1 © 1999, cisco systems, inc. mosaddaq turabi mpls traffic engineering -session a- (mpls bootcamp)...

1© 1999, Cisco Systems, Inc. Mosaddaq Turabi

MPLS Traffic MPLS Traffic EngineeringEngineering

-SESSION A--SESSION A-

(MPLS BOOTCAMP)(MPLS BOOTCAMP)

Mosaddaq Turabi Mosaddaq Turabi ([email protected])([email protected])

2MPLS BOOTCAMP ( Mosaddaq Turabi) © 2000, Cisco Systems, Inc.

What is Traffic Engineering?What is Traffic Engineering?

• “Traffic Engineering is the process of controlling how traffic flows through one’s network so as to optimize resource utilization and network performance”

(Global Crossing, IEEE)(Global Crossing, IEEE)


Traffic Engineering: MotivationsTraffic Engineering: Motivations

• Reduce the overall cost of operations by more efficient use of bandwidth resources

– by preventing a situation where some parts of a service provider network are over-utilized (congested), while other parts under-utilized

The ultimate goal is cost saving !cost saving !


The “Overlay” SolutionThe “Overlay” Solution

• Routing at layer 2 (ATM or FR) is used for traffic engineering

• Full mesh of VCs between routers; each router has a direct VC to every other router in the mesh

L3L3

L3L3

L3L3

L3L3

L3L3

L3L3

L3L3

L2L2

L2L2

L2L2

L2L2

L2L2

L2L2

L3L3

L3L3

L3L3

L3L3 L3L3

Physical Logical


Traffic Engineering with OverlayTraffic Engineering with Overlay

R1R1

R2R2

R4R4

R3R3

TRAFFIC ENGINEERING

AT LAYER 2

R1R1

L2L2

L2L2 L2L2

L2L2R2R2

R4R4 R3R3

R1R1

L2L2

L2L2 L2L2

L2L2R2R2

R4R4 R3R3

R1R1

R2R2

R4R4

R3R3

R1’s VIEW OF THE NETWORK

AT LAYER3


““Overlay” Solution: DrawbacksOverlay” Solution: Drawbacks

• Extra network devices (cost)

• More complex network management (cost)

– two-level network without integrated network management

– additional training, technical support, field engineering

• IGP routing scalability issue for meshes

• Additional bandwidth overhead (“cell tax”)


Issues with IGP RoutingIssues with IGP Routing

• IGPs forward packets based on shortest path (metric).

• Flows from multiple sources may go over some common link(s) causing congestion.

• Alternate longer and underutilized path will not be used.

• IGP metric change may have side effects.


Traffic Engineering With Layer 3Traffic Engineering With Layer 3R2

R3

R1

IP routing: destination-based least-cost routingIP routing: destination-based least-cost routing

under-utilized alternate pathunder-utilized alternate path

Path for R2 to R3 trafficPath for R2 to R3 traffic



Traffic Engineering with Layer 3Traffic Engineering with Layer 3

R2

R3

R1

IP routing: destination-based least-cost routingIP routing: destination-based least-cost routing

under-utilized alternate pathunder-utilized alternate path




Traffic Engineering with Layer 3 Traffic Engineering with Layer 3 What is Missing ?What is Missing ?

• Path computation based just on IGP metric is not enough

• Packet forwarding in IP network is done on a hop by hop basis, derived from IGP

• Support for “explicit” routing (aka “source routing”) is not available


Routing Solution to Traffic Routing Solution to Traffic Engineering Engineering

• Construct routes for traffic streams within a service provider in such a way as to avoids causing some parts of the provider’s network to be over-utilized, while others parts remain under-utilized

R2

R3

R1


MPLS Traffic MPLS Traffic EngineeringEngineering

12© 1999, Cisco Systems, Inc.


