Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1999-07-16
2003-05-13
Nguyen, Chau (Department: 2663)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S410000
Reexamination Certificate
active
06563834
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a network path controlling method and an apparatus therefor, and in particular to a method and an apparatus for controlling a hierarchized network.
As an internet/intranet is rapidly spread in offices and campuses, former experimental networks have been transforming into networks which bear the nucleus of business. Accordingly, a hierarchized network which simplifies the management of network by simplifying the composition of network has been remarkable.
2. Description of the Related Art
1. IP Address and Notation
An IPv4 (IPversion4) address which is an IP (Internet Protocol) address generally used at present has an address length of 32 bits as shown in
FIG. 10
, and is notated (hierarchized or layered) by the division with ‘.’ per an arbitrary number of e.g. 8 bits. The address is allotted to every node and is composed of two portions, i.e. a network portion indicating a network NW to which the node belongs and a host portion indicating an individual node (host) HST. Also, the bit number of an objective network portion is notated with ‘/’ after the IP address.
In one example of address “133.160.115.5/24” shown in
FIG. 10
, the top 24 bits (133.160.115) of “133.160.115.5” indicate the network portion, and “5” of same indicates the host portion. In addition, the IP address whose host portion is “0” means the network itself. Namely, the network of the address “133.160.115” is notated as “133.160.115.0/24”.
2. Composition of the Present IP Network
In the present IP networks, as shown in
FIG. 11
, when networks NW
1
and NW
2
are connected with a router R
A
, networks NW
2
and NW
3
are connected with a router R
B
, and networks NW
2
and NW
4
are connected with a router R
C
, the network NW
1
whose address is “133.160.115.0/24” and the network NW
3
whose address is “133.160.116.0/24” are not adjoining with each other, and the network NW
2
lies between them.
Thus, it is possible that an arbitrary network lies between the IP networks having an address according to the above-mentioned notation, and no hierarchization based on the address is considered.
3. Path Selecting Method of IPv4.
A packet has a path (route) selection directed by an router which is set up on the boundary of the networks, and path information required for the path selection is periodically exchanged between routers.
An exchange example of the path information in the prior art is shown in FIG.
12
. The path information of the address “133.160.115.0/24” is exchanged from the router R
A
into the router R
B
, thereby enabling the router R
B
to recognize the existence of the network NW
1
whose address is “133.160.115.0/24” ahead of the address “150.123.212.0/24”.
Likewise, the router R
A
recognizes that the network NW
3
whose address is “133.160.116.0/24” exists ahead of the network NW
2
whose address is “150.123.212.0/24” from the path information of the router R
B
. The exchange of the path information between the router R
C
and the routers R
A
and R
B
is performed in the same way. Each of the routers tables this path information to be renewed at the next path exchange.
FIG. 13
shows an example of packet relay in the network where the path is exchanged in
FIG. 12
, which will be sequentially described as follows:
(1) An IP packet P
1
having a destination address (Dst) “133.160.116.1” which has been transmitted from a host Ha to a host Hb is given to the router R
A
which is a router of the network NW
1
whose address is “133.160.115.0/24”.
(2) The router R
A
retrieves a path information table (a routing table) about the whole network portion (133.160.116.) of the destination address at the router R
A
itself. In this example, the network NW
3
whose address is “133.160.116.0/24” on the router R
B
and the network NW
4
whose address is “133.160.117.0/24” on the router R
C
are stored in the table.
(3) As a result of the table retrieval, the router R
A
recognizes that the router R
B
is the next destination and transfers the packet P
1
to the router R
B
.
(4) The router R
B
which has received the packet P
1
recognizes from the network portion (133.160.116) of the packet P
1
that the packet is addressed to the network NW
3
which is its own subordinate, and then transfers the packet P
1
to the host Hb with watching the host portion (0/24) of the packet P
1
.
It should be intensively noted that the path retrieval is performed about the whole of the network in the above-mentioned (2) and (4). This is because the network is not hierarchized based on the IP address so that the router R
A
, for instance, can not determine to which router R
B
or R
C
the packet should be transmitted only with the retrieval about a part (133.160) of the network portion.
In accordance with a recent large-scaled internet/intranet, there has been increased needs of simplifying the network composition and facilitating centralized controls. For the needs, the construction of the hierarchized IP network has been remarkable.
However, there are problems for the achievement of the above-mentioned hierarchized IP network.
{circle around (1)} A network itself has no hierarchical structure based on an IP address.
{circle around (2)} A path control has no construction attending to hierarchization.
The former problem {circle around (1)} is being solved because a new version IP=IPv6 (version6) which hierarchizes the network composition itself by promoting the address hierarchization is studied by a standardizing organization. However, the latter problem {circle around (2)} has not yet been solved.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a network path controlling method and an apparatus therefor which performs a path retrieval based on path information exchanged between routers in order that networks which share IP addresses hierarchized by arbitrarily dividing the IP addresses by an arbitrary bit length from an upper bit can be mutually connected through an upper one of hierarchized networks of the hierarchized IP addresses in which hierarchy information can be simply exchanged by limiting an area of destination address to be referred upon the path retrieval to achieve a high-speed path retrieval.
1. Basic Concept
A path control in the hierarchized network is not required to be performed to the whole of a network of IP address but has only to be performed per each hierarchy. For example, the network shown in
FIG. 1
is hierarchized based on the structure of IP address.
In this example, when a host H
A
on a network NW
111
whose address is “&agr;.A.a.0/24” transmits a packet P to a host H
B
on a network NW
221
whose address is “&bgr;.B.a.0/24”, it is enough to perform a path selection with paying attention only to “&bgr;” at the address of the host H
B
in a network NW
10
whose address is “&agr;.0.0.0.8”. However, the host H
B
has no need to perform the path selection until the packet enters a network NW
20
whose address is “&bgr;.0.0.0/8”. Namely, there is always no need to perform the path retrieval for the whole of network.
In this way, by the methods of {circle around (1)} exchanging not only the above-mentioned path information in the prior art but also the hierarchy information, and {circle around (2)} allotting the hierarchy information to the destination IP address of the packet, it becomes possible to perform a path selection to a part of the destination address, that is an only adequate hierarchical position in the network portion upon the path retrieval of each router.
2. Solution Means
FIG. 1
shows a hierarchized network constructed according to the rules described hereinbelow:
{circle around (1)} An upper hierarchy must include a lower hierarchy. In the example of
FIG. 1
, a network whose address is e.g. “&agr;.B.b.0/24” can not be provided between the network NW
111
whose address is “&agr;.A.a.0/24” and a network NW
112
whose address is “&agr;.A.b.0/24”.
{circle around (2)} The networks at the same hierarchy common to the same upper hierarchy can be connected
Fujitsu Limited
Katten Muchin Zavis & Rosenman
Lee Andy
Nguyen Chau
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