Methods and systems preventing frame mis-ordering in explicitly routed networks

A network node comprising:

• a user card adapted to receive frames;
• a first network card connected to a first outgoing tunnel LSP;
• a second network card connected to a second outgoing tunnel LSP;
• a switching matrix connecting the user card to the first and second network cards;
• the user card being adapted to forward received frames to the first network card for forwarding over the first outgoing tunnel LSP, the frames including a last frame, the user card marking the last frame transmitted over the first tunnel LSP with an LF (last frame) marker;
• the user card being adapted to switch from the first tunnel LSP to a second tunnel LSP, and thereafter forward received frames to the second network card for forwarding over the second outgoing LSP, the user card marking the first frame transmitted over the second tunnel LSP is marked with a FF (first frame) marker.

A network node comprising:

• a user card adapted to transmit frames;
• a first network card connected to a first incoming tunnel LSP adapted to forward frames to the user card;
• a second network card connected to a second incoming tunnel LSP adapted to forward frames to the user card;
• a switching matrix connecting the user card to the first and second network cards adapted to forward frames to the user card;
• the user card being adapted to examine frames forwarded by the first or second network card for a FF marker and an LF marker, and upon receipt of the FF marker prior to receipt of an LF marker, to discard or buffer all frames until the LF marker is received.

A method of performing frame forwarding from a path diverge point to a path merge point for an explicitly routed connection comprising:

• at the path diverge point:
• a) forwarding frames over a first tunnel LSP, the frames including a last frame;
• b) marking the last frame transmitted over the first tunnel LSP with an LF (last frame) marker;
• c) waiting for an acknowledgement frame in response to the frame marked with the LF marker;
• d) switching from the first tunnel LSP to a second tunnel LSP;
• e) upon receipt of the acknowledgement transmitting frames over the second tunnel LSP;
• at a node containing the path merge point:
• f) receiving frames over the first tunnel LSP;
• g) upon receipt of this LF marker, transmitting back an acknowledgement frame;
• h) subsequently receiving frames over the second tunnel LSP.

A network node comprising:

• a user card adapted to receive frames;
• a first network card connected to a first outgoing tunnel LSP;
• a second network card connected to a second outgoing tunnel LSP;
• a switching matrix connecting the user card to the first and second network cards;
• the user card being adapted to forward received frames to the first network card for forwarding over the first outgoing tunnel LSP, the frames including a last frame, the user card marking the last frame transmitted over the first tunnel LSP with an LF (last frame) marker;
• the user card being adapted to wait for an acknowledgement to the LF marker and then switch from the first tunnel LSP to a second tunnel LSP, and thereafter forward received frames to the second network card for forwarding over the second outgoing LSP.

A network node comprising:

• a user card adapted to transmit frames;
• a first network card connected to a first incoming tunnel LSP adapted to forward frames to the user card;
• a second network card connected to a second incoming tunnel LSP adapted to forward frames to the user card;
• a switching matrix connecting the user card to the first and second network cards adapted to forward frames to the user card;
• the first network card being adapted to examine incoming frames for a frame containing a FF marker, and upon receipt of such a frame send an acknowledgement of a FF marker back to a starting point of the first LSP.

A method of performing frame forwarding from a path diverge point to a path merge point for an explicitly routed connection comprising:

• at the path diverge point:
• a) forwarding frames over a first tunnel LSP interconnecting the path diverge point and the path merge point, the frames including a last frame;
• b) switching from the first tunnel LSP to a second tunnel LSP interconnecting the path diverge point and the path merge point;
• c) transmitting frames over the second tunnel LSP including a first frame;
• d) marking the first frame transmitted over the second tunnel LSP is marked with a FF (first frame) marker;
• at the path merge point:
• e) receiving frames over the first tunnel LSP and forwarding them on to an output port;
• f) upon receipt of the FF marker over the second tunnel LSP, signalling a network card for the first tunnel LSP to stop forwarding frames to the output port;
• g) receiving frames over the second tunnel LSP and buffering these frames after the FF marker is received for a period long enough for the signalling of the network card for the first tunnel LSP to be completed.

