One document matched: draft-deng-mip4-host-configuration-01.txt
Differences from draft-deng-mip4-host-configuration-00.txt
Network Working Group H. Deng
Internet-Draft China Mobile
Intended status: Standards Track P. Yang
Expires: August 27, 2009 Hitachi (China) R&D Corp
February 23, 2009
DHCP Based Configuration of Mobile Node from Home Network
draft-deng-mip4-host-configuration-01
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 27, 2009.
Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document.
Deng & Yang Expires August 27, 2009 [Page 1]
Internet-Draft DHCP MN Configuration February 2009
Abstract
This document describes the mechanism for providing the host
configuration parameters needed for network service from home network
based on DHCPINFORM. DHCPINFORM message has been widely used by
client to obtain other configuration information and could be sent to
local broadcast address or server unicast address. Mobile IP
specification could support DHCPINFORM broadcast or unicast message
straightfully without any revision.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Home DHCP server's address unknown with DHCP relay on HA . . . 4
2.1. MIP4 Co-CoA case . . . . . . . . . . . . . . . . . . . . . 4
2.2. MIP4 FA CoA Case . . . . . . . . . . . . . . . . . . . . . 8
3. Home DHCP server's address unknown without DHCP relay on
home agent . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1. MIP4 Co-CoA case . . . . . . . . . . . . . . . . . . . . . 13
3.2. MIP4 FA CoA Case . . . . . . . . . . . . . . . . . . . . . 17
4. Home DHCP server's address known . . . . . . . . . . . . . . . 22
5. Security Considerations . . . . . . . . . . . . . . . . . . . 24
6. IANA Consideration . . . . . . . . . . . . . . . . . . . . . . 25
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26
8. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 27
9. Normative References . . . . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29
Deng & Yang Expires August 27, 2009 [Page 2]
Internet-Draft DHCP MN Configuration February 2009
1. Introduction
Mobile node could use DHCP mechanism to configure local information
when it attach to the foreign network. But it may have to get
configuration information from the home network as well. The common
mechanism to configure the mobile host is preferable in Mobile IP.
If a mobile node has obtained a network address through some other
means, it may use a DHCPINFORM request message to obtain other local
configuration parameters. This DHCPINFORM message could be sent to
local broadcast address or server unicast address(know it from out of
band delivery). DHCP Server receiving a DHCPINFORM message construct
a DHCPACK message with any local configuration parameters appropriate
for the mobile node.
This document has analysed the process about how Mobile IP
specification could straightfully support DHCPINFORM broadcast or
unicast message for host configuration without any revision.
Deng & Yang Expires August 27, 2009 [Page 3]
Internet-Draft DHCP MN Configuration February 2009
2. Home DHCP server's address unknown with DHCP relay on HA
2.1. MIP4 Co-CoA case
If the 'D' bit was set in the mobile node's Registration Request
message, and code field of the received registration reply indicate
successly registered. This means that the mobile node is using a co-
located care-of address.
Section 5.3 of Reverse tunneling [RFC3024] recommend that a mobile
node using a co-located care-of address send the broadcast/multicast
packet are handled according to Sections 4.3 and 4.4 of the Mobile IP
specification [RFC3344].
Section 4.3 of [RFC3344] doesn't specify how a mobile node send
datagrams to a broadcast address in detail. Section 4.4 of [RFC3344]
specify that a mobile node which tunnels a multicast datagram to its
home agent MUST use its home address as the IP source address of both
the (inner) broadcast datagram and the (outer) encapsulating
datagram. Anyway this tunnel is not topologically correct.
The mobile node simply tunnels appropriate broadcast DHCPINFORM
message to the home agent.The source address of this DHCPINFORM
message is the mobile node's home address. Home agent just work as a
simple DHCP relay agent as shown in figure 1.
+-----+ +-------+
| HA/ | | Home |
|DHCP |----| DHCP |
|Relay| | Server|
+-----+ +-------+
//
// Home Network
-------------//-----------------------
// Visiting Network
//
// +----+
+----+ | |
| MN |----| AR |
+----+ | |
+----+
Figure 1: Home network configuration in the case of Co-CoA
Deng & Yang Expires August 27, 2009 [Page 4]
Internet-Draft DHCP MN Configuration February 2009
+----+ +-------+ +------+
| | | HA | |DHCP |
| MN | | DHCP | |Server|
| | | relay | | |
+----+ +-------+ +------+
| RRQ | |
|--------------------------->| |
| RRP | |
|<---------------------------| |
| 1 | |
|--------------------------->| |
| | 2 |
| |--------->|
| | |
| | 3 |
| |<---------|
| 4 | |
|<---------------------------| |
Figure 2: Message sequence for host configuration in Co-CoA
Figure 2 shows the message sequence for host configuration in Co-CoA.
