Hi Julien,
On 10-09-08 12:32 PM, Laganier, Julien wrote:
Hi Suresh,
Please see two comments below:
Suresh Krishnan wrote:
Hi Shree,
Thanks for the comments. Please find responses inline.
On 10-09-07 09:38 AM, JOSHI, SHRINIVAS ASHOK (SHRINIVAS ASHOK) wrote:
Suresh,
One of the main challenge in implementing the model proposed by the
draft is that edge router has no reliable indication if a host (once it has
sent an RS) is present on the network or not.
I agree that this is the main challenge.
[...]
1. Prefix Lifetime Binding/Expiry..
Unlike DHCP there is no mechanism with SLAAC for a host (client)
to renew its address/prefix binding. Relying on host to send a router
solicitation (as a keep alive) toward edge router is not a viable option.
RFC 4861 (section 6.3.7 )
Router solicitation "may" be sent after following events
- The interface is initialized at system startup time.
- The interface is reinitialized after a temporary interface
failure or after being temporarily disabled by system
management.
- The system changes from being a router to being a host, by
having its IP forwarding capability turned off by system
management.
- The host attaches to a link for the first time.
- The host re-attaches to a link after being detached for some
time.
In such an situation what is the mechanism for edge router to
time out a binding from its database ?
Right. The BBF deployment will have periodic RAs sent to the client
with the PIOs after the initial RS is sent. The client does not need to
periodically retransmit the RSs.
Sending periodic RAs with the PIO does not help with the two problems that were
pointed out:
- the network does not necessarily know when a host attaches, because the host
may timeout sending RSs before the link layer is available to carry these RS's
up to the node assigning a prefix. As a result the network does not know that a
host attached, does not allocate a prefix, and cannot send a periodic RA that
contains the PIO necessary for that hosts to complete SLAAC. The hosts ends up
with no connectivity.
Correct. There needs to be some work done in BBF to convey the
information about the line coming up from the AN to the Edge Router.
- the network never knows when a host detaches, because the host does not send a "goodbye" RS. As a result, if a prefix were allocated by the network for the host, it cannot be returned to a free prefix pool based on signaling from the host. Are you planning to collect unused prefix based on an unused timer?
Prefixes are never "reclaimed" in SLAAC anyway. The Router will keep
advertising the prefix on the link no matter if there are any other
hosts on it or not. The prefix stays assigned to the link.
Thanks
Suresh
--------------------------------------------------------------------
IETF IPv6 working group mailing list
ipv6@ietf.org
Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
--------------------------------------------------------------------
