1 © 2001, cisco systems, inc. course number presentation_id mpls te toi [email protected]
TRANSCRIPT
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1© 2001, Cisco Systems, Inc.
Course NumberPresentation_ID
MPLS TE TOIMPLS TE TOI
[email protected]@cisco.com
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2Presentation_ID © 2001, Cisco Systems, Inc.
AgendaAgenda
• How MPLS TE works
• What Code Is MPLS TE In?
• Platform Issues in Implementation
• Lab Demo - config
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3Presentation_ID © 2001, Cisco Systems, Inc.
How MPLS TE WorksHow MPLS TE Works
• Prerequisites
• How MPLS-TE Works
• Basic Configuration
• Knobs! Knobs! Knobs!
• Deploying and Designing
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4Presentation_ID © 2001, Cisco Systems, Inc.
PrerequisitesPrerequisites
You should already understand…
• How to configure a Cisco router
• Basic MPLS concepts like push/pop/swap, EXP, and LFIB
• How a link-state routing protocol works
• Basic QoS mechanisms like MDRR and LLQ
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5Presentation_ID © 2001, Cisco Systems, Inc.
AgendaAgenda
• Prerequisites
• How MPLS-TE Works
• Basic Configuration
• Knobs! Knobs! Knobs!
• Deploying and Desiginig
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6Presentation_ID © 2001, Cisco Systems, Inc.
How MPLS-TE WorksHow MPLS-TE Works
• How MPLS-TE Works
-What good is MPLS-TE?
-Information Distribution
-Path Calculation
-Path Setup
-Forwarding Traffic Down A Tunnel
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7Presentation_ID © 2001, Cisco Systems, Inc.
What Good Is MPLS-TE?What Good Is MPLS-TE?
• There are two kinds of networks
1. Those that have plenty of bandwidth everywhere
2. Those with congestion in some places, but not in others
• The first kind always evolve into the second kind!
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8Presentation_ID © 2001, Cisco Systems, Inc.
What Good Is MPLS-TE?What Good Is MPLS-TE?
• MPLS-TE introduces a 3rd kind:1. Those that have plenty of bandwidth everywhere
2. Those with congestion in some places, but not in others
3. Those that use all of their bandwidth to its maximum efficiency, regardless of shortest-path routing!
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9Presentation_ID © 2001, Cisco Systems, Inc.
What Good Is MPLS-TE?What Good Is MPLS-TE?
MultiProtocolLabelSwitching -TrafficEngineering
MagicProblem-solvingLaborSubstitute which isTotallyEffortless
This stuff takes work, but it’s worth it!!!
What is MPLS-TE? What is it not?
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10Presentation_ID © 2001, Cisco Systems, Inc.
Information DistributionInformation Distribution
• You need a link-state protocol as your IGP
IS-IS or OSPF
• Link-state requirement is only for MPLS-TE!
Not a requirement for VPNs, etc!
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11Presentation_ID © 2001, Cisco Systems, Inc.
Need for a Link-State ProtocolNeed for a Link-State Protocol
• Why do I need a link-state protocol?
1. To make sure info gets flooded
2. To build a picture of the entire network
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12Presentation_ID © 2001, Cisco Systems, Inc.
Need for a Link-State ProtocolNeed for a Link-State Protocol
Consider the following network:
- All links have a cost of 10
- RtrA’s path to RtrE is A->B->E, cost 20
- All traffic from A to {E,F,G} goes A->B->E
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
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13Presentation_ID © 2001, Cisco Systems, Inc.
What a DV Protocol SeesWhat a DV Protocol Sees
Node Next-Hop Cost
B B 10
C C 10
D C 20
E B 20
F B 30
G B 30
• RtrA doesn’t see all the links
• RtrA only knows about the shortest path
• This is by design
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
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14Presentation_ID © 2001, Cisco Systems, Inc.
What a LS Protocol SeesWhat a LS Protocol Sees
Node Next-Hop Cost
B B 10
C C 10
D C 20
E B 20
F B 30
G B 30
• RtrA sees all links
• RtrA only computes the shortest path
• Routing table doesn’t change
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
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15Presentation_ID © 2001, Cisco Systems, Inc.
The Problem With Shortest-PathThe Problem With Shortest-Path
Node Next-Hop Cost
B B 10
C C 10
D C 20
E B 20
F B 30
G B 30
• Some links are DS3, some are OC3
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
OC3
OC3
DS3
DS3
DS3
OC3
OC3
• RtrA has 40Mb of traffic for RtrF, 40Mb of traffic for RtrG
• Massive (44%) packet loss at RtrB->RtrE!
• Changing to A->C->D->E won’t help
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16Presentation_ID © 2001, Cisco Systems, Inc.
What MPLS-TE AddrsWhat MPLS-TE Addrs
Node Next-Hop Cost
B B 10
C C 10
D C 20
E B 20
F Tunnel0 30
G Tunnel1 30
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
OC3
OC3
DS3
DS3
DS3
OC3
OC3
• RtrA sees all links
• RtrA computes paths on properties other than just shortest cost
• No congestion!
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17Presentation_ID © 2001, Cisco Systems, Inc.
How MPLS-TE WorksHow MPLS-TE Works
• How MPLS-TE Works
-What good is MPLS-TE?
-Information Distribution
-Path Calculation
-Path Setup
-Forwarding Traffic Down A Tunnel
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18Presentation_ID © 2001, Cisco Systems, Inc.
Information DistributionInformation Distribution
• OSPF
-Uses Type 10 (Opaque Area-Local) LSAs
-See draft-katz-yeung-ospf-traffic
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19Presentation_ID © 2001, Cisco Systems, Inc.
Information DistributionInformation Distribution
• IS-IS
-Uses Type 22 TLVs
-See draft-ietf-isis-traffic
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20Presentation_ID © 2001, Cisco Systems, Inc.
Information DistributionInformation Distribution
• IS-IS and OSPF propagate the same information!
-Link identification
-TE Metric
-Bandwidth info (max physical, max reservable, available per-class)
-Attribute flags
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21Presentation_ID © 2001, Cisco Systems, Inc.
Information DistributionInformation Distribution
• TE flooding is local to a single {area|level}
• Inter-{area|level} TE harder, but possible (think PNNI)
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22Presentation_ID © 2001, Cisco Systems, Inc.
How MPLS-TE WorksHow MPLS-TE Works
• How MPLS-TE Works
-What good is MPLS-TE?
-Information Distribution
-Path Calculation
-Path Setup
-Forwarding Traffic Down A Tunnel
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23Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Modified Dijkstra at tunnel head-end
• Often referred to as CSPF
Constrained SPF
• …or PCALC (path calculation)
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24Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Normal SPF – find shortest path across all links
• See Perlman (2nd ed), Moy, etc. for explanation of SPF
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to all routers?”
