draft-ietf-mpls-tp-ethernet-addressing-07.txt   draft-ietf-mpls-tp-ethernet-addressing-08.txt 
MPLS D. Frost MPLS D. Frost
Internet-Draft S. Bryant Internet-Draft S. Bryant
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: October 10, 2013 M. Bocci Expires: January 25, 2014 M. Bocci
Alcatel-Lucent Alcatel-Lucent
April 08, 2013 July 24, 2013
MPLS-TP Next-Hop Ethernet Addressing MPLS-TP Next-Hop Ethernet Addressing
draft-ietf-mpls-tp-ethernet-addressing-07 draft-ietf-mpls-tp-ethernet-addressing-08
Abstract Abstract
The Multiprotocol Label Switching (MPLS) Transport Profile (MPLS-TP) The Multiprotocol Label Switching (MPLS) Transport Profile (MPLS-TP)
is the set of MPLS protocol functions applicable to the construction is the set of MPLS protocol functions applicable to the construction
and operation of packet-switched transport networks. This document and operation of packet-switched transport networks. This document
presents considerations for link-layer addressing of Ethernet frames presents considerations for link-layer addressing of Ethernet frames
carrying MPLS-TP packets. carrying MPLS-TP packets.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 10, 2013. This Internet-Draft will expire on January 25, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Point-to-Point Link Addressing 2. Point-to-Point Link Addressing
When two MPLS-TP nodes are connected by a point-to-point Ethernet When two MPLS-TP nodes are connected by a point-to-point Ethernet
link, the question arises as to what destination Ethernet Media link, the question arises as to what destination Ethernet Media
Access Control (MAC) address should be specified in Ethernet frames Access Control (MAC) address should be specified in Ethernet frames
transmitted to the peer node over the link. The problem of transmitted to the peer node over the link. The problem of
determining this address does not arise in IP/MPLS networks because determining this address does not arise in IP/MPLS networks because
of the presence of the Ethernet Address Resolution Protocol (ARP) of the presence of the Ethernet Address Resolution Protocol (commonly
[RFC0826] or IP version 6 Neighbor Discovery protocol [RFC4861], referred to as Address Resolution Protocol and shortened to
which allow the unicast MAC address of the peer device to be learned ARP)[RFC0826] or IP version 6 Neighbor Discovery (ND) protocol
dynamically. [RFC4861], which allow the unicast MAC address of the peer device to
be learned dynamically.
If existing mechanisms are available in an MPLS-TP network to If existing mechanisms are available in an MPLS-TP network to
determine the destination unicast MAC addresses of peer nodes -- for determine the destination unicast MAC addresses of peer nodes, for
example, if the network also happens to be an IP/MPLS network, or if example, if the network also happens to be an IP/MPLS network, or if
Link Layer Discovery Protocol (LLDP) [LLDP] is in use, or if it Link Layer Discovery Protocol (LLDP) [LLDP] is in use, these methods
implements the procedures in Section 4 of this document -- such SHOULD be used. If ARP, ND and LLDP are not available, and both
mechanisms SHOULD be used. The remainder of this section discusses peers implement the procedures in Section 4 of this document, then
the available options when this is not the case. the GAP mechanism described in this memo SHOULD be used. The
remainder of this section discusses alternative options that might be
employed when none of the preceding MAC address learning mechanism
are available.
Each node MAY be statically configured with the MAC address of its One common approach is for each node to be statically configured with
peer. Note however that static MAC address configuration can present the MAC address of its peer. However static MAC address
an administrative burden and lead to operational problems. For configuration can present an administrative burden and lead to
example, replacement of an Ethernet interface to resolve a hardware operational problems. For example, replacement of an Ethernet
fault when this approach is used requires that the peer node be interface to resolve a hardware fault when this approach is used
manually reconfigured with the new MAC address. This is especially requires that the peer node be manually reconfigured with the new MAC
problematic if the peer is operated by another provider. address. This is especially problematic if the peer is operated by
another provider.
Another approach which may be considered is to use the Ethernet Another approach which may be considered is to use the Ethernet
broadcast address FF-FF-FF-FF-FF-FF as the destination MAC address in broadcast address FF-FF-FF-FF-FF-FF as the destination MAC address in
frames carrying MPLS-TP packets over a link that is known to be frames carrying MPLS-TP packets over a link that is known to be
point-to-point. This may, however, lead to excessive frame point-to-point. This may, however, lead to excessive frame
distribution and processing at the Ethernet layer. Broadcast traffic distribution and processing at the Ethernet layer. Broadcast traffic
may also be treated specially by some devices and this may not be may also be treated specially by some devices and this may not be
desirable for MPLS-TP data frames. desirable for MPLS-TP data frames.
