Additional Block of IP's from ISP - CISCO ASA 5510

Posted on 2008-11-10
Last Modified: 2012-05-05
Hi All,

We currently have a subnet assigned to us from our ISP.

Subnet:       /28
Default route is:

We have asked for more IP's and they have said they have routed the following subnet to us:

Subnet: /27

Couple of questions:

On our ASA 5510 - how do it up to listen for these extra IP's?
Will these new IP's still use the default gateway of the current IP's?

Question by:chouckham
    LVL 43

    Accepted Solution

    As long as your ISP is routing the new subnet to you, you don't need to do anything but configure the static NAT statements and access-list entries for the new IP addresses.  You don't need to bind the IP addresses to an interface and yes, the current default route on the ASA will be used to route traffic from this subnet to your ISP.
    LVL 3

    Author Comment

    That easy???

    Just so that I can give you these easy points :-) ...could you explain what they have done to route these IP's to me?

    LVL 43

    Assisted Solution

    Yes, it is that easy.  Most likely your ISP is simply static routing the new subnet to your current ASA, i.e. in Cisco lingo:

    ip route <your ASA outside interface IP address>

    They would then need to redistribute that static route into whatever routing protocol they are running.  Most of the headache is with the setup with your ISP, i.e. they don't properly route the subnet to you.
    LVL 43

    Expert Comment

    Are you all set with this question or do you need further assistance?
    LVL 3

    Author Closing Comment

    Thanks! - great information!

    Featured Post

    Live: Real-Time Solutions, Start Here

    Receive instant 1:1 support from technology experts, using our real-time conversation and whiteboard interface. Your first 5 minutes are always free.

    Join & Write a Comment

    Suggested Solutions

    If you have an ASA5510 then this sort of thing would be better handled with a CSC Module, however on an ASA5505 thats not an option, and if you want to throw in a quick solution to stop your staff going to facebook during work time, then this is the…
    There are many useful and sometimes not well documented or forgotten IOS or ASA/PIX commands. See IPE article here , there was also one on PacketU and on Cisco Tips & Tricks. Below are my favorites. I give also a few most often used for Cisco IPS an…
    how to add IIS SMTP to handle application/Scanner relays into office 365.
    Polish reports in Access so they look terrific. Take yourself to another level. Equations, Back Color, Alternate Back Color. Write easy VBA Code. Tighten space to use less pages. Launch report from a menu, considering criteria only when it is filled…

    745 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    15 Experts available now in Live!

    Get 1:1 Help Now