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25Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Normal SPF – find shortest path across all links
• See Perlman (2nd ed), Moy, etc. for explanation of SPF
RtrA
“what’s the shortest path to all routers?”
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26Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Normal SPF – find shortest path across all links
• See Perlman (2nd ed), Moy, etc. for explanation of SPF
RtrA
RtrB
RtrC
“what’s the shortest path to all routers?”
![Page 27: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/27.jpg)
27Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Normal SPF – find shortest path across all links
• See Perlman (2nd ed), Moy, etc. for explanation of SPF
RtrA
RtrB
RtrC RtrD
“what’s the shortest path to all routers?”
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28Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Normal SPF – find shortest path across all links
• See Perlman (2nd ed), Moy, etc. for explanation of SPF
RtrA
RtrB
RtrC
RtrE
RtrD
“what’s the shortest path to all routers?”
![Page 29: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/29.jpg)
29Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Normal SPF – find shortest path across all links
• See Perlman (2nd ed), Moy, etc. for explanation of SPF
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to all routers?”
![Page 30: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/30.jpg)
30Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Normal SPF – find shortest path across all links
• See Perlman (2nd ed), Moy, etc. for explanation of SPF
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to all routers?”
![Page 31: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/31.jpg)
31Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Normal SPF – find shortest path across all links
• See Perlman (2nd ed), Moy, etc. for explanation of SPF
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to all routers?”
![Page 32: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/32.jpg)
32Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Normal SPF – find shortest path across all links
• See Perlman (2nd ed), Moy, etc. for explanation of SPF
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to all routers?”
![Page 33: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/33.jpg)
33Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Constrained SPF – find shortest path to a specific node
• Consider more than just link cost!
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to router F with 40Mb available??”
OC3
OC3
DS3
DS3
DS3
OC3
OC3
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34Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Constrained SPF – find shortest path to a specific node
• Consider more than just link cost!
RtrA
“what’s the shortest path to router F with 40Mb available??”
![Page 35: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/35.jpg)
35Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Constrained SPF – find shortest path to a specific node
• Consider more than just link cost!
RtrA
RtrB
RtrC
“what’s the shortest path to router F with 40Mb available??”
OC3
OC3
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36Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Constrained SPF – find shortest path to a specific node
• Consider more than just link cost!
RtrA
RtrB
RtrC RtrD
“what’s the shortest path to router F with 40Mb available??”
OC3
OC3
DS3
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37Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Constrained SPF – find shortest path to a specific node
• Consider more than just link cost!
RtrA
RtrB
RtrC
RtrE
RtrD
“what’s the shortest path to router F with 40Mb available??”
OC3
OC3
DS3
DS3
![Page 38: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/38.jpg)
38Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Constrained SPF – find shortest path to a specific node
• Consider more than just link cost!
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to router F with 40Mb available??”
OC3
OC3
DS3
DS3
OC3
OC3
![Page 39: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/39.jpg)
39Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Constrained SPF – find shortest path to a specific node
• Consider more than just link cost!
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to router F with 40Mb available??”
OC3
OC3
DS3
DS3
DS3
OC3
OC3
![Page 40: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/40.jpg)
40Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Constrained SPF – find shortest path to a specific node
• Consider more than just link cost!
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to router F with 40Mb available??”
OC3
OC3
DS3
DS3
DS3
OC3
OC3
![Page 41: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/41.jpg)
41Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Constrained SPF – find shortest path to a specific node
• Consider more than just link cost!
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to router F with 40Mb available??”
OC3
OC3
DS3
DS3
OC3
OC3
![Page 42: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/42.jpg)
42Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Constrained SPF – find shortest path to a specific node
• Consider more than just link cost!
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
“what’s the shortest path to router F with 40Mb available??”
OC3
OC3
DS3
DS3
OC3
![Page 43: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/43.jpg)
43Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Constrained SPF – find shortest path to a specific node
• Consider more than just link cost!
RtrA
RtrB
RtrE
RtrF
“what’s the shortest path to router F with 40Mb available??”
OC3
DS3OC3
![Page 44: 1 © 2001, Cisco Systems, Inc. Course Number Presentation_ID MPLS TE TOI eosborne@cisco.com](https://reader030.vdocuments.mx/reader030/viewer/2022032804/56649e445503460f94b381fa/html5/thumbnails/44.jpg)
44Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• “But Wait! There’s nothing different between the two SPF results!”
• ….but….
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45Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What about the 2nd path?
• Available bandwidth has changed!
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to router G with 40Mb available??”
OC3
OC3
5MB
DS3
DS3
OC3
OC3
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46Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What about the 2nd path?
• Available bandwidth has changed!
RtrA
“what’s the shortest path to router G with 40Mb available??”
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47Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What about the 2nd path?
• Available bandwidth has changed!
RtrA
RtrB
RtrC
“what’s the shortest path to router G with 40Mb available??”
OC3
OC3
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48Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What about the 2nd path?
• Available bandwidth has changed!
RtrA
RtrB
RtrC RtrD
“what’s the shortest path to router G with 40Mb available??”
OC3
OC3
DS3
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49Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What about the 2nd path?
• Available bandwidth has changed!
RtrA
RtrB
RtrC
RtrE
RtrD
“what’s the shortest path to router G with 40Mb available??”
OC3
OC3
5MB
DS3
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50Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What about the 2nd path?
• Available bandwidth has changed!
RtrA
RtrB
RtrC
RtrE
RtrD
“what’s the shortest path to router G with 40Mb available??”
OC3
OC3
5MB
DS3
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51Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What about the 2nd path?
• Available bandwidth has changed!
RtrA
RtrB
RtrC RtrD
“what’s the shortest path to router G with 40Mb available??”
OC3
OC3
DS3
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52Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What about the 2nd path?
• Available bandwidth has changed!
RtrA
RtrC RtrD
“what’s the shortest path to router G with 40Mb available??”
OC3
DS3
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53Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What about the 2nd path?
• Available bandwidth has changed!
RtrA
RtrC
RtrE
RtrD
“what’s the shortest path to router G with 40Mb available??”
OC3
DS3
DS3
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54Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What about the 2nd path?
• Available bandwidth has changed!
RtrA
RtrC
RtrE
RtrD
RtrF
RtrG
“what’s the shortest path to router G with 40Mb available??”
OC3
DS3
DS3
OC3
OC3
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55Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What about the 2nd path?
• Available bandwidth has changed!
RtrA
RtrC
RtrE
RtrD
RtrG
“what’s the shortest path to router G with 40Mb available??”
OC3
DS3
DS3OC3
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56Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
Node Next-Hop Cost
B B 10
C C 10
D C 20
E B 20
F Tunnel0 30
G Tunnel1 30
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
OC3
OC3
DS3
DS3
DS3
OC3
OC3
• End result:
-bandwidth used efficiently!
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57Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• Happy! Happy!
• Joy! Joy!
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58Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
• What if there’s more than one path that meets the minimum requirements (BW, etc)?
