topic Ok thanks that makes sense, in Routing and SD-WAN

Route-Maps and interface Tracking

NeilGouws — Tue, 05 Mar 2019 10:28:01 GMT

Hoping to find a better solution with the implementation of Route-Maps, any advice will be appreciated

Here is the scenario

I am running Cisco 887VAG routers, which gives you an ADSL connection & a Cellular (3G) connection.

In my scenario the ADSL connection is the preferred connection & the 3G is the backup connection.

PBR allows for Office365 traffic to break out "locally" on the above interfaces, while WAN traffic goes over DMVPN tunnels.

There are no default routes.

Both the ADSL and 3G get dynamically assigned IPs by the respective ISPs, based on that, I don't know what the next hop will be.

If i knew what the next hop would be I could do tracking, & based on availiblilty I could set the next hop.

NAT is configured and working, for both the Dialer (ADSL) and Cellular interface

Because I don't know what the next hop is, I have to set the interface to send traffic to

So here's the other config option :

interface Vlan1

ip policy route-map LOCAL-BREAK-OUT
!
route-map LOCAL-BREAK-OUT permit 10
match ip address O365traffic
set interface Dialer1 Cellular0

Now this is all good & well, it works 100% while the ADSL connection is UP.

in theory, if Dialer1 goes down then the next interface that will be used is Cellular)

1 thing to note, the Dialer interface is Virtual, so even if the ADSL connection goes down, the Dialer interface is still up. So the route-map will continue to try and forward tracking to the Dialer interface, even if the ADSL is down.

I thought about applying tracking to the Dialer interface in the route-map, but for some reason (REALLY CISCO ???) you can't apply tracking when you set the interface (and not the next hop)

So here is what I did to get the router to do what I need it to do.

This is not what I prefer, but it's the only way I could find, if you have any advice I am very open to suggestions

So below I don't track the interface status, I track the routability of the Dailer interface, this works very well.

With EEM i get the router router to do what I need, but like I said, it's not the way I want to do it.

track 1 interface Dialer1 ip routing

interface Vlan1

ip policy route-map LOCAL-BREAK-OUT
!
route-map LOCAL-BREAK-OUT permit 10
match ip address O365traffic
set interface Dialer1

event manager applet Track_Dialer1_Down
description **--ADSL interface Tracking Down--**
event track 1 state down
action 1.0 syslog msg "**--EEM-Track_Dialer1_DOWN---PBR-moved-to-Cellular0--**"
action 1.1 cli command "enable"
action 1.2 cli command "configure term"
action 1.3 cli command "route-map LOCAL-BREAK-OUT permit 10"
action 1.4 cli command "no set interface Dialer 1"
action 1.5 cli command "set interface Cellular 0"
action 1.6 cli command "end"
event manager applet Track_Dialer1_Up
description **--ADSL interface Tracking Up--**
event track 1 state up
action 1.0 syslog msg "**--EEM-Track_Dialer1_UP---PBR-moved-back-to-Dialer1--**"
action 1.1 cli command "enable"
action 1.2 cli command "configure term"
action 1.3 cli command "route-map LOCAL-BREAK-OUT permit 10"
action 1.4 cli command "no set interface Cellular 0"
action 1.5 cli command "set interface Dialer 1"
action 1.6 cli command "end"

Can you not run a trace from

Mark Malone — Tue, 06 Oct 2015 12:22:14 GMT

Can you not run a trace from local device to see what the next-hop is then you can use tracking in pbr there ip is unlikely going to be dynamic on there side upstream

Hi MarkI will give that a go,

NeilGouws — Tue, 06 Oct 2015 12:35:47 GMT

Hi Mark

I will give that a go, will test with traces over a few days and see if the IP stays the same

thanks for the advice

Another option would be to

Jose Jara — Tue, 06 Oct 2015 15:38:48 GMT

Another option would be to set to a dummy next-hop instead of the dialer interface. This next hop would point to the dialer interface doing tracking in the static route to reach this dummy next hop:

ip route x.x.x.x y.y.y.y.y dialer1 track 1

Hi Josehow will the route

NeilGouws — Tue, 06 Oct 2015 19:48:37 GMT

Hi Jose

how will the route with tracking work with the route-map that sets to either the Dialer or Cellular interface ?

with your example the "dummy route" will not be added if the dialer interface is down, but that won't make any difference in the route-map

Am I understanding you wrong ?

Hi Neil,you´re right and in

Jose Jara — Wed, 07 Oct 2015 09:28:37 GMT

Hi Neil,

you´re right and in order to route to the cellular interface you'll add the same dummy route reachable through the cellular interface with a worse AD:

ip route x.x.x.x y.y.y.y Cellular0 50

Josehow will a static route

NeilGouws — Wed, 07 Oct 2015 09:36:45 GMT

Jose

how will a static route help with the route-map and setting the interface in the route-map

No default routing is used/allowed.

The route-map basically decides, based on a ACL, if traffic is allowed to go out the Dialer/Cellular interface.

In this case, that traffic is Office 365 traffic

You will set the next-hop in

Jose Jara — Wed, 07 Oct 2015 10:07:21 GMT

You will set the next-hop in the route-map to a dummy route reachable through the dialer interface, in order to do the tracking. Then, in case the tracking fails, you will reach this dummy route (the same) through the Cellular interface. So, you do not need to set the interface in the route-map just this dummy next-hop.

Ok thanks that makes sense,

NeilGouws — Wed, 07 Oct 2015 11:25:14 GMT

Ok thanks that makes sense, provided that I know what the next hop is and hoping that it doesn't change unexpectedly

Just an update, still waiting

NeilGouws — Tue, 13 Oct 2015 05:29:02 GMT

Just an update, still waiting for telecoms company to supply more info on reliability of the next hop

Mark

in theory and in 1 instance your recommendation worked, but at this stage it's not the complete solution

Regards

Hopefully it does work or we

Mark Malone — Tue, 13 Oct 2015 07:16:22 GMT

Hopefully it does work or we can try come up with another solution, from working in ISPs I never seen dynamic ips though on there side usually just the client side connecting in.

Hi Neil,

jesurexon.jegaprathaban — Thu, 07 Jul 2016 03:53:27 GMT

Hi Neil,

I am also facing the same problem, cloud you let me know if you have resolved it.

Also regarding the below configuration, is it the complete one.

track 1 interface Dialer1 ip routing

interface Vlan1

ip policy route-map LOCAL-BREAK-OUT
!
route-map LOCAL-BREAK-OUT permit 10
match ip address O365traffic
set interface Dialer1,

There is no Track command after the set interface dialer1 command, so how will track get executed. how will the failover to Dialer0 happen.

It could be great if you can help me with this.