TE - KEY COMPONENTSTE - KEY COMPONENTS

- Be able to set up a LSP based on BW availability (RSVP)

- Be able to set up a LSP based on user defined policies (Explicit Path or Link resource-class attribute string)

- Flooding of resource availability and policies to all the routers in the network (IS-IS or OSPF)

- Be able to run C-SPF based on constraints defined by a user

- MPLS as the forwarding mechanism



R2

R3

R1

- RSVP (extensions) on all links to reserve and monitor reservations per LSP plus Label distribution

- Resource-class attribute string (policy) defined on all links

- IS-IS or OSPF (extensions) to flood policy and resource availability

- C-SPF to find the path meeting the constraints



- TE tunnel (LSP) is initiated from the source (R1 and R2)

- Source of TE tunnel (LSP) is called “Head End” (R1 and R2)

- Destination of the TE tunnel (LSP) is called “Tail End” (R3)

- All the intermediate LSR are called “Mid Points”

- TE tunnel (LSP) is unidirectional and traffic flows from Head-end to the Tail-end

R2

R3

R1


What is a “traffic trunk” ?What is a “traffic trunk” ?

• Aggregation of (micro) flows that are:

– forwarded along a common path (within a service provider)

– often from a POP to another POP

• Essential for scalability

D

A B

C


TE basicsTE basics

• Traffic within a Service Provider as a collection of “POP to POP traffic trunks” with known bandwidth and policy requirements

• TE provides traffic trunk routing that meets the goal of Traffic Engineering

– via a combination of on-line and off-line procedures


MPLS TE MPLS TE REQUIREMENTSREQUIREMENTS



RequirementsRequirements

• Differentiating traffic trunks:

– large, ‘critical’ traffic trunks must be well routed in preference to other trunks

• Handling failures:

– automated re-routing in the presence of failures

• Pre-configured paths:

– for use in conjunction with the off-line route computation procedures

• Support of multiple Classes of Service


Requirements (cont.)Requirements (cont.)

• Constraining sub-optimality:

– should re-optimize on new/restored bandwidth• in a non-disruptive fashion - maintain the existing route until the new route is established, without any double counting

• Ability to “spread” traffic trunk across multiple Label Switched Paths (LSPs)

– could provide more efficient use of networking resources

• Ability to include/exclude certain links for certain traffic trunks


Design ConstraintsDesign Constraints

• Constrained to a single routing domain

– initially constrained to a single area

• Requires OSPF or IS-IS

• Unicast traffic

• Focus on supporting routing based on a combination of administrative + bandwidth constraints


Trunk AttributesTrunk Attributes




• Configured at the head-end of the trunk

• Bandwidth

• Priorities

– setup priority: priority for taking a resource

– holding priority: priority for holding a resource



• Ordered list of Path Options

– possible administratively specified paths (via an off-line central server) - {explicit list}

– Constrained-based dynamically computed paths based on combo of BW and policies

• Re-optimization

– each path option is enabled or not for re-optimization, interval given in seconds.

– Max 1 week (7*24*3600), Disable 0, Def 1h.



• Resource class affinity (Policy)

– supports the ability to include/exclude certain links for certain traffic trunks based on a user-defined Policy

– Tunnel is characterized by a

• 32-bit resource-class affinity bit string

• 32-bit resource-class mask (0 = don’t care, 1 = care)

– Link is characterized by a 32-bit resource-class attribute string

– Default-value of tunnel/link bits is 0

– Default value of the tunnel mask = 0x0000FFFF


Example 1: 4-bit String, DefaultExample 1: 4-bit String, Default

• Trunk A to B:

– tunnel = 0000, t-mask = 0011

• ADEB and ADCEB are possible

A B

0000

0000 0000

00000000

C

D E


Example 1a: 4-Bit StringExample 1a: 4-Bit String

• Setting a link bit in the lower half drives all tunnels off the link, except those specially configured

• Trunk A to B:

– tunnel = 0000, t-mask = 0011

• Only ADCEB is possible

A B

0000

0000 0000

00100000

C

D E


Example 1b: 4-Bit StringExample 1b: 4-Bit String

• A specific tunnel can then be configured to allow such links by clearing the bit in its affinity attribute mask

