Re: do I need external ip address , if yes what block
You will need to contact your ISP (I believe Telepacific Communications) and explain the current network setup and what you want to do. The ISP should have staff to assist you. I am guessing your changes will go something like this.
Currently your 2621 is assigned .106. It is likely the 2621 default gateway is .105. Both the ISP router (.105) and your 2621 serial 0/0 (.106) will need new IP addresses (network). The ISP will give/tell you what the new IP addresses and network will be. The netmask will likely be 255.255.255.252 (not 255.255.255.248 like the current). Once the ISP and you reconfigure your routers, you will be able to assign your address block (184.108.40.206/29) to any devices you want. You will probably want to assign .105 to the 2621 Fast Ethernet 0/0. The ASA outside interface will get .106. The remaining addresses (.107 - .110) can be used however you like.
You mentioned that VPN connections terminate on the 2621 serial interface (.106). I suggested assigning the ASA .106 (above) as a way to minimize configuration changes on the other end of the VPN connections. Prior to your changes, the remote-side of the VPN connects to your 2621 (.106). After your changes, the remote-side will still connect to .106 (ASA).
Do you need more address space? Using my example above, you will have four addresses available for use (.107 - .110). These addresses could be used to host a publicly accessible web server, e-mail server, ftp server, etc. Unless you know that you will need more addresses, I would stick current eight addresses (220.127.116.11/29). Making several changes at once (adding the ASA and changing public IP addresses) can be difficult and add complexity. I would make one change at a time (adding the ASA).
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...