• PCALC algorithm:
1. find all paths with the lowest IGP cost
2. then pick the path with the highest minimum bandwidth along the path
3. then pick the path with the lowest hop count (not IGP cost, just hop count)
4. then just pick one path at random
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59Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
all left-side linksare {10,100M}
all right-side linksare {5,50M}
{cost,available BW}
RtrA RtrZ
{8,90M}
{8,90M}
{4,90M}
{10,100M}
{8,80M}
What’s the bestpath from A to Z with BW of 20M?
Path has cost of 25, not the
lowest cost!
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60Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
all left-side linksare {10,100M}
all right-side linksare {5,50M}
{cost,available BW}
RtrA RtrZ
{8,90M}
{8,90M}
{4,90M}
{8,80M}
What’s the bestpath from A to Z with BW of 20M?
Path min BW is lower than the other paths!
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61Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
all left-side linksare {10,100M}
all right-side linksare {5,50M}
{cost,available BW}
RtrA RtrZ
{8,90M}
{8,90M}
{4,90M}
What’s the bestpath from A to Z with BW of 20M?
Hop count is 5, other paths are
4!
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62Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
all left-side linksare {10,100M}
all right-side linksare {5,50M}
{cost,available BW}
RtrA RtrZ
{8,90M}
What’s the bestpath from A to Z with BW of 20M?
Pick a path at random!
{8,90M}
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63Presentation_ID © 2001, Cisco Systems, Inc.
Path CalculationPath Calculation
all left-side linksare {10,100M}
all right-side linksare {5,50M}
{cost,available BW}
RtrA RtrZ
{8,90M}
What’s the bestpath from A to Z with BW of 20M?
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64Presentation_ID © 2001, Cisco Systems, Inc.
How MPLS-TE WorksHow MPLS-TE Works
• How MPLS-TE Works
-What good is MPLS-TE?
-Information Distribution
-Path Calculation
-Path Setup
-Forwarding Traffic Down A Tunnel
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65Presentation_ID © 2001, Cisco Systems, Inc.
Path SetupPath Setup
• Cisco MPLS-TE uses RSVP
• RFC2205, plus draft-ietf-mpls-rsvp-lsp-tunnel
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66Presentation_ID © 2001, Cisco Systems, Inc.
Path SetupPath Setup
• Once the path is calculated, it is handed to RSVP
• RSVP uses PATH and RESV messages to request an LSP along the calculated path
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67Presentation_ID © 2001, Cisco Systems, Inc.
Path SetupPath Setup
• PATH message: “Can I have 40Mb along this path?”
• RESV message: “Yes, and here’s the label to use.”
• LFIB is set up along each hop
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
= PATH messages
= RESV messages
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68Presentation_ID © 2001, Cisco Systems, Inc.
Path SetupPath Setup
• Errors along the way will trigger RSVP errors
• May also trigger re-flooding of TE info if appropriate
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69Presentation_ID © 2001, Cisco Systems, Inc.
How MPLS-TE WorksHow MPLS-TE Works
• How MPLS-TE Works
-What good is MPLS-TE?
-Information Distribution
-Path Calculation
-Path Setup
-Forwarding Traffic Down A Tunnel
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70Presentation_ID © 2001, Cisco Systems, Inc.
Forwarding Traffic Down a TunnelForwarding Traffic Down a Tunnel
• There are three ways traffic can be forwarded down a TE tunnel
-Autoroute
-Static routes
-Policy routing
• For the first two, MPLS-TE gets you unequal-cost load-balancing.
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71Presentation_ID © 2001, Cisco Systems, Inc.
AutorouteAutoroute
• Autoroute = “use the tunnel as a directly connected link for SPF purposes”
• This is not the CSPF (for path determination), but the regular IGP SPF (route determination)
• Behavior is intuitive, operation can be confusing
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72Presentation_ID © 2001, Cisco Systems, Inc.
AutorouteAutoroute
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
RtrH
This is the physical topology
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
RtrI
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73Presentation_ID © 2001, Cisco Systems, Inc.
AutorouteAutoroute
This is RtrA’s logical topology
Other routers don’t see the tunnel!
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
RtrH
Tunnel1
RtrI
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74Presentation_ID © 2001, Cisco Systems, Inc.
AutorouteAutoroute
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
RtrH
Tunnel1
Node Next-Hop Cost
B B 10
C C 10
D C 20
E B 20
F B 30
G Tunnel1 30
H Tunnel1 40
I Tunnel1 40
Router A’s routing table, built via autoroute.
Everything “behind” the tunnel is routed via the tunnel.
RtrI
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75Presentation_ID © 2001, Cisco Systems, Inc.
Static routingStatic routing
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
RtrH
RtrA(config)#ip route H.H.H.H 255.255.255.255 Tunnel1
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
RtrH
RtrI
Tunnel1
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76Presentation_ID © 2001, Cisco Systems, Inc.
Static routingStatic routing
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
RtrHRtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
RtrH
RtrI
Node Next-Hop Cost
B B 10
C C 10
D C 20
E B 20
F B 30
G B 30
H Tunnel1 40
I B 40
RtrH is known via the tunnel.
RtrG is not routed to over the tunnel, even though it’s the tunnel tail!
Tunnel1
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77Presentation_ID © 2001, Cisco Systems, Inc.
Unequal-Cost Load BalancingUnequal-Cost Load Balancing
• IP routing has equal-cost load-balancing, but not unequal-cost*
• Unequal-cost load balancing difficult to do while guaranteeing a loop-free topology
*EIGRP has ‘variance’, but that’s not as flexible, and besides, MPLS-TE and EIGRP are two different things
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78Presentation_ID © 2001, Cisco Systems, Inc.
Unequal-Cost Load BalancingUnequal-Cost Load Balancing
• Since MPLS doesn’t forward based on IP header, permanent routing loops don’t happen.
• 16 hash buckets for next-hop, shared in rough proportion to tunnel BW
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79Presentation_ID © 2001, Cisco Systems, Inc.
Unequal-cost, Example 1Unequal-cost, Example 1
RtrA RtrE
RtrF
RtrG
40MB
20MB
gsr1#show ip route 192.168.1.8Routing entry for 192.168.1.8/32 Known via "isis", distance 115, metric 83, type level-2 Redistributing via isis Last update from 192.168.1.8 on Tunnel0, 00:00:21 ago Routing Descriptor Blocks: * 192.168.1.8, from 192.168.1.8, via Tunnel0 Route metric is 83, traffic share count is 2 192.168.1.8, from 192.168.1.8, via Tunnel1 Route metric is 83, traffic share count is 1
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80Presentation_ID © 2001, Cisco Systems, Inc.
