Transparent Interconnection of Lots of Links (TRILL) Smart Endnodes
RFC 8384
| Document | Type | RFC - Proposed Standard (July 2018; No errata) | |
|---|---|---|---|
| Authors | Radia Perlman , fangwei hu , Donald Eastlake , Ting Liao | ||
| Last updated | 2018-07-11 | ||
| Replaces | draft-perlman-trill-smart-endnodes | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text html pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Susan Hares | ||
| Shepherd write-up | Show (last changed 2018-02-19) | ||
| IESG | IESG state | RFC 8384 (Proposed Standard) | |
| Action Holders |
(None)
|
||
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Alia Atlas | ||
| Send notices to | (None) | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | RFC-Ed-Ack | ||
Internet Engineering Task Force (IETF) R. Perlman
Request for Comments: 8384 Dell EMC
Category: Standards Track F. Hu
ISSN: 2070-1721 ZTE Corporation
D. Eastlake 3rd
T. Liao
Huawei Technologies
July 2018
Transparent Interconnection of Lots of Links (TRILL) Smart Endnodes
Abstract
This document addresses the problem of the size and freshness of the
endnode learning table in edge Routing Bridges (RBridges), by
allowing endnodes to volunteer for endnode learning and
encapsulation/decapsulation. Such an endnode is known as a "Smart
Endnode". Only the attached edge RBridge can distinguish a "Smart
Endnode" from a "normal endnode". The Smart Endnode uses the
nickname of the attached edge RBridge, so this solution does not
consume extra nicknames. The solution also enables endnodes that are
Fine-Grained Label (FGL) aware.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8384.
Perlman, et al. Standards Track [Page 1]
RFC 8384 TRILL Smart Endnodes July 2018
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 4
4. Smart-Hello Mechanism between Smart Endnode and RBridge . . . 6
4.1. Smart-Hello Encapsulation . . . . . . . . . . . . . . . . 6
4.2. Edge RBridge's Smart-Hello . . . . . . . . . . . . . . . 8
4.3. Smart Endnode's Smart-Hello . . . . . . . . . . . . . . . 8
5. Processing Data Packets . . . . . . . . . . . . . . . . . . . 10
5.1. Data-Packet Processing for Smart Endnodes . . . . . . . . 10
5.2. Data-Packet Processing for Edge RBridge . . . . . . . . . 11
6. Multihoming Scenario . . . . . . . . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . 16
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
Perlman, et al. Standards Track [Page 2]
RFC 8384 TRILL Smart Endnodes July 2018
1. Introduction
The IETF TRILL (Transparent Interconnection of Lots of Links)
protocol [RFC6325] [RFC7780] 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 [IS-IS]
[RFC7176] 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" or
"edge TRILL Switch", whereas one that exclusively forwards
encapsulated frames is known as a "transit RBridge" or "transit TRILL
Switch". An edge RBridge traditionally is the one that encapsulates
a native Ethernet frame with a TRILL header or that receives a TRILL-
encapsulated packet and decapsulates the TRILL header. To
encapsulate efficiently, the edge RBridge must keep an "endnode
table" consisting of (Media Access Control (MAC), Data Label, TRILL
egress switch nickname) sets, for those remote MAC addresses in Data
Labels currently communicating with endnodes to which the edge
RBridge is attached.
These table entries might be configured, received from End Station
Address Distribution Information (ESADI) [RFC7357], looked up in a
directory [RFC7067], or learned from decapsulating received traffic.
If the edge RBridge has attached endnodes communicating with many
remote endnodes, this table could become very large. Also, if a MAC
address / Data Label pair in the table have moved to a different
remote TRILL switch, it might be difficult for the edge RBridge to
notice this quickly; and because the edge RBridge is encapsulating to
the incorrect egress RBridge, the traffic will get lost.
2. Conventions Used in This Document
2.1. Terminology
BUM: Broadcast, Unknown unicast, and Multicast.
Edge RBridge: An RBridge providing endnode service on at least one of
its ports. It is also called an edge TRILL Switch.
Data Label: VLAN or FGL.
DRB: Designated RBridge [RFC6325].
ESADI: End Station Address Distribution Information [RFC7357].
Perlman, et al. Standards Track [Page 3]
RFC 8384 TRILL Smart Endnodes July 2018
FGL: Fine-Grained Label [RFC7172].
