Abstract: A first network device may receive a first advertisement of a network destination from a second network device and may detect multihoming with the second network device. The second network device may detect the multihoming with the first network device. The first network device and the second network may enable egress protection for the multihoming. The first network device may allocate, from a first pool, a protection group identifier for a group of multihomed network devices and may allocate, from a second pool, a network destination identifier for the network destination. The first network device may provide, to a network and the second network device, a second advertisement that includes the protection group identifier and the network destination identifier. The protection group identifier and the network destination identifier may cause the network to direct traffic for the network destination, via the group of multihomed network devices.

Abstract: A network device may receive, from a transmission network device, a link state message associated with an origination network device. The network device may determine an order of a set of one-hop neighbor network devices from the transmission network device. The network device may determine, based on the link state message and the order of the set of one-hop neighbor network devices, whether the network device is to send a copy of the link state message to at least one one-hop neighbor network device of the network device. The network device may send, or refraining from sending, by the network device and based on determining whether the network device is to send the copy of the link state message to the at least one one-hop neighbor network device of the network device, the link state message to the at least one one-hop neighbor network device of the network device.

Abstract: A network device may receive policy data identifying a first segment routing (SR) policy and a second SR policy. The first SR policy may be associated with a first path through a network and a first next hop, and the second SR policy may be associated with a second path through the network and a second next hop. The network device may advertise, to another device, reachability associated with the first next hop and the second next hop, and may receive, from the other device, a packet with a header. The network device may determine, from the header, data identifying the first next hop or the second next hop, without performing a lookup, and may cause the packet to be routed to a destination address, via the first path or the second path, based on the policy data associated with the first next hop or the second next hop.

Abstract: Echo or traceroute functionality is supported in a path spanning multiple autonomous systems (ASes) having segment routing (SR) enabled, the path including an ingress node and an egress node, by: (a) obtaining a return label stack to reach the ingress node from either (A) the egress node, or (B) a transit node in the path; (b) obtaining a label stack to reach, from the ingress node, either (A) the egress node, or (B) the transit node; (c) generating a request message including the return label stack; and (d) sending the request message towards either (A) the egress node, or (B) the transit node using the label stack.

Abstract: A secure IGP topology or other link state topology can be implemented by a network security unit that runs in a centralized environment on servers separate from a network associated with the IGP topology. The network security unit acquires the topology information, such as by participating in IGP or through border gateway protocol with link state (BGP-LS). The network security unit detects possible network problems, such as indicators of potential network attacks. Once an indicator of a potential network attack is detected, the network security unit identifies the node that is compromised. Once the compromised node is identified, the network security unit can report the node for manual or automated intervention. In some aspects, the network security unit can isolate the compromised node by shutting down links connected to the compromised node.

Abstract: A network device may receive topology data identifying a spine and leaf topology of network devices, and may set link metrics to a common value to generate modified topology data. The network device may remove data identifying connections from leaf network devices to any devices outside the topology from the modified topology data to generate further modified topology data, and may process the further modified topology data, with a model, to determine path data identifying paths to destinations. The network device may determine particular path data identifying shorter paths and longer paths to corresponding destinations, and may determine hop counts associated with the paths. The network device may determine whether the hop counts are all odd values, all even values, or odd and even values, and may perform actions based on whether the hop counts are all odd values, all even values, or odd and even values.

Abstract: A first network device may receive an advertisement that includes a prefix for a second network device, wherein the advertisement is destined for a third network device. The first network device may determine, based on a network topology, whether a next hop is one hop away or multiple hops away. The first network device may selectively modify the advertisement to include a first segment identifier, based on the next hop being one hop away and to generate a first modified advertisement, or may modify the advertisement to include a second segment identifier, based on the next hop being multiple hops away and to generate a second modified advertisement. The first network device may forward the first modified advertisement or the second modified advertisement toward the third network device.

Abstract: Ping or traceroute functionality is supported in a path spanning multiple autonomous systems (ASes) having segment routing (SR) enabled, the path including an ingress node in a first autonomous system (AS) and an egress node in an AS other than the first AS, using a reverse path label pair including (1) a node segment identifier (SID) corresponding to an AS Border Router (ASBR) of the second AS (second ASBR), and (2) an egress peer engineering (EPE) SID corresponding to a segment between the second ASBR to an ASBR of the first AS (first ASBR). Responsive to receiving a ping or traceroute request by a router in the second AS, the router generates a ping or traceroute reply including the reverse path label pair. The ping or traceroute reply is forwarded to the second ASBR using the node SID of the reverse path label pair. The ping or traceroute reply is then forwarded from the second ASBR to the first ASBR using the EPE SID of the reverse path label pair.

Abstract: A network device may receive, from a transmission network device, a link state message associated with an origination network device. The network device may determine an order of a set of one-hop neighbor network devices from the transmission network device. The network device may determine, based on the link state message and the order of the set of one-hop neighbor network devices, whether the network device is to send a copy of the link state message to at least one one-hop neighbor network device of the network device. The network device may send, or refraining from sending, by the network device and based on determining whether the network device is to send the copy of the link state message to the at least one one-hop neighbor network device of the network device, the link state message to the at least one one-hop neighbor network device of the network device.

Abstract: In some implementations, a first network device may receive an advertisement from a second network device. The advertisement may be associated with indicating that the second network device is configured to support a particular flex-algorithm. The first network device may identify, in the advertisement, an address of the second network device. The first network device may configure a routing table of the first network device to indicate that the second network device is capable of receiving traffic associated with the particular flex-algorithm based on the address. The first network device may perform, using the routing table, an action associated with routing the traffic associated with the particular flex-algorithm.

