TRILL WG Radia. Perlman
Internet-Draft Intel Labs
Intended status: Standards Track Fangwei. Hu
Expires: October 24, 2014 ZTE Corporation
Donald. Eastlake 3rd
Huawei technology
Kesava. Krupakaran
Dell
Ting. Liao
ZTE Corporation
April 22, 2014
TRILL Smart Endnodes
draft-perlman-trill-smart-endnodes-03.txt
Abstract
This draft addresses the problem of the size and freshness of the
endnode learning table in edge RBridges, by allowing endnodes to
volunteer for endnode learning and encapsulation/decapsulation. Such
an endnode is known as a "smart endnode". Only the attached RBridge
can distinguish a "smart endnode" from a "normal endnode". The smart
endnode uses the nickname of the attached RBridge, so this solution
does not consume extra nicknames.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on October 24, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. TRILL-Hello Content . . . . . . . . . . . . . . . . . . . . . 3
2.1. Edge RBridge's TRILL-Hello . . . . . . . . . . . . . . . 4
2.2. Smart Endnode's TRILL-Hello . . . . . . . . . . . . . . . 4
3. Frame Processing . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Frame Processing for Smart Endnode . . . . . . . . . . . 5
3.2. Frame Processing for Edge RBridge . . . . . . . . . . . . 6
4. Multi-homing . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
The IETF TRILL (Transparent Interconnection of Lots of Links)
protocol implemented by devices called RBridges (Routing Bridges,
[RFC6325]), provides optimal pair-wise data frame forwarding without
configuration, safe forwarding even during periods of temporary
loops, and support for multipathing of both unicast and multicast
traffic. TRILL accomplishes this by using IS-IS([RFC1195])
([RFC6165]) ([I-D.ietf-isis-rfc6326bis])link state routing and
encapsulating traffic using a header that includes a hop count.
Devices that implement TRILL are called "RBridges" (Routing Bridges)
or TRILL Switches.
An RBridge that attaches to endnodes is called an "edge RBridge",
whereas one that exclusively forwards encapsulated frames is known as
a "transit RBridge". An edge RBridge traditionally is the one that
encapsulates a native Ethernet packet with a TRILL header, or that
receives a TRILL-encapsulated packet and removes the TRILL header.
To encapsulate, the edge RBridge must keep an "endnode table"
consisting of (MAC, TRILL egress switch nickname) pairs, for those
MAC addresses currently communicating with endnodes to which the edge
RBridge is attached.
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These table entries might be configured, received from ESADI
([I-D.ietf-trill-esadi]), looked up in a
directory([I-D.ietf-trill-directory-framework]), or learned from
received traffic. If the edge RBridge has many attached endnodes,
this table could become large. Also, if one of the MAC addresses in
the table has moved to a different switch, it might be difficult for
the edge RBridge to notice this quickly, and because the edge RBridge
is tunneling to the incorrect egress RBridge, the traffic will get
lost.
For these reasons, it is desirable for an endnode E (whether it is a
server, hypervisor, or VM) to maintain the endnode table for nodes
that E is corresponding with. This eliminates the need for the
attached RBridge R to know about those nodes (unless some non-smart
endnode attached to R is also corresponding with those nodes), and it
enables E to immediately discard an entry of (D, egress nickname), if
E cannot talk to D. Then E can attempt to acquire a fresh entry for D
by flooding to D, listening for ESADI,or consulting a directory.
The mechanism in this draft is that E issue a TRILL-Hello (even
though E is just an endnode), indicating E's desire to act as a smart
endnode, together with the set of MAC addresses that E owns, and
whether E would like to receive ESADI frame. E learns from R's
Hello, whether R is capable of having a smart endnode neighbor, what
R's nickname is, and which trees R can use when R ingresses
multidestination frames. Although E transmits TRILL-Hellos, E does
not transmit or receive LSPs.
R will accept already-encapsulated packets from E (perhaps verifying
that the source MAC is indeed one of the ones that E owns, that the
ingress RBridge field is R's, and if the packet is an encapsulated
multidestination frame, the tree selected is one of the ones that R
has claimed it will choose). When R receives (from the campus) a
TRILL-encapsulated frame with R's nickname as egress, R checks
whether the destination MAC address in the inner packet is one of the
MAC addresses that E owns, and if so, R forwards the packet onto E's
port, keeping it encapsulated.
2. TRILL-Hello Content
Suppose endnode E is attached to RBridge R. In order for E to act as
a smart endnode, both E and R have to be signaled. The logical
choice of frame to do this is TRILL-Hello.
