HIP Working Group G. Camarillo
Internet-Draft A. Keranen
Intended status: Experimental Ericsson
Expires: September 9, 2010 March 8, 2010
Host Identity Protocol (HIP) Multi-hop Routing Extension
draft-ietf-hip-via-01.txt
Abstract
This document specifies two extensions to HIP to implement multi-hop
routing. The first extension allows implementing source routing in
HIP. That is, a host sending a HIP packet can define a set of hosts
that the HIP packet should traverse. The second extension allows a
HIP packet to carry and record the list of hosts that forwarded it.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3
2.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Protocol Definitions . . . . . . . . . . . . . . . . . . . . . 4
3.1. Creating and Processing Via Lists . . . . . . . . . . . . . 4
3.2. Creating Destination Lists . . . . . . . . . . . . . . . . 4
3.3. Processing Destination Lists . . . . . . . . . . . . . . . 5
4. Packet Formats . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Source and Destination Route List Parameters . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
When HIP [RFC5201] is used in certain contexts, hosts need the
ability to perform source routing. That is, a host needs the ability
to send a HIP packet that will traverse a set of hosts before
reaching its destination. Such features are needed, e.g., in HIP
BONE [I-D.ietf-hip-bone] overlay networks or if two hosts wish to
keep a third, or more, HIP hosts on the signaling path. This
document defines an extension that provides HIP with this
functionality.
Additionally, when HIP packets are routed through multiple hosts,
some of these hosts (e.g., the destination host) need the ability to
know the hosts a particular packet traversed. This document defines
another extension that provides HIP with this functionality.
These two extensions enable multi-hop routing in HIP. Before these
extensions were specified, there were standardized ways for
supporting only a single intermediate host (e.g., a rendezvous server
[RFC5204]) between the source of a HIP packet and its destination.
2. Terminology
2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2.2. Definitions
The following terms used in this document are similar to those
defined by RELOAD [I-D.ietf-p2psip-base] but used here in context of
HIP.
Destination list: A list of HITs of the hosts that a HIP packet
should traverse.
Via list: A list of HITs of the hosts that a HIP packet has
traversed.
Symmetric routing: A response to a message is routed back using the
same set of intermediary nodes as the original message used,
except in reversed order. Also known as symmetric recursive
routing.
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3. Protocol Definitions
The multi-hop routing extensions may be used in different contexts
and whether a new HIP packet should, for example, include a Via list
or have different options enabled, can depend on the particular use
case, local policies, and different protocols using the extension.
This section defines how the new parameters are handled, but when to
use these extensions is out of scope for this document.
3.1. Creating and Processing Via Lists
When a host sending a HIP packet needs to record the hosts that are
on the path that the HIP packet traverses, it includes an empty
ROUTE_VIA parameter to the packet.
A host that receives a packet with a ROUTE_VIA parameter SHOULD add
its own HIT to the end of the ROUTE_VIA parameter, unless it is the
receiver of the packet. If the host uses a different HIT on the HIP
association it used for receiving the packet than for sending it
forward, it SHOULD also add the receiving HIT to the route list
before the sending HIT.
If the host is the receiver of the packet, and the received packet
generates a response HIP packet, the host checks the SYMMETRIC flag
from the ROUTE_VIA parameter. If the SYMMETRIC flag is set, the host
MUST create a ROUTE_DST parameter from the ROUTE_VIA parameter, as
described in Section 3.2, and include it in the response packet.
Also, if an intermediary host generates a new HIP packet (e.g., an
error NOTIFY packet) due to a HIP packet that had a ROUTE_VIA
parameter with SYMMETRIC flag set, and the new packet is intended for
the sender of the original HIP packet, the host SHOULD construct and
add a ROUTE_DST parameter into the new packet as in the previous
case.
3.2. Creating Destination Lists
A host that needs to define the other hosts that should be on the
path a HIP packet traverses adds a ROUTE_DST parameter to the HIP
packet. The host may either decide the path independently, or it may
create the path based on a ROUTE_VIA parameter. Only the originator
of a signed HIP packet can add a ROUTE_DST parameter to the HIP
packet since the parameter is covered by the signature.
When a host creates a ROUTE_DST parameter due to receiving a packet
with a ROUTE_VIA parameter, it copies all the HITs in the ROUTE_VIA
parameter to the ROUTE_DST parameter, but in reversed order. This
results in HIP response packet being forwarded using the same set of
hosts as the packet for which the response was generated for.
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3.3. Processing Destination Lists
When a host receives a HIP packet that contains a ROUTE_DST
parameter, it first looks up its own HIT from the route list. If
host's own HIT is not in the list and the host is not the receiver of
the packet, the packet was incorrectly forwarded and MUST be dropped.
If the host's HIT is in the list more than once, the list is invalid
and the packet MUST be dropped to avoid forwarding loops. Next hop
for the packet is the HIT after host's own HIT in the list. If the
host's HIT was the last HIT in the list, the next hop is the
receiver's HIT in the HIP header.
If the MUST_FOLLOW flag in the ROUTE_DST parameter is not set, the
host SHOULD check whether it has a valid locator for one of the hosts
later in the list, or for the receiver of the packet, and it MAY
select such a host as the next hop. If the MUST_FOLLOW flag is set,
the host MUST NOT skip any hosts in the list.
