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MPLS Traffic Engineering

MPLS Traffic Engineering provides mechanisms to optimize network traffic flow and efficiently utilize bandwidth. It determines paths based on additional parameters like available resources and constraints. This allows load balancing across unequal paths and routing around failed links or nodes. MPLS TE uses extensions to IGPs to distribute link attributes and tunnel information. Constrained Shortest Path First (CSPF) is used for path computation to find paths meeting constraints like bandwidth and affinities. Tunnels are set up using RSVP-TE and traffic can be forwarded down tunnels using methods like static routes, auto-routing, or policy routing. Fast Re-Route provides local repair of TE tunnels if a link or node fails to minimize traffic loss.

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MPLS Traffic Engineering Tutorial APNIC 44 14 September 2017 Jessica Wei
Acknowledgement • Cisco Systems 2
Overview of MPLS TE 3
Why MPLS Traffic Engineering? • Handling unexpected congestion • Better utilization of available bandwidth • Route around failed links/nodes • Capacity planning 4
Optimal Traffic Engineering 5 Tunnel 1 Tunnel 2 R1 R2 R3 R4 R5 R6 IP TE MPLS TE Shortest path Determines the path at the source based on additional parameters (available resources and constraints, etc.) Equal cost load balancing Load sharing across unequal paths can be achieved.
MPLS Application Scenario 6 MPLS CORE Enterprise Enterprise Enterprise L3VPN L2VPN L2VPN Enterprise TE Backup Path for PE1-PE3 PE1 P PE2 PE3 PE4 P P P TE Main Path for PE1-PE3
How MPLS TE Works 7 • What is the information? • Dynamically • Manually • RSVP-TE • Autoroute • Static • Policy Information Distribution Path Calculation Path Setup Forward the Traffic Down to the Tunnel
Terminology—Head, Tail, LSP Upstream R1 R2 Downstream R3 TE Tunnel R1 to R4 R4 Head- End Tail-EndMid-Points
Information Distribution 9
Attributes 10 • Available Bandwidth • Attribute flags (Link Affinity) • Administrative weight (TE-specific link metric) Tunnel Attributes • Tunnel Required Bandwidth • Tunnel Affinity & Mask • Priority TE Tunnel
Bandwidth on Physical Link • Bandwidth – the amount of reservable bandwidth on a physical link 11 R1(Config)# interface gigabitethernet 0/0/5 R1(config-if)# mpls traffic-eng tunnels R1(config-if)# ip rsvp bandwidth 512 R1 Reserved bandwidth is 512 kbps GE0/0/5
Bandwidth Required by Tunnel • Bandwidth required by the tunnel across the network • Not a mandatory command. If not configured, tunnel is requested with zero bandwidth. 12 R1(config)# interface tunnel 1 R1(config-if)# tunnel mpls traffic-eng bandwidth 100 R1 R2 TE Tunnel LSP
Priority • Each tunnel has 2 priorities: – Setup priority – Holding priority • Value: 0~7, 0 indicated the highest priority, 7 indicates the lowest priority. 13 TE Tunnel 1 R1 to R4 R1 R2 R3 R4 BW=300 Kbps BW=200 kbps Priority: S1=3 H1=3 TE Tunnel 2 R1 to R3 BW=200 kbps Priority: S2=2 H2=2 S2 < H1
Priority • Each tunnel has 2 priorities: – Setup priority – Holding priority • Value: 0~7, 0 indicated the highest priority, 7 indicates the lowest priority. 14 TE Tunnel 1 R1 to R4 R1 R2 R3 R4 BW=300 Kbps BW=200 kbps Priority: S1=3 H1=3 TE Tunnel 2 R1 to R3 BW=200 kbps Priority: S2=2 H2=2 S2 < H1 Tunnel 2 preempts the BW, tunnel 1 has been torn down. Torn down Set up
Configure Priority 15 R1(config)# interface tunnel 1 R1(config-if)# tunnel mpls traffic-eng priority 3 3 R 1 R 2 TE Tunnel • Recommended that priority S=H; if a tunnel can setup at priority “X”, then it should be able to hold at priority “X” too! • Configuring S > H is illegal; tunnel will most likely be preempted • Default is S = 7, H = 7
Attribute Flags • An attribute flag is a 32-bit bitmap on a link that indicate the existence of up to 32 separate properties on that link, also called link affinity or administrative group. 16 R1(config)# interface ethernet 0/1 R1(config-if)# mpls traffic-eng attribute-flags 0x8 R 1