(1) After the mobile node successfully registered to the home agent
based on Registration Request(RRQ) and Registration Response(RRP)
message, it sends a DHCPINFORM message to request specific
configuration parameters by including the 'parameter request list'
option from home network. The mobile node generates and records a
random transaction identifier and inserts that identifier into the
'xid' field. The mobile node places its own home address in the
'ciaddr' field.
The mobile node will send DHCPINFORM message to the limited (all 1s)
broadcast address. DHCPINFORM messages MUST be directed to the 'DHCP
server' UDP port.
The mobile node will encapsulate this DHCPINFORM broadcast message
with IP in IP tunnel and send to the home agent, DHCPINFORM Packet
format sent by the mobile node is shown below:
Deng & Yang Expires August 27, 2009 [Page 5]
Internet-Draft DHCP MN Configuration February 2009
IP fields (encapsulating header):
Source Address = mobile node's home address
Destination Address = home agent's address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = mobile node's home address
Destination Address = broadcast address
UDP Src Port: bootpc(68), Dst Port: bootps(67)
Bootstrap Protocol:
field:
op = BOOTREQUEST
htype = Ethernet or (From "Assigned Numbers" RFC)
hlen = 6 or (Hardware address length in octets)
hops = 0
xid = selected by client
secs = 0
flags = 0
ciaddr = mobile node's home address
yiaddr = 0
siaddr = 0
giaddr = 0
chaddr = mobile node's MAC address
options:
option 53: DHCP Message Type = DHCPINFORM
option 61: Client Identifier = mobile node's MAC address
option 55: Parameter request List (Domain Name Server,... et al.)
(2) Since the home agent acts as the DHCP relay agent, after
receiving a unicast tunnel message, it detunneled the unicast
encapsulated header, and should look at the the 'giaddr' field of
DHCPINFORM message. If zero, it should plug its own IP address into
this field. It may also use the 'hops' field to optionally control
how far the packet is reforwarded. Hops should be incremented on
each forwarding.
DHCPINFORM Packet format forwarded by the home agent:
IP fields:
Source Address = home agent's address
Destination Address = DHCP server's address
UDP Src Port: bootps(67), Dst Port: bootps(67)
Bootstrap Protocol:
field:
giaddr = home agent's address
(3) DHCP server receiving a DHCPINFORM message construct a DHCPACK
message with any home configuration parameters appropriate for the
mobile node according to Section 3.4 of [RFC2131] . The DHCP server
Deng & Yang Expires August 27, 2009 [Page 6]
Internet-Draft DHCP MN Configuration February 2009
SHOULD unicast the DHCPACK reply to the address given in the 'ciaddr'
field (mobile node's home address) of the DHCPINFORM message.
DHCPACK Packet format sent by the DHCP Server:
IP fields:
Source Address = DHCP server's address
Destination Address = home address of mobile node
(from 'ciaddr' of DHCPINFORM)
UDP Src Port: bootps(67), Dst Port: bootps(68)
Bootstrap Protocol:
field:
op = BOOTREPLY
htype = Ethernet or (From "Assigned Numbers" RFC)
hlen = 6 or (Hardware address length in octets)
hops = 0
xid = same as "xid" field of DHCPINFORM message
secs = 0
flags = 0
ciaddr = mobile node's home address (from 'ciaddr' of DHCPINFORM)
yiaddr = 0
siaddr = 0
giaddr = home agent's address (from 'giaddr' of DHCPINFORM)
chaddr = mobile node's MAC address (from 'chaddr' of DHCPINFORM)
options:
option 53: DHCP Message Type = DHCPACK
option 61: Server Identifier = DHCP server's MAC address
option 6: Domain Name Server
all other options: if needed
(4) The home agent intercepting a unicast DHCPACK message will
tunnels this datagram to the mobile node's currently registered
care-of address.
DHCPACK Packet format forwarded by the home agent:
IP fields (encapsulating header):
Source Address = home agent's address
Destination Address = mobile node's care-of-address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = DHCP server's address
Destination Address = mobile node's home address
UDP Src Port: bootps(67), Dst Port: bootpc(68)
Bootstrap Protocol
Once a DHCPACK message with an 'xid' field matching that in the
mobile node's DHCPINFORM message arrives from any server, the mobile
Deng & Yang Expires August 27, 2009 [Page 7]
Internet-Draft DHCP MN Configuration February 2009
node's configuration process is finished.
