Abstract: Techniques are described for signaling aliasing capability between routers in a multi-tenant data center that uses VPNs, such as Ethernet VPNs. In the multi-tenant data center, two or more PE routers may be connected to a CE router by a multi-homed L2 segment in an all-active mode. Aliasing refers to the ability of a PE router to signal that it can reach a given multi-homed L2 segment even when the PE router has learned no MAC addresses over that multi-homed L2 segment. The PE routers on the multi-homed L2 segment advertise aliasing capability using a route advertisement on a per-L2 segment basis. When the multi-tenant data center uses global VPN identifiers, no additional information is needed by a remote PE to build an ECMP next hop to the PE routers that support aliasing, and transmission of a route advertisement on a per-VPN basis may be suppressed.

Abstract: In general, techniques are described for a path computation delay timer for multi-protocol label switched networks. As an example, an ingress network device configured to act as an ingress for a label switched path (LSP) may perform the techniques. The ingress network device comprises an interface and a processor. The interface may receive a message indicating an error along the LSP. The processor may delay an operation performed to configure a replacement LSP to be used in place of the LSP in order to provide time during which a cause of the error along the LSP is able to be determined. When the cause of the error is determined to be a failure of a network device supporting operation of the LSP, the processor may further perform the operation to configure the replacement LSP with the ingress network device such that the replacement LSP avoids the failed network device.

Abstract: A device may transmit, to one or more network devices of a portion of a network, information indicating that the device is configured to perform a static designated forwarder election procedure. The device may determine that the one or more network devices of the portion of the network are each configured to perform the static designated forwarder election procedure. The device may enable a static designated forwarder configuration of the device based on determining that the one or more network devices of the portion of the network are each configured to perform the static designated forwarder election procedure.

Abstract: Techniques are described for signaling aliasing capability between routers in a multi-tenant data center that uses VPNs, such as Ethernet VPNs. In the multi-tenant data center, two or more PE routers may be connected to a CE router by a multi-homed L2 segment in an all-active mode. Aliasing refers to the ability of a PE router to signal that it can reach a given multi-homed L2 segment even when the PE router has learned no MAC addresses over that multi-homed L2 segment. The PE routers on the multi-homed L2 segment advertise aliasing capability using a route advertisement on a per-L2 segment basis. When the multi-tenant data center uses global VPN identifiers, no additional information is needed by a remote PE to build an ECMP next hop to the PE routers that support aliasing, and transmission of a route advertisement on a per-VPN basis may be suppressed.

Abstract: The techniques of this disclosure may improve multicast forwarding in an Ethernet Virtual Private Network when delivering multicast traffic to receivers on a different IP subnet than the multicast source. A method may include configuring first and second layer-2 domains to forward network traffic; configuring a first layer-3 Integrated Routing and Bridging (IRB) interface for the first layer-2 domain and a second layer-3 IRB interface for the second layer 2 domain; receiving a multicast packet from a multicast source device, the multicast source device being included in the first layer-2 domain, the multicast packet having a multicast receiver device in the second layer-2 domain; and forwarding, using the first and second layer-3 IRB interfaces, the multicast packet to the multicast receiver device, without receiving the multicast packet from another provider edge router that has been elected as the designated router on the second IRB interface for the second layer-2 domain.

Abstract: In general, techniques are described for performing a mass withdrawal of media access control (MAC) addresses using a reduced number of route withdrawal messages within a singly-homed segment of an Ethernet Virtual Private Network (EVPN). The techniques may include determining a segment identifier of the segment and sending a route advertisement to advertise a route for the segment identifier to a provider edge network device. The techniques may include sending a route advertisement to advertise one or more media access control (MAC) routes for the layer two segment. The techniques may also include, responsive to determining a link failure between a first provider edge network device and a customer edge network device, sending a withdrawal message to the second provider edge network device for the route associated with the segment identifier to withdraw all of the plurality of MAC routes at the second provider edge network device.

Abstract: In general, techniques are described for configuring a provider edge (PE) network device of an Ethernet virtual private network (EVPN) to use a common traffic engineering label (e.g., MPLS label) for different EVPN route types associated with the same EVPN. In some examples, the techniques include sending a first layer three (L3) control plane message that indicates a label-switched network protocol label that corresponds to a first EVPN route type, wherein the first L3 control plane message indicates that a first PE network device is reachable in the L2 segment. The techniques may include performing L2 address learning to determine at least one L2 address associated with the layer two segment of the EVPN. The techniques may include sending a second L3 control plane message that indicates the same label included in the first L3 control plane message corresponds to a second EVPN route type.