Unequal-cost, Example 1Unequal-cost, Example 1
RtrA RtrE
RtrF
RtrG
40MB
20MB
Note that the load distribution is 11:5 – very close to 2:1, but not quite!
gsr1#sh ip cef 192.168.1.8 int………Load distribution: 0 1 0 1 0 1 0 1 0 1 0 0 0 0 0 0 (refcount 1) Hash OK Interface Address Packets Tags imposed
1 Y Tunnel0 point2point 0 {23} 2 Y Tunnel1 point2point 0 {34}………
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81Presentation_ID © 2001, Cisco Systems, Inc.
Unequal-cost, Example 2Unequal-cost, Example 2
RtrA RtrE
RtrF
RtrG
100MB10MB
Q:How does 100:10:1 fit into a 16-deep bucket?
1MB
gsr1#sh ip rou 192.168.1.8Routing entry for 192.168.1.8/32 Known via "isis", distance 115, metric 83, type level-2 Redistributing via isis Last update from 192.168.1.8 on Tunnel2, 00:00:08 ago Routing Descriptor Blocks: * 192.168.1.8, from 192.168.1.8, via Tunnel0 Route metric is 83, traffic share count is 100 192.168.1.8, from 192.168.1.8, via Tunnel1 Route metric is 83, traffic share count is 10 192.168.1.8, from 192.168.1.8, via Tunnel2 Route metric is 83, traffic share count is 1
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82Presentation_ID © 2001, Cisco Systems, Inc.
Unequal-cost, Example 2Unequal-cost, Example 2
RtrA RtrE
RtrF
RtrG
100MB10MB
A:Any way it wants to! 15:1, 14:2, 13:2:1, it depends on the order the tunnels come up.Deployment guideline: don’t use tunnel metrics that don’t reduce to 16 buckets!
1MB
gsr1#sh ip cef 192.168.1.8 internal
………
Load distribution: 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (refcount 1)
Hash OK Interface Address Packets Tags imposed
1 Y Tunnel0 point2point 0 {36}
2 Y Tunnel1 point2point 0 {37}
………
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83Presentation_ID © 2001, Cisco Systems, Inc.
Policy routingPolicy routing
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
RtrH
RtrI
Tunnel1
RtrA(config-if)#ip policy route-map set-tunnel
RtrA(config)#route-map set-tunnel
RtrA(config-route-map)#match ip address 101
RtrA(config-route-map)#set interface Tunnel1
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84Presentation_ID © 2001, Cisco Systems, Inc.
Policy routingPolicy routing
Node Next-Hop Cost
B B 10
C C 10
D C 20
E B 20
F B 30
G B 30
H B 40
I B 40
Routing table isn’t affected by policy routing.
Need (12.0(16)ST or 12.2T) or higher for ‘set int Tunnel’ to work (CSCdp54178)
RtrA
RtrB
RtrC
RtrE
RtrD
RtrF
RtrG
RtrH
RtrI
Tunnel1
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85Presentation_ID © 2001, Cisco Systems, Inc.
Forwarding Traffic Down a TunnelForwarding Traffic Down a Tunnel
• You can use any combination of autoroute, static routes, or PBR.
• …but simple is better unless you have a good reason.
• Recommendation: either autoroute or statics to BGP next-hops, depending on your needs.
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86Presentation_ID © 2001, Cisco Systems, Inc.
AgendaAgenda
• Prerequisites
• How MPLS-TE Works
• Basic Configuration
• Knobs! Knobs! Knobs!
• Deploying and Desiginig
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87Presentation_ID © 2001, Cisco Systems, Inc.
Basic ConfigurationBasic Configuration
• Basic Configuration
-Basic Midpoint/Tail Config
-Basic Headend Config
-Path-option
-Bandwidth
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88Presentation_ID © 2001, Cisco Systems, Inc.
Basic Midpoint/Tail ConfigBasic Midpoint/Tail Config
(globally)
ip cef {distributed}
mpls traffic-eng tunnels
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89Presentation_ID © 2001, Cisco Systems, Inc.
Basic Midpoint/Tail ConfigBasic Midpoint/Tail Config
(per interface)
mpls traffic-eng tunnels
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90Presentation_ID © 2001, Cisco Systems, Inc.
Basic Midpoint/Tail ConfigBasic Midpoint/Tail Config
(if IGP == OSPF)
router ospf <x>
mpls traffic-eng router-id Loopback0
mpls traffic-eng area <y>
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91Presentation_ID © 2001, Cisco Systems, Inc.
Basic Midpoint/Tail ConfigBasic Midpoint/Tail Config
(if IGP == OSPF)
• MPLS TE is a single area only (usually area 0)
• RID must be set (unlike OSPF RID)
It’s a Very Very Good idea to make it a /32 loopback.
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92Presentation_ID © 2001, Cisco Systems, Inc.
Basic Midpoint/Tail ConfigBasic Midpoint/Tail Config
(if IGP == IS-IS)
router isis <x>
mpls traffic-eng router-id Loopback0
mpls traffic-eng level-{1,2}
metric-style wide
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93Presentation_ID © 2001, Cisco Systems, Inc.
Basic Midpoint/Tail ConfigBasic Midpoint/Tail Config
(if IGP == IS-IS)
• MPLS TE is a single level only
• RID must be set (unlike OSPF RID)
It’s a Very Very Good idea to make it a /32 loopback.
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94Presentation_ID © 2001, Cisco Systems, Inc.
Basic Midpoint/Tail ConfigBasic Midpoint/Tail Config
‘metric-style wide’ - ???
• IS-IS must have wide metrics enabled
• This is discussed in more detail later in this presentation; see also www.cisco.com.
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95Presentation_ID © 2001, Cisco Systems, Inc.
Basic Midpoint/Tail ConfigBasic Midpoint/Tail Config
• Total config tally so far:
1 line globally
1 line per interface
2 lines if OSPF
3 lines if IS-IS
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96Presentation_ID © 2001, Cisco Systems, Inc.
Basic Headend ConfigBasic Headend Config
• Headend needs the 4-5 ‘mid/tail’ lines
• But wait – there’s more!
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97Presentation_ID © 2001, Cisco Systems, Inc.
Basic Headend ConfigBasic Headend Config
• Create the tunnel interfaceinterface Tunnel0
ip unnumbered Loopback0
tunnel mode mpls traffic-eng
tunnel source Loopback0
tunnel destination <tunnel endpoint>
tunnel mpls traffic-eng autoroute
tunnel mpls traffic-eng path-option 10 dynamic
unnumbered to Loop0
path-option tells the tunnel how to get to tail’10’ is the priority of the path-option
there are other options besides dynamic
autoroute is not strictly necessary, but is useful
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98Presentation_ID © 2001, Cisco Systems, Inc.
Basic Headend ConfigBasic Headend Config
• Total config tally:
1 line globally
1 line per interface
2 lines if OSPF
3 lines if IS-IS
7 lines per tunnel at headend
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99Presentation_ID © 2001, Cisco Systems, Inc.
