Abstract: The subject matter described herein includes a packet forwarding device that implements next hop scaling. Rather than storing a complete set of next hop bindings at each packet processor, the storage of next hop bindings is distributed among packet processors in the packet forwarding device such that each packet processor stores next hop bindings for the hosts that are directly connected to the packet processor. For hosts that are not directly connected to a packet processor, the packet processor stores relay entries. Because of the distributed storage of next hop bindings, the number of hosts that can be served by a single packet forwarding device is increased over packet forwarding devices where each packet processor stores a complete set of next hop bindings for all connected hosts.

Abstract: Systems, mechanisms, apparatuses, and methods are disclosed for dynamically tagging VLANs. For example, in one embodiment such means include: means for receiving a packet having identified therein a source Media Access Control (MAC) address and a Virtual Local Area Network (VLAN) Identifier, wherein the VLAN identifier corresponds to a VLAN which is non-existent on a network switch; means for modifying the packet received to include two VLAN tags, a first VLAN tag corresponding to the VLAN identifier identified within the packet received and a second VLAN tag, distinct from the first; means for determining no forwarding database entry exists for the modified packet; and means for creating the VLAN on the network switch to handle received packets tagged with the VLAN identifier.

Abstract: The subject matter described herein includes methods, systems, and computer readable media for next hop scaling with link aggregation. According to one aspect of the subject matter described herein, a system for next hop scaling is provided. The system includes a packet forwarding device including a plurality of packet processors for performing next hop and link aggregation group (LAG) selection operations. Within this plurality of packet processors, ingress packet processors are configured to indicate, for received packets that have a next hop on a different packet processor, that an egress next hop selection operation is needed. Egress packet processors of the plurality of packet processors are configured to perform the egress next hop and member selection operations for the packets for which an egress next hop selection operation is indicated, wherein forwarding of the packets is limited to active LAG group members local to the egress packet processor.

Abstract: Methods, systems, and computer readable media for performing stateless load balancing of network traffic flows are disclosed. According to one aspect, the subject matter described herein includes a method for performing stateless load balancing of network traffic flows. The method occurs at a layer 3 packet forwarding and layer 2 switching device. The method includes responding to address resolution protocol (ARP) requests from clients, the ARP requests including a virtual IP (VIP) address shared by the device and a plurality of servers coupled to the device, with the medium access control (MAC) address of the device. The method also includes receiving, from the clients, packets addressed to the VIP address and having the MAC address of the device. The method further includes load sharing the packets among the servers using a layer 3 forwarding operation that appears to the clients as a layer 2 switching operation.

Abstract: The subject mailer described herein includes methods, systems, and computer readable media for automatically selecting between Internet protocol switching modes on a per-module basis in a packet forwarding device. According to one aspect, a method may include determining capacities of hardware longest prefix matching (LPM) tables located on each input/output (I/O) module in a multi-module IP packet forward device. The number of routes currently stored in a software LPM table may be determined. If the software LPM table can be stored within the hardware LPM table for an I/O module, an LPM mode may be automatically selected for that I/O module. If the contents of software LPM table cannot be stored within the hardware LPM table for a particular I/O module, the I/O module may be automatically transitioned to operate in an Internet protocol forwarding database (IPFDB) mode.

Abstract: The subject matter described herein includes methods and systems for conserving multicast port lists in an IP packet forwarding device. According to one embodiment, the method includes providing an IP multicast packet port data structure containing at least a first port list and a second port list. The first and second port lists each contain zero or more port addresses for indicating the ports to which a received IP multicast packet including a group IP address is to be forwarded. An IP multicast packet forwarding database (FDB) is provided where the FDB has at least a first FDB entry and a second FDB entry for forwarding the received IP multicast packet based on its group IP address. The first and second FDB entries each include at least one multicast group IP address and are associated with at least one of the first and the second port lists. It is then determined whether the first and second port lists contain identical information.

