Internet DRAFT - draft-hao-trill-address-flush
draft-hao-trill-address-flush
TRILL Working Group Weiguo Hao
INTERNET-DRAFT Donald Eastlake
Intended status: Proposed Standard Yizhou Li
Huawei
Expires: September 20, 2015 March 21, 2016
TRILL: Address Flush Message
<draft-hao-trill-address-flush-01.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 a message by which an originating TRILL
switch can explicitly request other TRILL switches to flush certain
MAC reachability learned through the egress of TRILL Data packets.
This is a supplement to the TRILL automatic address forgetting and
can assist in achieving more rapid convergence in case of topoogy or
configuration change.
Status of This Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Distribution of this document is unlimited. Comments should be sent
to the TRILL working group mailing list: trill@ietf.org.
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W. Hao, et al. [Page 1]
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Table of Contents
1. Introduction............................................3
1.1 Terminology and Acronyms...............................3
2. Address Flush Message Details...........................5
2.1 VLAN Block Case........................................6
2.2 Extensible Case........................................7
3. IANA Considerations....................................11
4. Security Considerations................................11
Normative References......................................12
Informative References....................................12
Acknowledgements..........................................12
Authors' Addresses........................................13
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1. Introduction
Edge TRILL (Transparent Interconnection of Lots of Links) switches
[RFC6325] [RFC7780], also called edge RBridges, by default learn end
station MAC address reachability 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 packet,
they learn the remote MAC address and remote attachment TRILL switch.
Such learning is all 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 and configuration
changes; however, there are circumstances under which it would be
helpful for a TRILL switch to be able to explicitly flush (purge)
certain learned end station reachability information in remote
RBridges to achieve more rapid convergence (see, for example,
[TCaware] and Section 6.2 of [RFC4762]).
A TRILL switch R1 can easily flush any locally learned addresses it
wants. This document specifies an RBridge Channel protocol [RFC7178]
message to request flushing address information learned from
decapsulating at remote 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
[ChannelTunnel] as well as the following:
Data Label - VLAN or FGL.
Edge TRILL switch - A TRILL switch attached to one or more links
that provide end station service.
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 [ChannelTunnel], 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.
W. Hao, et al. [Page 3]
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RBridge - A alterntive name for a TRILL switch.
TRILL switch - A device implementing the TRILL protocol.
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2. Address Flush Message Details
The Address Flush message is an RBridge Channel protocol message
[RFC7178].
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 the Protocol field in the RBridge Channel
Header that indicates how to interpret the Channel Protocol Specific
Payload [RFC7178].
+----------------------------------+
| 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 Protocol Message Structure
An Address Flush RBridge Channel message by default applies to
addresses within the 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. Such messages SHOULD be sent at priority 6 since they are
important control messages but lower priority than control messages
that establish or maintain adjacency.
Nevertheless:
- There are provisions for optionally indicating the Data Label(s)
to be flushed for cases where the Address Flush message is sent
over a Managagement VLAN or the like.
- An Address Flush message can be sent unicast, if it is desired to
clear addresses at one TRILL switch only.
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2.1 VLAN Block Case
Figure 2 below expands the RBridge Channel Header and Channel
Protocol Specific Payload from Figure 1 for the case of the VLAN
based Address Flush message. This form of the Address Flush message
is optimized for flushing MAC addressed based on nickname and blocks
of VLANs.
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 | Channel Protocol = TBD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address Flush Protocol Specific:
+-+-+-+-+-+-+-+-+
| K-nicks |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nickname 1 | Nickname 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nickname ... | Nickname K-nicks |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| K-VBs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Start.VLAN 1 | RESV | End.VLAN 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Start.VLAN 2 | RESV | End.VLAN 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Start.VLAN ... | RESV | End.VLAN ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Start.VLAN K-VBs | RESV | End.VLAN K-VBs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2. Address Flush Message - VLAN Case
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).
K-nicks: K-nicks is the number of nicknames present as an unsigned
integer. If this is zero, the ingress nickname in the TRILL
Header is considerted to be the only nickname to which the
message applies. If non-zero, it given the number of nicknames
present to which the message applies. The messages flushes
address learning due to egressing TRILL Data packets that had a
ingress nicknam to which the message applies.
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Nickname: A listed nickname to which it is intended that the
Address Flush message apply. If an unknown or reserved
nickname occurs in the list, it is ignored but the address
flush operation is still executed with the other nicknames. If
an incorrect nickname occurs in the list, so some address
learning is flushed that should not have been flush, the
network will strill operate correctly but will be less
efficient as the incorrectly flushed learning is re-learned.
K-VBs: K-VBs is the number of VLAN blocks present as an unsigned
integer. If this byte is zero, the message is the more general
format specified in Section 2.2. If it is non-zero, it gives
the number of blocks of VLANs present.
RESV: 4 reserved bits. MUST be sent as zero and ignored on
receipt.
Start.VLAN, End.VLAN: These 12-bit fields give the beginning and
ending VLAN IDs of a block of VLANs. The block includes both
the starting and endiing values so a block of size one is
indicated by setting End.VLAN equal to Start.VLAN. If
Start.VLAN is 0x000, it is treated as if it was 0x001. If
End.VLAN is 0xFFF, it is treated as if it was 0xFFE. If
End.VLAN is smaller than Start.VLAN, considering both as
unsigned integers, that VLAN block is ignored but the address
flush operation is still executed with any other VLAN blocks in
the message.
This message flushes all addresses learned from egressing TRILL Data
packets with an applicable nickname and a VLAN in any of the blocks
given. To flush addresses for all VLANs, it is easy to specify a
block covering all valid VLAN IDs, this is, from 0x001 to 0xFFE.
