Single router, dual gateway, route weights/metrics

[Tekmazter]

Hi Everyone,

My design is as follows:

MPLS Cloud
|
T3 Multilink
| |
ROUTER
|
LAN

My router is a CISCO 3845. I recently installed a T3 which is now operational. However, still in place are the orginal bonded T1s which were the default gateway handling all traffic to/from the MPLS. OSPF has been setup and pointing to area 0 since the beginning.

Now I would like to make the T3 the default gateway while keeping the T1s for failover (secondary gateway). I've setup basic route metrics/weighting with the T3 having a metric of 1 and the bonded T1s (Multilink) having a metric of 254. However, where my confusion is now is how to force OSPF to update its table so that it uses the DS3 for routing into the MPLS cloud instead of the bonded T1s. Running 'clear ip ospf process' appears to dump and rebuild the OSPF routes but again they continue to point to the Multilink and not the T3.

I have not rebooted the router (very limited time to do so). Does anyone know what it is that I'm missing?

 

[North323]

can you post your config?

 

[Minue]

Hello
You can use the "ip ospf cost" on the interface to influence the routes.
Regards

 

[Tekmazter]

I'll see about posting the config.

Minue: I was under the impression that by default the IOS automatically assigns an OSPF cost value to the interface on turn-up. I've verified that my T3 does have a lower overall cost than the multilink.

Thoughts?

 

[Minue]

Hello
Well from your post it seems that the Multilink have the better metric's because OSPF is using it as the exit point.In any case when you post your conf,thing will be much clearer.Please also post the show ip route,show ip ospf,show ip ospf database etc.
Regards

 

[Tekmazter]

It was determined that my carrier had me pointing to the wrong OSPF area. Creating a new process on the router and applying that to the T3 interface (S1/0) I was able to get this going. However, this has created a new question ...

How do I force all traffic over the T3 and not load balance on this router? It appears even though I've weighted by routes ([S1/0 = 1, and Multilink1 = 254]) that traffic is traversing outbound on the T3 and inbound on the Multilink. I've pasted some of my config below:

version 12.4
!
card type t1 0 0
card type t1 0 1
card type t1 0 2
card type t3 1
!
no aaa new-model
!
resource policy
!
no network-clock-participate wic 0
no network-clock-participate wic 1
no network-clock-participate wic 2
ip subnet-zero
no ip source-route
ip cef
ip tcp synwait-time 10
!
!
controller T1 0/0/0
framing esf
linecode b8zs
channel-group 0 timeslots 1-24
!
controller T1 0/0/1
framing esf
linecode b8zs
channel-group 0 timeslots 1-24
!
controller T1 0/1/0
framing esf
linecode b8zs
channel-group 0 timeslots 1-24
!
controller T1 0/1/1
framing esf
linecode b8zs
channel-group 0 timeslots 1-24
!
controller T1 0/2/0
framing esf
linecode b8zs
channel-group 0 timeslots 1-24
!
controller T1 0/2/1
framing esf
linecode b8zs
channel-group 0 timeslots 1-24
!
controller T3 1/0
!
interface Loopback0
ip address 4.4.4.4 255.255.255.0
!
interface Multilink1
bandwidth 9264
ip address <IP removed> <Mask removed>
ip access-group 101 in
ip nbar protocol-discovery
ip flow ingress
ip flow egress
no ip mroute-cache
ip ospf network point-to-point
ip ospf 201 area 0
no cdp enable
ppp multilink
ppp multilink fragment disable
ppp multilink group 1
!
interface GigabitEthernet0/0
description Not in use
ip address <IP removed> <Mask removed>
no ip redirects
no ip unreachables
no ip proxy-arp
duplex auto
speed auto
media-type rj45
negotiation auto
no mop enabled
!
interface GigabitEthernet0/1
description $ES_LAN$$FW_INSIDE$$ETH-LAN$
bandwidth 1000000
ip address <IP removed> <Mask removed>
ip access-group 101 in
no ip redirects
no ip unreachables
no ip proxy-arp
ip accounting output-packets
ip nbar protocol-discovery
ip flow ingress
ip flow egress
ip route-cache flow
ip ospf network point-to-point
ip ospf 201 area 0
duplex auto
speed auto
media-type rj45
negotiation auto
!
no cdp enable
no mop enabled
!
interface Serial0/0/0:0
ip unnumbered Loopback0
encapsulation ppp
no keepalive
no fair-queue
no cdp enable
ppp multilink
ppp multilink group 1
!
interface Serial0/0/1:0
ip unnumbered Loopback0
encapsulation ppp
no keepalive
no fair-queue
no cdp enable
ppp multilink
ppp multilink group 1
!
interface Serial0/1/0:0
ip unnumbered Loopback0
encapsulation ppp
no keepalive
no fair-queue
no cdp enable
ppp multilink
ppp multilink group 1
!
interface Serial0/1/1:0
ip unnumbered Loopback0
encapsulation ppp
no keepalive
no fair-queue
no cdp enable
ppp multilink
ppp multilink group 1
!
interface Serial0/2/0:0
ip unnumbered Loopback0
encapsulation ppp
no keepalive
no fair-queue
no cdp enable
ppp multilink
ppp multilink group 1
!
interface Serial0/2/1:0
ip unnumbered Loopback0
encapsulation ppp
no keepalive
no fair-queue
no cdp enable
ppp multilink
ppp multilink group 1
!
interface Serial1/0
description T3 Interface
ip address <IP removed> <Mask removed>
ip access-group 101 in
ip nbar protocol-discovery
ip flow ingress
ip flow egress
no ip mroute-cache
ip ospf network point-to-point
ip ospf 200 area 1
dsu bandwidth 44210
no cdp enable
!
router ospf 201
log-adjacency-changes
network 10.x.x.x x.x.x.255 area 0
network 10.x.x.x x.x.x.255 area 0
!
router ospf 200
log-adjacency-changes
network 10.x.x.x x.x.x.255 area 1
network 10.x.x.x x.x.x.255 area 1
!
ip classless
ip route 0.0.0.0 0.0.0.0 <S1/0 IP removed>
ip route 0.0.0.0 0.0.0.0 <Multilink1 IP Removed> 254

 

[Tekmazter]

I'm starting to think this is a carrier issue as well, but feel free to chime in if anyone has thoughts around this.

Thanks much!

 

[Minue]

I would say the problem is with the carrier.You should tell the them about this issue,because there's not anything that you can do the influence the return traffic.
Regards

 

[burtsbees]

Do you still need OSPF 201, or is the multilink also supposed to be area 1 of OSPF 200?

Burt

 

[Tekmazter]

I spoke with the carrier. There are numerous issues here (all on behalf of the carrier). There is some history here but I will give everyone the nutshell point of view ...

Area 1 should not be used but when Area 0 wasn't working I was told to use it. Area 1 is not supposed to be able to talk to Area 0 --this has the carrier baffled as they are talking just fine.

Remediation from the carrier is to collapse everyone into Area 0 and then look to leverage BGP and get off of OSFP. I guess BGP is being used inside the cloud, but from CPE to PER its OSPF.

Anyway, it's definitely a carrier issue and thank you for all of your help.