MPLS Operation

1. MPLS Operation BXR-48000 Switch Router

2. Objectives • Identify the value of MPLS over traditional IP • Explain IP with connection-orientation • Define MPLS tunnels • List examples of permanent and signaled LSPs • Describe the ATM PWE3 tunnel • Describe BGP VPNs and virtual routers

3. IPLookup IPLookup LSP Conceptual Model • Regardless of the network path, the labeled IP traffic is going to a destination LSR responsible for the final IP lookup and forwarding • Therefore, LSPs are generally built as LSR-to-LSR versus port-to-port as with Frame Relay or ATM virtual connections

4. Packets and Cells • Although physical ports can be POS or IPA ATM, LSRs will forward traffic on a packet basis • Simple operation on packet interfaces such as POS • IPA ATM ports support LSPs but originating and terminating interfaces must segment/reassemble the traffic so the Layer 3 header can be read • IP traffic from an ATM attached router must be accommodated • Encapsulations from RFC 2684 (formerly 1483) are supported • Interoperability with conventional router vendors

5. Satisfying Both Communities • MPLS would not have been accepted if it was simply another way for routers to exchange IP traffic • It had to offer more, such as improving on best effort and providing traffic engineering • It also had to provide the connectivity already in the market (FR, Ethernet & ATM) • The result is Layer 3-oriented LSPs and Layer 2-oriented LSPs

6. Added Value of MPLS • MPLS networks support hop-by-hop routing (no labels) • MPLS adds network-wide traffic engineering • Full mesh of dynamic tunnels (best effort) • Best effort signaled tunnels • Traffic engineered tunnels • Explicit routing • MPLS adds hop-specific, traffic managed quality of service • MPLS DiffServ • Hose/Pipe Tunnels • These properties can be used in combination

7. MPLS Tunnel (Data Plane) Defined Destination Control Plane and Data Plane • MPLS separates the control plane and the data plane • Routers are aware of each other using existing routing protocols • Labeled traffic flows on connections with specific attributes Topology fromRouting Protocols(Control Plane) Shortest Hop-By-Hop Path

8. Bringing Connection-Orientation to IP • An LSR gains efficiency by sending packets into tunnels which end at other LSRs • Between the ingress and egress points, there is no IP routing • Tunnels are an alternative to the hop-by-hop, best effort path to the destination, they can use: • Best effort signaled connections • Traffic engineered signaled connections • Explicitly routed signaled connections • Permanent connections • Tunnels define the IP endpoint and attributes, connections define the label value

9. Label = 28 Label = 183 Mapping IP Traffic to a Tunnel Service Level Classification High Priority DefaultBest Effort Dest: Z Premium Dest: Z Dest: Z Dest: Z Standard

10. MPLS Tunnel • At the ingress of the MPLS connection, the LSR must know how to classify traffic • The classifications define if and how traffic is labeled • IP policies can redirect a specific IP flow to a tunnel • Other IP flows can be sent to a best-effort tunnel • The tunnel has specific destination and attributes which are communicated from end-to-end • Any specific traffic attributes must be supported by each LSR, not just the ingress LSR • One or more LSPs (signaled or permanent) are bound to the tunnel

11. D C B A Label = 81 Label = 28 Differentiated IP Services IP Flows Classification Policy 1 Policy 2 Policy 3 Policy 4 Default Tunnels LSPs IP IP Label = 183 IP IP Label = 342 IP Label = 67

12. Tunnel Types • Hose tunnels carry IP traffic and use the point-to-cloud model, no IP TM policies and use a committed access rate • The access rate is not a guaranteed bandwidth, it’s a way to upgrade the service • Pipe tunnels carry constrained IP traffic, use the point-to-point model, use IP TM policies and provide a committed information rate • The information rate is specific to the destination and is respected by each transit LSR • Pseudo Wire Emulation End-to-End (PWE3), carries ATM cell streams from one point to another through the MPLS core • Tunnels can have traffic specifications and path affinity

13. Multiple Tunnel Instances • With tunnel properties defined, one or more LSP instances can be created • Multiple instances have the same endpoints but travel different routes through the network • Signaled routes can be programmed to be disjoint • Load balancing occurs on up to 3 instances with the same endpoints • The load balancing is dynamic; topology changes could add or remove an instance from the load balancing distribution

14. Tunnel Syntax BXR_Pgh:mpls tunnel-> new Usage: [[-index] <integer>] Tunnel Index (default: 1) [[-instance] (1..65535)] Instance Index (default: 1) [[-from] <IP Address>] Source Router Address (default: 10.10.91.23) [-to] <IP Address> Destination Router Address [[-trafficSpecIndex] <integer>] Traffic Spec Index [[-pathIndex] <integer>] Path Index [[-instancePriority] (0..255)] Instance Priority (default: 100) [[-adminstatus] (up|down)] Administrative Status (default: up) [[-name] <text>] Name [[-description] <text>] Description (default: "“) : [[-sigProtocol] <sig_proto>] Sig Protocol (default: rsvp) [[-usageMode] (hose|pipe|propL2|pwe3)] Usage Mode (default: hose) : [[-primaryPathRef] <integer>] Reference for Disjoint Path [[-disjointPathOpt] (partial|full)] Disjoint Path Option (default: none) [[-origTunnelIndex] <integer>] Originating LSR Tunnel Index

