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Preserving Established Communications in IPv6 Multi-homed Sites with MEX Juan F. Rodríguez, Marcelo Bagnulo, A. García-Martínez, I. Soto, A. Azcorra. Dept.

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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:

1 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

2 Título 2 Index u Introduction u Multihoming through Extension Headers (MEX). u MEX Walkthrough  Normal Operation.  Fault Tolerance Support. u MEX Requirements u Conclusions.

3 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.

4 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

5 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.

6 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

7 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.

8 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

9 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

10 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.

11 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

12 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.

13 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.


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