If the mobile node does not receive a DHCPACK within a reasonable
period of time (60 seconds or 4 tries if using timeout suggested in
section 4.1), then it SHOULD display a message informing the user of
the problem, and then SHOULD begin network processing using suitable
defaults as per Appendix A of [RFC2131].
2.2. MIP4 FA CoA Case
If the 'D' bit was not set in the mobile node's Registration Request
message, and code field of the received registration reply indicate
successly registered. This means that the mobile node is using a
foreign agent care-of address.
Reverse tunneling [RFC3024] in Mobile IP has mandate that a mobile
node using a foreign agent care-of address MUST use the encapsulating
delivery style. So the operation of DHCPINFORM broadcast message to
the home network in this case should follow the encapsulating
delivery style.
+-----+ +-------+
| HA/ |____| Home |
|DHCP |----| DHCP |
|Relay| | Server|
+-----+ +-------+
||
|| Home Network
----------------||--------------------
|| Visiting Network
||
+----+
+----+______| |
| MN |------| FA |
+----+ | |
+----+
Figure 3: Home network configuration in the case of FA-CoA
Deng & Yang Expires August 27, 2009 [Page 8]
Internet-Draft DHCP MN Configuration February 2009
+----+ +-----+ +-------+ +------+
| | | | | HA | |DHCP |
| MN | | FA | | DHCP | |Server|
| | | | | relay | | |
+----+ +-----+ +-------+ +------+
| | | |
| RRQ | |
|---------------------------->| |
| RRP | |
|<----------------------------| |
| 1 | | |
|-------------->| | |
| | 2 | |
| |------------>| |
| | | 3 |
| | |--------->|
| | | 4 |
| | |<---------|
| | 5 | |
| |<------------| |
| 6 | | |
|<--------------| | |
Figure 4: Message sequence for host configuration in FA-CoA
Figure 4 shows the message sequence for host configuration in Co-CoA.
(1) After the mobile node successfully registered to the home agent
based on Registration Request(RRQ) and Registration Response(RRP)
messages, it sends a DHCPINFORM message to request specific
configuration parameters by including the 'parameter request list'
option from home network. The mobile node generates and records a
random transaction identifier and inserts that identifier into the
'xid' field. The mobile node places its own home address in the
'ciaddr' field.
The mobile node send DHCPINFORM the message to the limited (all 1s)
broadcast address. DHCPINFORM messages MUST be directed to the 'DHCP
server' UDP port.
The mobile node will encapsulate this DHCPINFORM broadcast message
with IP in IP tunnel and send to the foriegn agent, DHCPINFORM Packet
format sent by the mobile node is shown below:
Deng & Yang Expires August 27, 2009 [Page 9]
Internet-Draft DHCP MN Configuration February 2009
IP fields (encapsulating header):
Source Address = mobile node's home address
Destination Address = foreign agent's address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = mobile node's home address
Destination Address = broadcast address
UDP Src Port: bootpc(68), Dst Port: bootps(67)
Bootstrap Protocol:
field:
op = BOOTREQUEST
htype = Ethernet or (From "Assigned Numbers" RFC)
hlen = 6 or (Hardware address length in octets)
hops = 0
xid = selected by client
secs = 0
flags = 0
ciaddr = mobile node's home address
yiaddr = 0
siaddr = 0
giaddr = 0
chaddr = mobile node's MAC address
options:
option 53: DHCP Message Type = DHCPINFORM
option 61: Client Identifier = mobile node's MAC address
option 55: Parameter request List (Domain Name Server,... et al.)
(2) Packet format forwarded by the foreign agent (Encapsulating
Delivery Style):
IP fields (encapsulating header):
Source Address = foreign agent's care-of-address
Destination Address = home agent's address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = mobile node's home address
Destination Address = broadcast address
UDP Src Port: bootpc(68), Dst Port: bootps(67)
Bootstrap Protocol
Since the home agent acts as the DHCP relay agent, after receiving a
unicast tunnel message, it detunneled the unicast encapsulated
header, and should look at the the 'giaddr' field of DHCPINFORM
message. If zero, it should plug its own IP address into this field.
It may also use the 'hops' field to optionally control how far the
packet is reforwarded. Hops should be incremented on each
forwarding.
