Zhenbin Li, Li Zhang, Yuanjiao Liu Huawei Technologies IETF 86, Orlando, FL, USA

draft-li-ospf-auto-mbb-te-path-00IETF 86 OSPF 1

OSPF Extensions for Automatic Computation of MPLS Traffic

Engineering Path Using Traffic Engineering Layers and Areas

draft-li-ospf-auto-mbb-te-path-00

Zhenbin Li, Li Zhang, Yuanjiao LiuHuawei Technologies

IETF 86, Orlando, FL, USA


Application of MPLS TE in MBB

E2E PWE3

2G TDM PW

3G ATM PW

3G ETH VRF

LTE VRF S1LTE VRF X2

E2E L3VPN

Tunnel

2G TDM PW

3G ATM PW

3G ETH VRF

LTE VRF S1

LTE VRF X2

TDM/ATM Services

Ethernet Service

MPLS TE is used in the network to carry L2VPN/L3VPN services, providing traffic engineering, OAM, etc. As the network scale expands, more MPLS TE tunnels have to be deployed. It is important to deploy MPLS TE tunnel easily.

ATM RNC

Last Mile Access Aggregation RNC/SGW/MME

RSG

RSG

CSG

BTS

NodeB / eNB

E1

Eth.

IP RNC/S-GW/MME

ATN

ATN

ATN

PEPE

NodeB

ATM

BSCSTM-1

STM-1

GE

AGG

AGG

P

CSG

CSG

ATN

CSG

ATN

CSG


Problem Statement of MPLS TE Auto Path Computation

Requirement 1: Completely disjointed primary and backup LSP Requirement 2: Avoid passing through different access rings

AGG

AGG

RSG

RSG

AGG

AGG

Aggregate Ring

CSG

CSG

CSG

CSG

CSG

Access Ring 1

Access Ring 4

Access Ring 2

Access Ring 3

OSPF Area 0


Existing Solutions and Challenge

Existing Solutions Solution 1: To set reasonable link cost Solution 2: To use explicit-path or affinity property(Color)

Challenge It will be very complex and time-consuming to adjust the cost for a large

scale network or change explicit path or affinity property for a great deal of

MPLS TE tunnels.


Architecture of MPLS TE Auto Path Computation: Concept of TA/TL

AGG

RSG RSG

AGGAGG

Aggregate Ring 1

CSG

CSG

CSG

CSG

Access Ring 1

Access Ring 2

Access Ring 3

TL2/TA0TA1TA2TL2/TA0TA3

TL3/TA0

TL2/TA0TA1TA2TA3

TL1/TA1TL1/TA3

TL1/TA1TL1/TA2

TL3/TA0Layer3

Layer2

Layer1

Concept of TA/TL• TL (TE Layer): It indicates the

physical layer of the node in the network.

• TA (TE Area): It indicates the physical ring of the node.

TL and TA are defined for MPLS TE path computation according to the natural topology of the mobile network.

IGP Flooding TA/TL Info• TL and TA information are flooded

and installed into TEDB.


Architecture of MPLS TE Auto Path Computation: Enhanced CSPF Algorithm

AGG

RSG RSG

AGGAGG

Aggregate Ring 1

CSG

CSG

CSG

CSG

Access Ring 1

Access Ring 2

Access Ring 3

TL2/TA0TA1TA2TL2/TA0TA3

TL3/TA0

TL2/TA0TA1TA2TA3

TL1/TA1TL1/TA3

TL1/TA1TL1/TA2

TL3/TA0Layer3

Layer2

Layer1

Rules for Enhanced CSPF Algorithm• Rule1: If the destination node of the LSP is not in the

same TA as the source node or the passed node, the node in the different layer will be the potential next-hop.

• Rule2: One LSP's TL track can not include TLh->TLl->TLh, this means that the LSP cannot pass through the low layer twice.

• Rule3: If the LSP reach a node that in the same TA as the destination node, the LSP must be calculated in this TA only.

• Rule 4: If the LSP reach a node that among more than one TAs, the node in different TA should be prior to be the next hop.

Rules for Determining Primary/Secondary LSP• Rule 5: The LSP which passes fewer TLs will be the

primary LSP.• Rule 6: If the two LSPs passes the same TLs, the one with

shorter metric in every layer from high to low will be the main LSP


OSPF Extensions: TA TLV and TL TLV

Elements of Procedure• The OSPF TA and TL TLV is carried within the OSPF Routing Information LSA.• The TA TLV and TL TLV may be advertised within an Area-local or Routing-domain

scope Router Information LSA, depending on the MPLS TE profile.

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 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TE-Area number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TE-Area number N | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TE-Layer number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


Next Steps• Get feedback on the architecture and OSPF extensions (on

mailing list)

Zhenbin Li, Li Zhang, Yuanjiao Liu Huawei Technologies IETF 86, Orlando, FL, USA

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