Bit indexed explicit replication using multiprotocol label switching
Various systems and methods for performing bit indexed explicit replication (BIER) using multiprotocol label switching (MPLS). For example, one method involves receiving a packet that includes a MPLS label. The packet also includes a multicast forwarding entry. The method also involves determining, based on the value of the MPLS label, whether to use the multicast forwarding entry to forward the packet. The method further includes forwarding the packet.
1. A method performed by a node in a network of nodes, the method comprising:
in response to receiving a packet comprising a top label that is associated with a BIER (bit indexed explicit replication) node, determining a first next-hop neighbor node;
determining whether the first next-hop neighbor node is a BIER enabled node;
in response to determining the first next-hop neighbor node is not a BIER enabled node:
adding a label to the packet, wherein the added label corresponds to label switched path (LSP) between the node and an egress node of the network;
forwarding the packet with the added label to the first next-hop neighbor node;
identifying a BIER-enabled node along a shortest path towards the egress node.
2. The method of claim 1 further comprising:
in response to determining the first next-hop neighbor node is a BIER enabled node:
selecting a bit forwarding table;
selecting a row as a selected row in the bit forwarding table, wherein the selected row is selected based, at least in part, on a bit position value corresponding to a first set bit in a packet bit mask (PBM) of the packet;
copying the packet to create a copied packet;
replacing the top label in the copied packet with a routing label from the selected row of the bit forwarding table; and
forwarding the copied packet to the first next-hop neighbor node, wherein the forwarding is based, at least in part, on the routing label.
3. The method of claim 2 further comprising
prior to forwarding the copied packet, modifying the copy of the PBM of the copied packet by clearing one or more bits that had been set in the packet.
4. The method of claim 2 , wherein the selected row comprises:
a bit mask value,
information identifying the first next-hop neighbor node, and
the routing label.
5. The method of claim 1 further comprising:
the first next-hop neighbor node receiving the packet with the added label;
the first next-hop neighbor removing the added label from the packet it receives;
the first next-hop neighbor forwarding the packet to a neighbor node after removing the added label.
6. The method of claim 5 further comprising:
the neighbor node receiving the packet from the first next-hop neighbor node;
the neighbor node determining whether a label of the packet it receives is associated with another BIER enabled node;
in response to determining that the label contained in the packet received from the first next-hop neighbor node is associated with another BIER node, the neighbor node accessing its bit forwarding table using the label contained in the packet received from the first next-hop neighbor node.
7. The method of claim 5 further comprising the first next-hop neighbor adding another label to the packet after the first next-hop neighbor removes the top label and before the first next-hop neighbor forwards the packet to the neighbor node.
8. The method of claim 1 , wherein the determining the first next-hop neighbor node comprises:
accessing a bit forwarding table using the top label and a packet bit mask (PBM) contained in the packet;
wherein the first next-hop neighbor node is mapped in an entry of the bit forwarding table to a set bit in the PBM.
9. The method of claim 8 wherein each bit in the PBM is mapped to a respective egress node of the network.
10. A node comprising:
one or more network interface cards;
a memory configured to store instructions; and
a processor configured to perform a method in response to executing the instructions stored in the memory, the method comprising:
in response to the node receiving a packet comprising a top label that is associated with a BIER node, determining a first next-hop neighbor node;
determining whether the first next-hop neighbor node is a BIER enabled node;
in response to determining the first next-hop neighbor node is not a BIER enabled node:
adding a label to the packet, wherein the added label corresponds to label switched path (LSP) between the node and an egress node of a network in which the node and the egress node are contained;
forwarding the packet with the added label to the first next-hop neighbor node;
identifying a BIER-enabled node along a shortest path towards the egress node.
11. The node of claim 10 wherein the method further comprises:
in response to determining the first next-hop neighbor node is a BIER enabled node:
selecting a bit forwarding table;
selecting a row as a selected row in the bit forwarding table, wherein the selected row is selected based, at least in part, on a bit position value corresponding to a first set bit in a packet bit mask (PBM) of the packet;
copying the packet to create a copied packet;
replacing the top label in the copied packet with a routing label from the selected row of the bit forwarding table; and
forwarding the copied packet to the first next-hop neighbor node, wherein the forwarding is based, at least in part, on the routing label.
12. The node of claim 11 wherein the method further comprises:
prior to forwarding the copied packet, modifying the copy of the PBM of the copied packet by clearing one or more bits that had been set in the packet.
13. The node of claim 11 , wherein the selected row comprises:
a bit mask value,
information identifying the first next-hop neighbor node, and
the routing label.
14. The node of claim 10 , wherein the determining the first next-hop neighbor node comprises:
accessing a bit forwarding table using the top label and a packet bit mask (PBM) contained in the packet;
wherein the first next-hop neighbor node is mapped in an entry of the bit forwarding table to a set bit in the PBM.
15. The node of claim 14 wherein each bit in the PBM is mapped to a respective egress node of the network.
16. A system comprising
a node configured to perform a method comprising:
in response to the node receiving a packet comprising a top label that is associated with a BIER node, determining a first next-hop neighbor node;
determining whether the first next-hop neighbor node is a BIER enabled node;
in response to determining the first next-hop neighbor node is not a BIER enabled node:
adding a label to the packet, wherein the added label corresponds to label switched path (LSP) between the node and an egress node of a network in which the node and the egress node are contained;
forwarding the packet with the added label to the first next-hop neighbor node;
identifying a BIER-enabled node along a shortest path towards the egress node.
17. The system of claim 16 wherein the method further comprises:
in response to determining the first next-hop neighbor node is a BIER enabled node:
selecting a bit forwarding table;
selecting a row as a selected row in the bit forwarding table, wherein the selected row is selected based, at least in part, on a bit position value corresponding to a first set bit in a packet bit mask (PBM) of the packet;
copying the packet to create a copied packet;
replacing the top label in the copied packet with a routing label from the selected row of the bit forwarding table; and
forwarding the copied packet to the second next-hop neighbor node, wherein the forwarding is based, at least in part, on the routing label.