AgendaAgenda
• Prerequisites
• How MPLS-TE Works
• Basic Configuration
• Knobs! Knobs! Knobs!
• Deploying and Desiginig
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100Presentation_ID © 2001, Cisco Systems, Inc.
Knobs! Knobs! Knobs!Knobs! Knobs! Knobs!
• Influencing the Path Selection
• Auto-Bandwidth
• Fast Reroute
• DiffServ-Aware Traffic Engineering
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101Presentation_ID © 2001, Cisco Systems, Inc.
Knobs! Knobs! Knobs!Knobs! Knobs! Knobs!
• Influencing the Path Selection
Bandwidth
Priority
Administrative Weight
Attributes & Affinity
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102Presentation_ID © 2001, Cisco Systems, Inc.
BandwidthBandwidth
ip rsvp bandwidth <x> <y>
• Per-physical-interface command
• X = amount of reservable BW, in K
• Y = not used by MPLS-TE
• default: X==Y==75% of link bandwidth
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103Presentation_ID © 2001, Cisco Systems, Inc.
PriorityPriority
tunnel mpls traffic-eng <S> {H}
• Configured on tunnel inteface
• S = setup priority (0-7)
• H = holding priority (0-7)
• lower number is more important, or better.
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104Presentation_ID © 2001, Cisco Systems, Inc.
PriorityPriority
• New tunnel with better setup priority will force teardown of already-established tunnel with worse holding priority
• Configuring S<H is illegal
• Default is S=7,H=7
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105Presentation_ID © 2001, Cisco Systems, Inc.
PriorityPriority
RtrB
RtrA
RtrC RtrD45MB
45MB
45MB
= 40MB tunnel with S=7, H=7
= 40MB tunnel with S=6, H=6
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106Presentation_ID © 2001, Cisco Systems, Inc.
PriorityPriority
RtrB
RtrA
RtrC RtrD45MB
45MB
45MB
= 40MB tunnel with S=7, H=7
= 40MB tunnel with S=6, H=6
ResvTear
• RtrC sends ResvTear to RtrA, tunnel is torn down.
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107Presentation_ID © 2001, Cisco Systems, Inc.
PriorityPriority
“Should I ever set S != H?”
No. Not unless you know you have a good reason to.
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108Presentation_ID © 2001, Cisco Systems, Inc.
Administrative WeightAdministrative Weight
mpls traffic-eng administrative-weight <X>
• Per-physical-interface command
• X = 0-(232 –1)
• gives a metric that be considered for use instead of the IGP metric
• this can be used as a per-tunnel delay-sensitive metric for doing VoIP TE
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109Presentation_ID © 2001, Cisco Systems, Inc.
Administrative WeightAdministrative Weight
tunnel mpls traffic-eng path-selection metric {te|igp}
• Per-tunnel command
• default is ‘igp’
• ‘te’ uses the configured administrative-weight to determine shortest cost
• use this as a delay-sensitve metric
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110Presentation_ID © 2001, Cisco Systems, Inc.
Delay-Sensitve Metric with Delay-Sensitve Metric with Adminastrative WeightAdminastrative Weight
tunnel mpls traffic-eng path-selection metric {te|igp}
mpls traffic-eng administrative-weight <x>
• configure admin weight == interface delay
• configure VoIP tunnels to use TE metric to calculate the path
• delay-sensitive metric!
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111Presentation_ID © 2001, Cisco Systems, Inc.
Attributes & AffinityAttributes & Affinity
• Link attribute – 32 separate link properties
• Tunnel affinity – desire for links to have certain properties set
• Invent your own property meanings
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112Presentation_ID © 2001, Cisco Systems, Inc.
Administrative WeightAdministrative Weight
mpls traffic-eng attribute-flags <0x0-0xFFFFFFFF>
• Per-physical-interface command
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113Presentation_ID © 2001, Cisco Systems, Inc.
Administrative WeightAdministrative Weight
tunnel mpls traffic-eng affinity <0x0-0xFFFFFFFF> {mask <0x0-
0xFFFFFFFF>}
• Per-tunnel command
• Mask is a collection of do-care bits
• ‘affinity 0x2 mask 0xA’ means ‘I care about bits 2 and 8; bit 2 must be set, bit 8 must be 0’
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114Presentation_ID © 2001, Cisco Systems, Inc.
Administrative WeightAdministrative Weight
• Q: How should I use admin-weight?
• A: To exclude some links from consideration by some tunnels
• …so give a satellite link an attribute of 0x2, and any VoIP tunnels can be configured with ‘affinity 0x0 mask 0x2’
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115Presentation_ID © 2001, Cisco Systems, Inc.
Knobs! Knobs! Knobs!Knobs! Knobs! Knobs!
• Influencing the Path Selection
• Auto-Bandwidth
• Fast Reroute
• DiffServ-Aware Traffic Engineering
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116Presentation_ID © 2001, Cisco Systems, Inc.
Auto-BandwidthAuto-Bandwidth
tunnel mpls traffic-eng auto-bw ? collect-bw Just collect Bandwidth info on this tunnel frequency Frequency to change tunnel BW max-bw Set the Maximum Bandwidth for auto-bw on this tunnel min-bw Set the Minimum Bandwidth for auto-bw on this tunnel <cr>
• Per-tunnel command
• Periodically changes tunnel BW reservation based on traffic out tunnel
• Timers are tunable to make auto-bw more or less sensitive
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117Presentation_ID © 2001, Cisco Systems, Inc.
Auto-BandwidthAuto-Bandwidth
tunnel mpls traffic-eng auto-bw ? collect-bw Just collect Bandwidth info on this tunnel frequency Frequency to change tunnel BW max-bw Set the Maximum Bandwidth for auto-bw on this tunnel min-bw Set the Minimum Bandwidth for auto-bw on this tunnel <cr>
• Per-tunnel command
• Periodically changes tunnel BW reservation based on traffic out tunnel
• Timers are tunable to make auto-bw more or less sensitive
tradeoff: quicker reaction vs. more churn
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118Presentation_ID © 2001, Cisco Systems, Inc.
Auto-BandwidthAuto-Bandwidth
gsr1#sh mpls traffic-eng tunnels t0…Config Parameters:… auto-bw: (86400/86259) 0 Bandwidth Requested: 100
• 86400 = reoptimization time (default 24h)tunnel mpls traffic-eng auto-bw frequency <x>
• 86259 = time left to reoptimization
• 0 = BW measured at end of last reopt interval
• bw requested = signalled tunnel BWtunnel mpls traffic-eng {max-bw|min-bw} <bw>
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119Presentation_ID © 2001, Cisco Systems, Inc.
Knobs! Knobs! Knobs!Knobs! Knobs! Knobs!
• Influencing the Path Selection
• Auto-Bandwidth
• Fast Reroute
• DiffServ-Aware Traffic Engineering
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120Presentation_ID © 2001, Cisco Systems, Inc.