Abstract: The subject matter described herein includes methods, systems, and computer readable media for next hop scaling. According to one aspect of the subject matter described herein, a system for next hop scaling is provided. The system includes a plurality of I/O modules, each having at least one I/O port for communicating packets to and receiving packets from hosts external to the packet forwarding device. The packet forwarding device further includes a plurality of packet processors associated with the I/O modules for performing packet forwarding operations.

Abstract: The subject matter described herein includes methods, systems, and computer readable media for next hop scaling with link aggregation. According to one aspect of the subject matter described herein, a system for next hop scaling is provided. The system includes a packet forwarding device including a plurality of packet processors for performing next hop and link aggregation group (LAG) selection operations. Within this plurality of packet processors, ingress packet processors are configured to indicate, for received packets that have a next hop on a different packet processor, that an egress next hop selection operation is needed. Egress packet processors of the plurality of packet processors are configured to perform the egress next hop and member selection operations for the packets for which an egress next hop selection operation is indicated, wherein forwarding of the packets is limited to active LAG group members local to the egress packet processor.

Abstract: The subject matter described herein includes methods and systems for dynamically rate limiting slowpath processing of exception packets. According to one embodiment, a method includes monitoring processing resources in a packet forwarding device used for performing slowpath processing of exception packets at the packet forwarding device. It is determined whether usage of the processing resources used for slowpath processing exceeds a first threshold and, in response to determining that the processing resources exceed the first threshold, rate limiting the slowpath processing of the exception packets.

Abstract: The subject matter described herein includes methods and systems for providing accidental stack join protection. According to one embodiment, a method includes connecting stacking ports of a first switch that is a member of a first stack and a second switch that is a member of a second stack and thereby joining the first and second stacks. The configurations of the first stack and of the second stack are detected and it is determined whether the detected configurations indicate a configuration mismatch between the first and second stacks. In response to determining that the detected configurations relate to a mismatch, the automatic joining of the first and second stacks is inhibited and the first and second stacks are allowed to continue switching traffic with their existing configurations.

Abstract: Methods, systems, and computer readable media for performing stateless load balancing of network traffic flows are disclosed. According to one aspect, the subject matter described herein includes a method for performing stateless load balancing of network traffic flows. The method occurs at a layer 3 packet forwarding and layer 2 switching device. The method includes responding to address resolution protocol (ARP) requests from clients, the ARP requests including a virtual IP (VIP) address shared by the device and a plurality of servers coupled to the device, with the medium access control (MAC) address of the device. The method also includes receiving, from the clients, packets addressed to the VIP address and having the MAC address of the device. The method further includes load sharing the packets among the servers using a layer 3 forwarding operation that appears to the clients as a layer 2 switching operation.

Abstract: An indication of a host route to be added to a forwarding database table as an entry is received. The host route is added to a first hardware table or a second hardware table if a space is available in the second hardware table or in a first storage area of the first hardware table. The first hardware table has both a first storage area and a second storage area. If a space is not available in the second hardware table or the first storage area of the first hardware table, the first storage area of the first hardware table is automatically expanded to include unused space in the second storage area of the first hardware table. The host route is then added to a space in the expanded first storage area of the first hardware table.

Abstract: The subject matter described herein includes methods, systems, and computer readable media for automatically selecting between Internet protocol switching modes on a per-module basis in a packet forwarding device. According to one aspect, the subject matter described herein includes a packet forwarding device including at least one input/output (I/O) module. The at least one I/O module includes a longest prefix matching (LPM) table, an Internet protocol forwarding database (IPFDB) and the packet forwarding device includes an IP routing table and an IPFDB. When the I/O module operates in an LPM mode, the IPFDB on the I/O module is populated with entries corresponding to active hosts, the LPM table on the I/O module is populated from the IP routing table with routes learned from IP routing protocols, and layer 3 packets received by the I/O module are routed using the IPFDB and LPM table of the I/O module. An automatic mode-selection module determines a capacity of the LPM table on the I/O module.