Deng & Yang Expires August 27, 2009 [Page 10]
Internet-Draft DHCP MN Configuration February 2009
(3) DHCPINFORM Packet format forwarded by the home agent:
IP fields:
Source Address = home agent's address
Destination Address = DHCP server's address
UDP Src Port: bootps(67), Dst Port: bootps(67)
Bootstrap Protocol:
field:
giaddr = home agent's address
(4) DHCP server receiving a DHCPINFORM message construct a DHCPACK
message with any home configuration parameters appropriate for the
mobile node according to Section 3.4 of [RFC2131] . The DHCP server
SHOULD unicast the DHCPACK reply to the address given in the 'ciaddr'
field (mobile node's home address) of the DHCPINFORM message.
DHCPACK Packet format sent by the DHCP Server:
IP fields:
Source Address = DHCP server's address
Destination Address = home address of mobile node
(from 'ciaddr' of DHCPINFORM)
UDP Src Port: bootps(67), Dst Port: bootps(68)
Bootstrap Protocol:
field:
op = BOOTREPLY
htype = Ethernet or (From "Assigned Numbers" RFC)
hlen = 6 or (Hardware address length in octets)
hops = 0
xid = same as "xid" field of DHCPINFORM message
secs = 0
flags = 0
ciaddr = mobile node's home address (from 'ciaddr' of DHCPINFORM)
yiaddr = 0
siaddr = 0
giaddr = home agent's address (from 'giaddr' of DHCPINFORM)
chaddr = mobile node's MAC address (from 'chaddr' of DHCPINFORM)
options:
option 53: DHCP Message Type = DHCPACK
option 61: Server Identifier = DHCP server's MAC address
option 6: Domain Name Server
all other options: if needed
(5) The home agent intercepting a unicast DHCPACK message will
tunnels this datagram to the foreign agent care-of address.
DHCPACK Packet format forwarded by the home agent:
Deng & Yang Expires August 27, 2009 [Page 11]
Internet-Draft DHCP MN Configuration February 2009
IP fields (encapsulating header):
Source Address = home agent's address
Destination Address = foreign agent's care-of-address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = DHCP server's address
Destination Address = mobile node's home address
UDP Src Port: bootps(67), Dst Port: bootpc(68)
Bootstrap Protocol
(6) DHCPACK Packet format forwarded by the foreign agent:
IP fields (encapsulating header):
Source Address = foreign agent's address
Destination Address = mobile node's home address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = DHCP server's address
Destination Address = mobile node's home address
UDP Src Port: bootps(67), Dst Port: bootpc(68)
Bootstrap Protocol
Once a DHCPACK message with an 'xid' field matching that in the
mobile node's DHCPINFORM message arrives from any server, the mobile
node's configuration process is finished.
If the mobile node does not receive a DHCPACK within a reasonable
period of time (60 seconds or 4 tries if using timeout suggested in
section 4.1), then it SHOULD display a message informing the user of
the problem, and then SHOULD begin network processing using suitable
defaults as per Appendix A of [RFC2131].
Deng & Yang Expires August 27, 2009 [Page 12]
Internet-Draft DHCP MN Configuration February 2009
3. Home DHCP server's address unknown without DHCP relay on home agent
This part is related to the cases as below:
o DHCP relay function is not supported by HA.
o DHCP relay function in HA will not be used for MN to get local
information.
For both cases above, there shall have DHCP server or another DHCP
relay on the same subnet as the home link of HA.
3.1. MIP4 Co-CoA case
If the 'D' bit was set in the mobile node's Registration Request
message, and code field of the received registration reply indicate
successly registered. This means that the mobile node is using a co-
located care-of address.
Section 5.3 of Reverse tunneling [RFC3024] recommend that a mobile
node using a co-located care-of address send the broadcast/multicast
packet are handled according to Sections 4.3 and 4.4 of the Mobile IP
specification [RFC3344].
The mobile node simply tunnels appropriate broadcast DHCPINFORM
message to the home agent.The source address of this DHCPINFORM
message is the mobile node's home address. Home agent simply
forwards the broadcast DHCPINFORM to the home network. The home DHCP
server can get this broadcast packet either directly or by the help
of another DHCP relay node. The topoloy is shown in figure 1.
