Presentation on theme: "Preserving Established Communications in IPv6 Multi-homed Sites with MEX Juan F. Rodríguez, Marcelo Bagnulo, A. García-Martínez, I. Soto, A. Azcorra. Dept."— Presentation transcript:
Preserving Established Communications in IPv6 Multi-homed Sites with MEX Juan F. Rodríguez, Marcelo Bagnulo, A. García-Martínez, I. Soto, A. Azcorra. Dept. de Ingeniería Telemática Universidad Carlos III de Madrid
Título 2 Index u Introduction u Multihoming through Extension Headers (MEX). u MEX Walkthrough Normal Operation. Fault Tolerance Support. u MEX Requirements u Conclusions.
Título 3 Introduction Provider-A Provider-B Multi-homed Site u Multihoming usually means “more than one provider”. Host multihomed: More than one address. More than one link.
Título 4 Introduction Provider-A Multi-homed Site Default Free Zone Site addr.block Site reachability information Provider-B u IPv4 Multihoming announces specific routes
Título 5 Introduction u Routing table scalability issue: CIDR: Aggregates routes. IPv4 Multihoming: Advertises more specific routes. u Expected growth will be driven by: The number of providers. The number of multihomed-sites. u IPv4 multihoming doesn’t scale well.
Título 6 Introduction u IPv6 routing architecture is stiffer: ISPs don’t announce other ISP’s prefixes. Addresses are aggregated by providers. u Some IPv6 Multihoming goals: Scalability. Interoperability with legacy IPv6 hosts. Transport-Layer Survivability Fault detection Recovery process
Título 7 MEX u Extends the IPv6 protocol to: Share reachability information end-2-end. Communicate alternative paths to the routing system. u Host based solution (active): Stores different prefixes for a given destination. Sends information to the routing system. u Router based solution (passive): The routing system takes over the recovery process.
Título 8 MEX u Alternative Prefix Destination Option: It informs the peer about the alternative prefixes. u Alternative Prefix Extension Header: It Informs the routers how to re-route packets if there’s no route to the destination. Opt. Type Opt. Length Reserved Alternative Prefix 1 Alternative Prefix N … Next HdrHdr Ext LenReserved Alternative Prefix 1 Alternative Prefix N … Segments Left
Título 9 Normal Operation ISP-C “Host A” (addrA1, addrA2) “Host B” (addrB1, addrB2) ISP-A ISP-B IPv6 header, dst = IPv6 Ext. Header with IPv6 Dst. Opt. w/ DNS Upper Layer Protocol
Título 10 Fault Tolerance support u MEX capable router (MEX-R): It understands the MEX Ext. Header. It’s able to attract packets when there’s a black- hole. u MEX-R walkthrough: It looks for the MEX Ext. Header. It swaps dest. prefix with one of the alternative prefixes. It looks at his routing table to forward the packet.
Título 11 Fault Tolerance support ISP-A ISP-B ISP-C ISP-D Host 2 (PA:PC:….::/64) (PB:PD:….::/64) Default Free Zone Host 1 MEX-R
Título 12 MEX Requirements u Changes on hosts: It requires upgrades on hosts to achieve multihoming benefits. u Changes on routers: Only some routers should be upgraded per ISP. “Normal” routers shouldn’t discard packets with the new Extension Header.
Título 13 Conclusion u Reduce Packet Loss. u It doesn’t pollute the IPv6 routing system. u Incremental Deployment. u Compatible with unmodified hosts. u Transparent to upper layers. Peers don’t realize of the addr. swapping. u Established communications are preserved. u Implemented on a FreeBSD-4.5 kame release.