A network node comprising:

• a user card adapted to receive frames;
• a first network card connected to a first outgoing tunnel LSP;
• a second network card connected to a second outgoing tunnel LSP;
• a switching matrix connecting the user card to the first and second network cards;
• the user card being adapted to forward received frames to the first network card for forwarding over the first outgoing tunnel LSP, the user card being adapted to switch from the first tunnel LSP to a second tunnel LSP, and thereafter forward received frames to the second network card for forwarding over the second outgoing LSP, the user card marking the first frame transmitted over the second tunnel LSP is marked with a FF (first frame) marker.

A network node comprising:

• a user card adapted to transmit frames;
• a first network card connected to a first incoming tunnel LSP adapted to forward frames to the user card;
• a second network card connected to a second incoming tunnel LSP adapted to forward frames to the user card;
• a switching matrix connecting the user card to the first and second network cards adapted to forward frames to the user card;
• the second network card being adapted to examine frames forwarded over the second tunnel LSP for a FF marker, and upon receipt of the FF marker to signal the first network card to stop forwarding frames to the user card, and to buffer frames long enough for the signalling to be completed and then start forwarding frames to the user card.

A method of performing frame forwarding from a path diverge point to a path merge point for an explicitly routed connection comprising:

• at the path diverge point:
• a) forwarding frames over a first tunnel LSP interconnecting the path diverge point and the path merge point, the frames;
• c) switching from the first tunnel LSP to a second tunnel LSP interconnecting the path diverge point and the path merge point;
• d) transmitting frames over the second tunnel LSP;
• at the path merge point:
• e) receiving frames over said first tunnel LSP at a first network port, amending the frames to have a first marker, and forwarding the frames thus amended towards an output port;
• e) receiving frames over said second tunnel LSP at a second network port, amending the frames to have a second marker different from said first marker, and forwarding the frames thus amended towards said output port;
• f) the output port receiving frames from the first network port with said first marker and forwarding these on through the output port;
• g) the output port upon receipt of a first frame from the second network port with said second marker, forwarding the frame on through the output port and filtering out all frames with the first marker for a period of time, and then continuing to receive frames from the second network port with said second marker and to forward these frames on through the output port.

A system adapted to perform frame forwarding from a path diverge point to a path merge point for an explicitly routed connection, the system comprising:

• a first node containing the path diverge point, the first node being adapted to forwarding frames over a first tunnel LSP, switch from the first tunnel LSP to a second tunnel LSP, and thereafter transmit frames over the second tunnel LSP;
• a second network node containing the path merge point, the second network node being adapted to:
• receive frames over a first tunnel LSP at a first network port, amend the frames to have a first marker, and forward the frames thus amended towards an output port;
• and
• receive frames over a second tunnel LSP at a second network port, amend the frames to have a second marker different from said first marker, and forward the frames thus amended towards said output port;
• the output port of the second network node being adapted to:
• receive frames from the first network port with said first marker and forward these on through the output port;
• upon receipt of a first frame from the second network port with said second marker, forward the frame on through the output port and filter out all frames with the first marker for a period of time, and then continue to receive frames from the second network port with said second marker and to forward these frames on through the output port.

A network node comprising:

• a user card adapted to transmit frames;
• a first network card connected to a first incoming tunnel LSP adapted to forward frames received over a first tunnel LSP towards the user card after marking each with a first marker;
• a second network card connected to a second incoming tunnel LSP adapted to forward frames received over a second tunnel LSP towards the user card after marking each with a second marker;
• a switching matrix connecting the user card to the first and second network cards adapted to forward frames to the user card;
• the user card being adapted to examine frames forwarded by the first or second network card for said first and second marker, and upon receipt of the frame having said second marker, to discard all further frames containing the first marker for a period of time.