Abstract: A route reflector (e.g., a flex-algorithm optimal route reflector (ORR)) may receive an advertisement communication from a network device of a network associated with the route reflector and may identify, in the advertisement communication, information identifying one or more flex-algorithms that are supported by the network device. The route reflector may determine, based on the information identifying the one or more flex-algorithms that are supported by the network device, a set of routing paths associated with a flex-algorithm of the one or more flex-algorithms. The route reflector may update a data structure to include routing path information that indicates the set of routing paths associated with the flex-algorithm and may transmit a routing communication that includes routing information associated with the routing path information to the network device.

Abstract: Techniques are disclosed for a link state routing protocol adjacency state machine. The adjacency state machine ensures that first and second logical links using different networking protocols are established on a single physical link between two network devices prior to indicating adjacency between the network devices. In some examples, the adjacency state machine determines that both the first and second links are active in response to determining that hello messages are generated by both network devices for both links. In some examples, the adjacency state machine determines that both the first and second logical links are active upon expiration of a predetermined time corresponding to a time required for a duplicate address detection (DAD) operation to complete. In some examples, the first and second logical links use Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6), respectively.

Abstract: In general, techniques are described by which to provide a scaled end-to-end view of link metrics to integrate multiple non-uniform Interior Gateway Protocol (“IGP”) domains. For example, an Accumulated Interior Gateway Protocol (“AIGP”) attribute, a non-transitive BGP attribute, which includes a link metric assigned to a link within a first IGP domain, is scaled to conform to a metric scale of the second IGP domain. The AIGP attribute may also add link metric assigned to a link within the second IGP domain and may add static metrics of non-IGP links connecting the IGP domains. An IGP domain may set its IGP to the scaled AIGP attribute such that the link metric may include a uniformly scaled end-to-end view of link metrics across the IGP domains. Additionally, a sham-link is assigned a metric value in accordance with the scaling techniques.

Abstract: Techniques are disclosed for a link state routing protocol adjacency state machine. The adjacency state machine ensures that first and second logical links using different networking protocols are established on a single physical link between two network devices prior to indicating adjacency between the network devices. In some examples, the adjacency state machine determines that both the first and second links are active in response to determining that hello messages are generated by both network devices for both links. In some examples, the adjacency state machine determines that both the first and second logical links are active upon expiration of a predetermined time corresponding to a time required for a duplicate address detection (DAD) operation to complete. In some examples, the first and second logical links use Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6), respectively.

Abstract: In general, techniques are described for conflict resolution in source packet routing in networking. For example, a first router receives a first advertisement originated in a first Interior Gateway Protocol (IGP) level. The first advertisement specifies a first prefix and a segment identifier (SID). The first router also receives a second advertisement originated in a second IGP level of the network. The second advertisement specifies a second prefix and the SID. Based on the first advertisement and the second advertisement specifying the same SID and based on the first IGP level having less visibility than the second IGP level, the first router selects the SID to be associated with a route to the first prefix.

Abstract: A first network device detects a link down event associated with a second network device, where the link down event is detected by the first network device prior to being detected by a third network device, and the second network device is a designated network device of a network. The first network device starts a delay timer before processing the link down event, and detects an event that includes at least one of receipt, from the third network device, of a link state advertisement message based on the link down event, or an expiration of the delay timer. The first network device determines the first network device to be a new designated network device for the network based on detecting the event, and provides, to the third network device, information indicating that the first network device is the new designated network device for the network.

Abstract: A first network device detects a link down event associated with a second network device, where the link down event is detected by the first network device prior to being detected by a third network device, and the second network device is a designated network device of a network. The first network device starts a delay timer before processing the link down event, and detects an event that includes at least one of receipt, from the third network device, of a link state advertisement message based on the link down event, or an expiration of the delay timer. The first network device determines the first network device to be a new designated network device for the network based on detecting the event, and provides, to the third network device, information indicating that the first network device is the new designated network device for the network.

Abstract: In one example, a method includes by a first network device positioned on a border of a first area of a multi-area hierarchical network and a second area of the multi-area hierarchical network, determining a cost associated with sending network traffic from a client group to the first network device, wherein the client group is positioned in the first area, the first area and the second area being distinct routing domains of the multi-area hierarchical network; and outputting, by the first network device to a second network device positioned in the second area, a routing advertisement that specifies the determined cost as a reverse metric. In some examples, a route reflector receives the routing advertisement and based on the cost from the client group to the area border network device, selects an egress point from among a plurality of egress points of the multi-area hierarchical network.

Abstract: In general, techniques are described for conflict resolution in source packet routing in networking. For example, a first router receives a first advertisement originated in a first Interior Gateway Protocol (IGP) level. The first advertisement specifies a first prefix and a segment identifier (SID). The first router also receives a second advertisement originated in a second IGP level of the network. The second advertisement specifies a second prefix and the SID. Based on the first advertisement and the second advertisement specifying the same SID and based on the first IGP level having less visibility than the second IGP level, the first router selects the SID to be associated with a route to the first prefix.

Abstract: Techniques are described for enhancements to multicast Label Distribution Protocol (mLDP) to support multicast only fast re-route (MoFRR) over a remote loop free alternate (RLFA) backup path. An egress router is configured to generate a modified mLDP control message to signal the RLFA backup path in which an address of a RLFA node is included in an LSPRoot field and an address of an ingress router is included in an opaque data field. In addition, the RLFA node of the RLFA backup path is configured to recognize that it is identified in the LSPRoot field of the modified mLDP control message, and, in response, look up the ingress router identified in the opaque data field of the modified mLDP control message. The RLFA node is further configured to send an mLDP control message that includes the address of the ingress router in the LSPRoot field towards the ingress router.

Abstract: In general, techniques are described by which to provide a scaled end-to-end view of link metrics to integrate multiple non-uniform Interior Gateway Protocol (“IGP”) domains. For example, an Accumulated Interior Gateway Protocol (“AIGP”) attribute, a non-transitive BGP attribute, which includes a link metric assigned to a link within a first IGP domain, is scaled to conform to a metric scale of the second IGP domain. The AIGP attribute may also add link metric assigned to a link within the second IGP domain and may add static metrics of non-IGP links connecting the IGP domains. An IGP domain may set its IGP to the scaled AIGP attribute such that the link metric may include a uniformly scaled end-to-end view of link metrics across the IGP domains. Additionally, a sham-link is assigned a metric value in accordance with the scaling techniques.

Abstract: Techniques are described for enhancements to multicast Label Distribution Protocol (mLDP) to support multicast only fast re-route (MoFRR) over a remote loop free alternate (RLFA) backup path. An egress router is configured to generate a modified mLDP control message to signal the RLFA backup path in which an address of a RLFA node is included in an LSPRoot field and an address of an ingress router is included in an opaque data field. In addition, the RLFA node of the RLFA backup path is configured to recognize that it is identified in the LSPRoot field of the modified mLDP control message, and, in response, look up the ingress router identified in the opaque data field of the modified mLDP control message. The RLFA node is further configured to send an mLDP control message that includes the address of the ingress router in the LSPRoot field towards the ingress router.