draft-ietf-pim-join-attributes-00.txt   draft-ietf-pim-join-attributes-01.txt 
PIM WG A. Boers PIM WG A. Boers
Internet-Draft IJ. Wijnands Internet-Draft IJ. Wijnands
Expires: April 4, 2006 E. Rosen Expires: September 2, 2006 E. Rosen
Cisco Systems, Inc. Cisco Systems, Inc.
october 2005 march 2006
Format for using TLVs in PIM messages Format for using TLVs in PIM messages
draft-ietf-pim-join-attributes-00 draft-ietf-pim-join-attributes-01
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2006).
Abstract Abstract
This document describes a generic TLV attribute encoding format to be This document describes a generic TLV attribute encoding format to be
added to PIM. added to PIM join messages.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Conventions used in this document . . . . . . . . . . . . . . . 3
2. Use of the Attribute Field in Join Messages . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Attribute join . . . . . . . . . . . . . . . . . . . . . . 3 3. Use of the Attribute Field in Join Messages . . . . . . . . . . 3
2.2. Transitive attributes . . . . . . . . . . . . . . . . . . . 3 3.1. Attribute join . . . . . . . . . . . . . . . . . . . . . . 3
2.3. Attribute Hello Option . . . . . . . . . . . . . . . . . . 3 3.2. Transitive attributes . . . . . . . . . . . . . . . . . . . 3
2.4. Conflicting Attributes . . . . . . . . . . . . . . . . . . 4 3.3. Attribute Hello Option . . . . . . . . . . . . . . . . . . 3
2.5. Attribute Convergence . . . . . . . . . . . . . . . . . . . 4 3.4. Conflicting attributes . . . . . . . . . . . . . . . . . . 4
2.6. Multiple Attributes . . . . . . . . . . . . . . . . . . . . 4 3.5. Attribute Convergence . . . . . . . . . . . . . . . . . . . 4
3. PIM Attribute packet format . . . . . . . . . . . . . . . . . . 5 3.6. Multiple attributes . . . . . . . . . . . . . . . . . . . . 5
3.1. PIM Join packet format . . . . . . . . . . . . . . . . . . 5 3.7. Applicability of the attributes . . . . . . . . . . . . . . 5
3.2. PIM Attribute Hello option . . . . . . . . . . . . . . . . 6 3.8. PIM attribute packet format . . . . . . . . . . . . . . . . 5
4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 6 3.8.1. PIM Join packet format . . . . . . . . . . . . . . . . 5
5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.8.2. PIM Attribute Hello option . . . . . . . . . . . . . . 6
5.1. Normative References . . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
5.2. Informative References . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 6
Intellectual Property and Copyright Statements . . . . . . . . . . 8 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
Intellectual Property and Copyright Statements . . . . . . . . . . 9
1. Introduction 1. Conventions used in this document
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 and
indicate requirement levels for compliant PIM-SM implementations.
2. Introduction
It is sometimes convenient to add additional information to PIM join It is sometimes convenient to add additional information to PIM join
messages. The generic PIM encoding format is not always optimal to messages. The generic PIM encoding format is not always optimal to
do this. This document defines a new field in the PIM Join message do this. This document defines a new field in the PIM Join message
that allows it to use TLVs, hereby called the attribute field. The that allows it to use TLVs, hereby called the attribute field. The
content and purpose of this attribute field is outside the scope of content and purpose of this attribute field is outside the scope of
this document, only the generic encoding format is described here. this document, only the generic encoding format is described here.
2. Use of the Attribute Field in Join Messages 3. Use of the Attribute Field in Join Messages
2.1. Attribute join 3.1. Attribute join
Attribute fields are defined similar to the PIM source encoding type Attribute fields are defined similar to the PIM source encoding type
as defined in [I-D.ietf-pim-sm-v2-new]. A source address without any as defined in [I-D.ietf-pim-sm-v2-new]. A source address without any
additional TLV's should be processed identically to a source address additional TLV's should be processed identically to a source address
in the default source encoding. in the default source encoding.
Multiple TLV's from the same or different type are permitted in a Multiple TLV's from the same or different type are permitted in a
single source address in any order. single source address in any order.
2.2. Transitive attributes 3.2. Transitive attributes
It may be desired to have routers that understand the generic It may be desired to have routers that understand the generic
attribute format, forward the attributes regardless if they attribute format, forward the attributes regardless of whether they
understand the TLV's encoded in the attribute not. For this the understand the TLV's encoded in the attribute not. For this the
first bit in the Type field is reserved. If this bit is set then the first bit in the Type field is reserved. If this bit is set then the
TLV is forwarded upstream in case the router does not understand that router MUST forward the TLV upstream in case the router does not
type. understand that type. If this bit is not set the router MUST NOT
forward the TLV upstream in the case the router does not understand
that type.
