Modifying configs

[dmcgarty1]

I've been forced to become a Cisco administrator overnight.  The company has asked me to modify our Cisco Catalyst 3750 switch and 5512X ASA to accommodate a change to our ISP, which will result in changes to our /28 block of public IP addresses.  I would like to know if it is possible to edit existing config to simply change any reference to current public IP to the new IP?

[casanavep]

DMC,

We would have to know more about your topology in order to assist.  Items such as:

- Are you advertising your company's /28 out to the world via BGP or is the ISP advertising it for you

- Is the 3750 in front of behind this firewall (internet or user side of the ASA)

- How are you routing to the world, default route learned via BGP or other routing protocol, or static route/s point to the ISP

- What exactly is changing, is the ISP to customer network (some call a GLUE network) staying the same but you all will simply be advertising out a new public block.

These are all general networking questions, so no Cisco specific knowledge needed.  You and we simply need to understand the basic networking part of this. 

-Pete

[dmcgarty1]

Thanks Pete,

- We are currently advertising our /28 block to the world via BGP, but we will not have BGP in new environment.

- Currently 3750's sit in front of ASA. Our current environment was built with redundancy in mind.  We have HA ASA and HA 3750's.  We have two ISPs and each carrier provides BGP.  ISP#1 terms on 3750-A and ISP#2 terms on 3750-B.

- However, to save money, management has decided to replace the two existing ISPs with one new ISP.  Consequently, our two current /28 blocks (one from each ISP) are being replaced (i.e. they're going away) with one new ISP and a new /28 block.  The new ISP is not providing BGP.f these ISPs (and the /28 block each has assigned to us) and replacing with one new ISP (who will assign a new /28 block).  

In our new single ISP environment, I was thinking that I could term the new ISPs ckt on the ASA and have 3750s sit behind ASA.

[Richard Burts]

In the original post you ask this question  "I would like to know if it is possible to edit existing config to simply change any reference to current public IP to the new IP?". The answer is that you can edit the existing config and change the reference to current IP. But your further description of changes in the environment make it very clear that what needs to change is much more than just changing the IP addressing. So changing the IP addressing is part of but not nearly all of the changes that need to be made.

HTH

Rick