Tunnel Affinity & Mask • Tunnel affinity helps select which tunnels will go over which links. • For example: a network with OC-12 and Satellite links will use affinities to prevent tunnels with VoIP traffic from taking the satellite links. Tunnel can only go over a link if (Tunnel Mask) && (Attribute Flags) == Tunnel Affinity R1(config)# interface tunnel 1 R1(config-if)# tunnel mpls traffic-eng affinity 0x80 mask 0x80 R 1 R 2 TE Tunnel
Administrative Weight (TE Metric) • Two costs are associated with a link – TE cost (Administrative weight) – IGP cost • The default TE cost on a link is the same as the IGP cost. We can also configure as following: 18 Router(config)# interface ethernet 0/1 Router(config-if)# mpls traffic-eng administrative-weight 20 R 1 R 2
Link-State Protocol Extensions/ IGP Flooding • TE finds paths other than shortest-cost. To do this, TE must have more info than just per-link cost • OSPF and IS-IS have been extended to carry additional information – Physical bandwidth – RSVP configured bandwidth – RSVP available bandwidth – Link TE metric – Link affinity RFC 3630 OSPF TE RFC 5305 IS-IS TE
When to Flood the Information • When a link goes up or down • When a link’s configuration is changed • Periodically reflood the router’s IGP information • When link bandwidth changes significantly 20
Bandwidth Significant Change • Each time a threshold is crossed, an update message is sent. 21 Ethernet 1/0 Tunnel 1 Tunnel 2 Tunnel 3 Tunnel 4 Update Update 30 50 70 80 90 100 BW%&Threshold
Path Calculation and Setup 22
Tunnel Path Selection • Tunnel has two path options 1. Dynamic 2. Explicit • Path is a set of next-hop addresses (physical or loopbacks) to destination • This set of next-hops is called Explicit Route Object (ERO)
Path Calculation • Modified Dijkstra • Often referred to as CSPF – Constrained SPF • Final result is an explicit route meeting desired constraint
C-SPF • Shortest-cost path is found that meets administrative constraints • These constraints can be – bandwidth – link attribute (aka color, resource group) – priority • The addition of constraints is what allows MPLS-TE to use paths other than just the shortest one
Path Computation 26 Demand Input Prune Link Compute Shortest Distance Path Tie-Break Output Operations
Path Computation - Demand 27 “On demand” by the tunnel’s head-end: 1. for a new tunnel 2. for an existing tunnel whose (current) LSP failed 3. for an existing tunnel when doing re-optimization
Path Computation - Input 28 Input 1. Configured attributes of tunnels originated at this router 2. Attributes associated with resources 3. Topology state information
Path Computation - Operation 29 Demand Input Prune Link if: 1. insufficient resources (e.g., bandwidth) 2. violates policy constraints Compute Shortest Distance Path 1. TE uses its own metric Tie-break(Cisco): 1. Path with the highest available bandwidth 2. Path with the smallest hop-count 3. Path found first in TE topology database Output Operations
Path Computation - Output 30 Output 1. explicit route - expressed as a sequence of router IP addresses • interface addresses • loopback address 2. used as an input to the path setup component
Strict and Loose Path 31 • Paths are configured manually. Each hop is a physical interface or loopback. Strict Path A network node and its preceding node in the path must be adjacent and directly connected. Loose Path A network node must be in the path but is not required to be directly connected to its preceding node. A B C D E A B C D E
RSVP-TE • After calculating the path, tunnel will be set up by using RSVP-TE. • RSVP has three basic functions: – Path setup and maintenance – Path teardown – Error signalling 32
Setup of TE LSP • In following topo, R1 will set up a TE tunnel from R1 to R4: 33 R1 R2 R3 R4 Path 1 Label request Path 2 Label request Path 3 Label request Resv 4 Label= Pop Label Resv 5 Label=300 Resv 6 Label=400 TE Tunnel LSP