Fast RerouteFast Reroute
• In an IP network, a link failure causes several seconds of outageThing Dependency TimeLink failure detection
Media- and platform-specific
~usecs (POS + APS)
Info propagation IGP timers, network size, collective router load
~5-30sec
Route recalculation LSDB size, CPU load ~1-2sec
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121Presentation_ID © 2001, Cisco Systems, Inc.
Fast RerouteFast Reroute
• In an MPLS network, there’s more work to be done, so a (slightly) longer outage happensThing Dependency TimeLink failure detection
Media- and platform-specific
~usecs (POS + APS)
Info propagation IGP timers, network size, collective router load
~5-30sec
Route recalculation LSDB size, CPU load ~1-2sec
New LSP setup network size, CPU load
~5-10sec
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122Presentation_ID © 2001, Cisco Systems, Inc.
Three Kinds of FRRThree Kinds of FRR
• Link Protection
the only scheme implemented today
• Node Protection
on the way
• Path Protection
on development radar
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123Presentation_ID © 2001, Cisco Systems, Inc.
Link ProtectionLink Protection
• TE tunnel A->B->D->E
RtrDRtrB
RtrC
RtrERtrA
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124Presentation_ID © 2001, Cisco Systems, Inc.
Link ProtectionLink Protection
• B has a pre-provisioned backup tunnel to the other end of the protected link (RtrD)
• B relies on the fact that D is using global label space
RtrDRtrB
RtrC
RtrERtrA
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125Presentation_ID © 2001, Cisco Systems, Inc.
Link ProtectionLink Protection
• B->D link fails, A->E tunnel is encapsulated in B->D tunnel
• Backup tunnel is used until A can recompute tunel path as A->B->C->D->E (so 10-30sec or so)
RtrC
RtrERtrA RtrDRtrB
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126Presentation_ID © 2001, Cisco Systems, Inc.
Link ProtectionLink Protection
• On tunnel headend:
tunnel mpls traffic-eng fast-reroute
RtrC
RtrERtrA RtrDRtrB
• On protected link:
mpls traffic-eng backup-path <backup-tunnel>
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127Presentation_ID © 2001, Cisco Systems, Inc.
Node ProtectionNode Protection
RtrA
RtrC
RtrERtrDRtrB RtrF
•RtrA has a tunnel A->B->D->E->F
•RtrB has a protect tunnel B->C->E->D
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128Presentation_ID © 2001, Cisco Systems, Inc.
Node ProtectionNode Protection
RtrA
RtrC
RtrERtrDRtrB RtrF
• Link protection is OK if the B->D link goes down
• What if Router D goes away?
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129Presentation_ID © 2001, Cisco Systems, Inc.
Node ProtectionNode Protection
RtrA
RtrC
RtrERtrDRtrB RtrF
• Solution: protect tunnel to the hop past the protected link
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130Presentation_ID © 2001, Cisco Systems, Inc.
Node ProtectionNode Protection
• Node protection still has the same convergence properties as link protection
• Deciding where to place your backup tunnels is a much harder to problem to solve large-scale
…turns out it’s an NP-complete problem.
• For small-scale protection, link may be better
• Cisco is developing tools to solve these hard problems for you (see TunnelVision, later)
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131Presentation_ID © 2001, Cisco Systems, Inc.
Path ProtectionPath Protection
RtrA
RtrC
RtrERtrDRtrB RtrF
• Path Protection: multiple tunnels from TE head to tail, across diverse paths
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132Presentation_ID © 2001, Cisco Systems, Inc.
Path ProtectionPath Protection
• Path Protection: least scalable, most resource-consuming, slowest convergence of all 3 protection schemes
• Path protection is useful in two places:
1) when you have more links than tunnels
2) when you need to protect links not using global label space
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133Presentation_ID © 2001, Cisco Systems, Inc.
Path vs. Local ProtectionPath vs. Local Protection
Thing Dependency TimeLink failure detection Media- and platform-
specific~usecs (POS + APS)
Local switchover to protect tunnel
RP->IPC communication time
~few msec or less
Thing Dependency TimeLink failure detection Media- and platform-
specific~usecs (POS + APS)
Info propagation IGP timers, network size, collective router load
~5-30sec
Headend switchover to protect LSP
network size, CPU load ~msec
Local (link/node) Protection
Path Protection
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134Presentation_ID © 2001, Cisco Systems, Inc.
Path vs. Local ProtectionPath vs. Local Protection
How Many Backup Tunels Are Required?
• consider 3 LSPs: A->J, B->J, C->
• how can we protect against a failure of RtrF?
RtrB RtrD
RtrA
RtrCRtrE
RtrF
RtrH
RtrG RtrI RtrJ
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135Presentation_ID © 2001, Cisco Systems, Inc.
Path vs. Local ProtectionPath vs. Local Protection
Protection Scheme 1 tunnel per…Link protection Protected link (since all protected links are p2p)
Number of Backup Tunnels Required
RtrB
RtrA
RtrCRtrE
RtrH
RtrG RtrI RtrJ
Protecting the D->F linkProtect LSP carries 2 LSPs inside it
RtrD RtrF
= protecting B,G
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136Presentation_ID © 2001, Cisco Systems, Inc.
Path vs. Local ProtectionPath vs. Local Protection
Protection Scheme 1 tunnel per…Node protection Next-next-hop
Number of Backup Tunnels Required
RtrB RtrD
RtrA
RtrCRtrE
RtrF
RtrH
RtrG RtrI RtrJ
Protecting Router F= protecting R
= protecting B,G
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137Presentation_ID © 2001, Cisco Systems, Inc.
Path vs. Local ProtectionPath vs. Local Protection
Protection Scheme 1 tunnel per…Path protection LSP
Number of Backup Tunnels Required
RtrB RtrD
RtrA
RtrCRtrE
RtrF
RtrH
RtrG RtrI RtrJ
Protecting Each LSPR and R’ have mutually exlusive reservations!
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138Presentation_ID © 2001, Cisco Systems, Inc.
Path vs. Local ProtectionPath vs. Local Protection
Protection Scheme 1 tunnel per…Link protection Protected link (since all protected links are p2p)
Node protection Next-next-hop
Path protection LSP
Number of Backup Tunnels Required
• So is Path Protection evil?
No. But it has some scalability limits.
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139Presentation_ID © 2001, Cisco Systems, Inc.
Knobs! Knobs! Knobs!Knobs! Knobs! Knobs!
• Influencing the Path Selection
• Auto-Bandwidth
• Fast Reroute
• DiffServ-Aware Traffic Engineering
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140Presentation_ID © 2001, Cisco Systems, Inc.
Diffserv-Aware Traffic Diffserv-Aware Traffic EngineeringEngineering
• MPLS can advertise and reserve bandwidth on a link
• Works great, but what if you send a mix of LLQ and BE traffic down a TE tunnel?