Abstract: In one example, a stitching point routing device, which stitches a previous segment of an end-to-end label-switched path (LSP) to a next segment of the end-to-end LSP, includes network interfaces configured to receive packets via the previous segment and send packets via the next segment, and one or more processors configured to determine whether the next segment supports entropy labels, determine whether a packet received from the previous segment is encapsulated by a label stack including an entropy label, when the next segment does not support entropy labels and when the packet is encapsulated by the label stack including the entropy label, remove the entropy label from the label stack, when the next segment supports entropy labels and when the packet is not encapsulated by the label stack including the entropy label, add an entropy label to the label stack, and forward the packet along the next segment.

Abstract: Techniques are described for signaling aliasing capability between routers in a multi-tenant data center that uses VPNs, such as Ethernet VPNs. In the multi-tenant data center, two or more PE routers may be connected to a CE router by a multi-homed L2 segment in an all-active mode. Aliasing refers to the ability of a PE router to signal that it can reach a given multi-homed L2 segment even when the PE router has learned no MAC addresses over that multi-homed L2 segment. The PE routers on the multi-homed L2 segment advertise aliasing capability using a route advertisement on a per-L2 segment basis. When the multi-tenant data center uses global VPN identifiers, no additional information is needed by a remote PE to build an ECMP next hop to the PE routers that support aliasing, and transmission of a route advertisement on a per-VPN basis may be suppressed.

Abstract: Techniques are described for utilizing Protocol Independent Multicast Sparse Mode (PIM-SM) to transport BUM (broadcast, unknown unicast, and multicast) traffic in a Virtual Extensible LAN (VXLAN) underlay of a data center, where the BUM traffic is received on active-active, multi-homed Ethernet virtual private network (EVPN) interconnects between multiple physical data centers. For example, the techniques may readily be applied to support usage of PIM-SM where provider edge (PE) routers of the EVPN operate as gateways between the EVPN and the VXLAN spanning the data center interconnect.

Abstract: In one example, a stitching point routing device, which stitches a previous segment of an end-to-end label-switched path (LSP) to a next segment of the end-to-end LSP, includes network interfaces configured to receive packets via the previous segment and send packets via the next segment, and one or more processors configured to determine whether the next segment supports entropy labels, determine whether a packet received from the previous segment is encapsulated by a label stack including an entropy label, when the next segment does not support entropy labels and when the packet is encapsulated by the label stack including the entropy label, remove the entropy label from the label stack, when the next segment supports entropy labels and when the packet is not encapsulated by the label stack including the entropy label, add an entropy label to the label stack, and forward the packet along the next segment.

Abstract: In general, techniques are described for providing control plane messaging in an active-active (or all-active) configuration of a multi-homed EVPN environment. In some examples, the techniques include receiving a control plane message comprising at least one address that identifies that second PE network device. The techniques may include configuring, based at least in part on the control plane message, a forwarding plane of a first PE network device to identify network packets having respective destination addresses that match the at least one address. The techniques may include determining that at least one address of the network packet matches the at least one address that identifies the second PE network device. The techniques may include, responsive to the determination, skipping a decrement of the Time-To-Live (TTL) value of the network packet, and forwarding the network packet to the second PE network device.

Abstract: Routers balance network traffic among multiple paths through a network according to an amount of bandwidth that can be sent on an outgoing interface computed for each of the paths. For example, a router receives a link bandwidth for network links that are positioned between the first router and a second router of the network, and selects a plurality of forwarding paths from the first router to the second router. Upon determining that one of the network links is shared by multiple of the plurality of forwarding paths, the router computes a path bandwidth for each of the plurality of forwarding paths so as to account for splitting of link bandwidth of the shared network link across the multiple forwarding paths that share the network link. The router assigns packet flows to the forwarding paths based at least on the computed amount of bandwidth for each of the forwarding paths.