Forwarding Traffic via Tunnels 34
Routing Traffic Down a Tunnel • Once the tunnel is established and operational, it’s ready to forward data traffic. • However, no traffic will enter the tunnel unless the IP routing tables and FIB tables are modified. • How to get traffic down the tunnel? 1. Static route 2. Auto route 3. Policy routing 35
Example Topology • In the following topology, cost=10 for each link. • Tunnel 1 has been created on Router A from A to G. Router F Router C Router D Router A Router B Router E Router I Router H Router G
Static Route • Router H is known via the tunnel • Router G is not routed to over the tunnel, even though it’s the tunnel tail! Router F Router H Router B Router C Router E Router D Router G Router A Router I 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 Routing Table of RouterA
Auto Route • Auto route allows a TE tunnel to participate in IGP route calculations as a logical link. The tunnel interface is used as the outbound interface of the route. – IGP Shortcut: The command is “autoroute announce” in Cisco IOS. Tunnel interface will be included in SPF tree on the Head-end router. – Forwarding adjacency: allows all nodes in IGP domains to see the TE tunnels and use them in the SPF calculation.
IGP Shortcut • Everything “behind” the tunnel is routed via the tunnel Router F Router C Router D Router A Router B Router E Router I Router H Router G 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 Routing Table of RouterA
Forwarding Adjacency • Bidirectional tunnels: tunnel 1 AtoG, tunnel 2 GtoA • Configure following commands on both Router A and G Router F Router C Router D Router A Router B Router E Router I Router H Router G Enable Forwarding Adjacency on both Router A and G
Before Configuring Forwarding Adjacency • Assume cost of the tunnels is 5. • Before FA configured, Router H does not include TE tunnel into its SPF calculation. Node Next-Hop Cost A G 40 … … ... Routing Table of RouterH Router F Router C Router D Router A Router B Router E Router I Router H Router G
After Configuring Forwarding Adjacency • After FA configured, Router G advertised as a link in an IGP network with the link's cost associated with it. • Router H can see the TE tunnel and use it to compute the shortest path for routing traffic throughout the network. Router F Router C Router D Router A Router B Router E Router I Router H Router G Node Next-Hop Cost A G 15 … … ... Routing Table of RouterH
Policy Routing • Routing table isn’t affected by policy routing • Cisco IOS Need (12.0(23)S or 12.2T) or higher for ‘set interface tunnel’ to work Router F Router H Router B Router C Router E Router D Router G Router A Router 1 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 of RouterA
MPLS TE Services 44
MPLS TE Services TE Fast Re-Route TE Path Protection TE Tunnel for VRF 45
MPLS TE Fast Re-Route • Traffic engineering fast reroute (TE FRR) provides protection for MPLS TE tunnels. • If a link or a node fails, FRR locally repairs the protected LSPs by rerouting them over backup tunnels that bypass failed links or node, minimizing traffic loss. 1. Link Protection 2. Node Protection 46
Link Failure • If the link between P1 to P3 is down, the TE tunnel LSP will be torn down and take time to recompute a new path if autoroute. 47 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4
Fast Re-Route ---- Link Protection • In link protection, the bypass tunnel has been set up to bypass only a single link of the LSP's path. 48 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel Set up a bypass tunnel from P1 to PE3 (P1-P2-PE4- PE3) to protect the link from P1 to PE3
Fast Re-Route ---- Link Protection • The bypass tunnel protects LSP if the protected link along their path fails by rerouting the LSP's traffic to the next hop (bypassing the failed link). 49 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel Traffic flow
