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Designing a Hierarchical DHCP server’s model to automatically provide dedicated
IP address anywhere in the world with mobility
Asjad Amin, Haseeb Ahmed, Abubakar Rafique, Muhammad Junaid Nawaz, Muhammad Salahudin
Department of Telecommunication and Electronic Engineering
The Islamia University of Bahawalpur, Pakistan
{[email protected], [email protected], [email protected], [email protected], [email protected]}
Abstract—A new organization of DHCP server’s is proposed in
this research paper. This hierarchical model is designed to
provide each user with a dedicated IP address with an option
to move anywhere in the world. This design makes a user’s IP
address independent of an ISP (Internet Service Provider).
DHCP servers are organized into three levels i) Organization
level DHCP server ii) Country level DHCP server iii) Root
level DHCP server. One IP address is bind against each
registered user and this information is stored at all root level
servers. A user can now access internet through any ISP, ISP
will use the hierarchical design to search for users dedicated IP
and a user will always be facilitated by his dedicated IP
address. A small protocol is also designed to provide effective
communication between different level DHCP servers, between
ISP and DHCP server and between client and ISP. This design
does not demand any complex changes in existing system
rather some intelligent organization of already existing DHCP
servers is sufficient to create the new model.
I. INTRODUCTION
Most of the Internet service providers use dynamic IP address system. DHCP manages a dynamic database for allocating IP addresses [1]. (DHCP) is an application layer protocol used to configure hosts in the computer communication network [5].A user request for an IP address from its local ISP, local ISP on receiving such request ask main DHCP server for available IP address. Then main DHCP server assigns an IP address to the user while involving the local ISP. The IP address which is assigned to the user is the first available IP address resides in the IP pool which is shown in the figure 1. With dynamic address allocation, as devices leave a network, DHCP servers can automatically recover the addresses assigned to those devices and return them to a pool of available addresses. The dynamic address assignment mechanism in DHCP is flexible enough to support, for example, network segments used by mobile devices like laptops [3]. In this system whenever a user changes his PC or laptop or any end system, the IP address which was assigned previously will also change and there is a very low probability that a user get the same old IP. A similar scenario is when a user changes his area or country. This frequent change of IP address may prove beneficial for internet service providers but it creates many problems for the user such as the routers involving in the connection’s path face a harsh load on their algorithm. Similarly if a user looses a connection during a downloading
session then it will fairly be difficult to rescue the previous session once a new IP has been assigned.
Sometimes a user requests its local ISP to fix an IP address against his device’s MAC address. MAC addresses are the actual addresses for the network terminal host [2]. Therefore whenever such user sends a request for a new IP address, his MAC address is searched from the table and such a user is always facilitated by the assigned dedicated IP address as shown in figure 2. It works fine till the user continues to use the same device. Once a user changes the device or if a user moves out of the local ISP area, it will not be possible for the user to get the same IP.
A new system is proposed in our research paper in which each user will have a dedicated IP of his own with facility to move anywhere in the world. We have not introduced any major changes in the existing system. In order to make the most of DHCP, we have to strengthen its power of regulation [4]. We have simply organized DHCP servers in a way that a dedicated IP is always available for a user irrespective of the fact where he is residing. With the introduction of IPv6, the numbers of IP addresses are not limited and providing each user with a dedicated IP address is fairly possible.
In our model we have designed a hierarchical DHCP server’s network in which an IP address is assigned permanently to a specific user. Mobility for IP address is provided by organizing DHCP server’s hierarchy which includes ISP, organization level DHCP servers, country level DHCP servers and root level DHCP servers.
Figure 1. Dynamic IP provided by ISP using DHCP
Figure 2. Static IP address provided by ISP after matching MAC address
II. HIERARCHICAL DESIGN MODEL
Each user is connected to a local internet service provider. Local ISP is then connected to an organization level DHCP server. Each organization level DHCP server is further connected to its relative country level DHCP server. Each country has its own DHCP server which is then further connected to a root level DHCP server. There are different DHCP servers that have been declared as root level DHCP server. All the root level DHCP servers are connected to each other. Every country level DHCP server is connected to a single or more root level DHCP servers.
The first step for any user is to get register for a dedicated IP address. Once a user is registered, he is always provided with his IP address no matter which ISP he uses or which area he moves. This is achieved so by our hierarchy design. Every root level DHCP must contain the data of all the registered users along with their IP.
If a user has just logged in and requests the local ISP for an IP address, his request is forwarded by local ISP to organization level DHCP server. Organization level DHCP server searches for the dedicated IP address of the user in its database. If a search process is successful, IP address is returned to local ISP and is provided to the user. In case of an unsuccessful search organization level DHCP server forwards the request further to country level DHCP server. The same searching process is repeated at country level DHCP server. In case of a successful search IP address is returned. In case of an unsuccessful search, country level DHCP server further request to a root level DHCP server. Each root level server contains the IP address of all the registered users so a request from a registered user will always match a successful IP address. As root level server contain all the registered IP addresses so a success rate of finding a registered dedicated IP address for a specific user is always hundred percent. After a successful search, IP address is returned to user passing through country level server, organization level server and local ISP. An IP address on its way back to user is cached at every server it passes through so that it may help when the same user login for the next time. In case of an unsuccessful search from all the servers, a user is assumed to be non-registered and is provided by a dynamic IP from the IP pool of local ISP using DHCP.