Abstract: A network device may receive topology data identifying a spine and leaf topology of network devices, and may set link metrics to a common value to generate modified topology data. The network device may remove data identifying connections from leaf network devices to any devices outside the topology from the modified topology data to generate further modified topology data, and may process the further modified topology data, with a model, to determine path data identifying paths to destinations. The network device may determine particular path data identifying shorter paths and longer paths to corresponding destinations, and may determine hop counts associated with the paths. The network device may determine whether the hop counts are all odd values, all even values, or odd and even values, and may perform actions based on whether the hop counts are all odd values, all even values, or odd and even values.

Abstract: A first network device may receive an advertisement that includes a prefix for a second network device, wherein the advertisement is destined for a third network device. The first network device may determine, based on a network topology, whether a next hop is one hop away or multiple hops away. The first network device may selectively modify the advertisement to include a first segment identifier, based on the next hop being one hop away and to generate a first modified advertisement, or may modify the advertisement to include a second segment identifier, based on the next hop being multiple hops away and to generate a second modified advertisement. The first network device may forward the first modified advertisement or the second modified advertisement toward the third network device.

Abstract: In some implementations, a first network device may receive an advertisement from a second network device. The advertisement may be associated with indicating that the second network device is configured to support a particular flex-algorithm. The first network device may identify, in the advertisement, an address of the second network device. The first network device may configure a routing table of the first network device to indicate that the second network device is capable of receiving traffic associated with the particular flex-algorithm based on the address. The first network device may perform, using the routing table, an action associated with routing the traffic associated with the particular flex-algorithm.

Abstract: A first network device may receive an advertisement that includes a prefix for a second network device, wherein the advertisement is destined for a third network device. The first network device may determine, based on a network topology, whether a next hop is one hop away or multiple hops away. The first network device may selectively modify the advertisement to include a first segment identifier, based on the next hop being one hop away and to generate a first modified advertisement, or may modify the advertisement to include a second segment identifier, based on the next hop being multiple hops away and to generate a second modified advertisement. The first network device may forward the first modified advertisement or the second modified advertisement toward the third network device.

Abstract: This disclosure describes techniques that include determining, at an egress node in an SRm6 network, how to process a packet that may arrive without a segment routing header and/or a compressed routing header. In one example, this disclosure describes a method that includes receiving, by an egress node of a segment routing network, segment routing advertisements; configuring, by the egress node and based on the segment routing advertisements, information enabling the egress node to recognize encapsulated packets arriving at the egress node without a compressed routing header; receiving, by the egress node, a packet that does not have a compressed routing header; and de-encapsulating, by the egress node and based on the stored information, the packet.

Abstract: A network device may receive policy data identifying a first segment routing (SR) policy and a second SR policy. The first SR policy may be associated with a first path through a network and a first next hop, and the second SR policy may be associated with a second path through the network and a second next hop. The network device may advertise, to another device, reachability associated with the first next hop and the second next hop, and may receive, from the other device, a packet with a header. The network device may determine, from the header, data identifying the first next hop or the second next hop, without performing a lookup, and may cause the packet to be routed to a destination address, via the first path or the second path, based on the policy data associated with the first next hop or the second next hop.

Abstract: An improved traceroute mechanism for use in a label-switched path (LSP) is provided by (a) receiving, by a device in the LSP, an echo request message, wherein the echo request includes a label stack having a least one label, and wherein each of the at least one label has an associated time-to-live (TTL) value; (b) responsive to receiving the echo request, determining by the device, whether or not the device is a penultimate hop popping (PHP) device for the outermost label of the label stack; and (c) responsive to determining that the device is the PHP device for the outermost label of the label stack, (1) generating an echo reply message corresponding to the echo request message, wherein the echo reply message is encoded to indicate that the device is the PHP device for the outermost label of the label stack, and (2) sending the echo reply message back towards a source of the echo request message.

Abstract: A network device may receive policy data identifying a first segment routing (SR) policy and a second SR policy. The first SR policy may be associated with a first path through a network and a first next hop, and the second SR policy may be associated with a second path through the network and a second next hop. The network device may advertise, to another device, reachability associated with the first next hop and the second next hop, and may receive, from the other device, a packet with a header. The network device may determine, from the header, data identifying the first next hop or the second next hop, without performing a lookup, and may cause the packet to be routed to a destination address, via the first path or the second path, based on the policy data associated with the first next hop or the second next hop.

Abstract: Techniques are described for providing end-to-end segment routing paths across metropolitan area networks. For example, a method comprises receiving, by an area border router (ABR) connected to one or more metropolitan area networks and a core network, a packet including a segment routing label stack including at least a label of the ABR, a context label associated with a routing instance of the ABR, and a subsequent label identifying a device in the segment routing path, determining, from a lookup of the context label in the metro routing table, a table next hop to the core routing table (or metro routing table); in response to determining the table next hop, determining, from a lookup of the subsequent label in the core routing table (or metro routing table), a next hop in the segment routing path; and sending, by the ABR, the packet toward the device in the segment routing path.

Abstract: Techniques are disclosed for service-based tunnel selection for forwarding network traffic. In one example, a network device obtains, based on service parameters associated with a network service, a service-specific tunnel selection scheme. The tunnel selection scheme identifies a primary mapping mode for mapping the network service to a primary transport tunnel and fallback mapping modes for mapping the network service to fallback transport tunnels. The primary mapping mode is categorized according to a first type comprising tunnel colorization, while the fallback mapping modes are categorized according to types other than tunnel colorization. In response to determining that the network service cannot be mapped to the primary transport tunnel according to the primary mapping mode, the network device, maps, based on the fallback mapping modes, the network service to the fallback transport tunnels.