TRILL Working Group Weiguo Hao
INTERNET-DRAFT Donald Eastlake
Intended status: Proposed Standard Huawei
Expires: April 17, 2015 October 18, 2015
TRILL: Address Flush Protocol
<draft-hao-trill-address-flush-00.txt>
Abstract
The TRILL (TRansparent Interconnection of Lots of Links) protocol, by
default, learns end station addresses from observing the data plane.
This document specifies an optional message by which an originating
TRILL switch can explicitly flush addresses learned by other TRILL
switches through the egress of data ingress by that originating TRILL
switch. This is a supplement to the TRILL automatic address
forgetting and can assist in achieving more rapid convergence.
Status of This Memo
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W. Hao & D. Eastlake [Page 1]
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Table of Contents
1. Introduction............................................3
1.1 Terminology and Acronyms...............................3
2. Address Flush Message Details...........................5
3. IANA Considerations.....................................9
4. Security Considerations.................................9
Normative References......................................10
Informative References....................................10
Acknowledgements..........................................10
Authors' Addresses........................................11
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1. Introduction
Edge TRILL (Transparent Interconnection of Lots of Links [RFC6325])
switches, also called RBridges, by default learn end station MAC
addresses from observing the data plane. On receipt of a native frame
from an end station, they would learn the local MAC address
attachment of the source end station. And on egressing
(decapsulating) a remotely originated TRILL Data frame, they learn
the remote MAC address and remote attachment TRILL switch. Such
learning is all appropriately scoped by data label (VLAN or Fine
Grained Label [RFC7172]).
TRILL has mechanisms for timing out such learning and appropriately
clearing it based on some network connectivity changes; however,
there are circumstances under which it would be helpful for a TRILL
switch to be able to explicitly flush (clear) learned end station
reachability information to achieve more rapid convergence (see, for
example, Section 6.2 of [RFC4762]). Obivously a TRILL switch R1 can
easily flush any locally learned addresses it wants. This document
specifies an optional message to request flushing such learned
address information at remote TRILL switches. This Address Flush
message makes use of the RBridge Channel facility [RFC7178], which
supports typed message transmission between RBridges.
1.1 Terminology and Acronyms
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 [RFC2119].
This document uses the terms and acronyms defined in [RFC6325] and
[RFCchannel] as well as the following:
AFN - Address Family Number ([RFC4760] where it is called Address
Family Identifier (AFI)).
FGL - Fine Grained Label [RFC7172].
Management VLAN - A VLAN in which all TRILL switches in a campus
indicate interest so that multi-destinaiton TRILL Data packets,
including RBridge Channel messages [RFCchannel], sent with that
VLAN as the Inner.VLAN will be delivered to all TRILL switches
in the campus. Usually no end station service is offered in the
Management VLAN.
RBridge - A alterntive name for a TRILL switch.
TRILL switch - A device implementing the TRILL protocol.
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Edge TRILL switch - A TRILL switch attached to one or more links
that provide end station service.
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2. Address Flush Message Details
The Address Flush message makes use of the RBridge Channel protocol
[RFC7178].
Although initial use is expected to be to flush 48-bit MAC addresses
[RFC7042], the protocol accommodates flushing other types of end
station addresses; there have been suggestion for TRILL switches to
learn IP addresses from the data plane [INFOCOM], TRILL might be
extended to accommodate 64-bit MAC addresses, or similar future
extensions might benefit from the ability to flush other types of
learned addresses.
The general structure of an RBridge Channel packet on a link between
TRILL switches is shown in Figure 1 below. The type of RBridge
Channel packet is given by a Protocol field in the RBridge Channel
Header that indicates how to interpret the Channel Protocol Specific
Payload [RFC7178l].
+-----------------------------------+
| Link Header |
+-----------------------------------+
| TRILL Header |
+--------------------------------+ |
| Inner Ethernet Addresses | |
+--------------------------------+ |
| Data Label (VLAN or FGL) | |
+--------------------------------+--+
| RBridge Channel Header |
+-----------------------------------+
| Channel Protocol Specific Payload |
+-----------------------------------+
| Link Trailer (FCS if Ethernet) |
+-----------------------------------+
Figure 1. RBridge Channel Packet Structure
An Address Flush RBridge Channel message normally applies to
addresses within the VLAN or FGL [RFC7178] Data Label in the TRILL
Header. Address Flush protocol messages are usually sent as multi-
destination packets (TRILL Header M bit equal to one) so as to reach
all TRILL switches offering end station service in the VLAN or FGL
specified by the Data Label. However, and address flush protocol
message can be sent unicast, if it is desired to clear addresses at
one TRILL switch only. And there are provisions for indicating the
Data Label with the address(es) to be flushed for cases where the
address flush protocol message is sent over a Managagement VLAN or
the like.
Figure 2 below expands the RBridge Channel Header and Channel
W. Hao & D. Eastlake [Page 5]
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Protocol Specific Payload from Figure 1 for the case of the Address
Flush message.
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
RBridge Channel Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | 0x0 | Ch. Protocol # (TBD) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address Flush Protocol Specific:
+-+-+-----------+---------------+
| SF| RESV | K |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ADDRESSES RECORD 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ADDRESSES RECORD 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ADDRESSES RECORD K |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2. Address Flush Channel Message Structure
The fields in Figure 2 related to the Address Flush message are as
follows:
Channel Protocol: The RBridge Channel Protocol value allocated
for Address Flush (see Section 3).
