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The ZebOS® Network Platform Multi-protocol Label Switching (MPLS) modules provide a complete solution for the rapid integration of MPLS functionality into enterprise, edge, and core communications equipment. ZebOS supports both MPLS Traffic Engineering (TE) and MPLS Virtual Private Network (VPN) capabilities, as well as extensions for the support of DiffServ (Differentiated Services) and DiffServ with Traffic Engineering (DiffServ-TE).
The ZebOS MPLS modules support the following protocols and features:
- Resource Reservation Protocol-Traffic Engineering (RSVP-TE) with Graceful Restart
- Label Distribution Protocol (LDP) with Graceful Restart and Control Word Signaling
- Constrained Shortest Path First (CSPF for OSPF and IS-IS)
- MPLS-VPN using Border Gateway Protocol (BGP) VPN extensions (RFC 2547)
- Virtual Private LAN Service (VPLS with Martini)
- DiffServ and DiffServ with TE Extensions
- Pseudowire (PW) support for Layer 2 VPN
Traffic Engineering
Traffic Engineering (TE) extensions use the RSVP and LDP dynamic-signaling protocols to communicate to the ZebOS MPLS Forwarder or a third-party MPLS forwarder. The RSVP-TE extension enables MPLS to scale into large and complex IP-based communications equipment.
The ZebOS Network Platform also supports the Constrained Shortest Path First (CSPF) algorithm. Using a TE database and pre-existing Label Switched Paths (LSPs), the CSPF module calculates — on demand — an optimum Explicit Route (ER), based on the specified constraints. The resulting ER is used by a signaling protocol, either RSVP-TE or LDP, to set up LSPs.
Virtual Private Networks
Providing Virtual Private Network (VPN) services can add significant value to provider-edge equipment. These solutions deliver the security needed by VPN service providers and help build a scalable infrastructure that can take advantage of the IP routing, traffic engineering, and MPLS switching features. IP Infusion offers optional MPLS Layer 2 VPN and Virtual Private LAN Service (VPLS) protocol modules that enhance MPLS by providing transparent LAN access between VPN sites.
Supported by the ZebOS MPLS Forwarder and Label Distribution Protocols (LDP) modules, the ZebOS ARS offers a Layer 3 MPLS-VPN solution by tightly integrating BGP-VPN extensions. It provides address space and routing separation through the use of per-VPN routing tables (VPN Routing and Forwarding) and MPLS switching in the MPLS core.
MPLS-VPN and Transparent LAN Services
Graceful Restart
Graceful Restart is a feature that reduces the impact on the MPLS Forwarder due to restart of either the RSVP or the LDP modules. Under normal conditions, LDP Label Switch Routers (LSR) clear FEC-Label bindings learnt from the restarting LSR. As a result, MPLS Forwarding is impacted across the restart. With Graceful Restart capability enabled, adjacent routers exchange each others' restart capability in during Initialization, so a per-session restart capability is established at session startup. Subsequently, whenever a router goes down, it preserves its MPLS forwarding table entries.
ZebOS Network Platform MPLS Suite
MPLS Layer 2 Virtual Circuit – The ZebOS Network Platform MPLS Layer 2 Virtual Circuit (VC) module implements draft-martini-12circuit-trans-mpls-09.txt and draft-martini-12circuit-encap-mpls-04.txt. It provides a point-to-point Layer 2 virtual circuit that allows extension of a LAN segment across an MPLS cloud. The ZebOS VPLS module includes MPLS Layer 2 VC, and also supports hub-and-spoke VPN and mesh VPN topologies. It combines the benefits of an MPLS Layer 2 VC with the flexibility and scalability of a multipoint-to-multipoint VPN.
MPLS Forwarder – Because ZebOS supports IPv4, IPv6 and MPLS networks, it is well positioned not only to support core, edge, and access routing and switching platforms, but also to act as the standard routing protocol for an entire range of IPv6-enabled devices, including Small Office Home Office (SOHO) gateways; wireless, access, and security devices; and devices that support VPNs and Voice-over-Internet Protocol (VoIP) technology, which require Quality of Service (QoS) and superior bandwidth management. All ZebOS protocols use the Network Services Manager (NSM) to update Information databases and to interface with the Forwarder.
