Electrical computers and digital processing systems: multicomput – Computer network managing – Network resource allocating
Reexamination Certificate
1998-10-20
2001-09-18
Coulter, Kenneth R. (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer network managing
Network resource allocating
C709S223000
Reexamination Certificate
active
06292832
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to accessing data in a network environment, such as the Internet, via a computer system. In particular, the present invention relates to a system and method for selecting a service for requested data.
BACKGROUND OF THE INVENTION
With the growing popularity of the Internet, providing speedy access to a requested location on the Internet is fast becoming a significant issue. For example, when a popular web page is hosted by a single computer, the Internet traffic to that computer can be overwhelming. To manage this problem, several computers can be utilized to host the same web page such that each hosting computer, typically referred to as a server, maintains a copy of the web page. If there are many servers at the same location, then the network connection to that location can become choked during a time of high Internet traffic. To avoid choking the network connection, mirrored servers are often located at different sites. These sites are herein referred to as mirrored sites. The use of multiple computers to host a network service, such as a web page, is typically referred to as mirrored services.
FIG. 1
is a block diagram illustrating a path taken by a client's request for a particular address. A client may be any entity which attempts to access a service. For example, the client may be a user, a company, or an automated computer system.
FIG. 1
shows a client
10
requesting an address for a network site, such as www.cisco.com, from a local domain name server
12
. The client's local domain name server
12
may be a service such as Netcom or AT&T. The local domain name server
12
then eventually learns the address of one of the mirrored services
14
A-
14
B, and replies to the client
10
with the address of one of the mirrored services
14
A-
14
B.
FIG. 2
illustrates a basic organization of the Internet. The Internet includes groups of networks and routers which combine to create an autonomous systems (ASs)
50
A-
50
E. A client may be located in one AS, such as AS
50
A, while the service that the client is attempting to access may be located in another AS, such as AS
50
E. In order to reach service
14
, the request from client
10
may be passed from AS
50
A to AS
50
B through AS
50
C, through AS
50
D, and finally reaching service
14
at AS
50
E.
In a mirrored service environment, the client
10
may be in one AS, such as AS
50
A, while the mirrored services may be located in various different autonomous systems, such as AS
50
E and AS
50
C. An address of one of these mirrored services is typically needed in response to the client's request.
There are several conventional ways of determining which mirrored service should be assigned to a requesting client. A selection of a mirrored service can be based on several factors. Ideally, the requested address should be returned to the client very quickly and downloaded into the client's computer system as quickly as possible. The time between the request being sent out by the client and the address being received is referred to as latency. The time it takes to download the requested address is typically determined by the bandwidth.
One conventional service assignment scheme is a round robin scheme. The round robin simply takes turns on which mirrored service is to be used. A potential problem with the round robin scheme is that it does not take into consideration the various loads of the mirrored services at any given time. Additionally, the round robin scheme also fails to take into consideration the location of the user. Accordingly, the two factors of latency and bandwidth are not typically considered in the round robin scheme.
When the service is a mirrored service, the mirrored services may be located in different autonomous systems. Some service selection methods attempt to measure a metric between the client
10
and each of the services
14
. Metric is herein meant to include a measurement of some characteristic of a connection, for example, a unit which indicates distance or time or both. For example, one such method measures “hop count”, wherein the number of autonomous systems located between client
10
and service
14
are counted. The mirrored service with the smallest hop count may be considered the best selection for that particular client.
Although the metric measurement methods are effective in many situations, there may be situations in which it is an advantage to have an alternate method for determining which mirrored service is best for a particular client. For example, one such situation is if the hop count between a client and a first server is the same as the hop count between the client and a second server. Although the hop count may be the same, the actual distances between the client and the first service and the client and the second service may be different. Another example of when an alternative method would be beneficial, is when an autonomous system is so large as to encompass more than one mirrored service. A client within that same autonomous system would not be able to use the hop count in order to determine which mirrored service is better for that client.
It would be desirable to have an alternative reliable system and method to determine which mirrored service is the best selection for a given client. It would also be desirable to quickly and efficiently obtain information regarding mirrored services to facilitate the selection of a mirrored service. The present invention addresses such a need.
SUMMARY OF THE INVENTION
The present invention relates to a system and method for selecting a service in a network, such as the Internet. According to an embodiment of the present invention, a user, such as a network administrator, may configure the system and method of the present invention to determine a “best” service based on a user configured metric. Examples of user configured metrics include director response protocol (DRP) external metrics, DRP internal metrics, DRP server metrics, DRP multi-exit discriminator (MED), and DRP round trip time (RTT). Metric information is herein meant to include any criteria related to a metric that may be used to select a “best” service. As previously mentioned, metric is herein meant to include a measurement of some characteristic of a connection, for example, a unit which indicates distance or time or both. Examples of metric information include portion, random, and administrative costs, as well as DRP external metrics, DRP internal metrics, DRP server, DRP MED, and DRP RTT. The service associated with the best metric information is then selected as a resolution for the requested host name.
According to an embodiment of the present invention, a user, such as a network administrator, may also configure service availability such that services may be checked periodically to determine if each service meets a predetermined criteria. For example, the predetermined criteria may be whether each service is functioning properly. Additionally, according to an embodiment of the present invention, a single system may facilitate the determination of best servers for a plurality of host names.
A method according to an embodiment of the present invention for selecting a service in a network environment is presented. The method comprises selecting at least one of a plurality of classes of metric information, resulting in a selected class, wherein the plurality of classes of metric information includes a border gateway protocol metric. The method also providing a first one of the selected class and a second one of the selected class; and comparing the first one of the selected class with the second one of the selected class. One of the first one of the selected class and the second one of the selected class is selected, resulting in a selected result; and a service associated with the selected result is selected.
In another aspect of the present invention, a method according to an embodiment of the present invention for selecting a service in a network environment is also presented. Accordi
Johnson Richard
Shah Dhaval N.
Cisco Technology Inc.
Coulter Kenneth R.
Vanpelt & Yi LLP
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