IS-IS: Intermediate System to Intermediate System [IS-IS].
LSP: Link State PDU.
PDU: Protocol Data Unit.
RBridge: Routing Bridge, an alternative name for a TRILL switch.
Smart Endnode: An endnode that has the capability specified in this
document including learning and maintaining (MAC, Data Label,
nickname) entries and encapsulating/decapsulating TRILL frame.
Transit RBridge: An RBridge that exclusively forwards encapsulated
frames. It is also called a transit TRILL Switch.
TRILL: Transparent Interconnection of Lots of Links
[RFC6325][RFC7780].
TRILL ES-IS: TRILL End System to Intermediate System, is a variation
of TRILL IS-IS designed to operate on a TRILL link among and between
one or more TRILL switches and end stations on that link [RFC8171].
TRILL Switch: a device that implements the TRILL protocol; an
alternative term for an RBridge.
2.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Solution Overview
The Smart Endnode solution defined in this document addresses the
problem of the size and freshness of the endnode learning table in
edge RBridges. An endnode E, attached to an edge RBridge R, tells R
that E would like to be a "Smart Endnode", which means that E will
encapsulate and decapsulate the TRILL frame, using R's nickname.
Because E uses R's nickname, this solution does not consume extra
nicknames.
Perlman, et al. Standards Track [Page 4]
RFC 8384 TRILL Smart Endnodes July 2018
Take Figure 1 as the example Smart Endnode scenario: RB1, RB2, and
RB3 are the RBridges in the TRILL domain and SE1 and SE2 are the
Smart Endnodes that can encapsulate and decapsulate the TRILL
packets. RB1 is the edge RB to which SE1 and SE2 have attached. RB1
assigns one of its nicknames to be used by SE1 and SE2.
Each Smart Endnode, SE1 and SE2, uses RB1's nickname when
encapsulating and maintains an endnode table of (MAC, Data Label,
TRILL egress switch nickname) for remote endnodes that it (SE1 or
SE2) is corresponding with. RB1 does not decapsulate packets
destined for SE1 or SE2 and does not learn (MAC, Data Label, TRILL
egress switch nickname) for endnodes corresponding with SE1 or SE2,
but RB1 does decapsulate and does learn (MAC, Data Label, TRILL
egress switch nickname) for any endnodes attached to RB1 that have
not declared themselves to be Smart Endnodes.
Just as an RBridge learns and times out (MAC, Data Label, TRILL
egress switch nickname), Smart Endnodes SE1 and SE2 also learn and
time out endnode entries. However, SE1 and SE2 might also determine,
through ICMP messages or other techniques that an endnode entry is
not successfully reaching the destination endnode, and it can be
deleted, even if the entry has not timed out.
If SE1 wishes to correspond with destination MAC D, and no endnode
entry exists, SE1 will encapsulate the packet as an unknown
destination, or consult a directory [RFC7067] (just as an RBridge
would do if there was no endnode entry).
+----------+
|SE1(Smart |
|Endnode1) | \ +------------------------------+
+----------+ \ / \
\ /+------+ +------+ +-----+ \ +-----------+
/-+-| RB 1 |---| RB2 |----| RB3 |-----+--|Endnode3 |
/ | +------+ +------+ +-----+ | |MAC=D |
+----------+ / \ / +-----------+
|SE2(Smart | \ /
| Endnode2)| +------------------------------+
+----------+
Figure 1: Smart Endnode Scenario
Perlman, et al. Standards Track [Page 5]
RFC 8384 TRILL Smart Endnodes July 2018
The mechanism in this document is that the Smart Endnode SE1 issues a
Smart-Hello, indicating SE1's desire to act as a Smart Endnode,
together with the set of MAC addresses and Data Labels that SE1 owns.
The Smart-Hello is used to announce the Smart Endnode capability and
parameters (such as MAC address, Data Label, etc.). The Smart-Hello
is a type of TRILL ES-IS PDU, which is specified in Section 5 of
[RFC8171]. The detailed content for a Smart Endnode's Smart-Hello is
defined in Section 4.