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2.1. Edge RBridge's TRILL-Hello
For smart endnode operation, R's TRILL-Hello must contain the
following information:
o RBridge's nickname. The nickname sub-TLV (Specified in section
2.3.2 in [I-D.ietf-isis-rfc6326bis])could be reused here, and TLV
242 (ISIS router capability) should be updated to be carried in
TRILL-Hello frame.
o Tree roots that R can use when ingressing multidestination frames.
The Tree Identifiers Sub-TLV(Specified in section 2.3.4 in
[I-D.ietf-isis-rfc6326bis]) could be reused here.
o Smart endnode neighbor list. The TRILL Neighbor TLV(Specified in
section 2.5 in [I-D.ietf-isis-rfc6326bis]) could be reused.
2.2. Smart Endnode's TRILL-Hello
A new TLV(S-MAC TLV)is defined for smart endnode. If there are
several VLANs for that smart endnode, the TLV could be filled several
times in smart endnode's TRILL-Hello.
+-+-+-+-+-+-+-+-+
| Type= S-MAC | (1 byte)
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|E|F|RESV| VLAN/FGL Data Label | (2 bytes or 4 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC (1) (6 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ................. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC (N) (6 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1 S-MAC TLV
o Type: S-MAC, the value is TBD.
o Length: Total number of bytes contained in the value field.
o E: one bit. If it sets to 1, which indicates that the endnode
could receive ESADI frame.
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o F: one bit. If it sets to 1, which indicats that the endnode
supports FGL data label, otherwise, the VLAN/FGL Data Label
(([I-D.ietf-trill-fine-labeling])) field is the VLAN ID.
o RESV: 2 bits or 6 bits, is reserved for the future use. If VLAN/
FGL Data Label indicates the VLAN ID(or F flag sets to 0), the
RESV field is 2 bits length, otherwise it is 6 bits.
o VLAN/FGL Data Label: This carries a 12-bits VLAN identifier or
24-bits FGL Data Label that is valid for all subsequent MAC
addresses in this TLV, or the value zero if no VLAN/FGL data label
is specified.
o MAC(i): This is the 48-bit MAC address reachable from the IS that
is announcing this TLV.
3. Frame Processing
3.1. Frame Processing for Smart Endnode
Smart endnode E does not issue LSPs, nor does it receive LSPs or
calculate topology. E does the following:
o E maintains an endnode table of (MAC, nickname) of end nodes with
which the smart endnode is communicating. If E is attached to
multiple VLANs (or FGL), there would be a separate (MAC, nickname)
table for each VLAN/FGL that E is attached to. Entries in this
table are populated the same way that an edge RBridge populates
the entries in its table:
* learning from (source, ingress) on packets it decapsulates.
* from ESADI([I-D.ietf-trill-esadi]).
* by querying a directory([I-D.ietf-trill-directory-framework]).
* by having some entries configured.
o When E wishes to transmit to unicast destination D, if (D,
nickname) is in E's endnode table, E encapsulates with ingress
nickname=R, egress nickname as indicated in D's table entry. If D
is unknown, D either queries a directory or encapsulates the
packet as a multidestination frame, using one of the trees that R
has specified in R's TRILL-Hello.
o When E wishes to transmit to a multicast destination, E
encapsulates the packet using one of the trees that R has
specified.
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The smart endnode E needs not send Hellos as frequently as normal
RBridges. These hellos MAY be periodically unicast to the Appointed
Forwarder R. In case R crashes and restarts, or the DRB changes, and
E receives the TRILL-Hello without mentioning E, then E SHOULD send a
Hello immediately. If R is AF for any of the VLANs that E claims, R
MUST list E in its Hellos as a smart endnode neighbor.
3.2. Frame Processing for Edge RBridge
The attached RBridge R does the following:
o If receiving an encapsulated unicast data frame from a port with a
smart endnode, with R's nickname as ingress, R forwards the frame
to the specified egress nickname, as with any encapsulated frame.
However, R MAY filter the encapsulation frame based on the inner
source MAC and VLAN (or FGL) as specified for the smart endnode.
If the MAC (or VLAN/FGL) are not among the expected set of the
smart endnode, the frame would be dropped by the edge RBridge.
o If receiving an mulitdestination data TRILL frame from a port with
smart endnode, RBridge R forwards the TRILL encapsulation to the
TRILL campus based on the distribution tree. If there are some
normal endnodes(i.e, non-smart endnode) attached to RBridge R, R
should decapsulates the frame and sends the native frame to these
ports.
o When R receives a mulicast frame from a remote RBridge, and the
exit ports includes hybrid endnodes, it should send two copies of
mulicast frames, one as native and the other as TRILL encapsulated
frame. When smart endnode receives the encapsulated frame, it
learns the remote address.