In view of the above considerations, the approach which SHOULD be In view of the above considerations, this document recommends that,
used, is therefore to configure both nodes to use the method if a non-negotiated address is to be used, both nodes are configured
described in this document which uses, as a destination MAC address, to use as a destination MAC address an Ethernet multicast address
an Ethernet multicast address reserved for MPLS-TP for use over reserved for MPLS-TP for use over point-to-point links. The address
point-to-point links. The address allocated for this purpose by the allocated for this purpose by the Internet Assigned Numbers Authority
Internet Assigned Numbers Authority (IANA) is 01-00-5E-90-00-00. An (IANA) is 01-00-5E-90-00-00. An MPLS-TP implementation MUST default
MPLS-TP implementation MUST process Ethernet frames received over a to passing MPLS packets received from a point-to-point Ethernet link
point-to-point link with this destination MAC address by default. with this destination MAC address to the MPLS sub-system.
The use of broadcast or multicast addressing for the purpose The use of broadcast or multicast addressing for the purpose
described in this section, i.e. as a placeholder for the unknown described in this section, i.e. as a placeholder for the unknown
unicast MAC address of the destination, is applicable only when the unicast MAC address of the destination, is applicable only when the
attached Ethernet link is known to be point-to-point. If a link is attached Ethernet link is known to be point-to-point. If a link is
not known to be point-to-point, these forms of broadcast or multicast not known to be point-to-point, these forms of broadcast or multicast
addressing MUST NOT be used. Thus the implementation MUST provide a addressing MUST NOT be used. Thus the implementation MUST provide a
means for the operator to declare that a link is point-to-point if it means for the operator to declare that a link is point-to-point if it
supports these addressing modes. Moreover, the operator is cautioned supports these addressing modes. Moreover, the operator is cautioned
that it is not always clear whether a given link is, or will remain, that it is not always clear whether a given link is, or will remain,
strictly point-to-point, particularly when the link is supplied by an strictly point-to-point, particularly when the link is supplied by an
external provider; point-to-point declarations must therefore be used external provider; point-to-point declarations therefore need to be
with care. Because of these caveats it is RECOMMENDED that used with care. Because of these caveats it is RECOMMENDED that
implementations support the procedures in Section 4 so that unicast implementations support the procedures in Section 4 so that unicast
addressing can be used. addressing can be used.
3. Multipoint Link Addressing 3. Multipoint Link Addressing
When a multipoint Ethernet link serves as a section [RFC5960] for a When a multipoint Ethernet link serves as a section [RFC5960] for a
point-to-multipoint MPLS-TP LSP, and multicast destination MAC point-to-multipoint MPLS-TP LSP, and multicast destination MAC
addressing at the Ethernet layer is used for the LSP, the addressing addressing at the Ethernet layer is used for the LSP, the addressing
and encapsulation procedures specified in [RFC5332] SHALL be used. and encapsulation procedures specified in [RFC5332] SHALL be used.
When a multipoint Ethernet link -- that is, a link which is not known When a multipoint Ethernet link, that is a link which is not known to
to be point-to-point -- serves as a section for a point-to-point be point-to-point, serves as a section for a point-to-point MPLS-TP
MPLS-TP LSP, unicast destination MAC addresses MUST be used for LSP, unicast destination MAC addresses MUST be used for Ethernet
Ethernet frames carrying packets of the LSP. According to the frames carrying packets of the LSP. According to the discussion in
discussion in the previous section, this implies the use of either the previous section, this implies the use of either static MAC
static MAC address configuration or a protocol that enables peer MAC address configuration or a protocol that enables peer MAC address
address discovery. discovery.