Figure 3 shows a scenario of two users connected to their local ISP’s. Each ISP must have its own organization level DHCP server which must be further connected a country level DHCP server. In the shown scenario User 1 is connected to ISP1 and User 2 is connected to ISP2 with both the ISP’s are further connected to their respective organization level DHCP server.
Figure 3. Users connected to ISP & ISP connected to organization level
DHCP server
Figure 4 is an extension to figure 3. All the organization level servers are connected to their respective country level DHCP servers. Each country level server is then connected to a root level DHCP server. All the root level servers are connected to each other. A connection between all the root level DHCP servers is necessary as it every root level server must be aware of any update if happen at any other root level server.
Figure 4. Interconnection between Organization level, Country level and
Root level DHCP server
III. PROTOCOL DESIGN FOR HIERARCHICAL DHCP MODEL
A protocol is required for smooth interaction between all the hierarchical servers. A very simple and small protocol is proposed to achieve effective communication between servers and to implement the proposed methodology successfully. This protocol is not meant to replace DHCP rather it will only run to provide the appropriate options for
the modified system. The protocol uses the following commands:
1. IP_req 2. IP_req ACK 3. Username_req 4. ID,PSWRD,CNIC 5. ID_reg 6. ID_reg ACK 7. IP_assign 8. IP_assign ACK 9. Conn_req 10. Username ACK 11. ID_srch 12. ID_srch ACK 13. ID_IP snd 14. ID_IP rcvd 15. ID_IP rcvd ACK 16. Conn_est ACK
The protocol has been divided into two parts. The 1
st part
is to facilitate the registration process of a new user. It involves assigning a dedicated IP to a new user. The second part is designed for the already existing users. It is designed to entertain the request of already registered users to provide them with their fixed IP address.
A. Protocol design to assign a dedicated IP to a new user
A new user sends a request to its local ISP for a dedicated IP address. This is done so by using the command IP_req. ISP sends an acknowledgment IP_req ACK and further asks users data by using Username_req. In response user provides its data that may include username, password, National identity number, email address etc. For a username to be unique, it is chosen to be the email id of client. On receiving all the desired data, ISP sends a request ID_reg to organization level DHCP server with the entire user’s data. Organization server sends an acknowledgment back to ISP and forwards the ID_reg request along with the user’s data to country level DHCP server. Country level server sends an acknowledgment back to organization server and further sends the ID_reg request with user’s data to root level DHCP server. Root level server searches for the available IP address that has not been assigned to any other user. An IP address is returned with the command IP_assign to country level DHCP server. Country level server sends an acknowledgment IP_assign ACK back to root level server and returns the IP address to organization level server using IP_assign command. IP address is further passed to organization level server and then returned to the client using IP_assign command. An acknowledgment IP_assign is send from organization server to country server and from client to organization server as well. Now this IP address is the property of a specific user. A user will always be facilitated by this dedicated IP address no matter which ISP he uses or which area he is residing. Figure 5 and figure 6 shows a scenario where a new user’s request is passed to root level server and IP address is sent back from root level DHCP server to user.
Figure 5. New IP address request from client to root level server
Figure 6. New IP address assigned by root level server to client
B. Protocol design to provide a registered user with his
dedicated IP
If an already registered client wants to establish a new connection, a request is sent to local ISP. This request is send by using conn_req command. On receiving such request an ISP asks the client to provide his username and password. Client provides the required data. On receiving the username and password, ISP sends an acknowledgment Username ACK back to the client and sends a request ID_srch with the username and password to organization level DHCP server. When an organization level server received ID_srch command it searches in its data base for the provided user. In case of a successful match the IP address is sent back using ID_IP snd command. In case of no match, organization server forwards the ID_srch command to country level DHCP server along with the username and password. Country level server searches for the respective user in its data base. If case of a successful match, IP address is sent back using ID_IP snd command. In case of an unsuccessful search the request is further forwarded to root level DHCP server using ID_srch command. Root level searches for the IP and returns the respective IP address back to country level DHCP server. On the way back IP address is send from one server to another server in a three way process. Country level server informs organization level server about the successful match of the IP address using ID_IP rcvd. Organization server acknowledges by sending ID_IP rcvd ACK. On receiving the acknowledgment country level server sends the requested IP address to organization server using ID_IP snd. The three ways process adds extra security to the whole
procedure. Similarly this IP address is returned to local ISP using the same three way process. On receiving the IP address client’s connection is established and he can use any kind of service with his own dedicated IP address. On establishment of connection the client sends conn_est ACK to confirm the connection. If a search is unsuccessful at root level server, a user is considered as an unregistered user. Such a user will be treated in a same way as any normal user is treated everyday using DHCP. A user will be facilitated by a dynamic IP instead of a dedicated IP address by its local ISP using DHCP. Figure 7, figure 8 and figure 9 shows a scenario where an already registered user’s request for a dedicated IP address is passed to a root level server and IP address is sent back from root level DHCP server to user.
