Upload
eliana-richmond
View
45
Download
0
Embed Size (px)
DESCRIPTION
Routing Extensions for G.709 OTN (draft-ashok-ccamp-gmpls-ospf-g709-02.txt). Rajan Rao ( [email protected] ) Ashok Kunjidhapatham ( [email protected] ) Khuzema Pithewan ( [email protected] ) Snigdho Bardalai ( [email protected] ). Outline. Goals Proposal - PowerPoint PPT Presentation
Citation preview
1
Routing Extensions for G.709 OTN (draft-ashok-ccamp-gmpls-ospf-g709-02.txt)
Rajan Rao ([email protected])Ashok Kunjidhapatham ([email protected])
Khuzema Pithewan ([email protected])Snigdho Bardalai ([email protected])
2
Outline
• Goals• Proposal• Discussion items• Advantages & Comparison• Backup
3
Goals
A generic, scalable BW model that:– covers all OTN services including ODUflex,– covers potential evolution of OTN standards,– Hides complexities of TS disparities,– is Backwards compatible (to RFC 4203),– supports G.709-v3 complete muxing hierarchy,– is ready for VCAT services
4
Proposal• Simple extensions to RFC-4202– Retains main ISCD format• Consistent with RFC-4202, RFC-4203 & RFC-4201
– Switching type =TDM & Encoding type = ODUk – Max LSP BW in bytes/sec
• Technology specific extensions in SCSI– Expands SCSI to carry G.709-v3 BW info• Advertise #of ODU containers for fixed rate ODUs• Advertise ODUflex BW in bytes/sec• Per Signal Type BW coverage
– for Max-LSP & Unreserved BW types• Coverage for complete muxing hierarchy (G.709-v3)
5
Proposal: ISCD & SCSI formats
6
Proposal: SCSI format (ODUflex)
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 (2) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ST=ODUflex |Bw Type| Flags | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Available BW in bytes/sec at Prio 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Available BW in bytes/sec at Prio 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Available BW in bytes/sec at Prio 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-+ | Available BW in bytes/sec at Prio 3 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Available BW in bytes/sec at Prio 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Available BW in bytes/sec at Prio 5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Available BW in bytes/sec at Prio 6 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Available BW in bytes/sec at Prio 7 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 (2) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ST=ODUflex |Bw Type| Flags | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Minimum LSP Bandwidth | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7
Example – Muxing Hierarchy Coverage
ST BW Type Available ODUs at priority Pi
ODU4 (4) 0 (Max-Lsp-Bw ) 1
ODU3 (3) 0 (Max-Lsp-Bw ) 2
ODU0 (5) 0 (Max-Lsp-Bw ) 82
ODUflex(10) 0 (Max-Lsp-Bw) ( 80x1,301,709 )/8 bytes/sec
ODUflex(10) 2 (Min-Lsp-Bw) 1,301,709 /8 bytes/sec
8
Discussion Items (1)1. Question-1: Use of ISCD::Max-LSP-BW results in path computation failure
when ODUflex is not supported (Danielle’s comment)– Authors agreed to the issue raised– Resolved by moving ODUflex BW advertisement to SCSI – Updated draft was sent out 10/28/10
2. Question-2: Value for ISCD::TDM:Minimum-LSP-BW field (Pietro’s comment)– Authors agreed to the issue raised
• The value is not restricted to TSG = {1.25, 2.5}. It is lowest switchable container
– Previously this field was used for ODUflex. With ODUflex moved to SCSI this is not the case. There is no issue in setting the value to lowest switchable container.
