IP SLA Track and Default Route

bolds04 · ‎01-30-2014

Hello Experts,

I have a qustion for all of you one IP SLA Tracking. I have been trying to figure this one out for a couple of days and it's bugging me. I am trying to do a simple failover between ISP 1 and ISP 2. Issue is they are not on the same router but separated between a Point-to-Point connection.

The drawing is what is in production, what I have in my configs is a dumbed down version in my lab using 5 different 1800s.

Here's my configs:

LOC_A

!

track 1 ip sla 1 reachability

delay down 5 up 1

!

track 2 ip sla 2 reachability

delay down 5 up 1

!

interface FastEthernet0/0

ip address 192.168.1.1 255.255.255.0

duplex auto

speed auto

!

interface Serial0/0/0:1

ip address 10.250.240.5 255.255.255.252

encapsulation ppp

!

router eigrp 1

redistribute static route-map ROUTE

network 10.250.240.4 0.0.0.3

network 10.250.240.8 0.0.0.3

network 10.250.240.12 0.0.0.3

network 192.168.1.0

no auto-summary

!

ip forward-protocol nd

ip route 0.0.0.0 0.0.0.0 192.162.1.254 2 track 1

ip route 0.0.0.0 0.0.0.0 192.168.3.254 3 track 2

ip route 0.0.0.0 0.0.0.0 192.168.1.254 5

ip http server

no ip http secure-server

!

ip sla 1

icmp-echo 12.249.198.237 source-ip 192.168.1.1

timeout 1000

threshold 2

frequency 5

ip sla schedule 1 life forever start-time now

ip sla 2

icmp-echo 8.8.8.8

frequency 10

ip sla schedule 2 life forever start-time now

access-list 101 permit icmp host 192.168.1.1 host 12.249.198.237

disable-eadi

!

route-map IP_SLA_PINEBLUFF permit 10

match ip address 101

set ip next-hop 192.168.1.254

!

route-map ROUTE permit 10

match ip address 101

set ip next-hop 192.168.1.254

!

LOC B

!

track 1 ip sla 1 reachability

!

interface FastEthernet0/0

ip address 192.168.3.1 255.255.255.0

duplex auto

speed auto

!

interface FastEthernet0/1

no ip address

shutdown

duplex auto

speed auto

!

interface Serial0/0/0:1

no ip address

encapsulation ppp

!

interface Serial0/0/1:1

ip address 10.250.240.6 255.255.255.252

encapsulation ppp

!

router eigrp 1

redistribute static

network 10.250.240.4 0.0.0.3

network 10.250.240.8 0.0.0.3

network 10.250.240.12 0.0.0.3

network 192.168.3.0

no auto-summary

!

ip forward-protocol nd

ip route 0.0.0.0 0.0.0.0 192.168.3.254 250 track 1

ip http server

no ip http secure-server

!

ip sla 1

icmp-echo 12.249.198.237 source-ip 192.168.3.1

timeout 1000

threshold 2

frequency 5

ip sla schedule 1 life forever start-time now

access-list 101 permit icmp host 192.168.3.1 host 12.249.198.237

disable-eadi

!

route-map IP_SLA permit 10

match ip address 101

set ip next-hop 192.168.3.254

!

route-map ROUTE permit 10

match ip address 101

set ip next-hop 192.168.3.254

!

I have tried this several differnet ways. I've tried it without IP SLA commands on LOC B router as well as several different scenarios of the config.

The main issue is I can get the tracks on LOC A to work, but the defaultt route never gets distributed to LOC B router. The route bounces back and forth in a loop between the two P2P interfaces.

Any ideas on I can do to fix it?

I've read a hundred different postings, web blogs as well as Cisco Press books but can't find the one correct config that makes it all work.

Thanks. Brandon

John Blakley · ‎01-30-2014

Brandon,

Can you tell us exactly how you want the traffic to flow? I see your diagram, but what's supposed to happen should Location A lose the Internet circuit? Is the "Outside" interface on the left side of the topology a firewall that shouldn't be taken into consideration for this issue? I can lab this up if needed, but I need to figure out what you're wanting to happen

What is the default gateway for users on the right side? Are they using 192.168.3.1 or .254, or is there pbr on the switch?

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***

bolds04 · ‎01-30-2014

John,

Traffic is to flow out the Primary Internet at Location A. In the event that circuit goes down, I would like to roll traffic to Location B internet. So on my Production router I have both Internet and Private P2P connections. To segment them, I did VRF-Lite so that I could have Public Internet and Private on the same router, that's why you see the FW in the diagram. It has a Default route to the FW Inside address.

Ip route 0.0.0.0 0.0.0.0 192.168.1.254 <-- Private traffic to FW

ip route vrf INT_VRF 0.0.0.0 0.0.0.0 Multilink1 <-- Internet Pipe

Now that's production configs.

My lab configs are almost the same just dumbed it down a little. I shut down the Interface Internet interface (within my lab) to simulate an outage. I can watch the track statements kick in and change the default route to 192.168.3.254. The problem is Location B never gets updated and still has its default route pointing to 10.250.240.5 (Location A). So the traffic just bounces back and forth in a loop.

Hope I cleared up what you was asking. Let me know if I answered your question. Thanks, Brandon

John Blakley · ‎01-30-2014

Brandon,

How does your Location B get its default route now? From what I'm seeing, I see a static route to the 192.168.3.254 as a next hop, so I would assume that's in your routing table unless you're learning the default from somewhere else. I don't see where you're advertising a default at A.

