Issue 224: RFC 3576bis and Renumbering
Submitter name: Bernard Aboba
Submitter email address: firstname.lastname@example.org
Date first submitted: March 19, 2007
Document: RFC 3576bis-00
Comment type: T
Rationale/Explanation of issue:
During the 16ng meeting, the need for renumbering support in 3576bis was
discussed. This would involve changing the Framed-IPv6-Prefix and
Delegated-IPv6-Prefix attributes in a CoA-Request, so that the new prefixes
could be advertised. In reviewing RFC 3576, it appears that
Framed-IPv6-Prefix is used as an identifying attribute and therefore it
cannot be changed in a CoA-Request (although it would be possible to use
Service-Type="Authorize Only" to change it). The same thing is true of
Framed-IP-Address and Framed-Interface-Id, although these attributes are
typically used with PPP, so they would only be effective if the user was
able to renegotiate NCP in mid-session, which most implementations don't
In rereading RFC 3576, it also seems to imply that only the attributes
listed in the table can be included in a CoA-Request, which would limit the
ability to include a Delegated-IPv6-Prefix attribute. However, the point is
really that a NAS might not support an attribute that is being changed (new
or old), so that the text should make that point instead.
Assuming that existing implementations aren't using the Framed-IP-Address,
Framed-IPv6-Prefix and Framed-Interface-Id attributes for session
identification, my recommendation is that we consider removing them from the
list of session identification attributes. Attributes such as
Acct-Session-Id, User-Name, NAS-Port, etc. remain and should be adequate for
We also should add the VLAN attributes defined in RFC 4675 to the list of
The required changes are as follows:
"This is true even for attributes
specified within [RFC2865], [RFC2868], [RFC2869],
[RFC3162] or [RFC3579] as allowable within Access-Accept packets.
As a result, if attributes beyond those specified in Section 3.5
"This is true even for attributes specified as allowable within
Access-Accept packets (such as within
[RFCFilter][RFCDelegated]). As a result, if unsupported attributes"
Remove Framed-IP-Address, Framed-Interface-Id and Framed-IPv6-Prefix from
the list of session identification attributes.
In the Attribute Table, change Framed-IP-Address, Framed-Interface-Id and
Framed-IPv6-Prefix from [Note 1] (Session Identification Attributes) to
[Note 3] authorization attributes changeable in a CoA-Request. Remove them
from the attributes includable in a Disconnect-Request. Add
Delegated-IPv6-Prefix as changeable in a CoA-Request (0+) [Note 3]. Add
Egress-VLANID, Ingress-Filters, Egress-VLAN-Name, User-Priority-Table
Attributes as changeable in the CoA-Request.
Add references to RFC 4675 and the Delegated-IPv6-Prefix documents.
Add the following statements to Appendix A:
Updated CoA-Request Attribute Table to include Filter-Rule,
Delegated-IPv6-Prefix, Egress-VLANID, Ingress-Filters, Egress-VLAN-Name,
Clarified use of Framed-IPv6-Prefix, Framed-IP-Address,
Delegated-IPv6-Prefix in renumbering.
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