SF: The 2-bit SF ("super flush") field values have the following
meanings:
0: No special effect.
1: All addresses learned at the receiving TRILL switch due to
egressing TRILL Data packets fror the TRILL switch
originating this Address Flush message are flushed for the
data label in the TRILL Header. Any ADDRESS RECORDs in the
rest of the message for that data label can be ignored but
there may be ADDRESS RECORDs present that apply to other
data labels.
2: All addresses learned at the receiving TRILL switch due to
egressing TRILL Data packets from the TRILL switch
originating this Address Flush message are flushed across
all data labels. The remainder of the Address Flush message,
including the value of K, are ignored.
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3: Reserved. Ignored on receipt.
RESV: 4 reserved flag bits. Must be sent as zero and ignored on
recipet.
K: The number of ADDRESS RECORDs present. See below.
The structure of the ADDRESSES RECORD is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L|N|R| Size | Count | AFN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Label (Optional)
+-+-+-+-+-+-+-+-+-+-+-+-+-...
| Address 1 ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| Address 2 ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| Address K ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3. Structure of ADDRESSES RECORD
L: Label present. If this bit is a one, the optional Data Label
shown in present. If it is zero, there is no data label and
the addresses listed are withing the data labe given in the
TRILL Header.
N: No Specific Addresses. If this bit is one and Count is
zero and L is one, then flush all addresses learned at the
receiving TRILL switch due to egressing TRILL Data packets
from the TRILL switch originating this Address Flush message
are flushed for the Data Label given in the ADDRESS RECORD.
If this bit is zero or Count is non-zero or L is zero, they
this special flush action is not performed.
R: A reserved bit that MUST be sent as zero and is ignored on
receipt.
Size: The size of each Address in bytes. The presence of this
field makes it possible for a receiving TRILL switch to skip
an ADDRESS RECORD even if it does not understand the value
in the AFN field. Size MUST NOT be zero; a zero size field
indicates a corrupt Addresses Flush message and the entire
message is ignored. MUST be the correct size for an Address
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of the type indicated by the AFN field, for example 6 for
48-bit MAC addresses. If these conditions are violated, the
Address Flush message is discarded.
Count: The number of occurrences of an Address to flush in this
ADDRESS RECORD. May be zero. All Addresses MUST fit within
the RBridge Channel Message. If they do not, the message is
discarded.
AFN: The Address Family Number for the type of addresses
present as assigned by IANA. (The AFN for 48-bit MAC
addresses is 0x4005.)
Data Label: An optional Data Label (VLAN or FGL) in the same
format as Data Labels that appear in the TRILL Header.
Included in an ADDRESS RECORD only if the L bit is a one.
Address: An instance of an address to be flushed.
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3. IANA Considerations
IANA has allocated tbd1 for the Address Flush RBridge Channel
Protocol number from the range of RBridge Channel protocols allocated
by Standards Action [RFC7178].
4. Security Considerations
The Address Flush RBridge Channel Protocol provides no security
assurances or features. However, use of the Address Flush protocol
can be nested inside the RBridge Channel Tunnel Protocol [RFCtunnel]
using the RBridge Channel message payload type. The Channel Tunnel
protocol can provide some security services.
See [RFC7178] for general RBridge Channel Security Considerations.
See [RFC6325] for general TRILL Security Considerations.
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Normative References
[RFC2119] - Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4760] - Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, January 2007.
[RFC6325] - Perlman, R., D. Eastlake, D. Dutt, S. Gai, and A.
Ghanwani, "RBridges: Base Protocol Specification", RFC 6325,
July 2011.
[RFC7172] - Eastlake 3rd, D., Zhang, M., Agarwal, P., Perlman, R.,
and D. Dutt, "Transparent Interconnection of Lots of Links
(TRILL): Fine-Grained Labeling", RFC 7172, DOI
10.17487/RFC7172, May 2014, <http://www.rfc-
editor.org/info/rfc7172>.
[RFC7178] - Eastlake 3rd, D., Manral, V., Li, Y., Aldrin, S., and D.
Ward, "Transparent Interconnection of Lots of Links (TRILL):
RBridge Channel Support", RFC 7178, DOI 10.17487/RFC7178, May
2014, <http://www.rfc-editor.org/info/rfc7178>.
Informative References
[INFOCOM] - Perlman, R., "RBridges: Transparent Routing", Proc.
Infocom 2005, March 2004.
[RFC4762] - Lasserre, M., Ed., and V. Kompella, Ed., "Virtual Private
LAN Service (VPLS) Using Label Distribution Protocol (LDP)
Signaling", RFC 4762, January 2007.
[RFC7042] - Eastlake 3rd, D. and J. Abley, "IANA Considerations and
IETF Protocol and Documentation Usage for IEEE 802 Parameters",
BCP 141, RFC 7042, DOI 10.17487/RFC7042, October 2013,
<http://www.rfc-editor.org/info/rfc7042>.
[RFCtunnel] - Eastlake, D., ... "TRILL: Channel Tunnel", draft-
eastlake-trill-channel-tunnel, work in progress.
Acknowledgements
The document was prepared in raw nroff. All macros used were defined
within the source file.
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Authors' Addresses
Weiguo Hao
Huawei Technologies
101 Software Avenue,
Nanjing 210012, China
Phone: +86-25-56623144
Email: haoweiguo@huawei.com
Donald E. Eastlake, 3rd
Huawei Technologies
155 Beaver Street
Milford, MA 01757 USA
Phone: +1-508-333-2270
EMail: d3e3e3@gmail.com
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