Routing mechanism with encapsulated FCS for a multi-ring local area network

Claim 2

In a telecommunication network system wherein a plurality of serial loop networks are being interconnected by a plurality of switching stations and each serial loop having thereon one or more stations, a method for maintaining end-to-end integrity of data comprising the steps of: (a) generating and transmitting from a source station a frame including a destination address, a source address, an RI field and a frame check sequence (FCS) pattern; (b) receiving the frame at a switching station connected to the loop; (c) preserving the FCS pattern; (d) calculating and appending a new FCS pattern to the received frame; (e) forwarding the frame; (f) receiving the frame at a switching station not connected to the loop; (g) calculating and appending a new FCS pattern to the received frame; (h) repeating steps (e) through (g) until the last switching station is reached whereby the station does not calculate a new FCS pattern but uses the preserved FCS pattern as the frame CRC.

Claim 3

In a telecommunication network system wherein a plurality of serial loop networks are being connected by a plurality of switching stations and each serial loop having one or more utilization stations connected thereto, a method for routing frames between stations comprising the steps of: (a) transmitting from a source station a frame including a destination address (DA) field, a source address (SA) field, an RI field containing routing path data, and a frame check sequence (FCS) pattern; (b) receiving the frame at a switching station; (c) analyzing the frame to determine the position of the switching station relative to the routing path; (d) saving the FCS pattern only if the switching station is the first in the routing path; (e) calculating and appending a new FCS pattern to the received frame; (f) forwarding the frame; (g) repeating steps (b) through (f) until the frame arrives at the last station in the routing path wherein a new FCS pattern is not calculated and the saved FCS pattern is used as the FCS pattern for the frame.

Claim 4

In a telecommunication network system wherein a plurality of serial loop networks are being connected by a plurality of switching stations and each serial loop having one or more utilization stations connected thereto, a method for routing frames between stations comprising the steps of: (a) transmitting from a source station a frame including a destination address (DA) field, a source address (SA) field, an RI field containing routing path data, and a frame check sequence (FCS) pattern; (b) receiving the frame at a switching station; (c) analyzing the frame to determine the position of the switching station relative to the routing path; (d) saving the FCS pattern only if the switching station is the first in the routing path; (e) calculating and appending a new FCS pattern to the received frame; (f) forwarding the frame; (g) repeating steps (b) through (f) until the frame arrives at the last station in the routing path wherein a new FCS pattern is not calculated and the saved FCS pattern is used as the FCS pattern for the frame.

Claim 5

The method recited in claim 2 wherein the DA and SA field includes a ring number section and a node address (ADDR) section, and the RI field includes a first two-stage directional (D) indicia identifying the order in which the frame will pass through the switching station, and a PTR section showing the next switching station to process said frame.

Claim 6

The method of claim 3 wherein the analyzing step further includes the steps of: (a) examining the two-state D indicia; (b) examining the PTR; (c) comparing the value of the PTR with a range of predetermined values; and (d) characterizing the switching station as being first on the route only if the two-state (D) indicia is in a first state and the value of the PTR is within a predetermined range.

Claim 7

The method of claim 4 wherein the switching station is being characterized as last on the route only if the two-state (D) indicia is in the opposite state and the PTR value falls within a predetermined range.

Claim 8

The method of claim 5 further including the steps of resetting the PTR only if the station is last on the route.

Claim 9

The method recited in claim 2 wherein the FCS is being saved by encapsulating it within the I-field of the frame.

Claim 10

The method of claim 6 further including a second two-state indicia positioned outside of the RI field.

Claim 11

The method of claim 8 further including the steps of setting the second two-state indicia only if the switching station is last on the route.