Subject: [eap] Fragmentation: RADIUS obligation to Framed-MTU

From: [email-masked] (tom bonacci)
Date: Fri, 04 Apr 2003 16:55:11 -0700

Fragmentation: RADIUS obligation to Framed-MTU
Submitter name: Tom Bonacci
Submitter email address: [email-masked]
Date first submitted: April 4th, 2003
Reference: 
Document: RFC 2869bis
Comment type: Technical
Priority: 
Section: 2.4
Rationale/Explanation of issue:

The "Fragmentation" section, 2.4, reads in relevant part:
  "... the Framed-MTU attribute may be included in an 
   Access-Request packet containing an EAP-Message 
   attribute so as to provide the RADIUS server with this
   information."

Does this (or should this) imply any obligation on the part of the
RADIUS server to observe the value forwarded by the NAS?  The current
wording indicates the NAS MAY provide this information but is silent on
how the RADIUS server is to properly react upon its receipt in an
Access-Request packet.

Possible resolution:
Augment the above with 
  "... the Framed-MTU attribute MAY be included in an 
   Access-Request packet containing an EAP-Message 
   attribute so as to provide the RADIUS server with this
   information.  A RADIUS server having received a Framed-MTU 
   attribute in an Access-Request packet MUST NOT send any
   subsequent packet in this EAP conversation containing 
   EAP-Message attributes whose values, when concatenated,
   exceed the length specified by the Framed-MTU value."

The above wording implies strict obligation on the part of the RADIUS
server to observe the Framed-MTU value.  If strict obligation is not
what's intended or desired, then the wording may be modified accordingly.

regards,
-tom