Telefonaktiebolaget Lm Ericsson (publ)

Ericsson Ab

Wenhu Lu

Uma S Chunduri

Alfred C Lindem, Iii

Sriganesh Kini

Vasant Shankargouda Patil

Ing-Wher Chen

Albert Jining Tian

Evgeny Tantsura

Ramanathan Lakshmikanthan

Srikanth Narayanan

Vasant S Patil

Alfred C Iii Lindem

Alfred C Lindem Iii

Kini Sriganesh

A method is implemented by a node for enabling shortest path bridging in a network that is scalable to support sixteen million virtual local area network (VLAN) identifiers using multiprotocol label switching (MPLS) encapsulation. The method comprises allocating a tunnel label using a distributed tunnel label allocation algorithm, allocating a source label using a distributed source label allocation algorithm, assigning a bridge instance a service label, and distributing the tunnel label, source label and service label to other nodes in the MPLS network.

Shortest path bridge with MPLS labels

A method of a network device identifies multi-homed prefixes in an intermediate system-intermediate system (IS-IS) area or IS-IS domain during shortest path first (SPF) computation for use in a loop free alternate (LFA) computation. The method and network device select a next node in a shortest path tree (SPT) and determine a set of prefixes associated with the selected node in the SPT. A next prefix from the set of prefixes of the selected node is selected and a check is made whether the selected prefix exists in the local RIB associated with another node of a same level, then the selected prefix is marked as a multi-homed prefix in the local RIB. A check is made whether all prefixes associated with the selected node are processed and whether all nodes in the SPT have been processed, before downloading the local RIB to a global RIB.

Procedure to identify multi-homed prefixes for IS-IS LFA

A method in a router for initiating fast flooding based fast convergence to recover from a network failure is disclosed. The method also starts with detecting a network failure. Responsive to the detected network failure, the router floods a layer 2 fast failure notification message out a set of one or more interfaces of the router. The fast failure notification message includes information that identifies the network failure and indicates to a router that receives the fast failure notification message to flood the fast failure notification message out its interfaces that are not blocked by a spanning tree protocol (STP) independently of updating its routing table to reflect the network failure. The method continues with the router updating a routing table to reflect the network failure.

Fast flooding based fast convergence to recover from network failures

A method and system implemented by a network device, where the network device is in a network having a plurality of nodes. The method computes a loop free alternative (LFA) next hop as a backup for a primary path next hop for intermediate system-intermediate system (IS-IS). The method improves LFA computation efficiency by minimizing expansion of prefixes. The method includes expanding all prefixes of the next LFA shortest path first (SPF) destination node and inheriting a next candidate next hop as a current LFA next hop where the next candidate next hop provides link or node protection and better protection than the current LFA next hop.

Optimization to expand IS-IS leaf nodes during LFA computation

An automated key transition method is executed by a node in a network. The network includes a set of nodes utilizing a current key identifier. A key identifier specifies an authentication protocol and an authentication key for use in the authentication of intermediate-system to intermediate-system (IS-IS) protocol data units. The method includes a set of steps including receiving a message at the node, where, the message includes a most recent key identifier to replace the current key identifier, verifying whether all reachable nodes in the set of nodes have advertised the most recent key identifier, continuing authentication using the current key identifier until all reachable nodes in the set of nodes have been verified to advertise the most recent key identifier, and switching authentication at the node to use the most recent key identifier upon verification that all reachable nodes in the set of nodes have advertised the most recent key identifier.

Mechanism for co-ordinated authentication key transition for IS-IS protocol

A method is executed by a network device to a calculate loop free alternative (LFA) for each node in an intermediate system-intermediate system (IS-IS) area or IS-IS domain where the network device is connected with other nodes via multiple parallel links. The method includes a shortest path first (SPF) computation of the primary paths for the network device that tracks directly connected links from each node in the IS-IS area or IS-IS domain to the network device which is a source node for the SPF. These tracked links can then be utilized in subsequent LFA computations to avoid unnecessary calculations.

Optimized approach to IS-IS LFA computation with parallel links

A method and system are provided to install a loop free alternative (LFA) next hop as a backup for a primary path next hop for an interior gateway protocol (IGP). The method enables testing of the LFA next hop to ensure proper handling of data forwarding on the LFA. The method includes receiving a trigger message from an administrative module indicating a switch to the LFA next hop the message including a prefix and an interface. A check is made whether a set of primary path next hops of the prefix have been exhausted. A next primary path next hop is selected from the set of primary path next hops of the prefix. A check is made whether the next primary path next hop matches the interface. The next primary path next hop is replaced by installing the LFA next hop into a global routing information base.