+-----+ +-------+
| HA | | Home |
| |====| DHCP |
| | | Server|
| | | /relay|
+-----+ +-------+
//
// Home Network
-------------//-----------------------
// Visiting Network
//
// +----+
+----+ | |
| MN |----| AR |
+----+ | |
+----+
Deng & Yang Expires August 27, 2009 [Page 13]
Internet-Draft DHCP MN Configuration February 2009
Figure 5: Home network configuration in the case of Co-CoA
+----+ +-------+ +------+
| | | HA | |home |
| MN | | | |DHCP |
| | | | |Server|
| | | | |/relay|
+----+ +-------+ +------+
| RRQ | |
|--------------------------->| |
| RRP | |
|<---------------------------| |
| 1 | |
|===========================>| |
| | 2 |
| |--------->|
| | |
| | 3 |
| |<---------|
| 4 | |
|<===========================| |
Figure 6: Message sequence for host configuration in Co-CoA
Figure 2 shows the message sequence for host configuration in Co-CoA.
(1) After the mobile node successfully registered to the home agent
based on Registration Request(RRQ) and Registration Response(RRP)
message, it sends a DHCPINFORM message to request specific
configuration parameters by including the 'parameter request list'
option from home network. The mobile node generates and records a
random transaction identifier and inserts that identifier into the
'xid' field. The mobile node places its own home address in the
'ciaddr' field.
The mobile node will send DHCPINFORM message to the limited (all 1s)
broadcast address. DHCPINFORM messages MUST be directed to the 'DHCP
server' UDP port.
The mobile node will encapsulate this DHCPINFORM broadcast message
with IP in IP tunnel and send to the home agent, DHCPINFORM Packet
format sent by the mobile node is shown below:
Deng & Yang Expires August 27, 2009 [Page 14]
Internet-Draft DHCP MN Configuration February 2009
IP fields (encapsulating header):
Source Address = mobile node's home address
Destination Address = home agent's address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = mobile node's home address
Destination Address = broadcast address
UDP Src Port: bootpc(68), Dst Port: bootps(67)
Bootstrap Protocol:
field:
op = BOOTREQUEST
htype = Ethernet or (From "Assigned Numbers" RFC)
hlen = 6 or (Hardware address length in octets)
hops = 0
xid = selected by client
secs = 0
flags = 0
ciaddr = mobile node's home address
yiaddr = 0
siaddr = 0
giaddr = 0
chaddr = mobile node's MAC address
options:
option 53: DHCP Message Type = DHCPINFORM
option 61: Client Identifier = mobile node's MAC address
option 55: Parameter request List (Domain Name Server,... et al.)
(2) Since the home agent does not acts as the DHCP relay agent, after
receiving a unicast tunnel message, it detunnels the unicast
encapsulated header, and simply forwards the inner broadcast packet
onto the home network.
(3) DHCP server may receive the broadcast DHCPINFORM message.
Another DHCP relay agent in home network may also help to relay the
DHCPINFORM message to DHCP server as defined in [RFC2131]. then, DHCP
server constructs a DHCPACK message with any home configuration
parameters appropriate for the mobile node according to Section 3.4
of [RFC2131] . The DHCP server SHOULD unicast the DHCPACK reply to
the address given in the 'ciaddr' field (mobile nodes' home address)
of the DHCPINFORM message.
DHCPACK Packet format sent by the DHCP Server:
Deng & Yang Expires August 27, 2009 [Page 15]
Internet-Draft DHCP MN Configuration February 2009
IP fields:
Source Address = DHCP server's address
Destination Address = mobile nodes's home address
UDP Src Port: bootps(67), Dst Port: bootps(68)
Bootstrap Protocol:
field:
op = BOOTREPLY
htype = Ethernet or (From "Assigned Numbers" RFC)
hlen = 6 or (Hardware address length in octets)
hops = 0
xid = same as "xid" field of DHCPINFORM message
secs = 0
flags = 0
ciaddr = mobile node's home address (from 'ciaddr' of DHCPINFORM)
yiaddr = 0
siaddr = 0
giaddr = 0 or the other DHCP relay agent's address invloved
chaddr = mobile node's MAC address (from 'chaddr' of DHCPINFORM)
options:
option 53: DHCP Message Type = DHCPACK
option 61: Server Identifier = DHCP server's MAC address
option 6: Domain Name Server
all other options: if needed
(4) The home agent intercepting this DHCPACK message will tunnels it
to the mobile node's currently registered care-of address.
DHCPACK Packet format forwarded by the home agent:
IP fields (encapsulating header):
Source Address = home agent's address
Destination Address = mobile node's care-of-address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = DHCP server's address
Destination Address = mobile node's home address
UDP Src Port: bootps(67), Dst Port: bootpc(68)
Bootstrap Protocol
Once a DHCPACK message with an 'xid' field matching that in the
mobile node's DHCPINFORM message arrives from any server, the mobile
node's configuration process is finished.
