What is claimed is:
1. A fuel cell comprising:
a pair of separators sandwiching outsides of a membrane electrode assembly composed of a pair of electrodes provided on both sides of a solid polymer electrolyte membrane; and
an outer seal member sandwiched by a pair of separators at a position surrounding an outer periphery of the membrane electrode assembly;
an inner seal member sandwiched by one of the pair of separators and an outer periphery of said electrolyte membrane; and
wherein a step is formed at contact surfaces of said inner seal member and said outer seal member on at least one of said pair of separators.
2. A fuel cell according to claim 1, further comprising:
a backing member for reinforcing said electrolyte member placed opposing to said inner member interposing said electrolyte membrane.
3. A fuel cell according to claim 2, wherein said backing member is said anode electrode or said cathode electrode.
4. A fuel cell according to claim 2, wherein said backing member is the other one of said pair of separators.
5. A fuel cell according to claim 1, wherein the height of said step is set to be the same dimension as that of an total thickness of the electrolyte membrane and a larger electrode among a pair of electrodes.
6. A fuel cell stack, which is formed by stacking a plurality of fuel cells according to claim 1.
7. A fuel cell stack, which is formed by stacking a plurality of fuel cells according to claim 2.
8. A fuel cell stack, which is formed by stacking a plurality of fuel cells according to claim 3.
9. A fuel cell stack, which is formed by stacking a plurality of fuel cells according to claim 4.
10. A fuel cell stack, which is formed by stacking a plurality of fuel cells according to claim 5.
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. A network address-port translation (NAPT) apparatus for a plurality of IP packets with a same identification, the IP packets comprising a first packet with Layer 4 information and a second packet without Layer 4 information, the apparatus comprising:
a packet translation unit for performing a NAPT operation for the first packet to generate a translation IP; and
a translation table, coupled to the packet translation unit, for storing a correspondence between the same identification and the translation IP;
wherein the packet translation unit translates one of a source IP and a destination IP of the second packet into the translation IP according to a forwarding direction of the second packet and the translation table.
2. The apparatus of claim 1, wherein the IP packets are IP fragment packets.
3. The apparatus of claim 1, wherein if the first packet is forwarded from an internal network to an external network, the translation IP is an external source IP of the first packet after the NAPT operation.
4. The apparatus of claim 3, wherein if the second packet is forwarded from the internal network to the external network, the packet translation unit translates the source IP of the second packet into the translation IP.
5. The apparatus of claim 1, wherein if the first packet is forwarded from an external network to an internal network, the translation IP is an internal destination IP of the first packet after the NAPT operation.
6. The apparatus of claim 5, wherein if the second packet is forwarded from the external network to the internal network, the packet translation unit translates the destination IP of the second packet into the translation IP.
7. The apparatus of claim 1, wherein the packet translation unit selects one of a plurality of storage elements of the translation table according to the same identification, a source IP and a destination IP of one of the IP packets.
8. The apparatus of claim 7, wherein the packet translation unit selects the corresponding storage element by a hash function.
9. The apparatus of claim 7, wherein each of the storage elements stores a direction indicator for indicating a forwarding direction corresponding to the underlying storage element.
10. The apparatus of claim 7, wherein each of the storage elements stores a validity indicator for indicating whether content of the underlying storage element is valid.
11. The apparatus of claim 1, further comprising a packet parser for parsing content of the IP packets.
12. A switch controller comprising the NAPT apparatus of claim 1.
13. A network address-port translation (NAPT) method for a plurality of IP packets with a same identification, the IP packets at least comprising a first packet with Layer 4 information and a second packet without Layer 4 information, the method comprising:
performing a NAPT operation for the first packet to generate a translation IP;
storing a correspondence between the same identification and the translation IP into a translation table; and
translating one of a source IP and a destination IP of the second packet into the translation IP according to a forwarding direction of the second packet and the translation table.
14. The method of claim 13, wherein the IP packets are IP fragment packets.
15. The method of claim 13, wherein if the first packet is forwarded from an internal network to an external network, the translation IP is an external source IP of the first packet after the NAPT operation.
16. The method of claim 15, wherein if the second packet is forwarded from the internal network to the external network, the translating step comprises translating the source IP of the second packet into the translation IP.
17. The method of claim 13, wherein if the first packet is forwarded from an external network to an internal network, the translation IP is an internal destination IP of the first packet after the NAPT operation.
18. The method of claim 17, wherein if the second packet is forwarded from the external network to the internal network, the translating step comprises translating the destination IP of the second packet into the translation IP.
19. The method of claim 13, further comprises:
selecting one of a plurality of storage elements of the translation table for each of the first and second packets according to the same identification, a source IP and a destination IP of the first and second packets respectively.
20. The method of claim 19, wherein the selecting step is executed by a hash function.