• Trunk A to B:

– tunnel = 0000, t-mask = 0001

• Again, ADEB and ADCEB are possible

A B

0000

0000 0000

00100000

C

D E


Example 1c: 4-Bit StringExample 1c: 4-Bit String

• A specific tunnel can be restricted to only such links by instead turning on the bit in its affinity attribute bits

• Trunk A to B:

– tunnel = 0010, t-mask = 0011

• No path is possible

A B

0000

0000 0000

00100000

C

D E


Example 2a: 4-Bit StringExample 2a: 4-Bit String

• Setting a link bit in the upper half drives has no immediate effect

• Trunk A to B:

– tunnel = 0000, t-mask = 0011

• ADEB and ADCEB are both possible

A B

0000

0000 0000

01000000

C

D E


Example 2b: 4-Bit StringExample 2b: 4-Bit String

• A specific tunnel can be driven off the link by setting the bit in its mask

• Trunk A to B:

– tunnel = 0000, t-mask = 0111

• Only ADCEB is possible

A B

0000

0000 0000

01000000

C

D E


Example 2c: 4-Bit StringExample 2c: 4-Bit String

• A specific tunnel can be restricted to only such links

• Trunk A to B:

– tunnel = 0100, t-mask = 0111

• No path is possible

A B

0000

0000 0000

01000000

C

D E


Trunk AttributeTrunk Attribute Resource Class Affinity (Policy)Resource Class Affinity (Policy)

• The user defines the semantics:

– this bit/mask says “low-delay path excluded”

– this bit/mask says “use only links 0C-3 or higher”

– this bit/mask says “use only links in region 1,2,3”


Link Attributes and Link Attributes and Their FloodingTheir Flooding



Link Resource AttributesLink Resource Attributes

• Resource attributes are configured on every link in a network

– Bandwidth

– Link Attributes

– TE-specific link metric


Link Resource AttributesLink Resource Attributes

• Resource attributes are flooded throughout the network

– Bandwidth per priority (0-7)

– Link Attributes (Policy)

– TE-specific link metric


Per-Priority Available BWPer-Priority Available BW

DT=0 Link L, BW=100 D advertises: AB(0)=100=…= AB(7)=100

AB(i) = “Available Bandwidth at priority I”

DT=2 Link L, BW=100 D advertises: AB(0)=AB(1)=AB(2)=100

AB(3)=AB(4)=…=AB(7)=70

T=1 Set-up of a tunnel over L at priority=3 for 30 units

DT=4 Link L, BW=100

D advertises: AB(0)=AB(1)=AB(2)=100 AB(3)=AB(4)=70 AB(5)=AB(6)=AB(7)=40

T=3 Set-up of an additional tunnel over L at priority=5 for 30 units


Information DistributionInformation Distribution

• Re-use the flooding service from the Link-State IGP

– opaque LSA for OSPF• draft-katz-yeung-ospf-traffic-00.txt

– new wide TLV for IS-IS• draft-ietf-isis-traffic-00.txt


Information DistributionInformation Distribution

• Periodic (timer-based)

• On significant changes of available bandwidth (threshold scheme)

• On link configuration changes

• On LSP Setup failure


Periodic TimerPeriodic Timer

• Periodically, a node checks if the current TE status is the same as the one last broadcasted

• If different, it floods its updated TE Links status


Significant ChangeSignificant Change

• Each time a threshold is crossed, an update is sent

• Denser population as utilization increases

• Different thresholds for Up and Down (stabler)

50%

100%

70%85%92%

Update

Update


LSP Setup FailureLSP Setup Failure

• Due to the threshold scheme, it is possible that one node thinks it can signal an LSP tunnel via node Z while in fact, Z does not have the required resources

• When Z receives the Resv message and refuses the LSP tunnel, it broadcasts an update of its status


Constrained-Based Constrained-Based Computation (C-SPF)Computation (C-SPF)



Constrained-Based RoutingConstrained-Based Routing

• “In general, path computation for an LSP may seek to satisfy a set of requirements associated with the LSP, taking into account a set of constraints imposed by administrative policies and the prevailing state of the network -- which usually relates to topology data and resource availability. Computation of an engineered path that satisfies an arbitrary set of constraints is referred to as "constraint based routing”.

