Preventing packet loops in unified networks
View Patent ↗Unified mobility switches often define a virtual LAN (VLAN), including a combination of mobility tunnels and access tunnels, via which packets are transported to a mobile device over a combination of physical connections and wireless links. A unified switch may have multiple ports available to route a packet to a particular destination, since the unified switches identify routing paths for both physical connections and VLANs. A particular unified switch may therefore have multiple routes to a common destination, which can lead to a routing loop across a network of switches supporting both physical and virtual connections. A unified mobility switch provides loop detection and prevention through a set of rules for qualifying connections as virtual tunnels or physical connections, and defining a single path where multiple potential paths exist.
1. A method of loop prevention in a unified split-plane mobility domain comprising:
identifying a topology of unified switches for transporting message traffic, the message traffic defined by packets;
identifying a set of links between the unified switches for forwarding message traffic packets, the links defined by ports on the unified switches;
computing, based on a destination, at least one port corresponding to the destination, each of the links corresponding to a virtual tunnel or a physical connection and accessible via a port on the unified switch;
determining, at a unified switch forwarding a packet to a destination, when forwarding on a particular port causes a loop back to the forwarding switch;
identifying, in response to the determined loop, a loop rule, the loop rule indicative of another port for forwarding to the destination; and
forwarding the packet on the port indicated by the loop rule, the indicated port corresponding to a different one of a tunnel or a physical port than the particular port causing the loop.
2. The method of claim 1 wherein determining includes computing a set of links defining a loop, each of the links accessible for forwarding via a port, the loop causing a routing path back to a node from which a packet was previously sent.
3. The method of claim 1 further comprising:
identifying a topology of unified switches in the mobility domain, the unified switches responsive to wired and wireless communication, each of the unified switches having a set of ports for forwarding packets to other unified switches for transporting packets of message traffic;
determining, from the topology, a path defined by a set of links;
computing if the path is a looping path, the looping path resulting in a packet route back to a previously traversed unified switch;
identifying a port corresponding to the computed looping path; and
forwarding the packet on another port.
4. The method of claim 1 wherein determining a loop further comprises:
identifying multiple redundant unified switches interconnected by a mobility tunnel, the mobility tunnel supporting roaming mobile devices corresponding to users; and
identifying a physical connection between at least two of the unified switches.
5. The method of claim 4 wherein the redundant unified switches act as a server for a virtual LAN (VLAN), the VLAN defined by ports, each of the ports corresponding to a tunnel or a physical connection, each of the tunnels accessing a transport path corresponding to physical connections.
6. The method of claim 5 wherein the tunnels include mobility tunnels between unified switches for forwarding to a roaming user, and access tunnels for forwarding to an access point corresponding to a mobile device of the roaming user.
7. The method of claim 2 wherein determining the loop further comprises determining that the destination is accessible by both a physical connection and a virtual tunnel, and the identified loop rule directs invocation of the physical connection for forwarding the packet.
8. The method of claim 2 wherein determining the loop further comprises determining that the destination is accessible via a plurality of virtual tunnels, each of the virtual tunnels defining a separate path including distinct unified switches;
identifying a virtual tunnel between the distinct unified switches; and
invoking a rule associating one of the distinct unified switches for packet forwarding for the destination.
9. The method of claim 8 further comprising:
identifying a plurality of mobile devices accessible via the same set of distinct unified switches; and
invoking a rule apportioning server unified switches among client unified switches for load balancing the mobile devices among the distinct unified switches.
10. The method of claim 1 wherein the loop rule is selectable from a set of loop rules, the identified loop rule further including:
determining if multiple links provide both a physical connection and a virtual tunnel to a destination, and if so, forwarding the packet on a port corresponding to a physical connection.
11. The method of claim 10 wherein the loop rules further include:
determining if the multiple links correspond to paths to at least two unified switches, the unified switches connected by a virtual tunnel, and if so, selecting, for each mobile device, a path corresponding to one of the unified switches for packets for the mobile device.
