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Question about failover with ISP's on a 3640

We are purchasing a 3640 and want to have two isps from different providers that will failover if one dies. my question is - if we all our dmz web servers are assigned IPs from the primary isp and it goes down, do we also need to add ips from the secondy isp, also?

Thanks]

Jenn

1 REPLY
Anonymous
N/A

Re: Question about failover with ISP's on a 3640

Jenn,

You will need another set of routeable addresses from the second ISP if you want redundancy for your internal servers. You can set up Network Address Translation to make this work. For example:

/----ISP 1

internal server ---- 3640 ----/

\----ISP 2

Let's say that ISP 1 is using 199.x.x.x and ISP 2 is using 200.x.x.x. You could either (1) assign a private address on your internal network and NAT to both 199 or 200 or (2) assign a routeable address to your server and only NAT when using ISP 2.

scenario 1: (internal server is 10.1.1.1)

int s0

description connection to ISP 1

ip nat outside

int s1

description connection to ISP 2

ip nat outside

ip nat inside source static 10.1.1.1 199.1.1.1 route-map ISP1

ip nat inside source static 10.1.1.1 200.1.1.1 route-map ISP2

route-map ISP1

match interface serial 0

route-map ISP2

match interface serial 1

scenario 2: (internal server is 199.1.1.1)

int s1

description connection to ISP 2

ip nat outside

ip nat inside source static 199.1.1.1 200.1.1.1 route-map ISP 2

route-map ISP2

match interface serial 1

Hope this helps!

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