Abstract: A multicast data packet sent from a source node is received by a transit node. The multicast data packet includes a source address and a multicast group address. A hardware cache miss is detected at the transit node for the multicast data packet. The multicast data packet is hardware-flooded onto ports of the network. The flooding consists of forwarding a copy of the multicast data packet to neighbor nodes of the transit node based on virtual local area network (VLAN) membership. A cache-miss copy of the multicast data packet is sent to an out-of-line processing unit where it is processed in software. The processing includes establishing, via a hardware abstraction layer, a hardware cache entry for the multicast data packet. The cache-miss copy is not forwarded onto the network.

Abstract: The subject matter described herein includes methods, systems, and computer program products for routing packets at a multi-mode layer 3 packet forwarding device. According to one aspect, the subject matter described herein includes operating a first of at least two modules in a host mode, and operating a second of at least two modules in a longest prefix matching (LPM) mode. Operating a module in a host mode includes populating a host table and an LPM table with entries corresponding to hosts and routing layer 3 packets received by the first module using the host and LPM tables. Operating a module in an LPM mode includes populating a host table with entries corresponding to hosts, populating an LPM table with entries corresponding to variable length Internet protocol (IP) addresses and next hop addresses, and routing layer 3 packets received by the second module using the host and LPM tables.

Abstract: The subject matter described herein includes methods and systems for dynamically rate limiting slowpath processing of exception packets. According to one embodiment, a method includes monitoring processing resources in a packet forwarding device used for performing slowpath processing of exception packets at the packet forwarding device. It is determined whether usage of the processing resources used for slowpath processing exceeds a first threshold and, in response to determining that the processing resources exceed the first threshold, rate limiting the slowpath processing of the exception packets.

Abstract: The subject matter described herein includes methods, systems, and computer program products for rate-based distribution of layer 2 packets for in-line processing at a layer 2 packet forwarding device. According to one aspect, the subject matter described herein includes a method for distributing layer 2 packets for in-line processing at a transmission rate less than a received transmission rate. The method includes receiving an input stream of layer 2 packets at an input port of a layer 2 packet forwarding device. The input port has a first transmission capacity. The input stream of layer 2 packets is divided into at least two substreams of layer 2 packets of different transmission rates. The first substream of layer 2 packets is layer 2 redirected to a first set of output ports of a slower transmission capacity than the input port. The second substream of layer 2 packets is flooded to a second set of output ports, with a transmission capacity equal to the first set of output ports.

Abstract: Methods, systems, and computer program products for controlling updating of a layer 3 host table based on packet forwarding miss counts are disclosed. According to one method, layer 3 packets are routed using at least one of a layer 3 host table containing entries corresponding to remote hosts and a longest prefix matching table containing prefixes corresponding to remote hosts. For each layer 3 destination address for which a lookup in at least one table fails, a number of packets received within a time period are counted. Remote destination entries in the host table are replaced based on the counts.

Abstract: A multicast data packet sent from a source node is received by a transit node. The multicast data packet includes a source address and a multicast group address. A hardware cache miss is detected at the transit node for the multicast data packet. The multicast data packet is hardware-flooded onto ports of the network. The flooding consists of forwarding a copy of the multicast data packet to neighbor nodes of the transit node based on virtual local area network (VLAN) membership. A cache-miss copy of the multicast data packet is sent to an out-of-line processing unit where it is processed in software. The processing includes establishing, via a hardware abstraction layer, a hardware cache entry for the multicast data packet. The cache-miss copy is not forwarded onto the network.

Abstract: Methods and systems for hybrid layer 2 address learning are disclosed. In one method, a packet with a layer 2 source address is received. Next, it is determined whether to implement hardware-based learning or software-based learning based on a classification of the received packet. In response to determining that software-based learning is required, the source address and corresponding forwarding information in the packet are learned using software. In response to determining that hardware-based learning is required, the source address and corresponding forwarding information are learned using hardware.