1. A load balancing routing method for networks, comprising:
receiving a network topology graph and a plurality of expected bandwidth demands corresponding to a plurality of source-destination pairs by using a network server;
calculating a plurality of link criticalities of a plurality of links established based on the source-destination pairs according to the network topology graph and the expected bandwidth demands and calculating a plurality of expected loads of the links according to the link criticalities by using the network server;
calculating a plurality of cost values according to a plurality of residual capacities and the corresponding expected loads of the links by using the network server; and
selecting a better transmission path corresponding to each of the source-destination pairs according to a weighted sum of the cost values corresponding to the links in the source-destination pair by using the network server.
2. The routing method according to claim 1, wherein the step of \u201cselecting the better transmission path corresponding to each of the source-destination pairs according to the weighted sum of the cost values corresponding to the links in the source-destination pair by using the network server\u201d comprises:
selecting a plurality of candidate transmission paths according to the weighted sum of the cost values corresponding to the links in each of the source-destination pairs by using the network server; and
selecting the better transmission path by the weighted sum which obtained according to a plurality of forwarding tables in the transmission paths by using the network server.
3. The routing method according to claim 2, wherein the step of \u201cselecting the better transmission path according to the forwarding tables in the transmission paths by using the network server\u201d comprises:
calculating a total quantity of forwarded information recorded in the forwarding tables and selecting the transmission path having the smallest total quantity among the transmission paths as the better transmission path by using the network server.
4. The routing method according to claim 1 further comprising:
arranging a processing sequence of the source-destination pairs according to the expected bandwidth demands by using the network server.
5. The routing method according to claim 1, wherein the link criticality corresponding to each of the links is yx, wherein x is a total number of paths between the source-destination pairs, and y is a number of paths between the source-destination pairs that pass through the link.
6. The routing method according to claim 5, wherein the expected load of each of the links is equal to a sum of products between the link criticalities and the expected bandwidth demands of the link corresponding to all source-destination pairs.
7. The routing method according to claim 6, wherein each of the cost values is obtained by dividing the expected load corresponding to each of the links by the residual capacity corresponding to the link.
8. The routing method according to claim 1 further comprising:
updating the expected bandwidth demands according to the better transmission path by using the network server.
9. The routing method according to claim 1 further comprising:
detecting a congestion link among the links by using the network server; and
removing the congestion link from the links of the source-destination pairs by using the network server.
10. The routing method according to claim 9 further comprising:
re-arranging the processing sequence of the source-destination pairs after the congestion link is removed according to the expected bandwidth demands by using the network server.
11. The routing method according to claim 1 further comprising:
selecting at least one second-better transmission path corresponding to each of the source-destination pairs as at least one backup transmission path according to a weighted sum of the cost values corresponding to the links in the source-destination pair.
12. The routing method according to claim 11 further comprising:
when the better transmission path comprises a congestion link, replacing the better transmission path with the backup transmission path as a new better transmission path.
13. The routing method according to claim 1, wherein the step of \u201cselecting the better transmission path corresponding to each of the source-destination pairs according to the weighted sum of the cost values corresponding to the links in the source-destination pair by using the network server\u201d comprising:
selecting a plurality of candidate transmission paths according to a plurality sums of the cost values; and
selecting the better transmission path among the candidate transmission paths according to the weighted sum of the cost values.
14. The routing method according to claim 13, wherein the weighted sum is operated according to at least one of a plurality of forwarding table entries of each of the candidate transmission paths, hop counts of each of the candidate transmission paths and sum processor’s speed of switches along each of the candidate transmission paths.
15. A network server, comprising:
a processor, used to receive a network topology graph and a plurality of expected bandwidth demands corresponding to a plurality of source-destination pairs, and calculates a plurality of link criticalities of a plurality of links established based on the source-destination pairs according to the network topology graph and the expected bandwidth demands and calculates a plurality of expected loads of the links according to the link criticalities, the processor further calculates a plurality of cost values according to a plurality of residual capacities and the corresponding expected loads of the links and selects a better transmission path corresponding to each of the source-destination pairs according to a weighted sum of the cost values corresponding to the links in the source-destination pair.
16. The network server according to claim 15, the processor selects a plurality of candidate transmission paths according to the weighted sum of the cost values corresponding to the links in each of the source-destination pairs by using the network server and selects the better transmission path by the weighted sum which obtained according to a plurality of forwarding tables in the transmission paths.