Configuration of Link Protection(1) - Primary Tunnel 50 interface tunnel 100 ip unnumbered loopback0 tunnel mode mpls traffic-eng tunnel destination 3.3.3.3 tunnel mpls traffic-eng bandwidth 256 tunnel mpls traffic-eng path-option 1 explicit name PRIMARY tunnel mpls traffic-eng autoroute announce PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Cisco IOS
Configuration of Link Protection(2) ---- Backup Tunnel 51 interface tunnel 1000 ip unnumbered loopback0 tunnel mode mpls traffic-eng tunnel destination 3.3.3.3 tunnel mpls traffic-eng bandwidth 256 tunnel mpls traffic-eng path-option 1 explicit name LINK_PRO_P1_P3 tunnel mpls traffic-eng autoroute announce PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel
Configuration of Link Protection(3) ---- Fast Re-Route 52 P1(config)# interface te 0/0/12 P1(config-if)# mpls traffic-eng backup-path tunnel 1000 PE1(config)# interface tunnel 100 PE1(config-if)# tunnel mpls traffic-eng fast-reroute PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel TE0/0/12
Configuration of Link Protection(4) ---- RSVP Signalling Hello 53 P1(config)# ip rsvp signalling hello P1(config)# interface te 0/0/12 P1(config-if)# ip rsvp signalling hello PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel TE0/0/12 P3(config)# ip rsvp signalling hello P3(config)# interface te 0/0/12 P3(config-if)# ip rsvp signalling hello TE0/0/12
Check Fast Reroute 54 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel TE0/0/12 TE0/0/12 P1#show mpls traffic-eng tunnels backup Router2_t1000 LSP Head, Admin: up, Oper: up Tun ID: 1000, LSP ID: 134, Source: 172.16.15.2 Destination: 172.16.15.5 Fast Reroute Backup Provided: Protected i/fs: Te0/0/12 Protected LSPs/Sub-LSPs: 1, Active: 0 Backup BW: any pool unlimited; inuse: 256 kbps Backup flags: 0x0
When the Protected Link is UP 55 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 TE0/0/12 TE0/0/12 Router1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds Type escape sequence to abort. 0 172.16.10.2 MRU 1512 [Labels: 201 Exp: 0] L 1 172.16.10.1 MRU 1512 [Labels: 521 Exp: 0] 3 ms L 2 172.16.12.2 MRU 1500 [Labels: implicit-null Exp: 0] 3 ms ! 3 172.16.10.26 3 ms
When the Protected Link is Down 56 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 TE0/0/12 TE0/0/12 Router1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds Type escape sequence to abort. 0 172.16.10.2 MRU 1512 [Labels: 201 Exp: 0] L 1 172.16.10.1 MRU 1512 [Labels: 1108/521 Exp: 0/0] 4 ms L 2 172.16.12.13 MRU 1512 [Labels: 816/521 Exp: 0/0] 3 ms L 3 172.16.12.9 MRU 1512 [Labels: 521 Exp: 0] 3 ms D 4 172.16.10.26 3 ms ! 5 172.16.10.26 3 ms Bypass Tunnel
When the Protected Link is Down 57 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 TE0/0/1 2 TE0/0/1 2 Bypass Tunnel P1#show mpls traffic-eng tunnels property fast-reroute P2P TUNNELS/LSPs: LSP Tunnel PE1_t100 is signalled, connection is up InLabel : GigabitEthernet0/0/0, 201 Prev Hop : 172.16.10.2 OutLabel : TenGigabitEthernet0/0/12, 521 Next Hop : 172.16.12.2 FRR OutLabel : Tunnel1000, 521 (in use) RSVP Signalling Info: Src 172.16.15.1, Dst 172.16.15.4, Tun_Id 100, Tun_Instance 3649 RSVP Path Info: My Address: 172.16.12.1 Explicit Route: 172.16.15.5 172.16.10.25 172.16.10.26 172.16.15.4 Record Route: NONE Tspec: ave rate=256 kbits, burst=1000 bytes, peak rate=256 kbits RSVP Resv Info: Record Route: 172.16.15.5(521) 172.16.15.4(3) Fspec: ave rate=256 kbits, burst=1000 bytes, peak rate=256 kbits
Node Failure • If one node on the LSP fails, TE tunnel also will be torn down. 58 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4
Fast Re-Route ---- Node Protection • Node protection is similar to link protection in most ways, the backup tunnel is set up to bypass the protected node. 59 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel Set up a bypass tunnel from P1 to PE3 to protect the node P3 and also the links.