Draft-li-mpls-igp-te-00.txt


Path ComputationPath Computation

“On demand” by the trunk’s head-end:

– for a new trunk

– for an existing trunk whose (current) LSP failed

– for an existing trunk when doing re-optimization



Input:

– configured attributes of traffic trunks originated at this router

– attributes associated with resources

• available from IS-IS or OSPF

– topology state information

• available from IS-IS or OSPF



• Prune links if:

– insufficient resources (e.g., bandwidth)

– violates policy constraints

• Compute shortest distance path

– TE uses its own metric

– Tie-break: selects the path with the highest minimum bandwidth so far, then with the smallest hop-count



Output:

– explicit route - expressed as a sequence of router IP addresses

• interface addresses for numbered links

• loopback address for unnumbered links

– used as an input to the path setup component


C-SPF AlgorithmC-SPF Algorithm

• Prune off the links that do not have the required BW

• Prune off the links that do not have the required affinity

• Run a dijkstra on the remaining topology, optimised based on the IGP metric (or RRR metric if configured)

• If several paths are still available, then do the following to ultimately select a single path

– choose the path that maximize the following value V

• V of a path is the minimum of the value L computed for each link. L on a link is the available bw at the required priority.

• This rule helps loadbalancing tunnels on various paths

– If several paths are still available, then select the path with the smallest number of hops

– If several paths are still available, select a random one


• Tunnel’s request:

– Priority 3, BW = 30 units,

– Policy string: 0000, mask: 0011

A B

0000

1000 0100

0000 0000

C

D E

10000010

G

BW(3)=60

BW(3)=50

BW(3)=80

BW(3)=20

BW(3)=50 BW(3)=70

BW(3)=80

BW/Policy ExampleBW/Policy Example


• Tunnel’s request:

– Priority 3, BW = 30 units,

– Policy string: 0000, mask: 0011

A B

C

D E

G

BW(3)=60

BW(3)=80

BW(3)=80

BW(3)=50 BW(3)=40

BW(3)=80

Tightest Constraint: 40

Tightest Constraint: 60

Maximizing the Tightest ConstraintMaximizing the Tightest Constraint


Load-Balancing TunnelsLoad-Balancing Tunnels

• all tunnels require 10

A B

C

D E

G

BW(3)=100

BW(3)=200

BW(3)=100

BW(3)=100 BW(3)=100

BW(3)=200




A B

C

D E

G

BW(3)=90

BW(3)=190

BW(3)=90

BW(3)=100 BW(3)=100

BW(3)=190




A B

C

D E

G

BW(3)=90

BW(3)=180

BW(3)=90

BW(3)=90 BW(3)=90

BW(3)=180




A B

C

D E

G

BW(3)=80

BW(3)=170

BW(3)=80

BW(3)=90 BW(3)=90

BW(3)=170




A B

C

D E

G

BW(3)=80

BW(3)=160

BW(3)=80

BW(3)=80 BW(3)=80

BW(3)=160


MPLS as the Forwarding MPLS as the Forwarding MechanismMechanism



MPLS LabelsMPLS Labels

Two types of MPLS Labels:

Prefix Labels & Tunnel Labels

LDP RSVP

MP-BGP CR-LDP

PIM

Distributed by:


MPLS as Forwarding EngineMPLS as Forwarding Engine

• Traffic engineering requires explicit routing capability

• IP supports only the destination-based routing

– not adequate for traffic engineering

• MPLS provides simple and efficient support for explicit routing

– label swapping

– separation of routing and forwarding


LSP Tunnel SetupLSP Tunnel Setup



RSVP Extensions to RFC2205RSVP Extensions to RFC2205for LSP Tunnelsfor LSP Tunnels