If the mobile node does not receive a DHCPACK within a reasonable
period of time (60 seconds or 4 tries if using timeout suggested in
section 4.1), then it SHOULD display a message informing the user of
the problem, and then SHOULD begin network processing using suitable
Deng & Yang Expires August 27, 2009 [Page 16]
Internet-Draft DHCP MN Configuration February 2009
defaults as per Appendix A of [RFC2131].
3.2. MIP4 FA CoA Case
If the 'D' bit was not set in the mobile node's Registration Request
message, and code field of the received registration reply indicate
successly registered. This means that the mobile node is using a
foreign agent care-of address.
Reverse tunneling [RFC3024] in Mobile IP has mandate that a mobile
node using a foreign agent care-of address MUST use the encapsulating
delivery style. So the operation of DHCPINFORM broadcast message to
the home network in this case should follow the encapsulating
delivery style.
+-----+ +-------+
| HA | | Home |
| |====| DHCP |
| | | Server|
| | |/relay |
+-----+ +-------+
||
|| Home Network
----------------||--------------------
|| Visiting Network
||
+----+
+----+______| |
| MN |------| FA |
+----+ | |
+----+
Figure 7: Home network configuration in the case of FA-CoA
Deng & Yang Expires August 27, 2009 [Page 17]
Internet-Draft DHCP MN Configuration February 2009
+----+ +-----+ +-------+ +------+
| | | | | HA | |DHCP |
| MN | | FA | | | |Server|
| | | | | | |/relay|
| | | | | | | |
+----+ +-----+ +-------+ +------+
| | | |
| RRQ | |
|---------------------------->| |
| RRP | |
|<----------------------------| |
| 1 | | |
|==============>| | |
| | 2 | |
| |============>| |
| | | 3 |
| | |--------->|
| | | 4 |
| | |<---------|
| | 5 | |
| |<============| |
| 6 | | |
|<==============| | |
Figure 8: Message sequence for host configuration in FA-CoA
Figure 4 shows the message sequence for host configuration in Co-CoA.
(1) After the mobile node successfully registered to the home agent
based on Registration Request(RRQ) and Registration Response(RRP)
messages, it sends a DHCPINFORM message to request specific
configuration parameters by including the 'parameter request list'
option from home network. The mobile node generates and records a
random transaction identifier and inserts that identifier into the
'xid' field. The mobile node places its own home address in the
'ciaddr' field.
The mobile node send DHCPINFORM the message to the limited (all 1s)
broadcast address. DHCPINFORM messages MUST be directed to the 'DHCP
server' UDP port.
The mobile node will encapsulate this DHCPINFORM broadcast message
with IP in IP tunnel and send to the foriegn agent, DHCPINFORM Packet
format sent by the mobile node is shown below:
Deng & Yang Expires August 27, 2009 [Page 18]
Internet-Draft DHCP MN Configuration February 2009
IP fields (encapsulating header):
Source Address = mobile node's home address
Destination Address = foreign agent's address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = mobile node's home address
Destination Address = broadcast address
UDP Src Port: bootpc(68), Dst Port: bootps(67)
Bootstrap Protocol:
field:
op = BOOTREQUEST
htype = Ethernet or (From "Assigned Numbers" RFC)
hlen = 6 or (Hardware address length in octets)
hops = 0
xid = selected by client
secs = 0
flags = 0
ciaddr = mobile node's home address
yiaddr = 0
siaddr = 0
giaddr = 0
chaddr = mobile node's MAC address
options:
option 53: DHCP Message Type = DHCPINFORM
option 61: Client Identifier = mobile node's MAC address
option 55: Parameter request List (Domain Name Server,... et al.)
(2) Packet format forwarded by the foreign agent (Encapsulating
Delivery Style):
IP fields (encapsulating header):
Source Address = foreign agent's care-of-address
Destination Address = home agent's address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = mobile node's home address
Destination Address = broadcast address
UDP Src Port: bootpc(68), Dst Port: bootps(67)
Bootstrap Protocol
(3) Since the home agent does not act as the DHCP relay agent, after
receiving a unicast tunnel message, it detunneled the unicast
encapsulated header, and simply forwards the inner broadcast packet
onto the home network.
(3) DHCP server may receive the broadcast DHCPINFORM message.