If RB1 supports having a Smart Endnode neighbor, it also sends Smart-
Hellos. The Smart Endnode learns from RB1's Smart-Hellos what RB1's
nickname is and which trees RB1 can use when RB1 ingresses multi-
destination frames. Although Smart Endnode SE1 transmits Smart-
Hellos, it does not transmit or receive Link State PDUs (LSPs) or
Extended Level 1 Flooding Scope (E-L1FS) FS LSPs [RFC7780].
Since a Smart Endnode can encapsulate TRILL Data packets, it can
cause the Inner.Label to be a Fine-Grained Label [RFC7172]; thus,
this method supports FGL-aware endnodes. When and how a Smart
Endnode decides to use the FGL instead of VLANs to encapsulate the
TRILL Data packet is out of scope in this document.
4. Smart-Hello Mechanism between Smart Endnode and RBridge
The subsections below describe Smart-Hello messages.
4.1. Smart-Hello Encapsulation
Although a Smart Endnode is not an RBridge, does not send LSPs or
maintain a copy of the link state database, and does not perform
routing calculations, it is required to have a "Hello" mechanism (1)
to announce to edge RBridges that it is a Smart Endnode and (2) to
tell them what MAC addresses it is handling in what Data Labels.
Similarly, an edge RBridge that supports Smart Endnodes needs a
message (1) to announce that support, (2) to inform Smart Endnodes
what nickname to use for ingress and what nickname(s) can be used as
egress nickname in a multi-destination TRILL Data packet, and (3) the
list of Smart Endnodes it knows about on that link.
The messages sent by Smart Endnodes and by edge RBridges that support
Smart Endnodes are called "Smart-Hellos". The Smart-Hello is a type
of TRILL ES-IS PDU, which is specified in [RFC8171].
Perlman, et al. Standards Track [Page 6]
RFC 8384 TRILL Smart Endnodes July 2018
The Smart-Hello Payload, both for Smart-Hellos sent by Smart Endnodes
and for Smart-Hellos sent by edge RBridges, consists of TRILL IS-IS
TLVs as described in the following two subsections. The non-extended
format is used so TLVs, sub-TLVs, and APPsub-TLVs have an 8-bit size
and type field. Both types of Smart-Hellos MUST include a Smart-
Parameters APPsub-TLV as follows inside a TRILL GENINFO TLV:
+-+-+-+-+-+-+-+-+-
|Smart-Parameters| (1 byte)
+-+-+-+-+-+-+-+-+-
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Holding Time | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Smart-Parameters APPsub-TLV
o Type: APPsub-TLV type Smart-Parameters, value is 22.
o Length: 4.
o Holding Time: A time in seconds as an unsigned integer. It has
the same meaning as the Holding Time field in IS-IS Hellos
[IS-IS]. A Smart Endnode and an edge RBridge supporting Smart
Endnodes MUST send a Smart-Hello at least three times during their
Holding Time. If no Smart-Hellos are received from a Smart
Endnode or edge RBridge within the most recent Holding Time it
sent, it is assumed that it is no longer available.
o Flags: At this time, all of the Flags are reserved and MUST be
sent as zero and ignored on receipt.
o If more than one Smart-Parameters APPsub-TLV appears in a Smart-
Hello, the first one is used and any following ones are ignored.
If no Smart-Parameters APPsub-TLVs appear in a Smart-Hello, that
Smart-Hello is ignored.
Perlman, et al. Standards Track [Page 7]
RFC 8384 TRILL Smart Endnodes July 2018
4.2. Edge RBridge's Smart-Hello
The edge RBridge's Smart-Hello contains the following information in
addition to the Smart-Parameters APPsub-TLV:
o RBridge's nickname. The nickname sub-TLV, specified in
Section 2.3.2 in [RFC7176], is reused here carried inside a TLV
242 (IS-IS router capability) in a Smart-Hello frame. If more
than one nickname appears in the Smart-Hello, the first one is
used and the following ones are ignored.
o Trees that RB1 can use when ingressing multi-destination frames.
The Tree Identifiers sub-TLV, specified in Section 2.3.4 in
[RFC7176], is reused here.
o Smart Endnode neighbor list. The TRILL Neighbor TLV, specified in
section 2.5 in [RFC7176], is reused for this purpose.
o An Authentication TLV MAY also be included.
4.3. Smart Endnode's Smart-Hello
A new APPsub-TLV (Smart-MAC TLV) for use by Smart Endnodes is as
defined below. In addition, there will be a Smart-Parameters APPsub-
TLV and there MAY be an Authentication TLV in a Smart Endnode Smart-
Hello.
