Technical Summary
Where the payload of a pseudowire comprises a number of distinct
flows, it can be desirable to carry those flows over the equal cost
multiple paths (ECMPs) that exist in the packet switched network.
Most forwarding engines are able to hash based on MPLS label stacks
and use this mechanism to balance MPLS flows over ECMPs.
This document describes a method of identifying the flows, or flow
groups, within pseudowires such that Label Switching Routers can
balance flows at a finer granularity than individual pseudowires.
The mechanism uses an additional label in the MPLS label stack.
Working Group Summary
The WG process was smooth.
An IPR disclosure was made after this document had completed IETF last call. A new IETF last call
was immediately made specifically calling out the IPR disclosure as the reason. The last call
announcment was copied to the PWE3 working group mailing list. No comments of any type were
received during the second last call.
Document Quality
There are no concerns with document quality.
Personnel
Matthew Bocci (matthew.bocci@alcatel-lucent.com) is the document shepherd.
Adrian Farrel (adrian@olddog.co.uk) is the responsible AD.
RFC Editor Note
Section 1.1
OLD
A similar design for general MPLS use has
also been proposed [I-D.kompella-mpls-entropy-label], Section 9.
NEW
A similar design for general MPLS use has
also been proposed [I-D.kompella-mpls-entropy-label], see Section
9 of this document.
END
Section 1.2
s/it will always be will preceded/it will always be preceded/
Section 1.2
OLD
This can be prevented by setting the flow LSE TTL to 1,
thereby forcing the packet to be discarded by the forwarder. Note
that this may be a departure from considerations that apply to the
general MPLS case.
NEW
This can be prevented by setting the flow LSE TTL to 1,
thereby forcing the packet to be discarded by the forwarder. Note
that setting the TTL to 1 regardless of the payload may be considered
a departure from the TTL procedures defined in [RFC3032] that apply to
the general MPLS case.
END
Section 1.2
OLD
This document does not define a use for the TC bits (formerly known
as the EXP bits) in the flow label. Future documents may define a
use for these bits, therefore implementations conforming to this
specification MUST set the TC bits to zero at the ingress and MUST
ignore them at the egress.
NEW
This document does not define a use for the TC field [RFC5462]
(formerly known as the EXP bits [RFC3032]) in the flow label. Future
documents may define a use for these bits, therefore implementations
conforming to this specification MUST set the TC field to zero at the
ingress and MUST ignore them at the egress.
END
Section 2
OLD
it is required that the NSP
NEW
it is REQUIRED that the NSP
END
Section 4
OLD
The absence of a FL Sub-TLV indicates that the PE is unable to
process flow labels. A PE that is using PW signalling and that does
not send a FL Sub-TLV MUST NOT include a flow label in the PW packet.
A PE that is using PW signalling and which does not receive a FL Sub-
TLV from its peer MUST NOT include a flow label in the PW packet.
This preserves backwards compatibility with existing PW
specifications.
NEW
The absence of a FL Sub-TLV indicates that the PE is unable to
process flow labels. An ingress PE that is using PW signalling
and that does not send a FL Sub-TLV MUST NOT include a flow label
in the PW packet. An ingress PE that is using PW signalling and
which does not receive a FL Sub-TLV from its egress peer MUST NOT
include a flow label in the PW packet. This preserves backwards
compatibility with existing PW specifications.
END
Section 4.1
OLD
o FL (value 0x17) is the flow label sub-TLV identifier assigned by
IANA (seeSection 11 ).
NEW
o FL (value 0x17) is the flow label indicator sub-TLV identifier
assigned by IANA (see Section 11).
END
OLD
7. OAM
NEW
7. Operations, Administration, and Maintenance (OAM)
END
Section 7
OLD
+-------------------------------+
| |
| VCCV Message | n octets
| |
+-------------------------------+
| Optional Control Word | 4 octets
+-------------------------------+
| Flow label | 4 octets
+-------------------------------+
| PW label | 4 octets
+-------------------------------+
| Router Alert label | 4 octets
+-------------------------------+
| MPLS Tunnel label(s) | n*4 octets (four octets per label)
+-------------------------------+
Figure 4: Use of Router Alert Label
NEW
+-------------------------------+
| |
| VCCV Message | n octets
| |
+-------------------------------+
| Optional Control Word | 4 octets
+-------------------------------+
| Flow LSE | 4 octets
+-------------------------------+
| PW LSE | 4 octets
+-------------------------------+
| Router Alert LSE | 4 octets
+-------------------------------+
| MPLS Tunnel LSE(s) | n*4 octets (four octets per label)
+-------------------------------+
Figure 4: Use of Router Alert Label
END
Section 8.5 Final line.
Delete "In a"
Section 11 first paragraph
NEW
IANA maintains the "Pseudowire Name Spaces (PWE3)" with sub-registry
"Pseudowire Interface Parameters Sub-TLV type Registry". IANA has
made an early allocation from this registry for the Flow Label
indicator sub-TLV type.
END
Section 12
OLD
The congestion considerations applicable to PWs as described in
[RFC3985] and any additional congestion considerations developed at
the time of publication apply to this design.
NEW
The congestion considerations applicable to PWs as described in
[RFC3985] apply to this design.
END
Authors' Addresses
OLD
Email: Alcatel-Lucent vach.kompella@alcatel-lucent.com
NEW
Email: vach.kompella@alcatel-lucent.com
END
OLD
Email: joe.regan@alcatel-lucent.comRegan
NEW
Email: joe.regan@alcatel-lucent.com
END
IANA Note
Please note that the registry used is under the Expert Review allocation policy.
One of the designated experts is Stewart Bryant who is principal editor of this document.
Please use the alternate expert, Danny McPherson.