Post IPv4

1
Post IPv4 completion Making IPv6
incrementally deployable by making it backward
compatible with IPv4.

• Alain Durand

2
Comcast

• As the largest cable operator in the United
  States, Comcast manages a large pool of IPv4
  resources and is an active and responsible member
  of the Internet community.
• We have been working within community-defined
  policies, maintaining effective utilization of
  resources.
• Comcast fully supports the community based,
  bottom-up, governance model of policy development
  to oversee those resources.
• The Internets private-sector, self-regulatory
  governance model is a significant factor in the
  success of the whole Internet industry.
• This model has proven responsive enough to meet
  the demands of a fast growing global industry.

3
Comcast IPv6 deployment

• Two phase approach
• 1) Infrastructures, Cable Modem management
• Done and/or in trial
• 2) Connection to the home
• Planning lab trials
• Lessons learned
• Early planning reduce cost
• Networking is rather straightforward, code is
  mostly there
• Software can be difficult to get from vendors
• 3rd party services are mostly non existent

4
IANA IPv4 completion is in front of us
IPv4 will not stop working!
Uncertainty

• Completion of IPv4 resources will not be
  uniform
• Large contiguous allocation requests might be
  denied by an RIR when fractioned space is still
  available.
• Small IPv4 allocation requests might be granted
  by an RIR long after completion of the IANA free
  pool.

5
A broadband ISP must supportcontinued,
un-interrupted growth regardless of IPv4
addressavailability

• DISCLAIMERComcast has not made any decisions
  to deploy any of the following technologies.

6
Post IPv4 completion

• IPv4 resources alone will not provide a viable
  supply to the industry for the long term.
• The Internet edges will still be mostly IPv4
• Many hosts in the home (Win 9.x, XP,) are
  IPv4-only.
• They will not function in an IPv6 only
  environment.
• Few of those hosts will upgrade to Windows
  Vista.
• Content servers (web, Mail,) hosted on the
  Internet by many different parties will take time
  to upgrade to support IPv6.

7
Provisioning color code
IPv4-only dual stack provisioned dual stack, IPv6-only provisioned
device
link
router
network
devices with pure IPv6-only code are out of
scope
8
Plan zero dual-stack
After IPv4 IANA completion, there will not be
enough IPv4 addresses to sustain this model.
Internet
Internet
ISP
legacy customer global v4 address home
gateway NAT v4-gtv4
IPv4IPv6 home gateway
IPv4IPv6home gateway
Today such deployments do not see much IPv6
traffic, mainly because there is little content
reachable with IPv6.
192.168/16
192.168/16
192.168/16
9
Plan A dual-stack corenew customers are
provisionedwith IPv6-only but no IPv4 support
lots of broken paths
Internet
ISP

• impact on new customers
• legacy IPv4 devices cant get out of the home.
• new IPv6 devices cant get to the IPv4
  Internet.

legacy customer global v4 address home
gateway NAT v4-gtv4
IPv6 provisionedhome gateway
IPv6 provisionedhome gateway
192.168/16
192.168/16
192.168/16
10
Plan B double NATnew customers are
provisionedwith overlays of RFC1918

• two layers of NAT
• no evolution to IPv6
• network gets increasingly complex to operate.
• Intersections of Net 10 overlays are prone to
  failures.

Internet
ISP
Carrier grade NAT
carrier-grade NAT
Net 10
Net 10
complex internal routing(source based?) to
handleboth legacy RFC1918customers on the
sameaccess router
legacy customer global v4 address home
gateway NAT v4-gtv4
private v4 address home gateway NAT v4-gtv4
private v4 address home gateway NAT v4-gtv4
192.168/16
192.168/16
192.168/16
11
Plan C dual-stack litenew customers are
provisionedwith IPv6-only IPv4 support

• simplifies network operation- provides an
  upgrade path to IPv6

Internet
ISP
Carrier grade NAT
carrier-grade NAT
carrier-grade NAT
Internet
legacy customer IPv4 provisioned home gateway NAT
v4-gtv4
IPv6 provisionedhome gateway
IPv6 provisionedhome gateway
Dual-stack lite provides IPv4support using
an IPv4/IPv6 tunnelto a IPv4/IPv4 NAT.
192.168/16
192.168/16
192.168/16
12
Plan C New stand-alone devices are
provisionedwith IPv6-only IPv4 support with
dual-stack lite
Internet
ISP
Internet
carrier-grade NAT
Dual-stack lite client dual stack
device IPv6-only provisioned no IPv4 address
Stand-alone, dual-stack, IPv6-only provisioned
devicescan use dual-stack lite to reach the IPv4
Internet.
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Dual-stack lite makes IPv6 incrementally
deployable