2.3. Attribute Hello Option 3.3. Attribute Hello Option
A new PIM source type has been defined to include the Attribute A new PIM source type has been defined to include the Attribute
field. This source type is included in a normal PIM Join. Each field. This source type is included in a normal PIM Join. Each
router on a connected network needs to be able to understand and router on a connected network needs to be able to understand and
parse the Join message. Therefore we include a new PIM hello option parse the Join message. Therefore we include a new PIM hello option
to advertise our capability to parse and process the new source type. to advertise our capability to parse and process the new source type.
We can only send a PIM Join which includes an attribute if ALL We can only send a PIM Join which includes an attribute if ALL
routers on the network support the new option. (Even a router which routers on the network support the new option. (Even a router which
is not the upstream neighbor must be able parse the packet in order is not the upstream neighbor must be able parse to the packet in
to do Join suppression or overriding.) Option value TBD. order to do Join suppression or overriding.) Option value TBD.
Having the attribute hello option does not guarantee that all Having the attribute hello option does not guarantee that all
neighbors understand all possible individual attributes. As there's neighbors understand all possible individual attributes. As there's
no immediate way to act on a neighbor's incapability to process no immediate way to act on a neighbor's incapability to process
certain attribute types, it is not desired to have a hello option for certain attribute types, it is not desired to have a hello option for
each possible attribute type. each possible attribute type.
2.4. Conflicting Attributes 3.4. Conflicting attributes
It's possible that a router receives conflicting attribute It's possible that a router receives conflicting attribute
information from different downstream routers. See Figure 2. information from different downstream routers. See Figure 2.
( Edge A1 ) ( Edge B1 )---- [R1] ( Edge A1 ) ( Edge B1 )---- [R1]
/ \ / / \ /
/ \ / / \ /
[S] ( Core ) [S] ( Core )
\ / \ \ / \
\ / \ \ / \
( Edge A2 ) ( Edge B2 )---- [R2] ( Edge A2 ) ( Edge B2 )---- [R2]
Figure 2 Figure 2
There are 2 receivers for the same group connected to Edge B1 and B2. An example join attribute in this case is an exit router. There are
Suppose that edge router B1 prefers A1 as the exit point and B2 2 receivers for the same group connected to Edge B1 and B2. Suppose
prefers A2 as exit point to reach the source S. If both Edge B1 and that edge router B1 prefers A1 as the exit point and B2 prefers A2 as
B2 send a Join including an attribute to prefer their exit router in exit point to reach the source S. If both Edge B1 and B2 send a Join
the network and they cross the same core router, the core router will including an attribute to prefer their exit router in the network and
get conflicting attribute information for the source. If this they cross the same core router, the core router will get conflicting
happens we use the Attribute from the PIM adjacency with the attribute information for the source. If this happens we use the
numerically smallest IP address. The Attributes from other sending Attribute from the PIM adjacency with the numerically smallest IP
routers may be kept around in case the best Attribute gets pruned or address. The attributes from other sending routers may be kept
expires, we are able to immediately use the second best Attribute and around in case the best attribute gets pruned or expires, we are able
converge quickly without waiting for the next periodic update. If a to immediately use the second best attribute and converge quickly
TLV has its own definition for conflict resolution it is preferred without waiting for the next periodic update. If a TLV has its own
over the conflict resolution above. definition for conflict resolution it is preferred over the conflict
resolution above.
2.5. Attribute Convergence 3.5. Attribute Convergence
An Attribute is included in a PIM Join message together with the An attribute is included in a PIM Join message together with the
source information. If the Attribute for this source is changed, we source information. If the attribute for this source is changed, we
trigger a new PIM Join message to the upstream router. This causes trigger a new PIM Join message to the upstream router. This causes
the new Attribute to be propagated. This new Attribute implicitly the new attribute to be propagated. This new attribute implicitly
removes the old Attribute upstream. If processing the new Attribute removes the old attribute upstream. If processing the new attribute
results in a change in the distribution tree, a PIM Prune message may results in a change in the distribution tree, a PIM Prune message may
be sent. This PIM Prune does not need to carry any Attribute, the be sent. This PIM Prune does not need to carry any attribute, the
sender of the prune and the source and group information is enough to sender of the prune and the source and group information is enough to
identify the entry. The attribute information is removed immediately identify the entry. The attribute information is removed immediately
and possibly a new attribute is chosen from the database if and possibly a new attribute is chosen from the database if
available. available.