– Clarification will be provided in next draft update
3. Question-3: No backwards compatibility issues as no ODU adv defined in RFC 4202/4203/4328 (Danielle’s comment)– Authors believe backwards compatibility with G.709-v1 is required to comply with the above
RFCs– The solution proposed addresses backwards compatibility fully (ref draft-ashok-02)– If WG agrees to not support backwards compatibility, we could use main ISCD for ODUflex
• ref to backup slides 15-17 for details
9
Discussion Items (2)4. Question-4: Full muxing not a requirement (Fatai’s comment)
– Authors didn’t agreed to the comment– Our interpretation of G.709-v3 is full hierarchy support is required– We agree with Deborah’s comments on NOT restricting GMPLS solution to a single
stage
10
Advantages & ComparisonAdvantages:• Re-using of existing ISCD definitions (RFC 4202)• Technology specific extensions consistent with GMPLS arch• Backwards compatible with G.709-v1 (RFC 4202, RFC 4203, RFC 4328)
– without the use of multiple ISCDs
• Coverage for complete muxing hierarchy (G.7090-v3 )• Doesn’t require MLN to address muxing hierarchy• Doesn’t prevent MLN deployments• More compact encoding
Comparison:• Not clear why we need a new technology agnostic ISCD for GMPLS as proposed by
other draft– Creating a new ISCD will cause backwards compatibility issues for existing GMPLS/MPLS /MPLS-TP
deployments (e.g. PSC, SONET/SDH, LSC)
• Requires MLN to support muxing hierarchy• Don’t agree with Termination/Switching capability advertisement
11
BACKUP SLIDES
12
Comparison (1)Draft-Ashok Draft-Ceccarelli
Model •Simple extensions to RFC4202•Consistent with GMPLS model•Technology specific extensions in SCSI
•New BA similar to ISCD already defined
Hierarchy Handling
•Full mux capability taken care•No FA-LSPs required to address G.709-v3 mux layers•Smaller TE-DB & Scalable
•Addresses only one level•Requires Te-Link per Mux layer to support G.709-v3 hierarchy•Not a scalable solution
Backward Compatibility
Compatible with G.709-v1 deployments (RFC-4202/4203/4328)
Redefines G.709 ISCD. Invalidates RFC 4328. In general breaks away from existing GMPLS model for BW advertisement.
Scalable Model
• Compact sub-TLVs defined •Further optimization possibilities with priority bit-map use•Easy to deal with future extensions
• ServiceType repeated per priority per signal type• use of 4 words unnecessary for advertising #of ODU containers• Future extensions may force having SCSI in BA (duplication of 4202 ISCD)
13
Comparison (2)Draft-Ashok Draft-Ceccarelli
Termination & Switching flags
•Don’t see the need•Not supported
•supported
VCAT Addressed using BW-Type=1 advertisement
Not addressed
Size1) OTU4 link with 7
signal types + 8 priorities
2) OTU4 link with 7 signal types + 5 priorities
Compact
1) 59 words
2) 50 words
Numbers are higher than draft-ashok model1) 114 words
2) 70 words
Simplicity Simple TLV structure, easy to encode/decode.
The unit of BW depends on M field. Depending on the value of M field, BW could be interpreted as simple unsigned integer or IEEE floating point number. Results in engineering complexity
14
ISCD Size Comparison for an OTU4 Link
Draft-Ashok Draft-Ceccarelli
Number of Priority Levels Supported 8 8 5 3
ODU4 6 16 10 6
ODU3 6 16 10 6
ODU2 - 16 10 6ODU2e - 16 10 6ODU2_ANY 6 - - -ODU1 6 16 10 6ODU0 6 16 10 6ODUflex 10 32 20 12 Total Variable 40 128 80 48Total Fixed 12 1 1 1 Total ISCD Size(in words) 52 129 81 49
Note: 1. Draft-Ashok uses signal type of ODU2_ANY for {ODU2 & ODU2e} 2. All units are in number of words (4 bytes).
15
Backwards Compatibility (1)
Link A-B: – G.709-v1 version compatible OTUk interface (2001)– Uses RFC 4328 for signaling– RFC 4203 & RFC 4201 based ISCD interpretation
Link B-C: – G.709-v3 version compatible OTUk interface (12/09)– Uses ISCD + SCSI extensions as per our draft
Node-A Node-B Node-C
16
Backwards compatibility(2)Link A-B
(G.709-v1 Telink RF C 4203/4201)
Link B-C(G.709-v3 Telink
based on our draft)Old CSPF Compatible Compatible
( Ref to Note below)New CSPF Compatible Compatible
Note:• The GOAL is to make TE-links with newer OTN capabilities
compatible with CSPF in deployed networks• The ISCD format proposed in our draft allows Node-A
