MPLS Multicast Encapsulations draftrosenmplsmulticastencaps00 txt Toerless Eckert eckertcisco

MPLS Multicast Encapsulations draft-rosen-mpls-multicast-encaps-00. txt Toerless Eckert (eckert@cisco. com) Eric Rosen (erosen@cisco. com) Rahul Aggarwal (rahul@juniper. net) Yakov Rekhter (yakov@juniper. net) Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 1

Issue § RFC 3032 defines two data link code points for MPLS – For Unicast and Multicast. But. . • There is no need to reserve a code point to determine whether the top label is a MPLS multicast label • The NHLFE will determine whether the top label is a MPLS multicast label • The developments in MPLS multicast have shown that the definition of these code points with respect to MPLS multicast is not adequate • Similar issue with RFC 4023 for MPLS in GRE Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 2

Solution § The semantics of the data link code points as defined in RFC 3032 and RFC 4023 need to be redefined for MPLS multicast • Align with developments in MPLS multicast § But before discussing details… Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 3

Downstream Assigned vs Upstream Assigned Labels § Consider Ru (upstream LSR) and Rd (downstream LSR) as adjacent in a LSP for FEC F. The top label of the MPLS packet sent by Ru to Rd is L. § Downstream Assigned Label - Rd distributes the binding of FEC F to label L to Ru § Upstream Assigned Label – Ru distributes the binding of FEC F to label L to Rd Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 4

MPLS Multicast and Upstream Assigned Labels § Ru is adjacent to <Rd 1…Rdn> in a LSP and is connected to to <Rd 1…Rdn> via a multi-access media or Tunnel. § Further Ru wishes to transmit a single copy of a MPLS Multicast packet belonging to the LSP to <Rd 1…Rdn> • The same top label must be received by <Rd 1. . Rdn> for this MPLS multicast packet § To accomplish this Ru assigns an upstream assigned label and distributes it to <Rd 1…Rdn> § Upstream label assignment architecture in draftraggarwa-mpls-upstream-label – Next presentation Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 5

Back to Code Points § Three different types of data links/tunnels • P 2 P – downstream assigned labels only • P 2 MP – All top labels must be downstream assigned or upstream assigned. Determined apriori • MP 2 MP - Top labels may be downstream assigned or upstream assigned. Encapsulation must provide a code-point to make this distinction Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 6

Ethernet Code Points and MPLS Multicast § Ethernet is an example of a MP 2 MP data link § 0 x 8847 [unicast code point] is used for MPLS multicast packets as long as the top label is downstream assigned. • The MAC address is that of the intended recipient i. e. a unicast MAC § 0 x 8848 [Former multicast code point] is used when the top label is upstream assigned • The MAC address is a multicast MAC derived from the label – 01 – 00 - 5 e - 8 a - bc - de [abcde is the 20 bit label value] Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 7

GRE Protocol Type and MPLS Multicast § Modifies RFC 4023 § If the destination address is an IP multicast address and both downstream and upstream assigned MPLS labeled packets are carried on the same tunnel • 0 x 8847 is used for downstream assigned lbls • 0 x 8848 is used for upstream assigned lbls § If the destination address is an IP multicast address and only upstream assigned or only downstream assigned MPLS labeled packets are carried • 0 x 8847 is always used Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 8

IP Protocol Number § IPv 4 protocol number or IPv 6 Next Header Field is always set to 137 • The top label is always downstream assigned or always upstream assigned Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 9

MPLS Upstream Label Assignment and Context Specific Label Space draft-raggarwa-mpls-upstream-label-00. txt Rahul Aggarwal (rahul@juniper. net) Yakov Rekhter (yakov@juniper. net) Eric Rosen (erosen@cisco. com) Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 10

Scope § RFC 3031 limits the MPLS architecture to downstream assigned labels § This draft generalizes the notion of a perinterface label space to a “context-specific” label space • Neighbor label space is introduced as an example of “context-specific” label space § This draft extends the MPLS architecture for upstream assigned labels Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 11

Context-Specific Label Space § RFC 3031 describes platform and interface based label spaces § This document describes the more general notion of a “context-specific” label space • A LSR may maintain multiple context-specific label spaces § A context-specific label space may be used for downstream-assigned or upstream-assigned labels § An interface-based label space is an example of a context-specific label space for downstream-assigned labels • Label space is determined by the interface Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 12

Context-Specific Label Space and Upstream Assigned Labels § Upstream Assigned Labels are always looked up in a context-specific label space § The context is provided by the LSR that assigns and distributes the upstream assigned label binding, L for LSP 1 § The LSR that receives the upstream assigned label binding must be able to determine the context when it receives a MPLS packet with a top label ‘L’ on LSP 1 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 13

Context-Specific Label Space and Upstream Assigned Labels… § Tunnel Specific Label Space • Determined by the tunnel on which the MPLS packet is received • If the tunnel is a MPLS tunnel, PHP must be turned off § Neighbor Specific Label Space • Determined by the neighbor from which the MPLS packet is received Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 14

Upstream Assigned Labels § Motivation was described earlier § A LSR may distribute upstream assigned labels for FEC F to its downstream LSRs and downstream assigned labels to its upstream LSRs § Two adjacent LSRs, Ru and Rd, on LSP 1 for FEC F must use either upstream label assignment or downstream label assignment for FEC F, for packets transmitted from Ru to Rd Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 15

Assigning Upstream Assigned Labels § An upstream assigned label must be unambiguous in the context-specific label space in which the downstream LSR will look it up § For the upstream LSR, an upstream assigned label is an outgoing label and forms part of the NHLFE Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 16

Distributing Upstream Assigned Labels § Must not be distributed unless its known that a downstream LSR supports them • Requires protocol discovery extensions • Assumption is that the downstream LSR can accept upstream assigned labels from the entire label range § Label distribution protocol considerations are based on RFC 3031 § Distribution is similar to ordered LSP control or independent LSP control of downstream assigned labels Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 17

Downstream LSR Requirements § A downstream LSR must be able to determine • Whether a label is upstream assigned and • The context-specific label space in which to lookup the packet Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 18

Data Link Encapsulation § Upstream assigned label is encapsulated directly in a data link header by Ru • Is the label upstream assigned ? – draft-rosen -mpls-mcast-encaps • Rd maintains a separate neighbor label space for Ru • What is the context ? Determined by the data link header. Eg. For ethernet, the source MAC address Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 19

MPLS Tunnel Encapsulation § Ru transmits the packet, the top label L of which is upstream assigned, by encapsulating it in a MPLS tunnel • Rd determines the context of this packet using the labels above L in the label stack • One or more labels above L may also be upstream assigned • Rd may maintain a separate label space for the tunnel or a single label space for Ru Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 20

GRE Tunnel Encapsulation § Ru transmits the packet, the top label L of which is upstream assigned, by encapsulating it in a GRE tunnel • Rd determines the context of this packet using the IP/GRE header – source/dest address • Rd may maintain a separate label space for the tunnel or a single label space for Ru Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 21

Conclusion § Comments are welcome § We would like these drafts to be WG drafts Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidential www. juniper. net 22