Thanks,

John

HTH, John *** Please rate all useful posts ***

bolds04 · ‎01-30-2014

John,

To be honest I've changed it so many times I don't really think I am in this config. That's one of my issues. I've tried it with floating static routes along with the default route with the track statement.

IE.

Ip route 0.0.0.0 0.0.0.0 192.168.1.254 10

Ip route 0.0.0.0 0.0.0.0 192.168.3.254 200

If I do this it still gets stuck on Location B on the P2P connection.

Thoughts?

John Blakley · ‎01-30-2014

So, you want Location B to go over the P2P link towards location A unless location A loses it's link? If it loses the link, you want it to go out of it's own local internet and have location A use location B's internet as well? I'm labbing this as we speak...

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***

bolds04 · ‎01-30-2014

Correct. Location A is the primary Internet connection with the bigger pipe. If it drops all traffic is then sent to Location B Internet pipe.

FYI I don't have to use EIGRP if that helps.

Thanks. Brandon

John Blakley · ‎01-30-2014

Brandon,

I was able to get this to work, but I'm not sure if it's the same type of setup you have. I have three routers laid out in a triangle. The top router is serving as the ISP and has a loopback address of 1.1.1.1/24. I have the 2nd router at the bottom left and it has a default route pointing to R1 and a floating route pointing to R3 (bottom right) pointing to the p2p subnet of 192.168.23.0/24. I'm sharing the 192.168.23.0/24 between R2 and R3:

R1

/ \

R2 ---- R3

SLA is configured on R2 and R3:

R2:

ip sla 1

icmp-echo 172.12.0.1 source-interface FastEthernet0/0

ip sla schedule 1 life forever start-time now

track 1 rtr 1 reachability

ip route 0.0.0.0 0.0.0.0 172.12.0.1 track 1

ip route 0.0.0.0 0.0.0.0 192.168.23.3 254

R3:

track 1 rtr 1 reachability

ip route 0.0.0.0 0.0.0.0 192.168.23.2 track 1

ip route 0.0.0.0 0.0.0.0 172.13.0.1 254

ip sla 1

icmp-echo 1.1.1.1 source-interface FastEthernet0/1

frequency 5

ip sla schedule 1 life forever start-time no

1.1.1.1 resides on R1 to simulate a host on the internet. When I shut the interface that leads toward R1, R2 tracking fails and points the default route to 192.168.23.3 on R3. R3 cannot ping 1.1.1.1 any longer because the wan circuit on R2 is shut, so it drops the 192.168.23.2 route and adds the default route that points out of the wan interface that leads to R1.

I am running eigrp between these routers btw...

HTH,

John

HTH, John *** Please rate all useful posts ***

bolds04 · ‎01-30-2014

Okay I'll try this. Shoot me exactly how you have EIGRP on both routers so I'll have the whole config.

John Blakley · ‎01-31-2014

It was a basic eigrp config:

R2:

router eigrp 100

no auto

network 192.168.23.0

network 172.12.0.0 0.0.0.255

R3:

router eigrp 100

network 172.13.0.0 0.0.0.255

network 192.168.23.0

no auto-summary

The 172.12.0.0/24 and 172.13.0.0/24 are the wan interfaces that lead to R1.

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***

bolds04 · ‎01-31-2014

John

Wanted to let you know I solved it. Remember I said I kept getting stuck in a routing loop on my P2P connection. So it finally came to me while I was debugging earlier this morning. If I make both routers ping the same IP on the outside and both remove the default route and point to where it needs to go on Location B network, then they both get updated and traffic flows as it should. Once the link comes up, the routes fail back to where they were....

Here's my final config:

LOCATION A

!

track 1 ip sla 1 reachability

delay down 10 up 1

!

interface FastEthernet0/0

ip address 192.168.1.1 255.255.255.0

!

interface Serial0/0/0:1

ip address 10.250.240.5 255.255.255.252

encapsulation ppp

!

router eigrp 1

network 10.250.240.4 0.0.0.3

network 10.250.240.8 0.0.0.3

network 10.250.240.12 0.0.0.3

network 192.168.1.0

no auto-summary

!

THESE TWO LINES ARE WHAT MAKES IT WORK OR NOT

ip route 0.0.0.0 0.0.0.0 192.168.1.254 100 track 1

ip route 0.0.0.0 0.0.0.0 192.168.3.254 254

!

ip sla 1

icmp-echo 12.249.198.237 source-interface FastEthernet0/0

timeout 1000

threshold 2

frequency 3

ip sla schedule 1 life forever start-time now

****************************************************************************************************************

LOCATION B

!

track 1 ip sla 1 reachability

delay down 10 up 1

!

interface FastEthernet0/0

ip address 192.168.3.1 255.255.255.0

!

interface Serial0/0/1:1

ip address 10.250.240.6 255.255.255.252

encapsulation ppp

!

router eigrp 1

network 10.250.240.4 0.0.0.3

network 10.250.240.8 0.0.0.3

network 10.250.240.12 0.0.0.3

network 192.168.3.0

no auto-summary

!

THESE TWO LINES ARE WHAT MAKES IT WORK

ip route 0.0.0.0 0.0.0.0 192.168.1.254 100 track 1

ip route 0.0.0.0 0.0.0.0 192.168.3.254 254

ip sla 1

icmp-echo 12.249.198.237 source-interface FastEthernet0/0

threshold 2

ip sla schedule 1 life forever start-time now

Thanks for your help....

John Blakley · ‎01-31-2014

Glad to hear you got it working!

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***