17. The network server according to claim 16, the processor calculates a total quantity of forwarded information recorded in the forwarding tables and selecting the transmission path having the smallest total quantity among the transmission paths as the better transmission path.
18. The network server according to claim 15, the processor arranges a processing sequence of the source-destination pairs according to the expected bandwidth demands.
19. The network server according to claim 15, wherein the link criticality corresponding to each of the links is yx, wherein x is a total number of paths between the source-destination pairs, and y is a number of paths between the source-destination pairs that pass through the link.
20. The network server according to claim 19, wherein the expected load of each of the links is equal to a sum of products between the link criticalities and the expected bandwidth demands of the link corresponding to all source-destination pairs.
21. The network server according to claim 20, each of the cost values is obtained by dividing the expected load corresponding to each of the links by the residual capacity corresponding to the link.
22. The network server according to claim 15, the processor updates the expected bandwidth demands according to the better transmission path.
23. The network server according to claim 15, the processor detects a congestion link among the links by using the network server, and removes the congestion link from the links of the source-destination pairs.
24. The network server according to claim 23, the processor further re-arranges the processing sequence of the source-destination pairs after the congestion link is removed according to the expected bandwidth demands.
25. The network server according to claim 15, the processor selects at least one second-better transmission path corresponding to each of the source-destination pairs as at least one backup transmission path according to a weighted sum of the cost values corresponding to the links in the source-destination pair.
26. The network server according to claim 25, when the better transmission path comprises a congestion link, the processor replaces the better transmission path with the backup transmission path as a new better transmission path.
27. The network server according to claim 15, the processor selects a plurality of candidate transmission paths according to a plurality sums of the cost values, and selects the better transmission path among the candidate transmission paths according to the weighted sum of the cost values.
28. The network server according to claim 27, the weighted sum is operated according to at least one of a plurality of forwarding table entries of each of the candidate transmission paths, hop counts of each of the candidate transmission paths and sum processor’s speed of switches along each of the candidate transmission paths.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An image forming apparatus, comprising:
a first conveying section for conveying media,
a first conveying section sensor for detecting the media being conveyed by said first conveying section,
a second conveying section for reversing the media and for conveying the reversed media, and
an image forming section for forming an image on a medium conveyed from said first conveying section or from said second conveying section,
wherein, in case that said first conveying section conveys a second medium after conveying a first medium,
said second conveying section conveys in said first medium from said image forming section and keeps said first medium, said first medium having completed forming an image, when a jam of said second medium is detected by said first conveying section sensor,
said first conveying section conveys a third medium after detecting relief of the jam of said second medium with said first conveying section sensor, and
said second conveying section conveys the kept first medium to follow said third medium.
2. An image forming apparatus according to the claim 1 wherein said image forming section forms an image, which should have been formed on said second medium, on a first face of said third medium, and succeedingly forms a succeeding image on a second face of said first medium.
3. An image forming apparatus according to the claim 1, further comprising:
a second conveying section sensor for detecting the media being conveyed by said second conveying section,
wherein a demand for a relief of the jam is put out when said second conveying section sensor has detected a change of the state of said second conveying section during a time interval between a time of catching said first medium in said second conveying section and a time of detecting the relief of the jam of said second medium with said first conveying section sensor.
4. An image forming apparatus according to the claim 3, wherein a forming of an image on a second face of said first medium is allowed when said second conveying section sensor has not detected the change of the state of said second conveying section during the time interval between the time of catching said first medium in said second conveying section and the time of detecting the relief of the jam of said second medium with said first conveying section sensor.
5. An image forming apparatus, comprising:
a first conveying section for conveying media,
a first conveying section sensor for detecting the media being conveyed by said first conveying section,
a second conveying section for reversing the media and for conveying the reversed media,
an image forming section for forming an image on a medium conveyed from said first conveying section or from said second conveying section, and
a second conveying section sensor for detecting a state of said second conveying section,
wherein, in case that said first conveying section conveys a second medium after conveying a first medium,
said second conveying section conveys in said first medium from said image forming section and keeps said first medium, said first medium having completed forming an image, when a jam of said second medium is detected by said first conveying section sensor, and
said second conveying section conveys the kept first medium, when said second conveying section sensor has not detected a change of the state of said second conveying section during a time interval between a time of catching said first medium in said second conveying section and a time of detecting a relief of the jam of said second medium with said first conveying section sensor.