• Downstream-on-demand label distribution

• Instantiation of explicit label switched paths

• Allocation of network resources (e.g., bandwidth) to explicit LSPs

• Re-routing of established LSP-tunnels in a smooth fashion using the concept of make-before-break

• Tracking of the actual route traversed by an LSP-tunnel

• Diagnostics on LSP-tunnels

• The concept of nodal abstraction

• Pre-emption options that are administratively controllable

draft-ietf-mpls-rsvp-lsp-tunnel-0X.txt


RSVP Extensions: New ObjectsRSVP Extensions: New Objects

• LABEL_REQUESTLABEL_REQUEST found in Path

• LABELLABEL

• EXPLICIT_ROUTE EXPLICIT_ROUTE found in Path

• RECORD_ROUTERECORD_ROUTE found in Path, Resv

• SESSION_ATTRIBUTESESSION_ATTRIBUTE found in Path 0x01 Fast Re-route Capable, 0x02 Permit Merging, 0x04 May Reoptimize => SE

• New C-Types are also assigned for the SESSIONSESSION, SENDER_TEMPLATESENDER_TEMPLATE, FILTER_SPECFILTER_SPEC, FLOWSPECFLOWSPEC objects

• All new objects are optional with respect to RSVP (RFC2205)

• The LABEL_REQUEST and LABEL objects are mandatory with respect to MPLS LSP signalisation specification


LSP SetupLSP Setup

• Initiated at the head-end of a trunk

• Uses RSVP (with extensions) to establish Label Switched Paths (LSPs) for traffic trunks


Path Setup - ExamplePath Setup - Example

Setup: Path (ERO = R1->R2->R6->R7->R4->R9)Setup: Path (ERO = R1->R2->R6->R7->R4->R9)

Reply: Resv communicates labels andReply: Resv communicates labels andreserves bandwidth on each linkreserves bandwidth on each link

Pop

Label 22

Label 49Label 17

R8

R2

R6

R3

R4

R7

R1R5

R9

Label 32


Path Setup - More Details Path Setup - More Details

R2 R3R1

Path: Common_HeaderSession(R3-lo0, 0, R1-lo0)PHOP(R1-2)Label_Request(IP)ERO (R2-1, R3-1)Session_Attribute (S(3), H(3), 0x04) Sender_Template(R1-lo0, 00) Sender_Tspec(2Mbps)Record_Route(R1-2)

2 21 1


Path Setup - More DetailsPath Setup - More Details

R3R1

Path State: Session(R3-lo0, 0, R1-lo0)PHOP(R1-2)Label_Request(IP)ERO (R2-1, R3-1)Session_Attribute (S(3), H(3), 0x04) Sender_Template(R1-lo0, 00) Sender_Tspec(2Mbps)Record_Route (R1-2)

2 1R2

21



R3R1

Path: Common_Header Session(R3-lo0, 0, R1-lo0)PHOP(R2-2)Label_Request(IP)ERO (R3-1)Session_Attribute (S(3), H(3), 0x04) Sender_Template(R1-lo0, 00) Sender_Tspec(2Mbps)Record_Route (R1-2, R2-2)

2 1R2

21



R3R12 1

R221

Path State: Session(R3-lo0, 0, R1-lo0)

PHOP(R2-2)Label_Request(IP)

ERO ()Session_Attribute (S(3), H(3), 0x04)

Sender_Template(R1-lo0, 00) Sender_Tspec(2Mbps)

Record_Route (R1-2, R2-2, R3-1)


Resv: Common_Header

Session(R3-lo0, 0, R1-lo0)PHOP(R3-1)

Style=SE FlowSpec(2Mbps)

Sender_Template(R1-lo0, 00) Label=POP

Record_Route(R3-1)


R3R12 1

R221



R3R12 1

R221

Resv State Session(R3-lo0, 0, R1-lo0)

PHOP(R3-1)Style=SE

FlowSpec (2Mbps) Sender_Template(R1-lo0, 00)