15. Create a Signaled Tunnel • LSR to LSR hose example BXR_Pgh:mpls tunnel-> new 5 -to 10.10.99.1 -instancePriority 100 -sigProtocol rsvp BXR_Pgh:mpls tunnel-> show Index Inst Origination Termination Admin Oper Proto Role Name 5 1 10.10.91.23 10.10.99.1 up up rsvp head

16. Full-Mesh Dynamic Tunnel • LSRs can be configured to create a full mesh of tunnels • Creates unidirectional, best effort tunnels to each egress LSR • Usually within an AS • IGP advertisements tie a destination network to the router ID • The router ID is tied to the dynamic tunnel BXR_Pgh:mpls dynamic-lsp-> modify Usage: [[-autolsp] (enabled|disabled)] Automatically Setup LSP BXR_Pgh:mpls dynamic-lsp-> modify –autolsp enabled BXR_Pgh:mpls dynamic-lsp-> mpls tunnel BXR_Pgh:mpls tunnel-> show Index Inst Origination Termination Admin Oper Proto Role Name 2 1 10.10.91.23 10.10.91.21 up up rsvp head Dyn_[2] 65536 1 10.10.91.21 10.10.91.23 up up rsvp tail Dyn_[1]

17. Configured Tunnel • A tunnel to an egress point is supported by one or more label switched paths (LSPs) • When LSRs are configured with signaling and routing protocols, the routing tables for each LSR should be populated with entries from their neighbors • Entries could be for IP prefixes or router IDs • In either case, the egress point is the destination LSR • Any destination (network or egress LSR) can be the target of a tunnel • Can be sold as a VPN service • Tunnels are supported with either: • Permanent LSPs can always be created hop-by-hop • Signaled LSPs can go to a specific network or simply an egress router

18. Originating Transit Terminating P-LSP P-LSP P-LSP Permanent LSPs (P-LSPs) • These unidirectional connections are built hop-by-hop always referencing the position on the LSP • Originating – pushed the first label • Transit – swaps labels • Terminating – pops the label • You control the label space; it is simple with one label, a stack takes more planning • Built with the connectionslsporiginating, transit and terminatingmenus

19. Originating Transit Terminating P-LSP P-LSP P-LSP Tunnel Tunnel P-LSP Behavior • Traffic will not flow to the P-LSP until a policy redirects to the associated tunnel • P-LSPs are DiffServ BE connections unless a traffic description is associated with the P-LSP • Create the P-LSP, associate with a new tunnel, then create the policy to redirect the traffic to the tunnel • Traffic specification is possible at each hop Policy Head Tail

20. Signaled Tunnels • Head end begins the communication • Can take the IGP’s shortest path • Can follow an explicit path

21. Traffic Engineered Tunnels • Anything beyond basic best-effort is referred to as a Traffic Engineered (TE) tunnel • Specify bandwidth constraints • DiffServ or IntServ classifications • Follows DS codepoints or can be manually configured • This alters the forwarding priority in hardware • BXR has configurable queues (WRR versus strict) • Controlled by the mpls traffic-spec menu • Explicit path through the network • Controlled by the mpls path menu

22. Cell traffic Cell traffic MPLS Pseudowires • These manually configured tunnels have a specific ingress and egress port (in place of IP lookups) • MPLS defines support for Ethernet, ATM and Frame Relay pseudowires • A Layer 2 VPN Frame relay traffic

23. PWE3 - “Layer 2” Tunnels • If it was originally IP traffic, a hose or pipe would work • ATM pseudowires fill the need for moving non-IP (cell) traffic across the packet core • A number of pseudowire types are defined; the BXR-48000 supports ATM pseudowires in Release 2.0 • Cell traffic is encapsulated as specified in the Martini draft • The services pw atm new command defines the port, path and channel it arrives on • The services pw new command defines the MPLS identity • Can specify type here - VPC or VCC

24. BGP VPNs • Defined in RFC 2547bis • Easy for the customer to manage • Extremely flexible • Scales easily • Privacy inside provider’s AS • Devices fit into these roles: • Customer Edge (CE) router • Provider Edge (PE) LSR • Provider (P) LSR

25. BGP VPNs (cont) • VPNs get unique identifiers at participating PE LSRs • PE LSRs require virtual routers, policies, IGP and BGP • Virtual router creates isolated routing and forwarding tables • One virtual router per VPN • Static route to CE router • BGP to other PE LSRs hosting the VPN • Provider LSRs configure IGP and RSVP-TE

26. Static Routes BGPPeering IGP BGP VPN Example CE2 PE2 PE3 PE1 CE1 P CE4 PE4 PE5

27. VPN Results • Security • Customer simplicity • Flexibility CE2 CE1 CE4

28. Virtual Router • More than one VPN per PE LSR • Multiple VPNs for one customer • VPNs for multiple customers on one POP • Virtual router advertises a VPN address • New extension to BGP-4 • Divorces VPNs from IPv4 address in routing/forwarding tables • This numbering space administered by the provider • Protocols, policies and tunnels become specific to the virtual router regardless of the rest of the LSR or co-resident virtual routers • Tunnels can specify bandwidth, Diffserv, IntServ • Configured in the vrf menu • RSVP-TE signals LSPs as needed

29. Summary • Identified value of MPLS over traditional IP • Explained IP with connection-orientation • Defined MPLS tunnels • Listed examples of permanent and signaled LSPs • Described the ATM PWE3 tunnel • Described BGP VPNs and virtual routers