Network Working Group Vijayanand Chandrasekar
INTERNET DRAFT Individual Contributor
Intended Status: Standards Track August 16, 2019
Expires: 15 Febraury, 2020
Advertising OTN Fixed Time slot constraints in OSPF
draft-vijay-ccamp-ospf-otn-timeslot-00.txt
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Abstract
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This document describes the extensions needed to OSPF for
advertising the constraints that exists in some OTN switches while
switching timeslots between ports. This advertisement would be
needed for computing path of LSP through these switches taking into
account the above mentioned constraint.
This document proposes extensions to existing OSPF for advertising
the timeslots available on each OTN port in a new sub-tlv and the
connectivity matrix representing the capability of the device to
cross connect these timeslots in another new sub-tlv
1. Introduction
In [RFC7138], a mechanism for advertising the ODU multiplexing
hierarchy is described. In [RFC7580], an optical node property TLV
is defined as an extension to the OSPF opaque LSA defined in
{RFC3630].
.
This document describes the use of OSPF-TE in carrying
information about the details of OTN time slots available in each
port of an OTN switch and the connectivity matrix describing the
connectivity between the timeslots of the different ports.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [RFC2110].
The reader is assumed to be familiar with the terminology in
RFC7138[RFC7138],RFC5780[RFC7580] and RFC3630{RFC3630]
3. OSPF Extensions
A new OTN timeslot sub-TLV and OTN Connectivity matrix sub-TLV
are proposed in this document. The OTN timeslot sub-TLV will be used
in conjunction with the SCSI described in section 4.1 of
RFC7138[RFC7138]. The OTN connectivity matrix will be carried in the
Optical node property TLV described in RFC7580[RFC7580]
3.1 OTN Timeslot sub-TLV
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 {TBD) | Length |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Pri | Bitmap Length | G | BitMap(variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitMap(variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Pri | Bitmap Length | G| BitMap(variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitMap(variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
TBD
Length
Length of Sub-TLV
Pri
Priority level (0-7) at which the bitmap is advertised
G: Timeslot granularity
0 - 1.25 Gbps
1 - 2.5 Gbps
2 - 5 Gbps
Priority (0-7) at which the bitmap is available
Bitmap Length
Length in bits of the bitmap following this
BitMap
The bitmap represents the timeslots available which is
advertised through this sub-TLB. A 1 in the bit position represents
that the timeslot is available , while a 0 represents that the
timeslot is not available.The Bitmap is padded to the nearest byte
boundary.
3.2 Connectivity matrix sub-TLV
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The Connectivity matrix TLV is described below.
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( TBD) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Link pairs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Bitmap pair pairs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Bit Map Length | G | TimeSlot BitMap |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitMap(contd) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Bit Map Length |G | TimeSlot BitMap |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitMap(contd) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
.
.
.
.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Bitmap pair pairs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Bit Map Length |G | TimeSlot BitMap |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitMap(contd) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Bit Map Length |G | TimeSlot BitMap |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitMap(contd) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
TBD
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Length
Length of Sub-TLV
Number of Link pairs
The number of pair of link identifiers advertised.
Link Identifier
An identifier for the port that is described
Number of Bitmap pairs
The number of pair of bitmaps advertised.
Bit Map Length
Length in bits of the bitmap
G
Timeslot granularity
0:1.25 Gbps
1:2.5 Gbps
2:5 Gbps
Timeslot BitmAp
The BitMap representing the timeslots
4. Operational overview
This section details the operation of the scheme proposed in
this document.
On some OTN switches there exists constraints on which OTN
timeslots can be cross connected to which other OTN timeslots.
Therefore, the node computing the path through such switches needs
to be aware of the OTN timeslots which are available and to which
other timeslots they can be cross connected.
The OTN timeslot sub-TLV is advertised along with the SCSI
defined in section 4.1 of RFC7138[RFC7138] as a separate sub-tlv of
the link tlv. The SCSI in RFC7138[RFC7138] only advertises the
number of timeslots available whereas this sub-TLV defines the exact
timeslots which are available in the form a bitmap.
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The connectivity matrix sub-TLV is advertised in the node
attribute TLV of the opaque LSA defined in RFC3630[RFC3630} in line
with the connectivity matrix that is advertised in [RFC7580]. This
advertisement describes exactly which timeslots of an OTN interface
can be cross connected to which other timeslots of another OTN
Interface. For every pair of link identifiers, multiple pairs of
bitmaps are advertised, this denotes that timeslots, of the first
interface in the interface identifier pair, identified in the first
bitmap of the bitmap pair can be cross connected to timeslots, of
the second interface in the interface identifier pair, identified in
the second bitmap of the bitmap pair. Like this several interface
pairs and their corresponding bitmap pairs can be advertised.
For example, if on Interface I1 timeslots (t1,t3,t5) can be cross-
connected to timeslots ( t2,t4,t6) on Interface I2 and ( t2,t4,t6)on
Interface I1 can be cross-connected to (t1,t3,t5) on Interface I2,
then there will be one interface Identifier pair (I1,I2) advertised
with two bitmap pairs corresponding to (t1,t3,t5), (t2,t4,t6) and (
t2,t4,t6), ( t1,t3,t5)
The above mentioned sub-TLVs together would help the node which
is computing the path to determine which timeslot to select on each
of the OTN ports to route the LSP on OTN switches which have
restriction on cross connecting OTN timeslots.
5. Interoperability Considerations
The feature described in this document would be operational only
if all the OSPF routers in area support the extension described
above.
6. Security considerations
None
7. IANA Considerations
IANA needs to allocate a new Type for the OTN timeslot sub-TLV
described in section 3.1 and a new Type for the connectivity matrix
sub-TLV described in section 3.2
8. Authors' Address
Vijayanand Chandrasekar
Individual Contributor
Email: vijayanandc159@outlook.com
9. References
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9.1 Normative References
[RFC7138], D. Ceccarelli, F. Zhang, S. Belotti, R. Rao and J. Drake,
" Traffic Engineering Extensions to OSPF for GMPLS Control of
Evolving G.709 Optical Transport Networks ",RFC7138,March 2014.
[RFC7580], F. Zhang, Y. Lee, J.Han, G. Bernstein and Y. Xu, " OSPF-
TE Extensions for General Network Element Constraints
",RFC7580, June 2015.
[RFC3630], D. Katz, K. Kompella and D. Yeung, " Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC3630, September 2003
.
9.2 Informative references
[RFC2110] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
[RFC5226] T. Narten and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226.
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