OutLabel=POPIntLabel=5

Record_Route(R3-1)



R3R12 1

R221

Resv:Common_Header


Style=SE FlowSpec (2Mbps)

Sender_Template(R1-lo0, 00) Label=5

Record_Route(R2-1, R3-1)



R3R12 1

R221

Resv state:Session(R3-lo0, 0, R1-lo0)PHOP(R2-1)Style=SEFlowSpec (2Mbps) Sender_Template(R1-lo0, 00)Label=5Record_Route(R1-2, R2-1, R3-1)


Trunk Admission ControlTrunk Admission Control

• Performed by routers along a Label Switched Path (LSP)

• Determines if resources are available

• May tear down (existing) LSPs with a lower priority

• Does the local accounting

• Triggers IGP information distribution when resource thresholds are crossed


Link Admission ControlLink Admission Control

• Already invoked by Path message

– if BW is available, this BW is put aside in a waiting pool (waiting for the RESV msg)

– if this process required the pre-emption of resources, LCAC notified RSVP of the pre-emption which then sent PathErr and/or ResvErr for the preempted tunnel

– if BW is not available, LCAC says “No” to RSVP and a Path error is sent. A flooding of the node’s resource info is triggered, if needed

– “draft-ietf-mpls-rsvp-lsp-tunnel-02.txt”


Path MonitoringPath Monitoring

• Use of new Record Route Object

– keep track of the exact tunnel path

– detects loops


Path Re-OptimizationPath Re-Optimization

• Looks for opportunities to re-optimize

– make before break

– no double counting of reservations

– via RSVP “shared explicit” style!


Non-Disruptive Rerouting - New Non-Disruptive Rerouting - New Path SetupPath Setup

Current Path (ERO = R1->R2->R6->R7->R4->R9)Current Path (ERO = R1->R2->R6->R7->R4->R9)

New Path (ERO = R1->R2->R3->R4->R9) - shared with Current PathNew Path (ERO = R1->R2->R3->R4->R9) - shared with Current Path

Until R9 gets new Path Message, current Resv is refreshedUntil R9 gets new Path Message, current Resv is refreshed

Pop

22

4917

R8

R2

R6

R3

R4

R7

R1R5

R9

32


Non-Disruptive Rerouting - Non-Disruptive Rerouting - Switching PathsSwitching Paths

PopPop

22

3849 17

R8

R2

R6

R3

R4

R7

R1R5

R9

32

Resv: allocates labels for both pathsResv: allocates labels for both pathsReserves bandwidth once per linkReserves bandwidth once per link

PathTear can then be sent to remove old path (and release PathTear can then be sent to remove old path (and release resources)resources)

8926


Reroute - More DetailsReroute - More Details

R2 R3R1

ERO (R2-1, R3-1R2-1, R3-1)Sender_Template(R1-lo0, 0000)

2

3

1

3

12

Session(R3-lo0, 0, R1-lo0)

ERO (R2-1, …, R3-3R2-1, …, R3-3)Sender_Template(R1-lo0, 0101)

00

01

0101

Resource Sharing



R2 R3R1

Path: Common_HeaderSession(R3-lo0, 0, R1-lo0)PHOP(R1-2)Label_Request(IP)ERO (R2-1, …,R3-3)Session_Attribute (S(3), H(3), 0x04) Sender_Template(R1-lo0, 01) Sender_Tspec(3Mbps)Record_Route(R1-2)

2

3

1

3

12



R2 R3R12 31 3

Path State: Session(R3-lo0, 0, R1-lo0)PHOP(R1-2)Label_Request(IP)ERO (R2-1, …,R3-3)Session_Attribute (S(3), H(3), 0x04) Sender_Template(R1-lo0, 01)Sender_Tspec(3Mbps) Record_Route (R1-2)



R2 R3R12 31 3



R2 R3R12 31 3

RSVP:Common_Header


Style=SE FlowSpec(3Mbps)

Sender_Template(R1-lo0, 01) Label=POP

Record_Route(R3-3)



