Subject: [MOBILE-IP] Differences in current RFC2002-bis Internet Draft

From: Charles Perkins <[email-masked]>
Date: Fri, 12 Nov 1999 12:39:49 -0800

Hello,

Here is a list of the changes between RFC 2002, and the recently
submitted
"draft-ietf-mobileip-rfc2002-bis-01.txt", intended to update RFC 2002.

Regars,
Charlie P.

==========================================================================

- Clarification that a mobility agent MAY use different settings
  for each of the 'R', 'H', and 'F' bits on different network
interfaces.

- Clarification that a mobility agent SHOULD only put its own
  addresses into the initial (i.e., not mobility-related) list of
  routers in the mobility advertisement.  RFC 2002 suggests that
  a mobility agent might advertise other default routers.

- Specification that a mobile node MUST ignore reserved bits in
  Agent Advertisements, as opposed to discarding such advertisements.
  In this way, new bits can be defined later, without affecting the
  ability for mobile nodes to use the advertisements even when the newly
  defined bits are not understood.  Furthermore, foreign agents
  can set the `R' bit to make sure that new bits are handled by
  themselves instead of some legacy mobility agent.

- Specification that the SPI of the MN-HA authentication extension
  is to be used as part of the data over which the authentication
  algorithm must be computed.

- Specification that the foreign agent MAY configure a maximum number
  of pending registrations that it is willing to maintain (typically 5).
  Additional registrations SHOULD then be rejected by the foreign agent
  with code 66.  The foreign agent MAY delete any pending Registration
  Request after the request has been pending for more than 7 seconds;
  in this case, the foreign agent SHOULD reject the Request with code
  75 (registration timeout).

- Specification that the foreign agent checks to make sure that the
  indicated home agent address does not belong to any of its network
  interfaces before relaying a Registration Request.  If the check
  fails, and the foreign agent is not the mobile node's home agent,
  then the foreign agent rejects the request with code 136
  (unknown home agent address).

- Specification that Registration Requests with the 'D' bit set to
  0, and specifying a care-of address not offered by the foreign
  agent, MUST be rejected with code 74 (invalid care-of address).

- Clarification that the foreign agent SHOULD consider its own
  maximum value when handling the Lifetime field of the Registration
  Reply.

----> Note that this introduces a problem with authentication, with
----> the partial solution that the mobile node can re-calculate with
----> its record of what Lifetime it had requested...

- Clarification that the home agent MUST ignore the setting of the
  'V' bit in any Registration Request, since it is only relevant
  to the foreign agent.

- Clarification that the home agent MUST ignore the 'B' bit (as
  opposed to rejecting the Registration Request) if it does not
  support broadcasts.

- Advice about the impossibility of using dynamic home agent
  discovery in the case when routers change the IP destination
  address of a datagram from a subnet-directed broadcast address to
  255.255.255.255 before injecting it into the destination subnet.

- Specification that the mobile node MAY use the IP source address
  of an agent advertisement as its default router address.

- Specification that, while they are away from the home network,
  mobile nodes MUST NOT broadcast ARP packets to find
  the MAC address of another Internet node.  Thus, the
  (possibly empty) list of Router Addresses from the ICMP Router
  Advertisement portion of the message is not useful for selecting
  a default router, unless the mobile node has some means not involving
  broadcast ARP and not specified within this document for obtaining
  the MAC address of one of the routers in the list.  Similarly,
  in the absence of unspecified mechanisms for obtaining
  MAC addresses on foreign networks, the mobile node MUST ignore
  redirects to other routers on foreign networks.

- Specification that a foreign agent MUST NOT use broadcast ARP for
  a mobile node's MAC address on a foreign network.  It may obtain
  the MAC address by copying the information from an Agent Solicitation
  or a Registration Request transmitted from a mobile node.

- Specification that a foreign agent's ARP cache for the mobile node's
  IP address MUST NOT be allowed to expire before the mobile node's
  visitor list entry expires, unless the foreign agent has some way
  other than broadcast ARP to refresh its MAC address associated to
  the mobile node's IP address.

- Relaxation of the requirement that, when a mobile node has joined
  a multicast group at the router on the foreign network, the mobile
  node MUST use its home address as the source IP address for multicast
  packets,

- Replacement of the terminology "recursive tunneling" by the
  terminology "nested tunneling".

- Clarification that keys with arbitrary binary values MUST be
  supported as part of mobility security associations.

- Specification that the default value may be chosen as 7 seconds,
  for allowable time skews between a home agent and mobile node
  using timestamps for replay protection.

- Wordsmithing

- Correction of syntactic editorial mistakes

- Updated citations

===========================================================================

Comments and discussion about other possible changes will be
appreciated.

Regards,
Charlie P.

---

From: Gabriel Montenegro <[email-masked]>
Date: Sat, 13 Nov 1999 00:55:01 -0800

>  75 (registration timeout).
..
>  agent, MUST be rejected with code 74 (invalid care-of address).

please choose  numbers other than 74 and 75.
these codes have been assigned already by iana to rfc2344:

  http://www.isi.edu/in-notes/iana/assignments/mobileip-numbers

i sent a previous email to the list about this,
please see the relevant message in the archives:

http://www17.nortelnetworks.com/scripts/wa.exe?A2=ind9907&L=MOBILE-IP&P=R1072

-gabriel