• Need some way to differentiate and reserve LLQ bandwidth on a link.
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141Presentation_ID © 2001, Cisco Systems, Inc.
Diffserv-Aware Traffic Diffserv-Aware Traffic EngineeringEngineering
• 2 tunnels across C<->E link
• 40MB each tunnel
• 100MB reservable on C<->E, with a 30MB LLQ
• What happens when both tunnels send 20MB of VoIP traffic?
RtrA
RtrB
RtrC
RtrE
RtrD RtrF
RtrG
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142Presentation_ID © 2001, Cisco Systems, Inc.
Diffserv-Aware Traffic Diffserv-Aware Traffic EngineeringEngineering
• Problem: only one pool on an interface, no way to differentiate what types of traffic are carried!
• Solution: advertise more than one pool!
RtrA
RtrB
RtrC
RtrE
RtrD RtrF
RtrG
30MB LLQ+40MB LLQ traffic = 10MB not LLQ’d!
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143Presentation_ID © 2001, Cisco Systems, Inc.
Diffserv-Aware Traffic Diffserv-Aware Traffic EngineeringEngineering
ip rsvp bandwidth <x> sub-pool <y>
• ‘this link has available bandwidth of X, Y of which is in a sub-pool’
• Not quite two pools, really – no sense in witholding bandwidth from global availabilty if it’s not in use
• …which means sub-pool tunnels need to have a better priority than non-sub-pool tunnels.
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144Presentation_ID © 2001, Cisco Systems, Inc.
Diffserv-Aware Traffic Diffserv-Aware Traffic EngineeringEngineering
tunnel mpls traffic-eng bandwidth <x> sub-pool
• ‘this tunnel wants to reserve X Kbps from a sub-pool’
• sub-pool BW is looked at instead of global pool BW
• if sub-pool BW is not available, tunnel won’t come up
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145Presentation_ID © 2001, Cisco Systems, Inc.
AgendaAgenda
• Prerequisites
• How MPLS-TE Works
• Basic Configuration
• Knobs! Knobs! Knobs!
• Deploying and Designing
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146Presentation_ID © 2001, Cisco Systems, Inc.
Deploying and DesigningDeploying and Designing
• Deployment Methodologies
• Scalability
• Management
• Security
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147Presentation_ID © 2001, Cisco Systems, Inc.
Deployment MethodologiesDeployment Methodologies
• Two ways to deploy MPLS-TE
-as needed to clear up congestion
-full mesh between a set of routers
• Both methods are valid, both have their pros and cons
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148Presentation_ID © 2001, Cisco Systems, Inc.
As NeededAs Needed
• Case study: a large US ISP
RtrA
RtrB
RtrD RtrE
RtrC
•All links are OC12•A has consistent 700MB to send to C•~100MB constantly dropped!
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149Presentation_ID © 2001, Cisco Systems, Inc.
As NeededAs Needed
• Solution: multiple tunnels, unequal-cost load sharing!
RtrB
RtrA
RtrD RtrE
RtrC
•Tunnels with bandwidth in 3:1 ratio•175MB sent the long way•525MB sent the short way•No out-of-order packet issues –
CEF’s normal per-flow hashing is used!
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150Presentation_ID © 2001, Cisco Systems, Inc.
As NeededAs Needed
• From RtrA’s perspective, topo is:
RtrB
RtrA
RtrD RtrE
RtrC
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151Presentation_ID © 2001, Cisco Systems, Inc.
As NeededAs Needed
• As Needed: easy, quick, but hard to track over time.
• Easy to forget why a tunnel is in place
• Inter-node BW requirements may change, tunnels may be working around issues that no longer exist
• Link protection pretty straightforward, node protection much harder to track
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152Presentation_ID © 2001, Cisco Systems, Inc.
Full MeshFull Mesh
• Put a full mesh of TE tunnels between routers
• Initially deploy tunnels with 0 BW
• Watch Tunnel inteface stats, see how much BW you are using between router pairs
-Tunnels are intefaces – use IF-MIB!
-Make sure that tunnel bw <= network bw
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153Presentation_ID © 2001, Cisco Systems, Inc.
Full MeshFull Mesh
• Some folks deploy full mesh just to get router-to-router (pop-to-pop) traffic matrix
• Largest TE network ~80 routers full mesh (~6400 tunnels)
• As tunnel BW is changed, tunnels will find the best path across your network
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154Presentation_ID © 2001, Cisco Systems, Inc.
Full MeshFull Mesh
RtrA
RtrB
RtrD RtrE
RtrC
• Physical topology is:
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155Presentation_ID © 2001, Cisco Systems, Inc.
Full MeshFull Mesh
RtrA
RtrB
RtrD RtrE
RtrC
• Logical topology is:
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156Presentation_ID © 2001, Cisco Systems, Inc.
Full MeshFull Mesh
• Things to remember with full mesh
-N routers, N*(N-1) tunnels
-Routing protocols not run over TE tunnels – unlike an ATM full mesh!
-Tunnels are unidirectional – this is a Good Thing
…can have different BW reservations in two different directions
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157Presentation_ID © 2001, Cisco Systems, Inc.
Full MeshFull Mesh
• Best practices for full mesh:
-periodically reoptimize tunnels based on need (just like an ATM network)
-TE was always designed to be a combination of online (router-based) and offline (NMS) calculation
-Node protection more practical in a full-mesh, offline-generate TE topo
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158Presentation_ID © 2001, Cisco Systems, Inc.
Deploying and DesigningDeploying and Designing
• Deployment Methodologies
• Scalability
• Management
• Security
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159Presentation_ID © 2001, Cisco Systems, Inc.
ScalabilityScalability
• How many tunnels on a router?
Code # headend tunnels
# of midpoints
12.0S 300 10,00012.0ST 600 10,000
• Tests were done on a GSR.
• RSP4, RSP8, VXR300, VXR400 will be similar
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160Presentation_ID © 2001, Cisco Systems, Inc.
ScalabilityScalability
• 300 headends = ~90,000 tunnels
• 600 headends = ~360,000 tunnels
• Largest TE network today = ~6400 tunnels
• 90,000 tunnels = 6400*14
• 360,000 tunnels = 6400*56
• There are other factors to consider
-IGP scaling, BGP, etc
• …but MPLS-TE is not the gating factor in network scaling!
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161Presentation_ID © 2001, Cisco Systems, Inc.
ScalabilityScalability
• Largest TE network today = ~6400 tunnels
• 80 routers, ~6400 tunnels full mesh
• 12.0S scales to 300 headends, ~90,000 tunnels full mesh
• 12.0ST – 600 headends, 360,000 tunnels full mesh
• 300=80*3.75
..or (90,000=6400*14) if you’re in marketing
• 600=80*7.50
… or (360,000=6400*56)
• Bottom line: MPLS-TE is not a gating factor in network scaling!