RSVP-TE – The Resource reSerVation Protocol (RSVP) is a signaling protocol that supports explicit routing capability. To do this, a simple Explicit Route (ER) object is incorporated into RSVP PATH messages. The object encapsulates a sequence of hops, which constitute the explicitly routed path. Using this object, the paths taken by the label-switched RSVP-MPLS flows can be pre-determined without conventional IP routing. The explicitly routed path can be administratively specified or computed based on CSPF and policy requirements dictated by the operator through the trunk node. A valuable application of explicit routing is Traffic Engineering (TE). Using explicitly routed LSPs, an ingress node can control the path through which traffic flows from itself, through the MPLS network, to the egress node. Explicit routing is therefore useful for the optimization of network resources and an increase in the quality of traffic oriented performance.
LDP – The Label Distribution Protocol (LDP) is a protocol in which two label-switched routers (LSR) exchange label mapping information. The two LSRs are called LDP peers and the exchange of information is bi-directional. LDP is used to build and maintain databases of LSR that are used to forward traffic through MPLS networks. LDP generates labels for, and exchanges labels between, peer routers. It works with other routing protocols (RIP, OSPF and BGP) to create the label-switched paths (LSP) used when forwarding packets. An LSP is the path taken by all packets that belong to the Forwarding Equivalence Class (FEC) corresponding to that LSP. This is analogous to establishing a virtual circuit in ATM (Asynchronous Transfer Mechanism). In this way, ZebOS LDP assigns labels to every destination address and destination prefix provided by ZebOS. The LDP interface to the MPLS forwarder adds labels to, and deletes labels from, the forwarding tables.
DiffServ – Differentiated Services (DiffServ) is a networking architecture that specifies a simple, scalable and coarse-grained mechanism for classifying and managing network traffic, and providing Quality of Service (QoS) guarantees for service providers. DiffServ employs a sophisticated policy to determine how to forward network data, so it is more advanced than earlier Quality of Service (QoS) or Type of Service (ToS) protocols. In order to provide a flexible DiffServe-over-MPLS solution, the ZebOS DiffServ module is available as an extension to the ZebOS RSVP-TE module. The ZebOS DiffServ module enables network traffic to be specified and prioritized by class, so that certain kinds of traffic, for example voice traffic, attain precedence over other types of traffic.
DiffServ-TE – Since DiffServ by itself lacks the ability to efficiently use network transmission resources, IP Infusion also offers a DiffServ-aware MPLS Traffic Engineering (DiffServ-TE) module compliant with RFC 4124. The ZebOS ARS DiffServ-TE module performs traffic engineering per DiffServ class, rather than at an aggregate level. By combining DiffServ with MPLS-TE, routing devices can simultaneously classify and prioritize traffic, and achieve fined-grained optimization of transmission resources.
Layer 2 VPNs – The ZebOS MPLS Layer 2 VPN uses MPLS labels to transport data between Provider Edge (PE) routers. VPNs are used by service providers to segregate their network for their customers, that enables them to transmit data over an IP network. ZebOS MPLS further supports Layer 2 VPNs with the use of Pseudowires (PW). A pseudowire emulates a native service over a Packet Switched Network (PSN). Pseudowires in ZebOS Network Platform are supported by an enhanced NSM.
Layer 3 VPNs – The ZebOS MPLS Layer 3 VPN solution provides address space and routing separation using per-VPN Routing and Forwarding tables (VRFs), and MPLS switching in the core and at the edge of an MPLS network. VPN customer routing information is imported into the VRFs utilizing the Route Target BGP extended community. This VPN routing information is identified uniquely using a Route Distinguisher (RD) and is distributed among Provider Edge (PE) routers using Multi-protocol BGP extensions.
Virtual Private LAN Service (VPLS) – ZebOS Virtual Private LAN Service (VPLS), in conjunction with an MPLS Layer 2 Virtual Circuit (VC), allows multiple customer sites connected across an MPLS network to share a single bridged domain. Consequently, all customer sites appear to be in the same Local Area Network (LAN), regardless of their geographical location. ZebOS ARS VPLS encapsulates Ethernet frames from a customer site with a VC label and forwards the frames over an MPLS tunnel to the intended destination. The egress Provider Edge (PE) router removes the VC label and sends the Ethernet frame to the remote VPN site.
MPLS OAM – Multi-Protocol Label Switching Operation and Management (MPLS OAM) provides remote monitoring, detection and resolution of path errors on an MPLS network. IP Infusion’s implementation of MPLS OAM supports RFC 4377, RFC 4378, and RFC 4379.
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