1. 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

2. 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
per-packet/from IP to app layer

3. 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. IP
Border
Translation
Spot
IPvX Backbone
IPvY
Internet
IPvX Edge BR
AFBR
Xlate
Translation
Spot IP
Border
IPvX Backbone
IPvY
Internet
IPvX Edge
Xlate TE BR
IPvY-over-IPvX Tunnel
AFBR TE
AFBR
Xlate

4. 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)
I-IP Internet
E-IP
Internet BR
AFBR
I-IP Client
Net
I-IP Backbone
E-IP Client
Net BR
Support alg myself; know my translation volume and total mapping number I’m capable of doing that; I can’t do translation at all
AFBR
I-IP Client
Net
E-IP Client
Net
I-IP Client
Net
E-IP Client
Net

5. 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