Dual ISPs on single cisco router attached to asa firewall outside and then core switch inside

[Francesco Molino]

Hi

1. To have dual ISP, 1 as active and 1 as standby you’ll need to use IP SLA with static route tracking.

To give you an example, let’s assume IP of ISP1 router is 192.168.1.1 and connected to your router on interface f1/0, and IP of ISP2 is 192.168.5.1 and connected to your router on interface f1/1, the config will looks like:

ip sla 10

   icmp-echo 192.168.1.1 source-interface FastEthernet1/0
   threshold 2
   frequency 3
ip sla schedule 10 life forever start-time now

track 10 ip sla 10 reachability

ip route 0.0.0.0 0.0.0.0 192.168.1.1 track 10

ip route 0.0.0.0 0.0.0.0 192.168.5.1 10

2. What do you mean by how to connect? You’ll need to have an interco subnet and on ASA you’ll have a default route going to the IP on your router within this same subnet.

3. Same way as previous point with an interco subnet. On your switch you’ll have a default route going to ASA inside interface.

4. You’ll need to configure the port on which the switch is attached as trunk with the specific vlan like:

interface gx/x

   switchport mode trunk

   switchport trunk allowed vlan 2

Hope that answers your question

[Ahsan Munir]

Hey Francesco Special Thanks for your Concern and sorry for my late reply

1.  Is there I have to configure NAT on ASA firewall for the access of internet or just i need to add default route ?

2. Is there any configuration i have to apply for inside interface of ASA so the ASA accept the traffic from Core switch ?

[Francesco Molino]

Hi

You can have nat done on asa but you'll need to configure correctly the routing as your router is between internet and your firewall, or you can have nat handled by your router and will be much easier.

By default, if you don't configure any acl, there's a default rule allowing communication from inside to outside. However I'll recommend creating an acl to filter what traffic is allowed to go from inside to outside.

[Ahsan Munir]

Thanks Francesco,

its not proper solution of my question but it helps me alot thank you

[Francesco Molino]

What do you mean is not proper solution? What did you expect?