trying to change one route on one router but its changes other routers as well ( EIGRP )

dschneidermars1 · ‎12-12-2016

I have a test router setup and I want traffic from that subnet to travel to a DR router and our a seperate DR connection. However when I make the ip route chance on the test router and the Dr router to pass traffic to a specific DR connection all the routers in the organization get that change. I dont want their traffic changing. The current config is below. I want all traffic for route 172.16.24.0/29 on the test network to go to 10.0.100.101. And from that router go to 10.0.1.243. How would i make static route changes to the test router and DR router without affecting every other router?

interface FastEthernet0/0
description MPLS Interface
ip address 10.0.100.109 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet0/1
description Risk Office LAN
ip address 10.0.9.253 255.255.255.0
ip flow ingress
duplex auto
speed auto
!
interface Serial0/3/0
no ip address
encapsulation frame-relay
no arp frame-relay
no frame-relay inverse-arp
frame-relay lmi-type ansi
!
interface Serial0/3/0.1 point-to-point
description P-t-P interface to Mars
ip address 10.0.5.18 255.255.255.252
frame-relay interface-dlci 711
!
interface Serial0/3/0.2 point-to-point
description P-t-P interface to Richland
ip address 10.0.5.34 255.255.255.252
frame-relay interface-dlci 710
!
!
router eigrp 1
network 10.0.0.0
network 10.0.6.0 0.0.0.255
network 10.0.100.0 0.0.0.255
neighbor 10.0.100.107 FastEthernet0/0
neighbor 10.0.100.103 FastEthernet0/0
neighbor 10.0.100.104 FastEthernet0/0
neighbor 10.0.100.102 FastEthernet0/0
neighbor 10.0.100.101 FastEthernet0/0
neighbor 10.0.100.100 FastEthernet0/0
neighbor 10.0.100.108 FastEthernet0/0
passive-interface default
no passive-interface FastEthernet0/0
eigrp router-id 10.0.9.253
!
router rip
version 2
passive-interface FastEthernet0/0
network 10.0.0.0
no auto-summary
!
ip forward-protocol nd
!
ip flow-export source FastEthernet0/0
ip flow-export version 9
ip flow-export interface-names
ip flow-export destination 10.0.0.78 2255
!
ip http server
ip http authentication local
no ip http secure-server
ip dns server
ip route 10.20.96.0 255.255.255.0 10.0.100.100
ip route 10.204.96.0 255.255.255.0 10.0.100.100
ip route 172.16.24.0 255.255.255.248 10.0.100.101
ip route 172.16.31.82 255.255.255.255 10.0.100.100
ip route 192.152.100.106 255.255.255.255 10.0.0.230
ip route 199.43.0.0 255.255.255.0 10.0.100.100
ip route 204.103.0.0 255.255.255.0 10.0.100.100
!
!
logging trap debugging
logging source-interface FastEthernet0/1
logging 10.0.0.242
!

Richard Burts · ‎12-12-2016

I believe that we need additional information to be able to give you good advice about your issue. I have looked at the config that is posted and I do not see anything that would send changes about that route to other routers in the network. You mention making changes on two routers and show us one config without indicating which router it is from. So perhaps we need to see the config of the other router and that might help us understand what is sending the changes.

It also occurs to me that we might need some clarification of what the problem really is. You describe the problem as being that routing changes are sent to all the routers in the network. I begin to wonder if that is really the case. Can you tell us from one of the other routers in the network what changes you observe in its routing table? (it would be especially helpful if you could post the output of show ip route (or some subset of that output if it is large) that shows the route for 172.16.24.0 before the change and for that prefix after the change.

Or perhaps it is not so much that all the routing tables change but is that the results of forwarding traffic change. Perhaps you could post the output of traceroute to an address in 172.16.24.0 from one of the other routers in the network before the change and the traceroute from that router after the change?

