.1.0.0 is directly connected, FastEthernet0/0
150.1.0.0/32 is subnetted, 2 subnets
C 150.1.3.3 is directly connected, Serial0/1
C 150.1.1.1 is directly connected, Loopback0
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address
Interface
150.1.3.3 0 FULL/ - 00:00:38 150.1.3.3
Serial0/1
R1#ping 150.1.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/29/32 ms
R1#ping 10.3.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/29/32 ms
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
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> -----Original Message-----
> From: Schulz, Dave [mailto:DSchulz@dpsciences.com]
> Sent: Tuesday, August 08, 2006 9:25 PM
> To: Brian McGahan; Olopade Olorunloba; Cisco certification
> Subject: RE: Routing through a ppp ipcp negotiated interface
>
> Brian -
>
> Actually, the RIP works fine. However, OSPF does not. Someone
> mentioned that this was due to the peer neighbor route, which shows up
> as a connected route (not a subnet issue). Therefore the routing
> protocol won't build its adjancency (since it is connected). Do you
see
> it this way?
>
>
> Dave Schulz,
> Email: dschulz@dpsciences.com
>
>
> -----Original Message-----
> From: Brian McGahan [mailto:bmcgahan@internetworkexpert.com]
> Sent: Tuesday, August 08, 2006 1:53 PM
> To: Olopade Olorunloba; Schulz, Dave; Cisco certification
> Subject: RE: Routing through a ppp ipcp negotiated interface
>
> OSPF does not require devices to be on the same subnet to
> establish adjacency, so it should work fine. In RIP this behavior can
> be disabled with the "no validate-update-source" process level
command.
>
>
> HTH,
>
> Brian McGahan, CCIE #8593
> bmcgahan@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987 x 705
> Outside US: 775-826-4344 x 705
> 24/7 Support: http://forum.internetworkexpert.com
> Live Chat: http://www.internetworkexpert.com/chat/
>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > Olopade Olorunloba
> > Sent: Tuesday, August 08, 2006 12:37 PM
> > To: 'Schulz, Dave'; 'Cisco certification'
> > Subject: RE: Routing through a ppp ipcp negotiated interface
> >
> > OSPF does not form because the mask negotiated is a host route, and
> > therefore the router believes that the remote end is not on the same
> > subnet.
> >
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > Schulz, Dave
> > Sent: 04 August 2006 21:41
> > To: Cisco certification
> > Subject: Routing through a ppp ipcp negotiated interface
> >
> > I discovered something interesting while setting up a network in my
> lab
> > with using ppp ipcp to negotiate the address across a serial link.
In
> > the following scenario, the address is negotiated fine. However, I
am
> > trying to run the various protocols across the link. EIGRP, but RIP
> > will not allow the database to be received at the router with the
> > negotiated interface. OSPF will not allow the adjacency to form.
> > BTW....I can get the routes to be sent from the negotiated interface
> to
> > the remote (negotiating) interface of the remote router. I am just
> > trying things and investigating ....so this may not be valid to do
> this.
> > Just wondering why EIGRP works in this way, but OSPF and RIP do not.
> > Thoughts?
> >
> > On RIP...I get the following debug error.....(I tried this both
> > multicast and unicast updates, with no difference).
> >
> > *Mar 16 11:07:12.927: RIP: ignored v2 update from bad source
25.5.5.5
> on
> > Serial0/1
> >
> > Here are the configs at the interface level......
> >
> > R3.....
> >
> > !
> > interface Serial1
> > ip address negotiated
> > encapsulation ppp
> > end
> >
> >
> > R5......
> > !
> > interface Serial0/1
> > ip address 35.5.5.5 255.255.255.0
> > encapsulation ppp
> > peer default ip address 35.5.5.3
> > clock rate 2000000
> > end
> >
> >
> >
> > Dave Schulz, CCDP, CCNP, CCSP
> > Email: dschulz@dpsciences.com <mailto:dschulz@dpsciences.com >
> >
> >
>
This archive was generated by hypermail 2.1.4 : Fri Sep 01 2006 - 15:41:56 ART