NAROS : Host-Centric IPv6 Multihomingwith Traffic Engineering

A solution to perform traffic engineering in a IPv6 multihomed end-site, using a multi-addressing scheme

draft-de-launois-multi6-naros-00.txt

Cédric de Launoisdelaunois@info.ucl.ac.be

1. Introduction

2. NAROS Principle

3. NAROS Protocol

4. NAROS Features

5. Conclusion

1. Introduction

Host-Centric IPv6 multihoming :(see draft-huitema-multi6-hosts-01.txt)

• Each host has several IPv6 addresses : one per provider• Site prefixes are aggregated within the larger prefixes of

the providers full route aggregation possible

• Providers perform ingress filtering choosing a source address = choosing a provider

1. Introduction (continued)

Problem : Which source address to use when a host contacts a destination ?

• « RFC3484 IPv6 default address selection algorithm » does not help when different global-scope IPv6 addresses are available (longest matching prefix rule used)

• A host has no information about which provider is the « best » for a particular destination. Best =

• With shortest path towards destination• With lower delay, higher bandwidth, lower cost…

Proposed solution :An IPv6 multihomed host inquires a NAROS server to determine the source address to use to contact a destination

Examples : • Host X uses PA:SA:X to reach Host W

(shortest path)

• Host X uses PB:SB:X to reach Host Z(B-C outbound load-balancing)

• Host Y uses PC:SC:Y to reach Host Z(B-C outbound load-balancing)

Multihomed site

Host XPA:SA:XPB:SB:XPC:SC:X

Host YPA:SA:YPB:SB:YPC:SC:Y

RCRB

INTERNET

ISP B ISP C

Host Z

Accepts only PB:SB:: Accepts only PC:SC::

2. NAROS Principle

Research Network

Host W

ISP A

RA

NAROS

Accepts only PA:SA::

• NAROS rationale : the burden of selecting the source address is delegated to the NAROS server, which has access to all the requirements and informations about the actual environnement.

• NAROS gives only a hint about the best source address to use. The final decision is still taken by the host (preserve end-to-end failure detection)

• NAROS is not intended to preserve flows. Other mechanisms can be used for this purpose.

• NAROS server : stateless wrt clients• NAROS service :

– can be anycast (avoid single point of failure !)– can be set up independently from the providers

2. NAROS Principle (continued)

3. NAROS Protocol

• NAROS Request : host server« I want to contact Host Z, select my best address between PA:SA:X and PB:SB:X »

• NAROS Response : server host« To contact any destination inside prefix PZ, your best address is PB:SB:X. This response is valid for 300 seconds. »

The response is cached in the host until the lifetime expires. Multihomed site

Host XPA:SA:XPB:SB:X

Host YPA:SA:YPB:SB:Y

RB +NAROS

RA +NAROS

INTERNET

ISP A ISP B

Host ZPZ:SZ:Z

request

response

4. NAROS Features• Outbound load-balancing

The server can use a round-robin or another scheme when selecting the best address. Unequal load-balancing possible without any additionnal complexity.

• Redundancy : NAROS can detect failures in the Internet if it gets access to the BGP tables of the site exit routers.

• NAROS can integrate in its address selection algorithm :

– Administrative policies

– Traffic engineering requirements

– Quality of Service requirements, …

5. Conclusion

• With NAROS, a IPv6 multihomed host is able to select its best source address. Route aggregation is preserved.

• By selecting the best source address, a NAROS server can influence the outbound load-balancing and can provide better redundancy.

• Requirements like cost, delay, bandwidth,… can be taken into account.

6. NAROS SimulationSimulation :• Based on a real traffic trace, during 24 hours• More than 7500 active hosts• Prefixes associated with the destinations are extracted from a

BGP table (±14000 different destination prefixes).• The lifetime used is 300s.

Results :• Expected bandwidth overhead : ±0.4%• NAROS server load average : 35 req/s• Cache size < 100 entries for 95% hosts• Good load-balancing performances

(similar as classical load-balancing mechanisms)

NAROS

CRC16