If there are several VLANs/FGL Data Labels for that Smart Endnode,
the Smart-MAC APPsub-TLV is included several times in the Smart
Endnode's Smart-Hello. This APPsub-TLV appears inside a TRILL
GENINFO TLV.
Perlman, et al. Standards Track [Page 8]
RFC 8384 TRILL Smart Endnodes July 2018
+-+-+-+-+-+-+-+-+
|Type=Smart-MAC | (1 byte)
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|F|M| RSV | VLAN/FGL Data Label | (4 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC (1) (6 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ................. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC (N) (6 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Smart-MAC APPsub-TLV
o Type: TRILL APPsub-TLV Type Smart-MAC, value is 23.
o Length: Total number of bytes contained in the value field of the
TLV, that is, the sum of the length of the F/M/RSV/FGL Data Label
fields and six times the number of MAC addresses present. So, if
there are n MAC addresses, this is 4+6*n.
o F: 1 bit. If it is set to 1, it indicates that the endnode
supports FGL Data Labels [RFC7172], and that this Smart-MAC
APPsub-TLV has an FGL in the following VLAN/FGL field. Otherwise,
the VLAN/FGL Data Label field is a VLAN ID. (See below for the
format of the VLAN/FGL Data Label field).
o M: 1 bit. If it is set to 1, it indicates multihoming (see
Section 6). If it is set to 0, it indicates that the Smart
Endnodes are not using multihoming.
o RSV: 6 bits; reserved for the future use.
o VLAN/FGL Data Label: 24 bits. If F is 1, this field is a 24-bit
FGL Data Label for all subsequent MAC addresses in this APPsub-
TLV. Otherwise, if F is 0, the lower 12 bits are the VLAN of all
subsequent MAC addresses in this APPsub-TLV, and the upper 12 bits
are not used (sent as zero and ignored on receipt). If there is
no VLAN/FGL Data Label specified, the VLAN/FGL Data Label is zero.
o MAC(i): This is a 48-bit MAC address reachable in the Data Label
sent by the Smart Endnode that is announcing this APPsub-TLV.
Perlman, et al. Standards Track [Page 9]
RFC 8384 TRILL Smart Endnodes July 2018
5. Processing Data Packets
The subsections below specify the processing of Smart Endnode data
packets. All TRILL Data packets sent to or from Smart Endnodes are
sent in the Designated VLAN [RFC6325] of the local link but do not
necessarily have to be VLAN tagged.
5.1. Data-Packet Processing for Smart Endnodes
A Smart Endnode does not issue or receive LSPs or E-L1FS FS LSPs or
calculate topology. It does the following:
o A Smart Endnode maintains an endnode table of (the MAC address of
remote endnode, Data Label, the nickname of the edge RBridge's
attached) entries of end nodes with which the Smart Endnode is
communicating. Entries in this table are populated the same way
that an edge RBridge populates the entries in its table:
* learning from (source MAC address ingress nickname) on packets
it decapsulates.
* by querying a directory [RFC7067].
* by having some entries configured.
o When Smart Endnode SE1 wishes to send unicast frame to remote node
D, if the (MAC address of remote endnode D, Data Label, nickname)
entry is in SE1's endnode table, SE1 encapsulates the ingress
nickname as the nickname of the RBridge (RB1), egress nickname as
indicated in D's table entry. If D is unknown, SE1 either queries
a directory or encapsulates the packet as a multi-destination
frame, using one of the trees that RB1 has specified in RB1's
Smart-Hello. The mechanism for querying a directory is given in
[RFC8171].
o When SE1 wishes to send a Broadcast, Unknown Unicast, and
Multicast (BUM) packet to the TRILL campus, SE1 encapsulates the
packet using one of the trees that RB1 has specified.
If the Smart Endnode SE1 sends a multi-destination TRILL Data packet,
the destination MAC of the outer Ethernet is the All-RBridges
multicast address.