R2 R3R12 31 3



R2 R3R12 31 3

RSVP:Common_Header


Style=SE FlowSpec (3Mbps)

Sender_Template(R1-lo0, 01) Label=6

Record_Route(R2-1, …, R3-3)Sender_Template(R1-lo0, 00)

Label=5Record_Route(R2-1, R3-1)



R2 R3R12 31 3

RSVP state:Session(R3-lo0, 0, R1-lo0)PHOP(R2-1)Style=SEFlowSpec Sender_Template(R1-lo0, 01)Label=6Record_Route(R2-1, …, R3-3)Sender_Template(R1-lo0, 00)Label=5Record_Route(R2-1, R3-1)


Fast RestorationFast Restoration

Handling link failures - two complementary mechanisms:

• Path protection

• Link/Node protection


Assigning Traffic to PathsAssigning Traffic to Paths (aka autoroute) (aka autoroute)



Enhancement to SPFEnhancement to SPF

• During SPF, each new node found is moved from a TENTative list to PATHS list. Now the first-hop is being determined via:

A. Check if there is any TE tunnel terminating at this node from the current router and, if so, do the metric check

B. If there is no TE tunnel and the node is directly connected, use the first-hop from adj database

C. In none of the above applies, the first-hop is copied from the parent of this new node


Enhancement to SPF - Metric CheckEnhancement to SPF - Metric Check

Tunnel metric:

A. Relative +/- X

B. Absolute Y

C. Fixed Z

The default is relative metric of 0

Example:

Metric of native IP path to the found node = 50

1. Tunnel with relative metric of -10 => 40

2. Tunnel with relative metric of +10 => 60

3. Tunnel with absolute metric of 10 => 10


Enhancement to SPF - Metric CheckEnhancement to SPF - Metric Check

• If the metric of the found TE tunnel at this node is higher then the metric for other tunnels or native IGP path, this tunnel is not installed as next-hop

• If the metric of the found TE tunnel is equal to other TE tunnels, the tunnel is added to the existing next-hops

• If the metric of the found TE tunnel is lower than the metric of other TE tunnels or native IGP, the tunnel replaces them as the only next-hop


ConfigurationConfiguration



Enabling a Device for MPLS-TEEnabling a Device for MPLS-TE

Router(config)# mpls traffic-eng tunnels


Enabling MPLS-TE On Enabling MPLS-TE On Physical InterfacesPhysical Interfaces

Router(config-if)# mpls traffic-eng tunnels

Router(config-if)# ip rsvp bandwidth <bw1> <bw2>


MPLS-TE Configuration for OSPFMPLS-TE Configuration for OSPF

Router(config)# router ospf <AS>Router(config-router)# mpls traffic-eng area <x>Router(config-router)# mpls traffic-eng router-id loopback0


MPLS-TE Configuration For IS-ISMPLS-TE Configuration For IS-IS

Router(config)# router isisRouter(config-router)# mpls traffic-eng level <level>Router(config-router)# mpls traffic-eng router-id loopback0Router(config-router)# metric-style wide


Configuring TE Tunnel On The Configuring TE Tunnel On The HeadendHeadend

Router(config)# interface tunnel1Router(config-if)# tunnel destination A.B.C.DRouter(config-if)# tunnel mode mpls traffic-engRouter(config-if)# tunnel mpls traffic-eng bandwidth <bw1>Router(config-if)# tunnel mpls traffic-eng affinity <A> mask <M>Router(config-if)# tunnel mpls traffic-eng autoroute announceRouter(config-if)# tunnel mpls traffic-eng autoroute metric rel/abs ... Router(config-if)# tunnel mpls traffic-eng path-option 1 explicit name testRouter(config-if)# tunnel mpls traffic-eng path-option 2 dynamic


SummarySummary



MPLS TE BenefitsMPLS TE Benefits

• Provides traffic engineering capabilities at Layer 3

– above and beyond of what is provided with ATM (e.g. load-sharing on unequal cost paths)

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