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162Presentation_ID © 2001, Cisco Systems, Inc.
ScalabilityScalability
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120limit/120st/120st14/scalable.htm
…or just search CCO for “Scalability Enhancements for MPLS Traffic Engineering”
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163Presentation_ID © 2001, Cisco Systems, Inc.
Deploying and DesigningDeploying and Designing
• Deployment Methodologies
• Combining VPN+TE
• Scalability
• Management
• Security
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164Presentation_ID © 2001, Cisco Systems, Inc.
Traffic Engineering MIBsTraffic Engineering MIBs
• Interfaces MIB
• MPLS-TE-MIB
• CISCO-TE-MIB
• MPLS-DS-TE-MIB
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165Presentation_ID © 2001, Cisco Systems, Inc.
MPLS-TE-MIBMPLS-TE-MIB
• Goal: Exposes MPLS TE tunnels
Configured tunnel heads and path(s)
Active path(s)
Back-up/stand-by path(s)
Traps
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166Presentation_ID © 2001, Cisco Systems, Inc.
MPLS-DS-TE-MIBMPLS-DS-TE-MIB
• Goal: Exposes DiffServ-Aware Traffic Engineering parameters.
• Extends the MPLS-TE-MIB and MPLS-LSR-MIBs.
• Work still in progress: presented version 00 in Minneapolis IETF meeting (March 2001).
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167Presentation_ID © 2001, Cisco Systems, Inc.
Cisco-TE-MIBCisco-TE-MIB
• Exposes non-standardized TE features such as additional CSPF extensions, auto-bandwidth tunnels, link/node protection, path options, etc…, etc….
• Other vendors have similar proprietary MIBs.
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168Presentation_ID © 2001, Cisco Systems, Inc.
TunnelVisionTunnelVision
• Need a tool to help manage TE LSPs?
• TunnelVision (server and client component, will run on Solaris and Win2k)
• Not a network modeling tool!
Use WANDL, Orchestream, MakeSys, Opnet, others
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169Presentation_ID © 2001, Cisco Systems, Inc.
TunnelVision ArchitectureTunnelVision Architecture
Browser
Data
Control
TVApplet
Solaris WorkStation
TV Server
Web Server
Telnet
http
ApplicationCommands
SNMP
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170Presentation_ID © 2001, Cisco Systems, Inc.
TunnelVision Client ScreenshotTunnelVision Client Screenshot
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171Presentation_ID © 2001, Cisco Systems, Inc.
TunnelVisionTunnelVision
• Cisco is also working with an external partner to add node protection path calculation
• The partner has world-class algorithm development experience
• TunnelVision will feed topology to this tool, tool will calculate backup paths
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172Presentation_ID © 2001, Cisco Systems, Inc.
Other ToolsOther Tools
• There are other MPLS-TE tools
WANDL, Make Systems, Orchestream, OpNet, etc.
• Off-net modeling and path calculation very important to help scale TE deployment
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173Presentation_ID © 2001, Cisco Systems, Inc.
Deploying and DesigningDeploying and Designing
• Deployment Methodologies
• Scalability
• Management
• Security
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174Presentation_ID © 2001, Cisco Systems, Inc.
SecuritySecurity
• MPLS-TE is not enabled on externally facing intefaces
• Biggest security risk is spoofed RSVP
-hacker would have to know a lot about your topo to do anything
-RSVP authentication exists (rfc2747), not implemented
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175Presentation_ID © 2001, Cisco Systems, Inc.
SecuritySecurity
• MPLS-TE can hide your network topology from the outside world
• Is this “security”? That’s debatable. But it’s certainly a neat knob!
RtrA(config)#no mpls ip propagate-ttl ?
forwarded Propagate IP TTL for forwarded traffic
local Propagate IP TTL for locally originated traffic
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176Presentation_ID © 2001, Cisco Systems, Inc.
ConclusionConclusion
• TE is cool
• You should use lots of it
• It will make you popular
• It also cures leprosy, rickets, and tennis elbow!
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177Presentation_ID © 2001, Cisco Systems, Inc.
AgendaAgenda
• How MPLS TE works
• What Code Is MPLS TE In?
• Platform Issues in Implementation
• Lab Demo - config
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178Presentation_ID © 2001, Cisco Systems, Inc.
What Code Is MPLS-TE In?What Code Is MPLS-TE In?
• IS-IS Support: 12.0(5)S, 12.0(6)T
• OSPF Support: 12.0(8)S, 12.1(3)T
• Also in future derivatives of these trains
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179Presentation_ID © 2001, Cisco Systems, Inc.
AgendaAgenda
• How MPLS TE works
• What Code Is MPLS TE In?
• Platform Issues in Implementation
• Lab Demo - config
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180Presentation_ID © 2001, Cisco Systems, Inc.
Platform Issues in ImplementationPlatform Issues in Implementation
• Basic TE needs software only
RSVP, IS-IS, OSPF, TE
• DS-TE
Needs some form of LLQ
Queueing not tied to advertisement (yet!)
• FRR
Need some quick way to communicate cutover to LCs
• Label Push/Pop
Could push 2 labels (TE+LDP), 3 if VPN also
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181Presentation_ID © 2001, Cisco Systems, Inc.
Reading MaterialReading Material
• ENG-59293 – MPLS Forwarding Spec
• ENG-42799 – TE FRR Design Spec
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182Presentation_ID © 2001, Cisco Systems, Inc.
AgendaAgenda
• How MPLS TE works
• What Code Is MPLS TE In?
• Platform Issues in Implementation
• Lab Demo - config
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183Presentation_ID © 2001, Cisco Systems, Inc.
Core TopologyCore Topology
SRP12N6
OC192N5
OC48N7
OC3POSN2
OC3POSN3
OC48N4
OC48N8
OC12N10 OC12
N11OC12N12
OC12N13
ATM OC12
ATM OC12
POS5/0 POS0/0
POS1/0 POS1/0
POS2/0
G S R 1
G S R 4 G S R 5
G S R 8
G S R 2
POS0/0
POS0/0
POS0/1
G S R 3
G S R 6
G S R 7
POS0/0
POS3/0
POS2/0 POS1/0
POS2/1
POS1/1
POS1/0
POS1/1
POS1/0
to vpnto vpn
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184Presentation_ID © 2001, Cisco Systems, Inc.
TE TopologyTE Topology
AS3402
G S R 1V XR 15V XR 14
V XR 13 V XR 16
N23
N20
N21
N 22
N 25
N24 B G P
R IP
A S 65001
G S R 8
V XR 12
V XR 11
V XR 10
V XR 9
N26
N27
N29
N30
N 31
N 28
O S P F
B G P A S 65501
Tun12
Tun11
Tun15
N O TE : Tun12 and Tun15flow across the bo ttom(long) path and arepro tected via the toppath .