The Smart Endnode SE1 need not send Smart-Hellos as frequently as
normal RBridges. These Smart-Hellos could be periodically unicast to
the Appointed Forwarder RB1. In case RB1 crashes and restarts, or
the DRB changes and SE1 receives the Smart-Hello without mentioning
Perlman, et al. Standards Track [Page 10]
RFC 8384 TRILL Smart Endnodes July 2018
SE1, SE1 SHOULD send a Smart-Hello immediately. If RB1 is Appointed
Forwarder for any of the VLANs that SE1 claims, RB1 MUST list SE1 in
its Smart-Hellos as a Smart Endnode neighbor.
5.2. Data-Packet Processing for Edge RBridge
The attached edge RBridge processes and forwards TRILL Data packets
based on the endnode property rather than for encapsulation and
forwarding the native frames the same way as the traditional
RBridges. There are several situations for the edge RBridges as
follows:
o If receiving an encapsulated unicast TRILL Data packet from a port
with a Smart Endnode, with RB1's nickname as ingress, the edge
RBridge RB1 forwards the frame to the specified egress nickname,
as with any encapsulated frame. However, RB1 SHOULD filter the
encapsulation frame based on the inner source MAC and Data Label
as specified for the Smart Endnode. If the MAC (or Data Label) is
not among the expected entries of the Smart Endnode, the frame
would be dropped by the edge RBridge. If the edge RBridge does
not perform this check, it makes it easier for a rogue end station
to inject bogus TRILL Data packets into the TRILL campus.
o If receiving a unicast TRILL Data packet with RB1's nickname as
egress from the TRILL campus, and the destination MAC address in
the enclosed packet is a MAC address that has been listed by a
Smart Endnode, RB1 leaves the packet encapsulated to that Smart
Endnode. The outer Ethernet destination MAC is the destination
Smart Endnode's MAC address, the inner destination MAC address is
either the Smart Endnode's MAC address or some other MAC address
that the Smart Endnode advertised in its Smart Hello, and the
outer Ethernet source MAC address is the RB1's port MAC address.
The edge RBridge still decreases the Hop count value by 1, for
there is one hop between the RB1 and Smart Endnode.
o If receiving a multi-destination TRILL Data packet from a port
with a Smart Endnode, RBridge RB1 forwards the TRILL encapsulation
to the TRILL campus based on the distribution tree indicated by
the egress nickname. If the egress nickname does not correspond
to a distribution tree, the packet is discarded. If there are any
normal endnodes (i.e., endnodes that are not Smart Endnodes)
attached to the edge RBridge RB1, RB1 decapsulates the frame and
sends the native frame to these ports possibly pruned based on
multicast listeners, in addition to forwarding the multi-
destination TRILL frame to the rest of the campus.
Perlman, et al. Standards Track [Page 11]
RFC 8384 TRILL Smart Endnodes July 2018
o If RB1 receives a native multi-destination data frame, which is
sent by an endnode that is not a Smart Endnode, from a port,
including hybrid endnodes (Smart Endnodes and endnodes that are
not Smart Endnodes), RB1 will encapsulate it as multi-destination
TRILL Data packet, and send the encapsulated multi-destination
TRILL Data packet out that same port to the Smart Endnodes
attached to the port, and also send the encapsulated multi-
destination TRILL Data packet to the TRILL campus through other
ports.
o If RB1 receives a multi-destination TRILL Data packet from a
remote RBridge, and the exit port includes hybrid endnodes (Smart
Endnodes and endnodes that are not Smart Endnodes), it sends two
copies of multicast frames out the port, one as native and the
other as a TRILL-encapsulated frame. When a Smart Endnode
receives a multi-destination TRILL Data packet, it learns the
remote (MAC address, Data Label, nickname) entry. A Smart Endnode
ignores native data frames. A normal (non-Smart) endnode receives
the native frame and learns the remote MAC address and ignores the
TRILL Data packet. This transit solution may bring some
complexity for the edge RBridge and waste network bandwidth
resource, so avoiding the hybrid endnodes scenario by attaching
the endnodes that are Smart and non-Smart to different ports is
RECOMMENDED.
6. Multihoming Scenario
Multihoming is a common scenario for the Smart Endnode. The Smart
Endnode is on a link attached to the TRILL domain in two places: edge
RBridges RB1 and RB2. Take Figure 4 as an example. The Smart
Endnode SE1 is attached to the TRILL domain by RB1 and RB2
separately. Both RB1 and RB2 could announce their nicknames to SE1.
. .....................
. +------+ .
. | RB1 | .
. /+------+ .
