What is claimed is:
1. A dielectric porcelain comprising a polycrystalline material of which a main component comprises oxides containing at least a rare earth element (Ln), Al, M (M represents at least one selected from Ca and Sr) and Ti as metal elements, wherein the thickness of a grain boundary layer is 20 nm or less.
2. The dielectric porcelain according to claim 1, wherein at least a part of the oxide of Al is included in the form of crystal comprising at least one selected from -Al2O3, -Al2O3 and -Al2O3.
3. The dielectric porcelain according to claim 1, wherein the main component comprises oxides containing at least a rare earth element (Ln), Al, M (M represents at least one selected from Ca and Sr) and Ti as metal elements, and in case that a compositional formula of the oxides is represented by aLn2Ox.bAl2O3.cMO.dTiO2 (3×4), molar ratios a, b, c and d satisfy the following relationships:
0.056a0.214; 0.056b0.214; 0.286c0.500; 0.230<d<0.470; and abcd1.
4. The dielectric porcelain according to claim 1, wherein at least one of metal elements Mn, W, Nb and Ta is contained in the total amount of 0.01 to 3% by weight on the basis of MnO2, WO3, Nb2O5 and Ta2O5.
5. The dielectric porcelain according to claim 1, wherein the main component comprises oxides containing at least a rare earth element (Ln), Al, M (M represents at least one selected from Ca and Sr) and Ti as metal elements, and a half width of a peak observed in a range from 700 to 900 cm1 of laser Raman spectrum is 120 cm1 or less.
6. The dielectric porcelain according to claim 1, wherein the main component comprises oxides containing at least a rare earth element (Ln), Al, M (M represents at least one selected from Ca and Sr) and Ti as metal elements; a half width of a peak observed in a range from 700 to 900 cm1 of laser Raman spectrum is 120 cm1 or less; and at least one of metal elements Mn, W, Nb and Ta is contained in the total amount of 0.01 to 3% by weight on the basis of MnO2, WO3, Nb2O5 and Ta2O5.
7. A dielectric porcelain comprising oxides, as a main component, containing at least Ti, Zr and Sn as metal elements, wherein a half width of a peak observed in a range from 700 to 900 cm1 of laser Raman spectrum is 120 cm1 or less.
8. The dielectric porcelain according to claim 7, wherein the main component comprises oxides containing at least Ti, Zr and Sn as metal elements, and in case that a compositional formula of the oxides is represented by hTiO2.iZrO2.jSnO2, molar ratios h, i and j satisfy the following relationships:
0.30h0.60; 0.25i0.60; 0.025j0.20; and hij1.
9. A dielectric resonator comprising the dielectric porcelain of any one of claims 1 to 8 disposed between a pair of input and output terminals, so as to function through electromagnetic coupling.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A virtual local area network (VLAN) tunneling system comprising:
a first switching node having an ingress port and an egress port, the ingress port being associated with a VLAN and receiving a data packet, the egress port being configured as an untagged port, the egress port adding VLAN information to the data packet and transmitting the data packet on a label-switched path;
a second switching node receiving the data packet transmitted from the first switching node via the label-switched path, the second switching node further identifying the data unit as a virtual bridged LAN data unit, retrieving the added VLAN information from the data packet, and transmitting the data packet to a final destination based on the retrieved VLAN information.
2. The VLAN tunneling system of claim 1 further including a third switching node in the label-switched path, the third switching node configured to add to the packet a label value reserved for packets originating from a port associated with a VLAN for informing the second switching node that VLAN information is embedded in the data packet.
3. The VLAN tunneling system of claim 2, wherein the second switching node receives the packet with the reserved label value and determines that the packet includes VLAN information associated with an originating port based on the reserved label.
4. A virtual local area network (VLAN) tunneling system including a switching node in a label-switched path, the switching node including:
an ingress port associated with a VLAN receiving a packet; and
an egress port configured as an untagged port, the egress port receiving the packet from the ingress port and adding to the packet VLAN information associated with the VLAN of the ingress port and transmitting the packet over the label-switched path.
5. A virtual local area network (VLAN) tunneling system including a switching node in a label-switched path, the switching node including:
an ingress port receiving a packet having an ingress label value; and
an egress port receiving the packet from the ingress port and replacing the ingress label value with a label value reserved for packets originating from a port associated with a VLAN, the egress port further transmitting the packet to a next switching node on the label-switched path based on the ingress label value.
6. The switching node of claim 5, wherein the next switching node is an egress edge switching node in the label-switched path.
7. The switching node of claim 6, wherein the egress edge switching node receives the packet with the reserved label value, determines that the packet includes VLAN information associated with an originating port based on the reserved label value, and processes the VLAN information for transmitting the packet to a final destination.
8. A virtual local area network (VLAN) tunneling system comprising:
a first switching node having a plurality of ports at least one of which has a VLAN associated therewith; and
a second switching node, characterized in that a data unit for transmission from said first switching node to said second switching node over said at least one port is checked for VLAN assignment prior to transmission and in that said data unit is transmitted from said first switching node to said second switching node on a label-switched path or not depending on a result of said check.
9. The system of claim 8 further characterized in that a VLAN identifier assigned to said data unit is applied to said data unit prior to transmission on said label-switched path.
10. The system of claim 9 further characterized in that said VLAN identifier applied to said data unit is referenced at said second switching node to identify the VLAN assignment of said data unit.
11. The system of claim 8, wherein said at least one port is untagged.
12. The system of claim 8 further characterized in that said data unit is bridged from said first switching node if not transmitted on said label-switched path.
13. A virtual local area network (VLAN) tunneling method comprising the steps of:
receiving a packet at an ingress port, the ingress port being associated with a VLAN;
forwarding the packet to an egress port, the egress port being configured as an untagged port;
adding to the packet at the egress port VLAN information and a label value associated with a next switching node in a label-switched path; and
transmitting the packet to the next switching node in the label-switched path.
14. A virtual local area network (VLAN) tunneling method comprising the steps of:
receiving a packet at an ingress port of a switching node, the packet having an ingress label value;
forwarding the packet to an egress port;
replacing the ingress label value with a label value reserved for packets originating from a port associated with a VLAN; and
transmitting the packet to a next switching node on a label-switched path based on the ingress label value.
15. The method of claim 16, wherein the next switching node is an egress edge switching node in the label-switched path.
16. The method of claim 15 further comprising the steps of:
receiving at the egress edge switching node the packet with the reserved label value;
determining that the packet includes VLAN information associated with an originating port based on the reserved label value;
retrieving the VLAN information; and
processing the VLAN information for transmitting the packet to a final destination.