4. Multi-homing
Now suppose E is attached to the TRILL campus in two places: to
RBridges R1 and R2. There are two ways for this to work:
(1) E can choose either R1 or R2's nickname, when encapsulating a
frame, whether the encapsulated frame is sent via R1 or R2. If
E wants to do active-active load splitting, and uses R1's
nickname when forwarding through R1, and R2's nickname when
forwarding through R2, which will cause the flip-floping of the
endnode table entry in the remote RBridges(or smart endnodes).
This issues could be solved by setting a multi-homing bit in the
RESV field of the TRILL data Frame. When remote RBs or smart
endnodes receive the data frame with the multi-homed bit set,
the MAC entry (E, R1's nickname) and (E, R2's nickname) will be
coexist as two entries for that MAC address.
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(2) R1 and R2 might indicate, in their Hello, a virtual nickname
that attached end nodes may use if they are multihomed to R1 and
R2, separate from R1 and R2's nicknames (which they would also
list in their Hello). This would be useful if there were many
end nodes multihomed to the same set of RBridges. This would be
analogous to a pseudonode nickname; return traffic would go via
the shortest path from the source to the endnode, whether it is
R1 or R2. If E loses connectivity to R2, then E would revert to
using R1's nickname. In order to avoid RPF check issue for
multi-destination frame, the affinity TLV ([I-D.ietf-trill-cmt])
is recommended to be used in this solution.
5. Security Considerations
For general TRILL Security Considerations, see([RFC6325]).
6. Acknowledgements
7. IANA Considerations
IANA is requested to allocate a S-MAC TLV identifier. TLV 242(ISIS
router capability) is required to updated to be carried by TRILL-
Hello frame.
8. Normative References
[I-D.ietf-isis-rfc6326bis]
Eastlake, D., Senevirathne, T., Ghanwani, A., Dutt, D.,
and A. Banerjee, "Transparent Interconnection of Lots of
Links (TRILL) Use of IS-IS", draft-ietf-isis-rfc6326bis-03
(work in progress), January 2014.
[I-D.ietf-trill-cmt]
Senevirathne, T., Pathangi, J., and J. Hudson,
"Coordinated Multicast Trees (CMT) for TRILL", draft-ietf-
trill-cmt-03 (work in progress), April 2014.
[I-D.ietf-trill-directory-framework]
Dunbar, L., Eastlake, D., Perlman, R., and I. Gashinsky,
"TRILL (Transparent Interconnection of Lots of Links):
Edge Directory Assistance Framework", draft-ietf-trill-
directory-framework-07 (work in progress), August 2013.
[I-D.ietf-trill-esadi]
Corporation, Z., hu, f., Perlman, R., Eastlake, D., and O.
Stokes, "TRILL: ESADI (End Station Address Distribution
Information) Protocol", draft-ietf-trill-esadi-07 (work in
progress), April 2014.
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[I-D.ietf-trill-fine-labeling]
Eastlake, D., Zhang, M., Agarwal, P., Perlman, R., and D.
Dutt, "TRILL (Transparent Interconnection of Lots of
Links): Fine-Grained Labeling", draft-ietf-trill-fine-
labeling-07 (work in progress), May 2013.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6165] Banerjee, A. and D. Ward, "Extensions to IS-IS for Layer-2
Systems", RFC 6165, April 2011.
[RFC6325] Perlman, R., Eastlake, D., Dutt, D., Gai, S., and A.
Ghanwani, "Routing Bridges (RBridges): Base Protocol
Specification", RFC 6325, July 2011.
Authors' Addresses
Radia Perlman
Intel Labs
2200 Mission College Blvd.
Santa Clara, CA 95054-1549
USA
Phone: +1-408-765-8080
Email: Radia@alum.mit.edu
Fangwei Hu
ZTE Corporation
No.889 Bibo Rd
Shanghai 201203
China
Phone: +86 21 68896273
Email: hu.fangwei@zte.com.cn
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Donald Eastlake,3rd
Huawei technology
155 Beaver Street
Milford, MA 01757
USA
Phone: +1-508-634-2066
Email: d3e3e3@gmail.com
Kesava Vijaya Krupakaran
Dell
Olympia Technology Park
Guindy Chennai 600 032
India
Phone: +91 44 4220 8496
Email: Kesava_Vijaya_Krupak@Dell.com
Ting Liao
ZTE Corporation
No.50 Ruanjian Ave.
Nanjing, Jiangsu 210012
China
Phone: +86 25 88014227
Email: liao.ting@zte.com.cn
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