+----------+ ./ +-----+ . +----------+
|SE1(Smart |/. | RB3 |......| Smart |
| Endnode1)| .\ +-----+ . | Endnode2 |
+----------+ . \ . +----------+
. +-----+ .
. | RB2 | TRILL .
. +-----+ Domain .
.......................
Figure 4: Multihoming Scenario
Perlman, et al. Standards Track [Page 12]
RFC 8384 TRILL Smart Endnodes July 2018
Smart Endnode SE1 can choose either the nickname of RB1 or RB2 when
encapsulating and forwarding a TRILL Data packet. If the active-
active load balance is considered for the multihoming scenario, the
Smart Endnode SE1 could use both the nickname of RB1 and RB2 to
encapsulate and forward TRILL Data packet. SE1 uses RB1's nickname
when forwarding through RB1 and RB2's nickname when forwarding
through RB2. This will cause MAC flip-flopping (see [RFC7379]) of
the endnode table entry in the remote RBridges (or Smart Endnodes).
The solution for the MAC flip-flopping issue is to set a multihoming
bit in the RSV field of the TRILL Data packet. When remote RBridge
RB3 or Smart Endnodes receive a data packet with the multihomed bit
set, the endnode entries (SE1's MAC address, label, RB1's nickname)
and (SE1's MAC address, label, RB2's nickname) will coexist as
endnode entries in the remote RBridge. (An alternative solution
would be to use the ESADI protocol to distribute multiple attachments
of a MAC address of a multihoming group. The ESADI is deployed among
the edge RBridges (see Section 5.3 of [RFC7357]).
7. Security Considerations
Smart-Hellos can be secured by using Authentication TLVs based on
[RFC5310]. If they are not secured, then it is easier for a rogue
end station that does not posses the required keying material to be
falsely recognized as a valid Smart Endnode.
For general TRILL Security Considerations, see [RFC6325]. As stated
there, since end stations are connected to edge RBridge ports by
Ethernet, those ports MAY require end stations to authenticate
themselves using [IEEE802.1X] and authenticate and encrypt traffic
to/from the RBridge port with [IEEE802.1AE].
If they misbehave, Smart Endnodes can forge arbitrary ingress and
egress nicknames in the TRILL headers of the TRILL Data packets they
construct. Decapsulating at egress RBridges or remote Smart Endnodes
that believe such a forged ingress nickname would send future traffic
destined for the inner-source MAC address of the TRILL data frame to
the wrong edge RBridge if data-plane learning is in use. Because of
this, an RBridge port should not be configured to support Smart
Endnodes unless the end stations on that link are trusted or can be
adequately authenticated.
As with any end station, Smart Endnodes can forge the outer MAC
addresses of packets they send (see Section 6 of [RFC6325].) Because
they encapsulate TRILL Data packets, they can also forge inner MAC
addresses. The encapsulation performed by Smart Endnodes also means
they can send data in any Data Label, which means they must be
trusted in order to enforce a security policy based on Data Labels.
Perlman, et al. Standards Track [Page 13]
RFC 8384 TRILL Smart Endnodes July 2018
The TRILL-Hello is a type of TRILL ES-IS and is defined in [RFC8171].
Receiving and processing TRILL-Hello for RBridges and Smart Endnodes
would not bring more security and vulnerability issues than the TRILL
ES-IS security defined in [RFC8171].
For added security against the compromise of data due to its
misdelivery for any reason, including the above, end-to-end
encryption and authentication should be considered; that is,
encryption and authentication from source end station to destination
end station.
The mechanism described in this document requires Smart Endnodes to
be aware of the MAC address(es) of the TRILL edge RBridge(s) to which
they are attached and the egress RBridge nickname from which the
destination of the packets is reachable. With that information,
Smart Endnodes can learn a substantial amount about the topology of
the TRILL domain. Therefore, there could be a potential security
risk when the Smart Endnodes are not trusted or are compromised.
8. IANA Considerations
IANA has allocated APPsub-TLV type numbers for the Smart-MAC and
Smart-Parameters APPsub-TLVs. The "TRILL APPsub-TLV Types under
IS-IS TLV 251 Application Identifier 1" registry has been updated as
follows.