– To interpret unReserved-BW, MaxLSP-BW and MinLSP-BW as per RFC4203 & RFC 4201• Crank-back possibilities if muxing limitations exist
– With or without Node-A going through software upgrade• Our BW model extended to support ODUflex
– ODUflex a separate sub-TLV in SCSI – Addresses the case when ODUflex is not supported (the scenario highlighted in
Daniele’s email)
17
Options to address Backwards Compatibility
1. If backwards compatibility needs to be addressed:– Use main ISCD as per RFC 4202/4203/4201– New sub-TLV for ODUflex in SCSI (BW in bytes/sec)
2. If backwards compatibility is not an issue:– Use main ISCD for ODUflex BW advertisement – No need for a separate sub-TLV for ODUflex
• Either option can be easily accommodated in our BW Model– Option#1 is preferred approach
18
OTN example
• The example below will be used where:– TE-link#1 is a link of type OTU2 supporting time-
slot granularity of 2.5G– TE-link#2 is ODU1 supporting time-slot granularity
of 1.25G– TE-link#3 is a link of type OTU2 supporting time-
slot granularity of 1.25GODU0 Service
TE-link#2
TE-link#1
TE-link#3
19
OTN example – first level• The advertisement for TE-link#1 (OTU2 with TS=2.5Gbps) would be:
– Available ODU2s @Pi : 1– Available ODU1s @Pi : 4– Available ODU0s @Pi : 0 (not supported on this link, not included in the adv)– Max-LSP-BW = 10Gpbs– Min-LSP-BW = 2.5Gbps (ODU1 nominal rate)
• The advertisement for TE-link#3 (OTU2 with TS=1.25Gbps) would be:– Available ODU2s @Pi : 1– Available ODU1s @Pi : 4– Available ODU0s @Pi : 8 (supported on this link)– Max-LSP-BW = 10Gpbs– Min-LSP-BW = 1.25Gbps (ODU0 nominal rate)
TE-link#1
TE-link#3
20
OTN example – second level• The advertisement for TE-link#2 (ODU1 FA-LSP) is:
– Available ODU2s @Pi : 0 (not included in the adv)– Available ODU1s @Pi : 1– Available ODU0s @Pi : 2 (supported on this link)– Max-LSP-BW = 2.5Gpbs– Min-LSP-BW = 1.25Gbps (ODU0 nominal rate)
• The advertisement for TE-link#1 (OTU2) changes to:– Available ODU2s @Pi : 0 (not included in the adv)– Available ODU1s @Pi : 3– Available ODU0s @Pi : 0 (not supported on this link, not included in the adv)– Max-LSP-BW = 7.5Gpbs– Min-LSP-BW = 2.5Gbps (ODU1 nominal rate)
TE-link#2
TE-link#1
TE-link#3
21
OTN example – third level• Establish ODU0 service.• The advertisement for TE-link#2 (ODU1) changes to:
– Available ODU2s @Pi : 0 (not included in the adv)– Available ODU1s @Pi : 0 (not included in the adv)– Available ODU0s @Pi : 1– Max-LSP-BW = 1.25Gpbs – Min-LSP-BW = 1.25Gbps (ODU0 nominal rate)
• The advertisement for TE-link#3 (OTU2) changes to:– Available ODU2s @Pi : 0 (not included in the adv)– Available ODU1s @Pi : 3– Available ODU0s @Pi : 7– Max-LSP-BW = 8.75Gpbs– Min-LSP-BW = 1.25Gbps (ODU0 nominal rate)
ODU0 service
TE-link#2
TE-link#1
TE-link#3
22
OTN example – Bundled links• Say TE-link#3 is a bundle of 3xOTU2s• The advertisement for TE-link#3 before ODU0 service is added:
– Available ODU2s @Pi : 3– Available ODU1s @Pi : 12– Available ODU0s @Pi : 24– Max-LSP-BW = 10.0Gpbs– Min-LSP-BW =1.25Gbps (ODU0 nominal rate)
• The advertisement for TE-link#3 after ODU0 service is added:– Available ODU2s @Pi : 2– Available ODU1s @Pi : 11– Available ODU0s @Pi : 23– Max-LSP-BW = 10.0Gpbs– Min-LSP-BW =1.25Gbps (ODU0 nominal rate)
ODU0 Service
TE-link#2
TE-link#1
TE-link#3
23
OTN example – ODUflex• Add ODUflex connection of 5.0Gbps on TE-link#1• The advertisement for TE-link#1 (OTU2) changes to:
– Available ODU2s @Pi : 0 (not included in the adv)– Available ODU1s @Pi : 1– Available ODU0s @Pi : 0 (not supported & not included in the adv)– SCSI::ODUflex:Max-LSP-BW = 2.5Gpbs (used for ODUflex)– SCSI::ODUflex:Min-LSP-BW = 2.5Gbps (ODU1 nominal rate used for ODUflex)
TE-link#1
TE-link#3
24
Issue with RFC4201Bundled Link with 5 component links, each with OTU2 rate and supports the following muxing capabilities:
ODU2/ODU0ODU2/ODU1ODU2/ODU1/ODU0
1. BW before any service is createdUnreserved BW = 50Gbps, Max-LSP-BW = 10G (ODU2), Min-LSP-BW = 1.25G (ODU0)
2. BW After creating four ODU0 service and each using separate component link in the bundled linkUnreserved BW = ~45Gbps, Max-LSP-BW = 10G (ODU2), Min-LSP-BW = 1.25G (ODU0)
3. The issue after step #2:A node computing ODU2-4v path for a 40G client would select this link if per layer BW information is not available; results in a crank back.