Another DHCP relay agent in home network may also help to relay the
DHCPINFORM message to DHCP server as defined in [RFC2131]. then, DHCP
Deng & Yang Expires August 27, 2009 [Page 19]
Internet-Draft DHCP MN Configuration February 2009
server constructs a DHCPACK message with any home configuration
parameters appropriate for the mobile node according to Section 3.4
of [RFC2131] . The DHCP server SHOULD unicast the DHCPACK reply to
the address given in the 'ciaddr' field (mobile node's home address)
of the DHCPINFORM message.
DHCPACK Packet format sent by the DHCP Server:
IP fields:
Source Address = DHCP server's address
Destination Address = mobile node's home address
UDP Src Port: bootps(67), Dst Port: bootps(68)
Bootstrap Protocol:
field:
op = BOOTREPLY
htype = Ethernet or (From "Assigned Numbers" RFC)
hlen = 6 or (Hardware address length in octets)
hops = 0
xid = same as "xid" field of DHCPINFORM message
secs = 0
flags = 0
ciaddr = mobile node's home address (from 'ciaddr' of DHCPINFORM)
yiaddr = 0
siaddr = 0
giaddr = 0 or the other DHCP relay agent's address invloved
chaddr = mobile node's MAC address (from 'chaddr' of DHCPINFORM)
options:
option 53: DHCP Message Type = DHCPACK
option 61: Server Identifier = DHCP server's MAC address
option 6: Domain Name Server
all other options: if needed
(5) The home agent intercepting a unicast DHCPACK message will
tunnels this datagram to the foreign agent care-of address.
DHCPACK Packet format forwarded by the home agent:
IP fields (encapsulating header):
Source Address = home agent's address
Destination Address = foreign agent's care-of-address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = DHCP server's address
Destination Address = mobile node's home address
UDP Src Port: bootps(67), Dst Port: bootpc(68)
Bootstrap Protocol
Deng & Yang Expires August 27, 2009 [Page 20]
Internet-Draft DHCP MN Configuration February 2009
(6) DHCPACK Packet format forwarded by the foreign agent:
IP fields (encapsulating header):
Source Address = foreign agent's address
Destination Address = mobile node's home address
Protocol field: 4 (IP in IP)
IP fields (original header):
Source Address = DHCP server's address
Destination Address = mobile node's home address
UDP Src Port: bootps(67), Dst Port: bootpc(68)
Bootstrap Protocol
According to [RFC3024], encapsulating delivery style is required for
reverse tunneling of broadcast/multicast. However, once the
encapsulated delivery style is negotiated, it applies to all reverse
tunneling, including unicast. But, it's obvious that the overhead of
DHCPACK message will be increase as shown in message (6) above.
[Chakrabarti08] has discussed this issue in detail.
Once a DHCPACK message with an 'xid' field matching that in the
mobile node's DHCPINFORM message arrives from any server, the mobile
node's configuration process is finished.
If the mobile node does not receive a DHCPACK within a reasonable
period of time (60 seconds or 4 tries if using timeout suggested in
section 4.1), then it SHOULD display a message informing the user of
the problem, and then SHOULD begin network processing using suitable
defaults as per Appendix A of [RFC2131].
Deng & Yang Expires August 27, 2009 [Page 21]
Internet-Draft DHCP MN Configuration February 2009
4. Home DHCP server's address known
If a mobile node has obtained a DHCP server address through some
other means (how to obtain is out scope of this document), after
registration process, it may send a DHCPINFORM unicast message to
obtain other local configuration parameters.
According to Section 1.7 of [RFC3344], in the reverse direction,
datagrams sent by the mobile node are generally delivered to their
destination using standard IP routing mechanisms, not necessarily
passing through the home agent.
The whole procedure is as below:
(1) After the mobile node successfully registered to the home agent
based on Registration Request(RRQ) and Registration Response(RRP)
message, it then unicasts the DHCPINFORM to the DHCP server based on
MIPv4 standard IP routing mechanisms.
DHCPINFORM Packet format sent by the mobile node is shown below (this
packet may be encapsulated inside tunnels if needed):
IP fields:
Source Address = mobile node's home address
Destination Address = DHCP server's address
UDP Src Port: bootpc(68), Dst Port: bootps(67)
Bootstrap Protocol:
field:
op = BOOTREQUEST
htype = Ethernet or (From "Assigned Numbers" RFC)
hlen = 6 or (Hardware address length in octets)
hops = 0
xid = selected by client
secs = 0
flags = 0
ciaddr = mobile node's home address
yiaddr = 0
siaddr = 0
giaddr = 0
chaddr = mobile node's MAC address
options:
option 53: DHCP Message Type = DHCPINFORM
option 61: Client Identifier = mobile node's MAC address
option 55: Parameter request List (Domain Name Server,... et al.)