2.2 Extensible Case
A more general form of the Address Flush message is provided to
support flushing by FGL and more efficient encodings of VLANs and
FGLs where using a set of contiguous blocks if cumbersome. This form
is also extensible to handle future requirements.
It is indicated by a zero in the byte shown in Figure 2 as "K-VBs".
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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 | Channel Protocol = TBD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address Flush Protocol Specific:
+-+-+-+-+-+-+-+-+
| K-nicks |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nickname 1 | Nickname 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nickname ... | Nickname K-nicks |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type Dependent Information
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
Figure 3. Address Flush Message - Extensible Case
Channel Protocol, K-nicks, Nickname: These fields are as specified
in Section 2.1.
Type: If the byte immediately before the Type field, which is the
byte labeled "K-VBs" in Figure 2, is zero, the the Type byte
indicates the type of extended Address Flush message as
follows:
Type Description
------ ------------
0 Reserved
1 Bit Map of VLANs
2 Blocks of FGLs
3 List of FGLs
4 Bit Map of FGLs
5-254 Unassigned
255 Reserved
Length: The length of the remaining information in the Address
Flush message.
Type Dependent Information: Depends on the value of the type field
as further specified below in this section.
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Type 1
Bit Map of VLANs: The Type Dependent Information consists of two
bytes with the 12-bit starting VLAN ID N right justified (the top
4 bits are as specified above for RESV). This is followed by bytes
with one bit per VLAN ID. The high order bit of the first byte is
for VLAN N, the next to the highest order bit is for VLAN N+1, the
low order bit of the first byte is for VLAN N+7, the high order
bit of the second byte, if there is a second byte, is for VLAN
N+8, and so on. If that bit is a one, the the Address Flush
message applies to that VLAN. If that bit is a zero, then
addresses that have been learned in that VLAN are not flushed.
Note that Length MUST be at least 3. If Length is 0, 1, or 2 for a
Type 1 extended Address Flush message, the message is corrupt and
MUST be discarded. VLAN IDs do not wrap around. If there are
enough bytes so that some bits correspond to VLAN ID 0xFFF or
nigher, those bits are ignored but the message is still processed
for bits corresponding to valid VLAN IDs.
Type 2
Blocks of FGLs: The Type Dependent Information consists of sets of
Start.FGL and End.FGL numbers. The Address Flush information
applies to the FGLs in that range, incluse. A single FGL is
indicated by have both Start.FGL and End.FGL to the same value. If
End.FGL is less than Start.FGL, considering them as unsigned
integers, that block is ignored but the Address Flush message is
still processed for any other blocks present. For this Type,
Length MUST be a multiple of 6; if it is not, the message is
considered corrup and MUST be discarded.
Type 3
List of FGLs: The Type Dependent Information consists of FGL numbers
each in 3 bytes. The Address Flush message applies to those FGLs.
For this Type, Length MUST be a multiple of 3; if it is not, the
message is considered corrup and MUST be discarded.
Type 4
Bit Map of FGLs: The Type Dependent Information consists of three
bytes with the 24-bit starting FGL N. This is followed by bytes
with one bit per FGL. The high order bit of the first byte is for
FGL N, the next to the highest order bit is for FGL N+1, the low
order bit of the first byte is for FGL N+7, the high order bit of
the second byte, if there is a second byte, is for FGL N+8, and so
on. If that bit is a one, the the Address Flush message applies to
that FGL. If that bit is a zero, then addresses that have been
learned in that FGL are not flushed. Note that Length MUST be at
least 4. If Length is 0, 1, 2, or 3 for a Type 1 extended Address
Flush message, the message is corrupt and MUST be discarded. FGLs
do not wrap around. If there are enough bytes so that some bits
correspond to an FGL higher than 0xFFFFFF, those bits are ignored
but the message is still processed for bits corresponding to valid
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FGLs.
There is no provision for a list of VLAN IDs as there are few enough
of them that an arbitrary subset of VLAN IDs can always be
represented as a bit map.
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3. IANA Considerations
IANA is requested to assign TBD as the Address Flush RBridge Channel
Protocol number from the range of RBridge Channel protocols allocated
by Standards Action [RFC7178].
The added RBridge Channel protocols registry entry on the TRILL
Parameters web page is as follows:
Protocol Description Reference
-------- -------------- ------------------
TBD Address Flush [this document]
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
[ChannelTunnel] using the RBridge Channel message payload type. The
Channel Tunnel protocol can provide 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.
[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>.
[RFC7780] - Eastlake 3rd, D., Zhang, M., Perlman, R., Banerjee, A.,
Ghanwani, A., and S. Gupta, "Transparent Interconnection of
Lots of Links (TRILL): Clarifications, Corrections, and
Updates", RFC 7780, DOI 10.17487/RFC7780, February 2016,
<http://www.rfc-editor.org/info/rfc7780>.
Informative References
[RFC4762] - Lasserre, M., Ed., and V. Kompella, Ed., "Virtual Private
LAN Service (VPLS) Using Label Distribution Protocol (LDP)
Signaling", RFC 4762, January 2007.
[ChannelTunnel] - Eastlake, D., M. Umair, Y. Li, "TRILL: RBridge
Channel Tunnel Protocol", draft-ietf-trill-channel-tunnel, work
in progress.
[TCaware] - Y. Li, et al., "Aware Spanning Tree Topology Change on
RBridges" draft-yizhou-trill-tc-awareness, 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
Yizhou Li
Huawei Technologies
101 Software Avenue,
Nanjing 210012
China
Phone: +86-25-56624629
Email: liyizhou@huawei.com
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