From: Elias Chari (elias.chari@gmail.com)
Date: Thu Dec 07 2006 - 19:57:30 ART
James,
I think this is what you have probably encountered.
Here is the problem replicated (below) with Frame Relay which is sometimes a
bit more difficult to spot. R5 is learning on its serial interface via InARP
remote router's IP address. R5 has ip address 162.1.0.5/25 configured on its
serial. One of the remote routers has 4.4.4.0/24. Both routers run eigrp. R4
and R5 have a PVC between them and that is how this mapping occurs. I have
seen things like this happening also with OSPF p-2-m where the spokes become
fully adjacent. When you do vendor practice labs the FR switches are pretty
much fully meshed, so you will come across these kind of issues.
You can disable inARP or create a FR sub i/f and move the offending DLCI's
to that.
Rack1R5#sr int s0/0
Building configuration...
Current configuration : 253 bytes
!
interface Serial0/0
ip address 162.1.0.5 255.255.255.0
ip hello-interval eigrp 1 1
encapsulation frame-relay
frame-relay map ip 162.1.0.3 503 broadcast
frame-relay lmi-type ansi
end
Rack1R5#sh frame-relay map
Serial0/0 (up): ip 4.4.4.4 dlci 504(0x1F8,0x7C80), dynamic,
broadcast,, status defined, active
Serial0/0 (up): ip 162.1.0.3 dlci 503(0x1F7,0x7C70), static,
broadcast,
CISCO, status defined, active
Serial0/0 (up): ip 162.1.0.4 dlci 504(0x1F8,0x7C80), dynamic,
broadcast,, status defined, active
Rack1R5#
*Mar 1 00:19:11.495: IP-EIGRP(Default-IP-Routing-Table:1): Neighbor
4.4.4.4not on common subnet for Serial0/0
*Mar 1 00:20:04.197: IP-EIGRP(Default-IP-Routing-Table:1): Neighbor
4.4.4.4not on common subnet for Serial0/0
*Mar 1 00:20:59.720: IP-EIGRP(Default-IP-Routing-Table:1): Neighbor
4.4.4.4not on common subnet for Serial0/0
On 12/7/06, James Ko <bacchus21@gmail.com> wrote:
>
> Hello, Brian.
>
> Thank you so much for your reply and advice.
> According to your message, it seems to me that this error message is more
> related with EIGRP hello, not subnet problem.
>
> What's the difference between hellos being received across a LAN and
> hellos
> being received across a LAN ?
>
> Is it alright if I get back to you when I get more detailed information?
>
> Thanks in advance!!
>
>
> 2006/12/8, Brian Dennis <bdennis@internetworkexpert.com>:
> >
> > Are the EIGRP hellos being received across a LAN or WAN interface? If
> > it's a WAN interface then you may have a remote router with a L3 to L2
> > mapping to the router in question that is sending the EIGRP hellos. If
> > it's a LAN interface then possibly another router with EIGRP enabled is
> > in the same VLAN.
> >
> > When trying to solve this issue you should look at all routers with any
> > "possible" connection to the router in question.
> >
> > HTH,
> >
> > Brian Dennis, CCIE4 #2210 (R&S/ISP-Dial/Security/SP)
> > bdennis@internetworkexpert.com
> >
> > Internetwork Expert, Inc.
> > http://www.InternetworkExpert.com <http://www.internetworkexpert.com/>
> > Toll Free: 877-224-8987
> > Direct: 775-745-6404 (Outside the US and Canada)
> >
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > James Ko
> > Sent: Thursday, December 07, 2006 7:43 AM
> > To: ccielab@groupstudy.com
> > Subject: Not on common subnet in EIGRP
> >
> > Hello, all.
> >
> > Does anyone know about 'Not on common subnet' in EIGRP?
> > I know if an EIGRP neighbor is located in different subnet, the message
> > will
> > appear.
> > But, I can't find any configuration mistakes. Is there any other
> > possibilities causing the message?
> >
> > One piece of advice will save me a lot.
> > Thanks in advance!!
> >
> > _______________________________________________________________________
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