Figure 7. Registered user is requesting for his dedicated IP address
Figure 8. Root level server provides user’s dedicated IP address to ISP
Figure 9. ISP provides the IP address received from root server to client
C. Cache at each level to improve hierarchical DHCP
model response
When a client travels to some other part of world he will request to the new local ISP for his dedicated IP address. ISP
will send a request to its respective root level DHCP passing through organization level DHCP server and country level DHCP server. A search will be conducted at each server. As the user has moved to a new country so a possibility of getting IP address other than from root server is very low. Root level server on finding the right match will return the address to client through country server, organization server and local ISP as described in previous section. This procedure will cost extra time and bandwidth and in case of large number of requests all the servers will be severely overloaded. Therefore we introduce cache system. All this procedure will take place for only 1
st time when user will
move to a new place. IP address of user on its return from root level to client will be cached at every server it passes through. Therefore if a user asks for an IP address for the next time from the same ISP his request will be entertained without consulting to any other server. Even if a user moves anywhere in the new country his request will always be entertained by country level server and involving root level server will not be required. Figure 10 shows the process of caching at each server.
Figure 10. A user’s dedicated IP address is cached at every server on its
way from root level server to client
IV. PROPOSED SOLUTION FOR SOME THE PROBLEMS
ARISING WITH HIERARCHICAL DHCP MODEL
A. Roaming benefits for the original IP address provider
When a person travels to a different area of the world he uses different ISP. Now how can a local ISP get benefit which assigns a specific IP address to the client? This issue can be resolved by introducing some roaming charges. The client pays some service charges to the new ISP as roaming charges. This amount will be transferred to the original IP address provider ISP and client can use IP address anywhere in the world.
B. Identity verification
Each person can only get one IP address so he must provide his National identity number at the time of new IP address request. In case of a large organization some special requests can be made. Such organizations can be provided with a pool of dedicated IP addresses for their employee’s.
C. IP validity
Validity period of a registered but unused IP has been fixed to one year. If a client does not uses an IP address for more than one year, the IP address is considered as free and can be assigned to any other client.
V. CONCLUSION
A new design of hierarchical DHCP is proposed to
provide a dedicated IP with option to move anywhere in the world or to choose any ISP of your choice without the fear of loosing your IP. A dedicated IP offers a lot of benefits that includes less down time from server. Secure socket layer certificate are easily provided with the help of fixed IP. FTP (file transfer protocol) software’s uploading and downloading sessions can be saved and retrieved at any time with the help of dedicated IP. Static IP addresses are more stable than dynamic address as they never change. Dynamic IP address is changed after few hours as computer refreshes which cause a lapse in the user connection. One of the disadvantages of the IP address once assigned to a computer is occupied by it even when we are not using internet. Limited IP addresses are available so we can use IPv6 for such static IP address to work more perfectly. A static IP address can easily be tracked .it is disadvantage for such websites that allow each visitor to download or view a set amount of content. Dynamic address system resolves this issue and tracking is difficult.
ACKNOWLEDGMENT
We would like to thank our family for all the prayers and support they gave us throughout. A very special thank to Prof. Jan Muhammad Kerio as his presence made a big difference today. A special thank to Shumaila for all the unasked motivation and support.
REFERENCES
[1] R.Droms, "Dynamic Host Configuration Protocol,” RFC 2131, March 1997.
[2] Ling-Feng Chiang, Jiang-Whai Dai, “A New Method to Detect Abnormal IP Address on DHCP”, Journal of Networks, VOL. 4, NO. 6, August 2009
[3] R.Droms, “Automated Configuration of TCP?IP with DHCP,” Journal of IEEE Internet Computing, Vol.3, No.4, pp. 45-53,July 1999
[4] Jenq-Haur Wang and Tzao-Lin Lee, “Enhanced Intranet Management in a DHCP-enabled Environment,” in Proc. 26 th Annual International Computer Software and Applications Conference (COMPSAC’02)
[5] Brijesh Kadri Mohandas and Ramiro Liscano, “IP Address Configuration in VANET using Centralized DHCP,” in Proc. 33rd IEEE conference on Local Computer Networks LCN 2008, October. 2008, doi: 10.1109/LCN.2008.4664252.
[6] R. Droms, “Procedure for Defining New DHCP Options,” RFC 2489 (BCP0029), ftp://ftp.rfc-editor.org/in-notes/ rfc2489.txt, Bucknell Univ., Lewisburg, Pa., Jan. 1999.
[7] H. Schulzrinne, “Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Option for Civic Addresses Configuration Information,” RFC 4776, November 2006.
