Electrical computers and digital processing systems: multicomput – Computer network managing
Reexamination Certificate
1998-10-08
2001-06-05
Vu, Viet D. (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer network managing
C709S220000, C709S238000, C709S245000
Reexamination Certificate
active
06243749
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to managing host addresses. More particularly, the present invention relates to managing dynamically allocated host addresses to allow subscribers to reliably locate other subscribers who have been dynamically allocated host addresses.
2. The Background
As shown in
FIG. 1
, the Internet, or any large computer network,
10
may be described as a group of interconnected computing networks (not shown) that are tied together through a backbone
12
. The computing networks, in turn, provide access points, such as access points
14
,
16
and
18
, through which users may connect to the Internet via a station (a computer having a connection to a network) or host, such as hosts
20
,
22
,
24
, and
26
. An access point is essentially a location on the Internet that permits access to the Internet. An access point may include a modem pool (not shown) maintained by an ISP (Internet Services Provider) which enables its subscribers to obtain Internet access through a host having a dial-up connection. Those of ordinary skill in the art will recognize that other types of access methods may be provided by an ISP such as frame relay, leased lines, ATM (asynchronous transfer mode), ADSL, and the like.
Regardless of the access method used, each device (e.g., a host or router) that receives, sends and/or routes information between or among other devices on Internet
10
is configured to communicate with other devices using a communication protocol that may be understood by the other devices. The current communication protocol used by these devices on the Internet is TCP/IP (transmission control protocol/internet protocol). In addition, each device that can send or receive information (e.g., a host device) must also have a unique host address. The type of host address used for the Internet, or an equivalent switched network that uses TCP/IP, is commonly referred to as an IP address. A standard TCP/IP address is 4 bytes (32 bits) in length, providing a total of 2
32
possible IP addresses. Those of ordinary skill in the art will readily recognize that not all of these possible IP addresses are available due to administrative expediencies, such as reserving blocks of IP addresses for future use.
Sending or receiving information using the TCP/IP protocol requires encapsulating information into packets. Each packet includes a header and a payload. The header contains information related to the handling of the payload by a receiving host or routing device, while the payload contains part or all of the user information. The information in the header includes the sender's and the recipient's addresses and is used to route the packet through the Internet until the packet is received by a host having an IP address that matches the packet's destination address (when referring to the source address and destination address of a packet, the source address and destination address are commonly referred to as “SA” and “DA”, respectively). This enables users to accurately send and receive information with each other through their respective host computers.
By implementing a protocol common to all devices using Internet
10
, users may send and receive information with other users on the Internet in a seamless manner regardless of geographic location or the type of host and/or interconnected network used. While IP addresses themselves are in numerical form, in order to make navigating the sea of addresses simpler, the Domain Name Service (DNS) was formed. DNS enables the central managing of host names to IP addresses. It is actually a distributed database which allows for the dissemination of new host information as needed. There are a great many DNS servers distributed throughout the Internet, and most large ISPs maintain their own DNS server.
FIG. 2
is a diagram illustrating the DNS hierarchy, which is similar to that of a computer file system, At the top of the hierarchy is the root domain
50
, which consists of a group of root servers to service the top-level domains. The top level domains are separated into organizational and geographical domains. Many countries have their own top-level domains, such as .uk for the United Kingdom, .de for Germany, and jp for Japan (not shown). The United States has no country-specific top-level domain, but is the main user of the six organizational top-level domains, which are net for network support organizations
52
, .gov for government agencies
54
, mil for military users
56
, org for not for profit organizations
58
, .com for commercial enterprises
60
, and .edu for educational facilities
62
. There are also a near infinite number of lower level domains. Each level of domain names may have another level of domain names below it. For example, a lower level domain .work
64
may be located under the .com domain
60
, and the lower level domain .univ
66
may be located under the .edu domain
62
. At the lowest level are the hosts. For example, the host labeled overtime
68
may be located under the .work sub-domain under the .com domain while the host labeled vax
70
may be located under the .univ sub-domain under the .edu domain. The proper way to read these two DNS host names would then be overtime.work.com and vax.univ.edu.
The steps of locating an IP address from a host, sub-domain, and domain name proceeds as in the following example. If a user in the vax.univ.edu domain wishes to contact a user with the user name sun in the work.com domain, the first step is to contact its own DNS server. Therefore, if the vax.univ.edu host is configured with a DNS server at the IP address 133.3.1.3, the user sends a DNS request to that IP address. The DNS server then searches for the entry in its database. Generally, DNS servers only maintain a database of host addresses (or sub-domain names) within its own subnet. Therefore, the DNS server would look for an IP address corresponding to the domain/sub-domain combination .univ.edu. It may or may not have information that precise. It may only have information regarding the IP address of the .com domain and not the .work.com domain. If it has information about the IP address of the DNS server of the .work.com domain, it passes this information to the user, which then contacts the .work.com DNS server and requests the IP address of the precise user it wishes to contact in the .work.com domain. If however, the DNS server associated with the vax.univ.edu host only has information about the address of the DNS server of the .com domain, it returns only that address, and the user must recursively navigate down the branches of DNS servers in the com domain until locating the address it needs (in the present example, it only searches down one level, but in more complicated hierarchies it may need to search through many levels of DNS servers).
It is also possible that a higher level DNS server will simply forward the request packet down the hierarchy and wait to inform the user of the host address until it hears back from the lower level DNS server, thus avoiding having to contact the user at each step in the hierarchy. However, this still presents the problem of recursing, which increases the complexity of a search.
The dramatic increase in popularity of the Internet in recent years has created a concern about the number of available IP addresses. ISPs and domains are generally allocated a finite number of IP addresses. The ISPs and domains, therefore, are constantly looking for ways to limit the number of IP addresses they use while still providing access to the greatest number of users.
One solution for mitigating the effect of the number of users requiring host addresses is to dynamically allocate host addresses for users who do not have dedicated connections to the Internet, such as users who use dial-up access methods to connect to an ISP. Dynamic allocation of IP addresses entails having a pool of IP addresses, such as IP address pool, from which an ISP can draw from each time a valid subscriber (who does not use a dedicated conn
Bhasham Sampath Kumar Sthothra
Dos Santos Maria Alice
Jin Jane Jiaying
Sitaraman Aravind
Cisco Technology Inc.
Hanish Marc S.
Thelen Reid & Priest LLP
Vu Viet D.
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