© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Deployment of IPv6 Understanding the IPv6 Multihoming Issues

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v IPv6 Multihoming Issues Host multihoming: More than one global unicast address on an interface Interfaces to more than one network Host Multihoming 2001:db8:1:1::f 2001:db8:2:2::f 2001:db8:1:1::f Host 2001:db8:2:2::f

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v IPv6 Multihoming Issues (Cont.) Site multihoming: Multiple connections to the same ISP Connections to multiple ISPs ISP 2001:db8:1::/n ISP1 2001:db8:1::/n Site Multihoming Site ISP2 2001:db8:2:::/n Site

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v No need for renumbering Explosion of the routing table Massive deaggregation IPv4 Provider Independence IPv6 Multihoming Issues (Cont.) /24 Enterprise AS BGP Announcements ISP 1ISP 2 R 2R 1

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v /48 prefixes assigned downstream from the ISP Address selection: How do enterprise devices perform address selection in this multihoming scenario? IPv6 Multihoming Issues (Cont.) Provider-Allocated 2001:DB8:2::/48 ISP :DB8:1::/48 ISP 2 Enterprise AS BGP Announcements R 2R 1

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Multihoming Requirements IPv6 Multihoming Issues (Cont.) IETF requirements for IPv6 site multihoming architectures: Must support redundancy Must support load-sharing Protection from performance difficulties Support for multihoming for external policy reasons Must not be more complex than current IPv4 solutions Must provide transport layer survivability No impact on DNS Must allow ingress filtering

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Multihoming and IPv6 IPv6 Multihoming Issues (Cont.) IPv6 is designed to have multiple unicast addresses per node: –Different scopes –Graceful renumbering Many hosts are expected to have multiple interfaces: –Physical interfaces –Pseudo interfaces to support transition mechanisms Sites that attach to multiple providers are expected to obtain multiple prefixes.

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Site Multihoming Issues IPv6 Multihoming Issues (Cont.) How to cause the working/best attachment point to be used for incoming/outgoing traffic How to achieve load-sharing across multiple attachment points for incoming and outgoing traffic How to receive packets addressed to a prefix if the attachment point to that prefix is down?

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v IPv6 Multihoming Status Approaches under development: The analysis and classification of existing proposals is currently being examined. Sites are broken down, as well as their motivations: –Minimal, small, large, international sites (on size and geographical breadth) –Immediate, short term, and long term as possible timelines

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Links 3 and 4 (IP-in-IP tunnels) are configured as secondary links. Primary and secondary links are on separate physical media for link redundancy. Prefixes advertised over secondary links have weak preference relative to prefixes advertised over primary links. Router-Based Solution IPv6 Multihoming Status (Cont.) Customer Site 2001:db8:1:1:: 2001:db8:2:2:: Internet link 1 link 2 link 3 link 4 link :db8:1:1:: 2001:db8:2:2:: 2001:db8:1:: SP 1 pref1 2001:db8:1:: SP 2 pref2 2001:db8:2:: 2001:db8:2:: link :db8:1:1:: 2001:db8:2:2:: E-BR-1 E-BR-2

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Router-Based Solution (Cont.) IPv6 Multihoming Status (Cont.) Advantages: No new protocols or modifications are needed. There is link fault tolerance. Link failure does not break established TCP sessions. Disadvantages: There is no fault tolerance if the ISP fails. There is no clear criteria for selecting among multiple interface addresses. There is no clear criteria for load-sharing among ISPs.

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v IGP, IBGP Enterprise Routing Example IPv6 Multihoming Status (Cont.) ISP-AISP-B Internet ISP-BR-AISP-BR-B E-BR-B E-BR-A P2 P1 P1,P2 P1P2 R 1R 2

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v A transport protocol managing several addresses per connection Connection uncorrelated, forming a single IP address such as TCP Path monitoring and path selection SCTP IPv6 Multihoming Status (Cont.) Internet SCTP Host 1Host 2 SCTP IP SCTP IP

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v No change in the infrastructure Endpoint identifier Mapped transport session Transport session: –Anchored to private addresses MAST IPv6 Multihoming Status (Cont.) MAST IP TCP IP TCP MAST IP TCP Internet Host 1Host 2

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v SHIM6 IPv6 Multihoming Status (Cont.) HostA 2001:db8:1:1::1 2001:db8:2:2::2 SHIM6 IP TCP SHIM6 IP TCP HostB 2001:db8:a:a::a 2001:db8:b:b::b No change in the infrastructure Transport session: – Initially anchored to original addresses Original source/destination/packets unmodified –Upon failure or forking, new locator pair is used SHIM6 extension header now added to every packet Internet

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v There is a new host identity name space: –Flat, unroutable, secure name space –Host ID = self generated public key Sockets are bound to host IDs. Host IDs are dynamically bound to one or more IP addresses. HIP IPv6 Multihoming Status (Cont.) Process Endpoint LocationIP Address Host ID ProcessSocket Endpoint IP AddressLocation

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Summary IPv6 nodes have multiple addresses and interfaces. Only packets sourced appropriately to the specific provider are routed outbound through the provider. Packets are received through the ISP for their prefixes only, and their routing announcements must be aggregated. A number of potential solutions for IPv6 multihoming, including SHIM6, SCTP, MAST, and HIP are being developed for small, large, and international sites. Additionally, SHIM6 is the current front-runner. Provider-independent addresses are an additional proposed solution.

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v