If the host has a valid locator for the next hop, it MUST forward the
HIP packet to the next hop host. If the host can not determine a
valid locator for the next hop host, it SHOULD drop the packet and
SHOULD send back a NOTIFY error packet with type UNKNOWN_NEXT_HOP
(value [TBD by IANA; 90]). The Notification Data field for the error
notifications SHOULD contain the HIP header of the rejected packet
and the ROUTE_DST parameter.
4. Packet Formats
This memo defines two new HIP parameters that are used for recording
a route via multiple hosts (ROUTE_VIA) and for defining a route a
packet should traverse by the sender of the packet (ROUTE_DST).
The ROUTE_DST parameter is integrity protected with the signature
(where present) but ROUTE_VIA is not so that intermediary hosts can
add their own HITs to the list. Both parameters have critical type
(as defined in Section 5.2.1 of [RFC5201]) since the packet will not
be properly routed unless all hosts on path recognize the parameters.
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4.1. Source and Destination Route List Parameters
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| HIT #1 |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . .
. . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| HIT #n |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type [ TBD by IANA
ROUTE_DST: 971
ROUTE_VIA: 65525 ]
Length length in octets, excluding Type and Length
(i.e., number-of-HITs * 16 + 4)
Flags bit flags that can be used for requesting special
handling of the parameter
Reserved reserved for future use
HIT Host Identity Tag of one of the hosts on the path
Figure 1: Format of the ROUTE_VIA and ROUTE_DST Parameters
Figure 1 shows the format of both ROUTE_VIA and ROUTE_DST parameters.
The ROUTE_DST parameter, if present, MUST have at least one HIT, but
the ROUTE_VIA parameter can also have zero HITs. Both can contain at
most 32 HITs. The Flags field is used for requesting special
handling for via and destination lists. The flags defined in this
document are shown in Table 1. The Reserved field can be used by
future extensions; it MUST be zero when sending and ignored when
receiving this parameter.
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+-----+-------------+-----------------------------------------------+
| Pos | Name | Purpose |
+-----+-------------+-----------------------------------------------+
| 0 | SYMMETRIC | The response packet MUST be sent with a |
| | | ROUTE_DST list made from the ROUTE_VIA list |
| | | containing this flag, i.e., using symmetric |
| | | routing. |
| 1 | MUST_FOLLOW | All the hosts in a ROUTE_DST list MUST be |
| | | traversed, i.e., even if a host would have a |
| | | valid locator for a host beyond the next hop, |
| | | it MUST NOT forward the packet there but to |
| | | the next hop host. |
+-----+-------------+-----------------------------------------------+
Table 1: Bit Flags in ROUTE_VIA and ROUTE_DST Parameters
The "Pos" column in Table 1 shows the bit position of the flag (as in
Figure 1) in the Flags field, "Name" gives the name of the flag used
in this document, and "Purpose" gives brief description of the
meaning of that flag.
The flags apply to both ROUTE_VIA and ROUTE_DST parameters and when a
ROUTE_DST parameter is added to a packet because of a ROUTE_VIA
parameter, the same flags MUST be copied to the ROUTE_DST parameter.
5. IANA Considerations
This section is to be interpreted according to [RFC5226].
This document updates the IANA Registry for HIP Parameter Types
[RFC5201] by assigning new HIP Parameter Type values for the new HIP
Parameters: ROUTE_VIA and ROUTE_DST (defined in Section 4). This
document also defines a new Notify Packet Type [RFC5201]
UNKNOWN_NEXT_HOP in Section 3.3.
6. Security Considerations
A malicious host could craft a destination route list that contains
the same HIT more than once and thus create a forwarding loop. The
check described in Section 3.3 should break such loops but hosts MAY
in addition utilize the OVERLAY_TTL [I-D.ietf-hip-bone] parameter for
additional protection against forwarding loops.
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7. Acknowledgments
Tom Henderson provided valuable comments and improvement suggestions
for this document.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5201] Moskowitz, R., Nikander, P., Jokela, P., and T. Henderson,
"Host Identity Protocol", RFC 5201, April 2008.
8.2. Informative References
[RFC5204] Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
Rendezvous Extension", RFC 5204, April 2008.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[I-D.ietf-hip-bone]
Camarillo, G., Nikander, P., Hautakorpi, J., Keranen, A.,
and A. Johnston, "HIP BONE: Host Identity Protocol (HIP)
Based Overlay Networking Environment",
draft-ietf-hip-bone-04 (work in progress), January 2010.
[I-D.ietf-p2psip-base]
Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and
H. Schulzrinne, "REsource LOcation And Discovery (RELOAD)
Base Protocol", draft-ietf-p2psip-base-07 (work in
progress), February 2010.
Authors' Addresses
Gonzalo Camarillo
Ericsson
Hirsalantie 11
02420 Jorvas
Finland
Email: Gonzalo.Camarillo@ericsson.com
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Ari Keranen
Ericsson
Hirsalantie 11
02420 Jorvas
Finland
Email: Ari.Keranen@ericsson.com
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