(2) DHCP server receiving a DHCPINFORM message construct a DHCPACK
message with any home configuration parameters appropriate for the
mobile node according to Section 3.4 of [RFC2131] . If the 'giaddr'
Deng & Yang Expires August 27, 2009 [Page 22]
Internet-Draft DHCP MN Configuration February 2009
field is zero and the 'ciaddr' field is nonzero, then the DHCP server
SHOULD unicast the DHCPACK reply to the address given in the 'ciaddr'
field of the DHCPINFORM message.
DHCPACK Packet format sent by the DHCP Server:
IP fields:
Source Address = DHCP server's address
Destination Address = mobile node's home address
(from 'ciaddr' of DHCPINFORM)
UDP Src Port: bootps(67), Dst Port: bootpc(68)
Bootstrap Protocol:
field:
op = BOOTREPLY
htype = Ethernet or (From "Assigned Numbers" RFC)
hlen = 6 or (Hardware address length in octets)
hops = 0
xid = same as "xid" field of DHCPINFORM message
secs = 0
flags = 0
ciaddr = mobile node's home address (from 'ciaddr' of DHCPINFORM)
yiaddr = 0
siaddr = 0
giaddr = 0
chaddr = mobile node's MAC address (from 'chaddr' of DHCPINFORM)
options:
option 53: DHCP Message Type = DHCPACK
option 61: Server Identifier = DHCP server's MAC address
option 6: Domain Name Server
all other options: if needed
(3) The home agent intercepting a unicast DHCPACK message will
tunnels this datagram to the mobile node's home address based on
standard mobile IP process.
Deng & Yang Expires August 27, 2009 [Page 23]
Internet-Draft DHCP MN Configuration February 2009
5. Security Considerations
This document just analyse the process of DHCPINFORM support in
mobile IP environment, it operates in the security constraints and
requirements of [RFC2131] and [RFC3344].
Deng & Yang Expires August 27, 2009 [Page 24]
Internet-Draft DHCP MN Configuration February 2009
6. IANA Consideration
This document makes no requests to IANA.
Deng & Yang Expires August 27, 2009 [Page 25]
Internet-Draft DHCP MN Configuration February 2009
7. Acknowledgments
The author thanks the discussion from Kent Leung, Alexandru Petrescu,
Charles E. Perkins, Jari Arkko, Vijay Devarapalli, Hans Sjostrand, et
al. in the development of this document.
The efforts of McCann Peter and Henrik Levkowetz in reviewing this
document are gratefully acknowledged.
Deng & Yang Expires August 27, 2009 [Page 26]
Internet-Draft DHCP MN Configuration February 2009
8. Conclusion
This document verified that mobile node could get home network
configuration based on DHCPINFORM without any revision of basic
mobile IP specification.
Deng & Yang Expires August 27, 2009 [Page 27]
Internet-Draft DHCP MN Configuration February 2009
9. Normative References
[Chakrabarti08]
Chakrabarti, Y., "IPv4 Mobility Extension for Multicast
and Broadcast Packets", draft-chakrabarti-mip4-mcbc-03.txt
(work in progress), October 2008.
[RFC0951] Croft, B. and J. Gilmore, "Bootstrap Protocol", RFC 951,
September 1985.
[RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", RFC 1700,
October 1994.
[RFC1701] Hanks, S., Li, T., Farinacci, D., and P. Traina, "Generic
Routing Encapsulation (GRE)", RFC 1701, October 1994.
[RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003,
October 1996.
[RFC2004] Perkins, C., "Minimal Encapsulation within IP", RFC 2004,
October 1996.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997.
[RFC3024] Montenegro, G., "Reverse Tunneling for Mobile IP,
revised", RFC 3024, January 2001.
[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
August 2002.
Deng & Yang Expires August 27, 2009 [Page 28]
Internet-Draft DHCP MN Configuration February 2009
Authors' Addresses
Hui Deng
China Mobile
53A,Xibianmennei Ave.,
Xuanwu District,
Beijing 100053
China
Email: denghui02@gmail.com
Peng Yang
Hitachi (China) R&D Corp
N-301, building C, Raycom Infotech Park
Haidian District,
Beijing 100190
China
Email: peng.yang.chn@gmail.com
Deng & Yang Expires August 27, 2009 [Page 29]
| PAFTECH AB 2003-2026 | 2026-04-24 02:43:18 |