Simplified approach to verify LFAS in deployment

A method and implementing system calculates a loop free alternative (LFA) next hop as a backup for a primary path next hop for an interior gateway protocol (IGP). The method enables consideration of the LFA next hop where a link to the next hop has a reverse cost that has a maximum value. The method includes selecting a next candidate next hop from a set of candidate next hops in the network, checking whether a link to the next candidate next hop is an administratively allowable link, and checking whether the link has a maximum forward cost. The method further checks whether the link is bi-directional and computes the LFA using the next candidate next hop where the link is administratively allowable link, where the link does not have a maximum forward cost and where the link is bi-directional without consideration of reverse cost of the link.

Enhanced procedure to compute LFAs with IGP max metric

A method is executed by a network device to determine a loop free alternate (LFA) for a multi-homed prefix in an IS-IS area or IS-IS domain. The method includes selecting a next node from the IS-IS area or the IS-IS domain and selecting a next prefix for the selected node. A check is made whether the selected prefix is a multi-homed prefix (MHP). A check is made whether a shortest path first (SPF) cost of the selected node and cost to the selected prefix is equal to an SPF cost of the selected prefix, whether a next hop of selected prefix is same as next hop of selected node, and whether a LFA next hop of the selected node is better protection than a current next hop protection of the selected prefix and the LFA next hop of the selected node is then inherited for the selected prefix.

Better alternate paths for multi homed IS-IS prefixes

The method and system to computes an LFA next hop as a backup for a primary path next hop that enables an administrator to control LFA selection for a given destination node using a tag and a weight. The method includes checking whether an interface of a next candidate node has a tag with a tag value matching a tag value of a primary SPF path for the destination node. The method further includes checking whether the destination node has any LFA, checking whether a stored tag differs from the tag value of the primary SPF path, and checking whether the interface of the next candidate node is preferred based on a comparison of a weight values, and replacing a stored LFA for the destination node with the next candidate node. Where conditions are met a stored LFA is replaced with the next candidate node.

Alternate method to give operators flexibility to choose LFAs

A method is implemented by a network device to determine loop free alternatives (LFA) for each next hop in a default route to border nodes of a level 1 intermediate system-intermediate system (IS-IS) area of the network device. The method selects a next next-hop for the default route and looks up a corresponding border node for the selected next-hop in a local routing information base (RIB). A next next-hop of the corresponding border node is selected. A check is made whether the selected next-hop of the corresponding border node is the same as selected next-hop of default route. Then an LFA of the selected next-hop of the corresponding border node is assigned as LFA of the selected next-hop of the default route.

Procedure to add alternate paths for IS-IS default route

A network element that has a broadcast interface to a broadcast network becoming operational determines whether at least one alternate path exists to the broadcast network. The broadcast interface is to carry traffic on a label switched path. If an alternate path exists, the broadcast interface will not be advertised to the broadcast network until label distribution protocol (LDP) is operational with all neighbors on the broadcast interface.

LDP IGP synchronization for broadcast networks

A network element of a communications network includes a fresh route queue, a stale route queue, a Routing Information Base (RIB), a network interface, and a routing protocol module. The network interface receives link state information from other network elements. The routing protocol module determines a plurality of routes from the link state information. The routing protocol module identifies among the plurality of routes a subset of routes that are present in the stale route queue, adds the subset of routes to the fresh route queue, and deletes the subset of routes from the stale route queue. The routing protocol module then remove routes in the RIB that correspond to any routes remaining in the stale route queue, and moves the routes from the fresh route queue to the stale route queue. Related methods for managing routes in a RIB of a network element are disclosed.

Managing stale route removal in a routing information base of a network element

An automated key transition method is executed by a node in a network. The network includes a set of nodes utilizing a current key identifier provided by a group key management server or provisioned manually. A key identifier specifies an authentication protocol and an authentication key for use in the authentication of intermediate-system to intermediate-system (IS-IS) protocol data units. The method includes receiving a message from the group key management server that includes a most recent key field to replace the current key identifier, advertising the most recent key identifier to all reachable nodes, verifying whether all reachable nodes have advertised the most recent key identifier, continuing authentication using the current key identifier until all reachable nodes have been verified to advertise the most recent key identifier, and switching authentication to use the most recent key identifier upon verification that all reachable nodes have advertised the most recent key identifier.

A network element is configured to reduce the synchronization costs for implementing Open Shortest Path First (OSPF) Nonstop routing (NSR). The reduced synchronization costs are achieved by reducing the number of acknowledgement messages that are needed to be sent though reliable inter-process communication (IPC) between the active OSPF instance and the standby OSPF instance. The number of acknowledgement messages is reduced by tracking the link state advertisements (LSAs) that have been sent by the active OSPF instance to the standby OSPF instance and by the standby OSPF replying with an acknowledgement of only the last LSA in a group of LSAs received from the active OSPF instance, where the group can have a variety of boundaries such as a group of LSAs in an IPC message. This avoids having a significant number of acknowledgement messages sent through the IPC.

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San Jose, CA, United States of America

Wenhu Lu