4. MAC Address Discovery via the G-ACh Advertisement Protocol 4. MAC Address Discovery via the G-ACh Advertisement Protocol
The G-ACh Advertisement Protocol (GAP) [I-D.ietf-mpls-gach-adv] The G-ACh Advertisement Protocol (GAP) [I-D.ietf-mpls-gach-adv]
provides a simple means of informing listeners on a link of the provides a simple means of informing listeners on a link of the
sender's capabilities and configuration. When used for this purpose sender's capabilities and configuration. When used for this purpose
on an Ethernet link, GAP messages are multicast to the address on an Ethernet link, GAP messages are multicast to the address
01-00-5e-80-00-0d (see [I-D.ietf-mpls-gach-adv] Section 7). If these 01-00-5e-80-00-0d (see [I-D.ietf-mpls-gach-adv] Section 7). If these
messages contain the unicast MAC address of the sender, then messages contain the unicast MAC address of the sender, then
listeners can learn this address and use it in the future when listeners can learn this address and use it in the future when
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TLV format is as defined in [I-D.ietf-mpls-gach-adv]: TLV format is as defined in [I-D.ietf-mpls-gach-adv]:
Source MAC Address (type = 0, length = 8): The Value of this Source MAC Address (type = 0, length = 8): The Value of this
object is an EUI-64 [EUI-64] unicast MAC address assigned to one object is an EUI-64 [EUI-64] unicast MAC address assigned to one
of the interfaces of the sender that is connected to this data of the interfaces of the sender that is connected to this data
link. The IEEE-defined mapping from 48-bit MAC addresses to link. The IEEE-defined mapping from 48-bit MAC addresses to
EUI-64 form is used. EUI-64 form is used.
Maximum Frame Size (MFS) (type = 1, length = 4): The Value of this Maximum Frame Size (MFS) (type = 1, length = 4): The Value of this
object is a 32-bit unsigned integer encoded in network byte order object is a 32-bit unsigned integer encoded in network byte order
that specifies the maximum frame size octets of an an Ethernet that specifies the maximum frame size in octets of an Ethernet
Frame that can be sent over the sending interface. Where MAC Frame that can be sent over the sending interface. Where MAC
address learning occurs by some other means, this TLV group MAY be address learning occurs by some other means, this TLV group MAY be
used to advertise only the MFS. If multiple advertisements are used to advertise only the MFS. If multiple advertisements are
made for the same parameter, use of these advertisements is made for the same parameter, use of these advertisements is
undefined. undefined.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=0 | Reserved | Length=8 | | Type=0 | Reserved | Length=8 |
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[I-D.ietf-mpls-gach-adv]). [I-D.ietf-mpls-gach-adv]).
If a minimum MFS is configured for a link and the MFS advertised by If a minimum MFS is configured for a link and the MFS advertised by
the peer is lower than that minimum, the operator MUST be notified of the peer is lower than that minimum, the operator MUST be notified of
the MFS mismatch. Under these circumstances the operator may choose the MFS mismatch. Under these circumstances the operator may choose
to configure the LSR to shut the link, thereby triggering a fault, to configure the LSR to shut the link, thereby triggering a fault,
and hence causing the end-to-end path to be repaired. Alternatively and hence causing the end-to-end path to be repaired. Alternatively
the operator may choose to configure the LSR to leave the link up so the operator may choose to configure the LSR to leave the link up so
that an OAM message can be used to verify the actual MFS. that an OAM message can be used to verify the actual MFS.
In the event a GAP message is not received within the previously A peer node could cease transmission of G-ACh advertisements, or
received associated Lifetime, the receiving node MUST assume that it cease to include a Source MAC Address TLV in advertisements, or cease
is now connected to a node that does not support these advertisements to be connected, any of which will cause the TLV lifetime to expire.
and must behave as configured for this eventuality. After the Source MAC Address TLV lifetime has expired, this MAC
Address MUST NOT be used as the peer MAC address. The node MUST
return to selecting MAC addresses as though no advertisements were
received, using the method configured for this eventuality.
5. Manageability Considerations 5. Manageability Considerations
The values sent and received by this protocol MUST be made accessible The values sent and received by this protocol MUST be made accessible
for inspection by network operators, and where local configuration is for inspection by network operators, and where local configuration is
updated by the received information, it MUST be clear why the updated by the received information, it MUST be clear why the
configured value has been changed. The advertised information SHOULD configured value has been changed. The information being advertised
be persistent across restarts. Received advertisements MUST be SHOULD be persistent across restarts. To ensure correct operation
discarded across restarts. If the received values change, the new when an equipment restarts in a new environment, previously received
values MUST be used and the change made visible to the network advertisements MUST be discarded across restarts. If the received
operators. values change, the new values MUST be used and the change made
visible to the network operators.
