Translation Spot Negotiation in IPv4/IPv6-Coexist Mesh

draft-cui-softwire-pet-03

Yong Cui, Mingwei Xu, Peng Wu

Jianping Wu, Xing Li, Chris Metz

Challenges of translation• Basic IPv4-IPv6 transition techniques– Tunnel for IPv4-over-IPv6/IPv6-over-IPv4 traversing– Translation for IPv4-IPv6 inter-connection

• But translation has technical challenges– Scalability: IPv4 addr consuming/mapping maintenance

– Application layer translation– Operation complexity: per-packet/from IP to app layer

– Lack of efficient NAT46 mechanism– Refer to RFC4966 for more details– Inherent properties due to the principle of translation

Tunnel for translation spot “transfer”• Naturally, translation happens on IP border• Use a tunnel to transfer the translation to other spot

– Tunnel for traversing between translation spot and IP border– Choose translation spot flexibly

• Translator with better hardware capability; traffic less-aggregated; support ALG or not; etc.

IPvX BackboneIPvX Edge

IPvY InternetBR AFBR

Xlate

IP Border

TranslationSpot

IPvX BackboneIPvX Edge

IPvY InternetBR IPvY-over-IPvX Tunnel AFBR

XlateAFBR

TEXlate

TE

IP Border

TranslationSpot

Real Problem in IPv4/IPv6-coexist mesh

• Mesh Scenario– Exists in CERNET2

• Communications– E-IP over I-IP

traversing(RFC5565)

– Inter-connection between E-IP & I-IP (the scope of this draft)

• Translation spot– AFBR (IP-border)– BR (non IP-border)

E-IPInternet

I-IP Backbone

I-IP Internet

E-IP ClientNet

I-IP ClientNet

I-IP ClientNet

I-IP ClientNet

E-IP ClientNetE-IP Client

Net

BR

BR

AFBR

AFBR

Solution• Softwire tunnel(RFC 5565) to transfer translation spot– E-IP over I-IP routing(RFC 5549) required for translation

• Translation spot negotiation using BGP on AFBRs/BRs– BGP already supported by AFBR/BR in mesh scenario– Protocol extensions: A new BGP Attribute "Translation

Information Attribute" with 4 TLVs, to• Decide translation spot• Deliver translation context

Type: 1 Length: 2

TP value for stateless translation

0 15 31

Type: 1 Length: 2

TP value for stateful translation

0 15 31

Type: 1 Length: variable

Translation Mapping Prefix(NLRI Encoding)

0 15 31

Type: 3 Length: variable

Translation Mapping Prefix(NLRI Encoding)

0 15 31