2.6. Multiple Attributes 3.6. Multiple attributes
A PIM Join can contain multiple Attributes. The Attributes are A PIM Join can contain multiple attributes. The attributes are
encoded as TLVs associated with a new PIM source type in the PIM encoded as TLVs associated with a new PIM source type in the PIM
message. When a PIM Join with multiple Attributes is received, the message. When a PIM Join with multiple attributes is received, the
first Attribute is processed, and the action taken depends upon the first attribute is processed, and the action taken depends upon the
Attribute type. This may or may not result in the processing of the attribute type. This may or may not result in the processing of the
next Attribute. Attributes not processed are passed upstream next attribute. Attributes that the router understands but are not
unchanged. processed MUST be passed upstream unchanged.
3. PIM Attribute packet format 3.7. Applicability of the attributes
3.1. PIM Join packet format PIM Joins with attributes can be applied to both shared-trees rooted
at a Rendezvous Point (RP) and shortest-path trees as described in
[I-D.ietf-pim-sm-v2-new].
3.8. PIM attribute packet format
3.8.1. PIM Join packet format
There is no space in the default PIM source encoding to include a There is no space in the default PIM source encoding to include a
Attribute field. Therefore we introduce a new source encoding type. attribute field. Therefore we introduce a new source encoding type.
The attributes are formatted as TLV's. The new Encoded source The attributes are formatted as TLV's. The new Encoded source
address looks like this: address looks like this:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Addr Family | Encoding Type | Rsrvd |S|W|R| Mask Len | | Addr Family | Encoding Type | Rsrvd |S|W|R| Mask Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Address | | Source Address (Encoded-Source format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|F|S| Type | Length | Value |F|S| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+..... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+.....
|F|S| Type | Length | Value |F|S| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+..... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+.....
. . . . . .
. . . . . .
F bit, Forward Unknown TLV. If this bit is set the TLV is forwarded F bit, Forward Unknown TLV. If this bit is set the TLV is forwarded
regardless if the router understands the Type. regardless if the router understands the Type.
skipping to change at page 6, line 5 skipping to change at page 6, line 18
Type field of the TLV is 6 bits. Type field of the TLV is 6 bits.
Length field of the TLV is 1 byte. Length field of the TLV is 1 byte.
The other fields are the same as described in the PIM spec. The other fields are the same as described in the PIM spec.
[I-D.ietf-pim-sm-v2-new]. [I-D.ietf-pim-sm-v2-new].
The source TLV encoding type: TBD. The source TLV encoding type: TBD.
3.2. PIM Attribute Hello option 3.8.2. PIM Attribute Hello option
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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OptionType = XX | OptionLength = 0 | | OptionType = TBD | OptionLength = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option type: TBD. Option type: TBD.
4. Acknowledgments 4. IANA Considerations
The authors would like to thank James Lingard for his comments on This document requires a new PIM Hello Option value and a new PIM
this topic. Join Encoding type.
5. References 5. Security Considerations
5.1. Normative References Security of the join attribute is only guaranteed by the security of
the PIM packet, so the security considerations for PIM join packets
as described in PIM-SM [I-D.ietf-pim-sm-v2-new] apply here.
6. Acknowledgments
The authors would like to thank James Lingard, Bharat Joshi, Marshall
Eubanks, Stig Venaas, Pekka Savola and Tom Pusateri for their input.
7. References
7.1. Normative References
[I-D.ietf-pim-sm-v2-new] [I-D.ietf-pim-sm-v2-new]
Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode PIM-SM): "Protocol Independent Multicast - Sparse Mode PIM-SM):
Protocol Specification (Revised)", Protocol Specification (Revised)",
draft-ietf-pim-sm-v2-new-11 (work in progress), draft-ietf-pim-sm-v2-new-11 (work in progress),
October 2004. October 2004.
5.2. Informative References 7.2. Informative References
Authors' Addresses Authors' Addresses
Arjen Boers Arjen Boers
Cisco Systems, Inc. Cisco Systems, Inc.
Avda. Diagonal, 682 Avda. Diagonal, 682
Barcelona 08034 Barcelona 08034
Spain Spain
Email: aboers@cisco.com Email: aboers@cisco.com
skipping to change at page 8, line 41 skipping to change at page 9, line 41
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
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