Abstract: In general, techniques are provided for receiving a first control plane message that indicates the reachability of the second PE network device as a designated forwarder in an Ethernet segment. The techniques include receiving a second control plane message comprising information that indicates, in the event of a network failure at the second PE router, that the third PE network device of the plurality of PE network devices is the designated forwarder in the layer two segment. The techniques also include forwarding layer two frames to the second PE network device identified as the designated forwarder in the layer two segment; and responsive to determining a network failure at the second PE network device, configuring, based at least in part on the second control plane message, a forwarding plane of the first PE network device to forward layer two frames to the third PE network device as the designated forwarder.

Abstract: In general, techniques are described for extending routing protocol advertisements to include respective attributes of constituent links of an aggregation group. In one example, a network device includes a management interface that receives configuration information that specifies first and second constituent links for a layer two (L2) aggregated interface. The first and second constituent links are physical links connected to respective physical interfaces of forwarding units of the network device. A routing protocol daemon of the control unit generates a link state message that specifies layer three (L3) routing information associated with the aggregated interface and further specifies an attribute of the first constituent link and an attribute of the second constituent link. The routing protocol daemon sends the link state message from the network device to another network device of the network in accordance with a routing protocol.

Abstract: An ingress router of a provider network receives a packet from a customer network, determines that the packet includes a customer network label and that the packet is to be tunneled through the provider network, based on the determination, adds a delimiter label to the packet indicative of a bottom of a provider network label stack and one or more provider network labels to the packet, and forwards the packet to a next routing device along the provider network tunnel. An egress routing device of the provider network receives a packet comprising a provider network label stack, removes the provider network label stack from the packet, determines whether the packet comprises a delimiter label following the provider network label stack, and, when the packet comprises the delimiter label, forwards the packet to a customer network interface device.

Abstract: Routers balance network traffic among multiple paths through a network according to an amount of bandwidth that can be sent on an outgoing interface computed for each of the paths. For example, a router receives a link bandwidth for network links that are positioned between the first router and a second router of the network, and selects a plurality of forwarding paths from the first router to the second router. Upon determining that one of the network links is shared by multiple of the plurality of forwarding paths, the router computes a path bandwidth for each of the plurality of outgoing interfaces so as to account for splitting of link bandwidth of the shared network link across the multiple forwarding paths that share the network link. The router assigns packet flows to the forwarding paths based at least on the computed amount of bandwidth for each of the outgoing interfaces.

Abstract: Routers balance network traffic among multiple paths through a network according to an amount of bandwidth that can be sent on an outgoing interface computed for each of the paths. For example, a router receives a link bandwidth for network links that are positioned between the first router and a second router of the network, and selects a plurality of forwarding paths from the first router to the second router. Upon determining that one of the network links is shared by multiple of the plurality of forwarding paths, the router computes a path bandwidth for each of the plurality of forwarding paths so as to account for splitting of link bandwidth of the shared network link across the multiple forwarding paths that share the network link. The router assigns packet flows to the forwarding paths based at least on the computed amount of bandwidth for each of the forwarding paths.

Abstract: A switching system. The switching system includes a first switch having a primary receive port and a secondary receive port. The switching system includes a second switch connected to the first switch. The second switch has n receive ports, where n is greater than or equal to 2 and is an integer. The second switch has m transmit ports, where m is greater than or equal to 2 and is an integer. The transmit ports are decoupled from the receive ports. The second switch has a connecting mechanism that includes a multicast mechanism which sends data out a primary transmit port of the m transmit ports to the primary receive port of the first switch to define a primary path, and out a secondary transmit port of the m transmit ports to a secondary receive port of the first switch to define a redundant path to the primary path so that if there is a failure of the primary path to provide the data to the first switch, the data is received by the first switch through the redundant path.

Abstract: A telecommunications system. The system includes a first area. The system includes a second area connected to the first area to form a single physical network for routing connections and in which there is selective propagation of information between each area in the network. A split switch. The split switch includes a first node adapted to be disposed in a first area. The split switch includes a second node adapted to be disposed in a second area. The second node is in communication with the first node. The first node prevents information from propagating into the first area from the second area which was provided to the second area from the first area or arose from the first area. A method for routing connections. The method includes the steps of propagating information concerning a connection from a first area of a physical network to a second area of the physical area. Then there is the step of preventing the information from forming a routing loop back to the first area.