HTH

Rick

HTH

Rick

dschneidermars1 · ‎12-13-2016

So if I make a change to a route it should not change on any other routers through EIGRP correct?

dschneidermars1 · ‎12-13-2016

On the test router I need to change this route

D EX 172.16.24.0/21 [170/30720] via 10.0.100.100, 3d19h, FastEthernet0/0 to this

D EX 172.16.24.0/21 [170/30720] via 10.0.100.101, 3d19h, FastEthernet0/0

And on the 10.0.100.101 router I need to change this router

S 172.16.24.0/21 [1/0] via 10.0.100.100 TO THIS

S 172.16.24.0/21 [1/0] via 10.0.1.243

My question is if I make these changes will this affect other routers? also what does the S mean and the D EX mean?

dschneidermars1 · ‎12-13-2016

I Tried to remove the route 172.16.24.0 255.255.248.0 10.0.100.100 which I see in the routing table but when I try and remove it states that there is no matching route which I don't understand

D EX     172.16.24.0/21 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
S        172.16.24.0/29 [1/0] via 10.0.100.101
      192.152.100.0/32 is subnetted, 2 subnets
D EX     192.152.100.99 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
S        192.152.100.106 [1/0] via 10.0.0.230
D EX 192.168.1.0/24 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
D EX 192.168.2.0/24 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
D EX 192.168.3.0/24 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
D EX 192.168.11.0/24 [170/335360] via 10.0.100.101, 3d20h, FastEthernet0/0
D EX 192.168.12.0/24 [170/335360] via 10.0.100.101, 3d20h, FastEthernet0/0
D EX 192.168.13.0/24 [170/335360] via 10.0.100.101, 3d20h, FastEthernet0/0
D EX 192.168.21.0/24 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
D EX 192.168.22.0/24 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
D EX 192.168.23.0/24 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
D EX 192.168.224.0/24 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
S     199.43.0.0/24 [1/0] via 10.0.100.100
S     204.103.0.0/24 [1/0] via 10.0.100.100
      206.123.251.0/32 is subnetted, 1 subnets
D EX     206.123.251.234 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
      208.75.4.0/24 is variably subnetted, 2 subnets, 2 masks
D EX     208.75.4.0/24 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
D EX     208.75.4.144/29 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
      208.87.15.0/24 is variably subnetted, 3 subnets, 3 masks
D EX     208.87.15.0/24 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
D EX     208.87.15.0/25 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
D EX     208.87.15.128/26 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
RiskRouter#
RiskRouter#
RiskRouter#CONFIG T
Enter configuration commands, one per line. End with CNTL/Z.
RiskRouter(config)#NO IP ROUTE 172.16.24.0 255.255.248.0 10.0.100.100
%No matching route to delete
RiskRouter(config)#

Richard Burts · ‎12-13-2016

There are several things in this thread to address.

- your comment saying "So if I make a change to a route it should not change on any other routers through EIGRP correct?" is overly broad and when stated this way is not correct. There are some routes where changes would be propagated to other routers and some routes where changes would not be propagated. If a static route is being redistributed into EIGRP or if it matches a network statement in EIGRP then changes in the static route would be propagated to other routers. What I was trying to say is that the particular route on that router that you were talking about for 172.16.24.0 does not match either of those conditions and so I would not expect changes in it to be propagated to other routers.

- in the output of the routing table the S indicates that this is a local static route. D EX in the output of the routing table means that this route was dynamically leaned by EIGRP and that the original route was redistributed into EIGRP.

When you have an S static route it is possible to change that route on that router. Whether that change affects other routers depends on whether EIGRP will learn that route and advertise it (as I described above).

When you have a D EX route it is not possible to change that route on this router. You might be able to change it on the router where the redistribution is done, and you might be able to change some things about how EIGRP advertises the route.

- the content that you post from the routing table is interesting. Note that you have two entries for 172.16.24.0.

D EX 172.16.24.0/21 [170/30720] via 10.0.100.100, 3d20h, FastEthernet0/0
S 172.16.24.0/29 [1/0] via 10.0.100.101

One entry is /21 and is dynamically learned by EIGRP. This would include addresses 172.16.24.0 through 172.16.31.255.

The other entry is /29 and is a local static route. This would include addresses 172.16.24.0 through 172.16.24.7.

So there is overlap between these entries. If a packet came to the router to be forwarded and matched the more specific /29 it would be forwarded toward 10.0.100.101. If the packet did not match the /29 but did match the larger /21 then it would be forwarded toward 10.0.100.100.

- when you attempted to remove the route you were attempting to remove the dynamically learned /21 (with mask 255.255.248.0). But you can not remove the dynamically learned route using the way that you tried. You could have removed the /29 since it is a local route.

I hope that these explanations are helpful. I do not understand well enough the topology of your network or what you are attempting to accomplish to be able to offer much advice about how to accomplish it. If you can provide some clarification then perhaps we might find a solution.

HTH

Rick

HTH

Rick