--- 1/draft-ietf-mpls-tp-ethernet-addressing-06.txt 2013-04-08 20:54:58.611841818 +0200 +++ 2/draft-ietf-mpls-tp-ethernet-addressing-07.txt 2013-04-08 20:54:58.627841943 +0200 @@ -1,20 +1,20 @@ MPLS D. Frost Internet-Draft S. Bryant Intended status: Standards Track Cisco Systems Expires: October 10, 2013 M. Bocci Alcatel-Lucent April 08, 2013 MPLS-TP Next-Hop Ethernet Addressing - draft-ietf-mpls-tp-ethernet-addressing-06 + draft-ietf-mpls-tp-ethernet-addressing-07 Abstract The Multiprotocol Label Switching (MPLS) Transport Profile (MPLS-TP) is the set of MPLS protocol functions applicable to the construction and operation of packet-switched transport networks. This document presents considerations for link-layer addressing of Ethernet frames carrying MPLS-TP packets. Status of This Memo @@ -182,70 +182,70 @@ parameters associated with the sending interface. The following Type-Length-Value (TLV) objects are defined for this application; the TLV format is as defined in [I-D.ietf-mpls-gach-adv]: Source MAC Address (type = 0, length = 8): The Value of this 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 link. The IEEE-defined mapping from 48-bit MAC addresses to EUI-64 form is used. - MTU (type = 1, length = 4): The Value of this object is a 32-bit - unsigned integer encoded in network byte order that specifies the - maximum transmission unit size in octets of an MPLS label stack - plus payload that can be sent over the sending interface. Where - MAC address learning occurs by some other means, this TLV group - MAY be used to advertise only the MTU. If multiple advertisements - are made for the same parameter, use of these advertisements is + Maximum Frame Size (MFS) (type = 1, length = 4): The Value of this + object is a 32-bit unsigned integer encoded in network byte order + that specifies the maximum frame size octets of an an Ethernet + Frame that can be sent over the sending interface. Where MAC + address learning occurs by some other means, this TLV group MAY be + used to advertise only the MFS. If multiple advertisements are + made for the same parameter, use of these advertisements is undefined. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type=0 | Reserved | Length=8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MAC Address in EUI-64 Format | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Source MAC Address Object Format 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type=1 | Reserved | Length=4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | MTU | + | Maximum Frame Size (MFS) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 2: TLV Object Format + Figure 2: MFS Object Format Per [I-D.ietf-mpls-gach-adv], MAC Address Discovery information needs to be periodically retransmitted and is to be retained by a receiver based on the period of time indicated by the associated Lifetime field. To expedite the initialization of a link it is RECOMMENDED that a node that has been reconfigured, rebooted or is aware that it have been disconnected from its peer send a GAP Ethernet Interface Parameter message, and that it issues a GAP request message for the Ethernet parameters at the earliest opportunity. When the MAC address in the received Source MAC Address TLV changes the new MAC address MUST be used (see Section 5.2 of [I-D.ietf-mpls-gach-adv]). - If a minimum MTU is configured for a link and the MTU 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 MTU 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, 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 - that an OAM message can be used to verify the actual MTU. + that an OAM message can be used to verify the actual MFS. In the event a GAP message is not received within the previously received associated Lifetime, the receiving node MUST assume that it is now connected to a node that does not support these advertisements and must behave as configured for this eventuality. 5. Manageability Considerations The values sent and received by this protocol MUST be made accessible for inspection by network operators, and where local configuration is @@ -265,21 +265,21 @@ point. The operator SHOULD take care to ensure that MPLS-TP nodes are aware of the Ethernet link type (point-to-point or multipoint). In the case of multipoint links, the operator SHOULD either ensure that no devices are attached to the link that are not authorized to receive the frames, or take steps to mitigate the possibility of excessive frame distribution, for example by configuring the Ethernet switch to appropriately restrict the delivery of multicast frames to authorized ports. An attacker could disrupt communications by modifying the Source MAC - Address or the MTU 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] which also describes other considerations applicable to the GAP protocol. Visibility into the contents of either of the TLVs could provide information that is useful for an attacker. This is best addressed by physical security of the links. 7. IANA Considerations 7.1. Ethernet Multicast Address Allocation @@ -304,21 +304,21 @@ 7.3. Creation of Ethernet Interface Parameters Registry IANA is requested to create a new registry, "G-ACh Advertisement Protocol: Ethernet Interface Parameters" within the "Pseudowire Name Spaces (PWE3)" with fields and initial allocations as follows: Type Name Type ID Reference ------------------ ------- ------------ Source MAC Address 0 (this draft) - MTU 1 (this draft) + Maximum Frame Size 1 (this draft) The range of the Type ID field is 0 - 255. The allocation policy for this registry is IETF Review. 8. Acknowledgements We thank Adrian Farrel for his valuable review comments on this document.