Where the link changes to a new type, i.e. from point-to-point to
point-to-multipoint the network operator SHOULD be informed. If the
new link type is incompatible with the addressing Ethernet method in
use the system MUST take the action that is configured under those
circumstances.
6. Security Considerations 6. Security Considerations
The use of broadcast or multicast Ethernet destination MAC addresses The use of broadcast or multicast Ethernet destination MAC addresses
for frames carrying MPLS-TP data packets can potentially result in for frames carrying MPLS-TP data packets can potentially result in
such frames being distributed to devices other than the intended such frames being distributed to devices other than the intended
destination node or nodes when the Ethernet link is not point-to- destination node or nodes when the Ethernet link is not point-to-
point. The operator SHOULD take care to ensure that MPLS-TP nodes point. The operator should take care to ensure that MPLS-TP nodes
are aware of the Ethernet link type (point-to-point or multipoint). are aware of the Ethernet link type (point-to-point or multipoint).
In the case of multipoint links, the operator SHOULD either ensure In the case of multipoint links, the operator should either ensure
that no devices are attached to the link that are not authorized to that no devices are attached to the link that are not authorized to
receive the frames, or take steps to mitigate the possibility of receive the frames, or take steps to mitigate the possibility of
excessive frame distribution, for example by configuring the Ethernet excessive frame distribution, for example by configuring the Ethernet
switch to appropriately restrict the delivery of multicast frames to switch to appropriately restrict the delivery of multicast frames to
authorized ports. authorized ports.
An attacker could disrupt communications by modifying the Source MAC An attacker could disrupt communications by modifying the Source MAC
Address or the MFS values, however this is mitigated by the use of Address or the MFS values, however this is mitigated by the use of
cryptographic authentication as described in [I-D.ietf-mpls-gach-adv] cryptographic authentication as described in [I-D.ietf-mpls-gach-adv]
which also describes other considerations applicable to the GAP which also describes other considerations applicable to the GAP
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7.3. Creation of Ethernet Interface Parameters Registry 7.3. Creation of Ethernet Interface Parameters Registry
IANA is requested to create a new registry, "G-ACh Advertisement IANA is requested to create a new registry, "G-ACh Advertisement
Protocol: Ethernet Interface Parameters" within the "Pseudowire Name Protocol: Ethernet Interface Parameters" within the "Pseudowire Name
Spaces (PWE3)" with fields and initial allocations as follows: Spaces (PWE3)" with fields and initial allocations as follows:
Type Name Type ID Reference Type Name Type ID Reference
------------------ ------- ------------ ------------------ ------- ------------
Source MAC Address 0 (this draft) Source MAC Address 0 (this draft)
Maximum Frame Size 1 (this draft) Maximum Frame Size 1 (this draft)
The range of the Type ID field is 0 - 255. The range of the Type ID field is 0 - 255.
The allocation policy for this registry is IETF Review. The allocation policy for this registry is IETF Review or IESG
approval.
8. Acknowledgements 8. Acknowledgements
We thank Adrian Farrel for his valuable review comments on this We thank Adrian Farrel for his valuable review comments on this
document. document.
9. References 9. References
9.1. Normative References 9.1. Normative References
[EUI-64] , "[EUI64] IEEE, "Guidelines for 64-bit Global Identifier [EUI-64] , "[EUI64] IEEE, "Guidelines for 64-bit Global Identifier
(EUI-64) Registration Authority", http:// (EUI-64) Registration Authority", http://
standards.ieee.org/regauth/oui/tutorials/EUI64.html, March standards.ieee.org/regauth/oui/tutorials/EUI64.html, March
1997.", . 1997.", .
[I-D.ietf-mpls-gach-adv] [I-D.ietf-mpls-gach-adv]
Frost, D., Bryant, S., and M. Bocci, "MPLS Generic Frost, D., Bryant, S., and M. Bocci, "MPLS Generic
Associated Channel (G-ACh) Advertisement Protocol", draft- Associated Channel (G-ACh) Advertisement Protocol", draft-
ietf-mpls-gach-adv-06 (work in progress), February 2013. ietf-mpls-gach-adv-08 (work in progress), June 2013.
[LLDP] , "IEEE, "Station and Media Access Control Connectivity [LLDP] , "IEEE, "Station and Media Access Control Connectivity
Discovery (802.1AB)", September 2009.", . Discovery (802.1AB)", September 2009.", .
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, January 2001. Encoding", RFC 3032, January 2001.
 End of changes. 20 change blocks. 
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