+-----------+-------------------+------------+
| Protocol | Description | Reference |
+-----------+-------------------+------------+
| 22 | Smart-Parameters | RFC 8384 |
| 23 | Smart-MAC | RFC 8384 |
+-----------+-------------------+------------+
Table 1
Perlman, et al. Standards Track [Page 14]
RFC 8384 TRILL Smart Endnodes July 2018
9. References
9.1. Normative References
[IS-IS] International Organization for Standardization,
"Information technology -- Telecommunications and
information exchange between systems -- Intermediate
System to Intermediate System intra-domain routeing
information exchange protocol for use in conjunction with
the protocol for providing the connectionless-mode network
service (ISO 8473)", ISO/IEC 10589:2002, Second Edition,
2002.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, DOI 10.17487/RFC5310, February
2009, <https://www.rfc-editor.org/info/rfc5310>.
[RFC6325] Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
Ghanwani, "Routing Bridges (RBridges): Base Protocol
Specification", RFC 6325, DOI 10.17487/RFC6325, July 2011,
<https://www.rfc-editor.org/info/rfc6325>.
[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,
<https://www.rfc-editor.org/info/rfc7172>.
[RFC7176] Eastlake 3rd, D., Senevirathne, T., Ghanwani, A., Dutt,
D., and A. Banerjee, "Transparent Interconnection of Lots
of Links (TRILL) Use of IS-IS", RFC 7176,
DOI 10.17487/RFC7176, May 2014,
<https://www.rfc-editor.org/info/rfc7176>.
[RFC7357] Zhai, H., Hu, F., Perlman, R., Eastlake 3rd, D., and O.
Stokes, "Transparent Interconnection of Lots of Links
(TRILL): End Station Address Distribution Information
(ESADI) Protocol", RFC 7357, DOI 10.17487/RFC7357,
September 2014, <https://www.rfc-editor.org/info/rfc7357>.
Perlman, et al. Standards Track [Page 15]
RFC 8384 TRILL Smart Endnodes July 2018
[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,
<https://www.rfc-editor.org/info/rfc7780>.
[RFC8171] Eastlake 3rd, D., Dunbar, L., Perlman, R., and Y. Li,
"Transparent Interconnection of Lots of Links (TRILL):
Edge Directory Assistance Mechanisms", RFC 8171,
DOI 10.17487/RFC8171, June 2017,
<https://www.rfc-editor.org/info/rfc8171>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References
[IEEE802.1AE]
IEEE, "IEEE Standard for Local and metropolitan area
networks -- Media Access Control (MAC) Security",
IEEE 802.1AE.
[IEEE802.1X]
IEEE, "IEEE Standard for Local and metropolitan area
networks -- Port-Based Network Access Control",
IEEE 802.1X.
[RFC7067] Dunbar, L., Eastlake 3rd, D., Perlman, R., and I.
Gashinsky, "Directory Assistance Problem and High-Level
Design Proposal", RFC 7067, DOI 10.17487/RFC7067, November
2013, <https://www.rfc-editor.org/info/rfc7067>.
[RFC7379] Li, Y., Hao, W., Perlman, R., Hudson, J., and H. Zhai,
"Problem Statement and Goals for Active-Active Connection
at the Transparent Interconnection of Lots of Links
(TRILL) Edge", RFC 7379, DOI 10.17487/RFC7379, October
2014, <https://www.rfc-editor.org/info/rfc7379>.
Acknowledgements
The contributions of the following persons are gratefully
acknowledged: Mingui Zhang, Weiguo Hao, Linda Dunbar, Kesava Vijaya
Krupakaran, and Andrew Qu.
Perlman, et al. Standards Track [Page 16]
RFC 8384 TRILL Smart Endnodes July 2018
Authors' Addresses
Radia Perlman
Dell EMC
176 South Street
Hopkinton, MA 01748
United States of America
Phone: +1-206-291-367
Email: radiaperlman@gmail.com
Fangwei Hu
ZTE Corporation
No.889 Bibo Rd
Shanghai 201203
China
Phone: +86 21 68896273
Email: hu.fangwei@zte.com.cn
Donald Eastlake
Huawei Technologies
1424 Pro Shop Court
Davenport, FL 33896
United States of America
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com
Ting Liao
Huawei Technologies
Nanjing, Jiangsu 210012
China
Email: liaoting1@huawei.com
Perlman, et al. Standards Track [Page 17]