12. The method of claim 11 wherein the loop rules further include:
determining if a plurality of unified switches in a VLAN are connected by at least one of physical connections or virtual tunnels; and
restricting forwarding on the connections in the VLAN for packets associated with a roaming mobile device.
13. The method of claim 12 wherein the loop rules further include:
determining if an overload or failure condition mandates failover from one of the unified switches to another unified switch in a common VLAN; and
terminating existing connections and associations for a failover user before initiating associations to the failover unified switch.
14. A mobility switch for loop prevention in a unified split-plane mobility domain comprising:
an interface configured to identify a topology of unified switches for transporting message traffic, the message traffic defined by packets;
a set of ports associated to links between the unified switches for forwarding message traffic packets, the links defined by ports on the unified switches;
forwarding logic for computing, based on a destination, at least one port corresponding to the destination, each of the links corresponding to a virtual tunnel or a physical connection and accessible via a port on the unified switch;
a set of rules configured for determining, at a unified switch forwarding a packet to a destination, when forwarding on a particular port causes a potential loop back to the forwarding switch; and
the forwarding logic configured to identify, in response to the determined potential loop, a loop rule identifying VLAN membership resulting in multiple forwarding ports causing the potential loop, the loop rule indicative of another port for forwarding to the destination, forward the packet on the port indicated by the loop rule, the indicated port corresponding to a different one of a tunnel or a physical port than the particular port causing the loop.
15. The mobility switch of claim 14 wherein the rules are further configured to compute a set of links defining a loop, each of the links accessible for forwarding via a port, the loop causing a routing path back to a node from which a packet was previously sent.
16. The mobility switch of claim 14 wherein the rules are further configured to:
identify a topology of unified switches in the mobility domain, the unified switches responsive to wired and wireless communication, each of the unified switches having a set of ports for forwarding packets to other unified switches for transporting packets of message traffic;
determine, from the topology, a path defined by a set of links;
compute if the path is a looping path, the looping path resulting in a packet route back to a previously traversed unified switch;
identify a port corresponding to the computed looping path; and
forward the packet on another port.
17. The mobility switch of claim 14 wherein the rules are further configured to:
identify multiple redundant unified switches interconnected by a mobility tunnel, the mobility tunnel supporting roaming mobile devices corresponding to users; and
identify a physical connection between at least two of the unified switches, the redundant unified switches defining a virtual LAN (VLAN), the VLAN defined by at least one tunnel, each of the tunnels including a plurality of links corresponding to physical connections.
18. The mobility switch of claim 14 wherein the loop rule is selectable from a set of loop rules, the identified loop rule further including:
determining if multiple links provide both a physical connection and a virtual tunnel to a destination, and if so, forwarding the packet on a port corresponding to a physical connection.
19. The mobility switch of claim 18 wherein the loop rules are further configured to:
identify a plurality of mobile devices accessible via VLAN membership associated with a plurality of distinct unified switches;
determine if the multiple links correspond to paths to at least two unified switches, the unified switches connected by a virtual tunnel, and if so, selecting, for each VLAN associated with the identified mobile devices, a path corresponding to one of the unified switches for packets for the mobile device; and
apportion unified switches among associated mobile devices for load balancing the mobile devices among the distinct unified switches.
20. A computer program product having computer program code encoded as a set of instructions on a non-transient computer readable storage medium that, when executed by a processor, cause the computer to perform a method for managing a split-plane wireless network, the method comprising:
identifying a topology of unified switches for transporting message traffic, the message traffic defined by packets;
identifying a set of links between the unified switches for forwarding message traffic packets, the links defined by ports on the unified switches;
computing, based on a destination, at least one port corresponding to the destination, each of the links corresponding to a virtual tunnel or a physical connection and accessible via a port on the unified switch;
determining, at a unified switch forwarding a packet to a destination, when forwarding on a particular port causes a loop back to the forwarding switch;
identifying, in response to the determined loop, a loop rule, the loop rule indicative of another port for forwarding to the destination; and
forwarding the packet on the port indicated by the loop rule, the indicated port corresponding to a different one of a tunnel or a physical port than the particular port causing the loop.