MPLS Multipoint Ethernet
Services
Marc Lasserre
Director, Office of Technology
Riverstone Networks
www.rstn.net

Point-to-Point vs Multipoint¾

Virtual Private Wire Service (VPWS) a.k.a.
Virtual Leased Line (VLL)¾Emulation of a p-t-p link¾

Virtual Private LAN Service (VPLS) a.k.a.
Transparent LAN Service (TLS)¾Emulation of a LAN

Point-to-Point Internet Drafts¾

Point-to-Point Solutions¾ Martini¾ draft-martini-ethernet-encap-mpls-01¾ draft-martini-l2circuit-trans-mpls-10¾ Use of LDP for signaling¾ Kompella¾ draft-kompella-ppvpn-l2vpn-02¾ Use of Martini encapsulation¾ Use of BGP for signaling¾Both drafts define a pseudo-wireMultipoint Internet Drafts¾Multipoint Solutions¾ VPLS/HVPLS¾ draft-lasserre-vkompella-ppvpn-vpls-02¾ VPLS: Mesh topology¾ HVPLS: Tree topology¾ Distributed VPLS
¾ GVPLS/LPE¾ draft-radoaca-ppvpn-gvpls-00¾ draft-ouldbrahim-l2vpn-lpe-02¾Distribution of MAC learning and forwarding
enginesOther Multipoint Internet Drafts¾Multipoint Solutions¾DTLS¾IPLS¾Subset of VPLS case to interconnect IP
hosts/routers¾ MAC Addresses learned via signaling¾ Proxy ARP¾HVLS¾MAC-in-MAC

Underlying Tunnels¾All VPLS models rely on Ethernet Martiniencapsulation¾Underlying tunnels can be
¾L2TP
¾MPLS
¾Q in Q

High Interest Level¾Standards Bodies¾IETF (PPVPN)¾MEF¾IEEE (802.1)¾ITU (SG 15)¾¾Service Providers
Vendors

Is it LAN Emulation again ?
¾Simple LAN segment emulation model¾No trying to be a full bridge¾Avoids LANE issues¾No Servers¾No bottlenecks¾No single points of failure¾No Packet Reordering issues

Is VPLS Re-Inventing Bridging ?
¾Isolation between VPLS specific rules
and 802.1D bridging rules¾VPLS dataplane defines specific forwardingrules¾It is not trying to emulate a full 802.1D bridge(“partial bridge”)¾Interaction between VPLS and bridging code
¾More clarification requiredWhere does VPLS fit ?
Attachment
circuit

CEPE
BridgeCodeVPLS
CodeVPLS
CodeBridge
CodeEmulatedLANVPLS
CodePseudo-Wires

BridgeCodeIEEE 802.1D bridging code

Interaction between VPLS and Bridging

IETF VPLS code

Emulated LAN instanceVPLS Code¾VPLS Forwarding Rules¾ Learns MAC addresses per pseudo-wire (VC LSP)
¾ Forwarding based on MAC addresses¾ Replicates multicast & broadcast frames¾ Floods unknown frames¾ Split-horizon for loop prevention¾VPLS Signaling Rules¾ Establishes pseudo-wires per VPLS between relevantPEs¾VPLS Discovery Rules (Manual, LDP, BGP,DNS)

Bridging Code
¾Standard IEEE 802.1D code
¾Used to interface with customer facing ports¾Might run STP with CEs¾Used to interface with VPLS
¾Might run STP between PEs

Interaction between VPLS andBridging pieces¾VPLS presents a transparent LAN segmentinterface (one instance per VPLS) to bridging¾ E.g. STP BPDUs carried transparently¾ Full mesh of pseudo-wires invisible to bridging¾¾

There are cases where tighter interaction leads
to faster convergence (e.g. MAC withdrawals)
Other L2 protocols might also benefit from acloser interaction (e.g. 802.3ad)

Scalability Parameters¾¾¾¾¾¾

Number of MAC Addresses
Number of replications
Number of LSPs
Number of VPLS instances
Number of LDP peers
Number of PEs

Solving Scalability¾Different approaches to solve scalability¾ Hierarchical: HVPLS¾ Smaller mesh
¾ Less PEs¾ Less LDP peers¾ Distributed approach¾ DTLS: Bridging (learning/replication/forwarding) at MTU andSignaling/Routing at PE¾ GVPLS: Hybrid model¾ Specialized hardware to handle large number of MACaddresses, replications and LSPs.

Applicability¾VPLS Metrics¾Number of PEs < 20-30¾VPLS¾Number of PEs > 30
¾HVPLS¾Number of MAC addresses per VPLS < 10K¾Number of sites per VPLS < 4K

Next Steps¾Align VPLS solutions drafts to commonformat¾Topology¾Control Plane¾Data Plane¾Deployment Scenarios¾Clarify VPLS & Bridging interaction

Conclusion¾ Emerging L2 VPN technology¾ Large support from
¾Service Providers¾Equipment builders¾ Solutions available today