Fast Re-Route ---- Node Protection • The backup tunnel can reroute the traffic to bypass the failure node. • Backup tunnels also provide protection from link failures, because they bypass the failed link and the node. 60 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel Traffic flow
Primary LSP Before Any Failure 61 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel PE1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds Type escape sequence to abort. 0 172.16.10.2 MRU 1512 [Labels: 203 Exp: 0] L 1 172.16.10.1 MRU 1512 [Labels: 522 Exp: 0] 3 ms L 2 172.16.12.2 MRU 1500 [Labels: implicit-null Exp: 0] 3 ms ! 3 172.16.10.26 3 ms
Bypass LSP Before Any Failure 62 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel P1#traceroute mpls traffic-eng tunnel 1500 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds Type escape sequence to abort. 0 172.16.12.14 MRU 1512 [Labels: 1113 Exp: 0] L 1 172.16.12.13 MRU 1512 [Labels: 804 Exp: 0] 4 ms L 2 172.16.12.9 MRU 1512 [Labels: 616 Exp: 0] 3 ms L 3 172.16.12.18 MRU 1500 [Labels: implicit-null Exp: 0] 4 ms ! 4 172.16.10.33 4 ms
Check Fast Reroute after the Node is Down 63 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel P1#show mpls traffic-eng tunnels property fast-reroute P2P TUNNELS/LSPs: LSP Tunnel PE1_t100 is signalled, connection is up InLabel : GigabitEthernet0/0/0, 202 Prev Hop : 172.16.10.2 OutLabel : TenGigabitEthernet0/0/12, 502 Next Hop : 172.16.12.2 FRR OutLabel : Tunnel1500, implicit-null (in use) RSVP Signalling Info: Src 172.16.15.1, Dst 172.16.15.4, Tun_Id 100, Tun_Instance 3684 RSVP Path Info: My Address: 172.16.12.1 Explicit Route: 172.16.15.4 172.16.15.4 Record Route: NONE Tspec: ave rate=256 kbits, burst=1000 bytes, peak rate=256 kbits RSVP Resv Info: Record Route: 172.16.15.5(502) 172.16.15.4(3) Fspec: ave rate=256 kbits, burst=1000 bytes, peak rate=256 kbits
Check LSP after the Node is Down 64 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel PE1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds Type escape sequence to abort. 0 172.16.10.2 MRU 1512 [Labels: 202 Exp: 0] L 1 172.16.10.1 MRU 1512 [Labels: implicit-null Exp: 0] 4 ms L 2 172.16.12.13 MRU 1512 [Labels: 804 Exp: 0] 3 ms L 3 172.16.12.9 MRU 1512 [Labels: 616 Exp: 0] 4 ms L 4 172.16.12.18 MRU 1500 [Labels: implicit-null Exp: 0] 4 ms ! 5 172.16.10.33 4 ms
MPLS TE Services TE Fast Re-Route TE Path Protection TE Tunnel for VRF 65
MPLS TE Path Protection • Path protection provides an end-to-end failure recovery mechanism for MPLS TE tunnels. • If the ingress node detects a failure of the primary LSP, it switches traffic to a backup LSP. After the primary LSP recovers, traffic switches back to the primary LSP. • Path protection reduces the time required to recalculate a route in case of a failure within the MPLS tunnel. 66
TE Path Protection Example • Under on tunnel, both main path and secondary path are created. 67 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3 CE CE CE CESecondary Path for Tunnel One tunnel has been created on PE1, to PE3
TE Path Protection Example • When main path is not available, secondary path will be active. Traffic will go via secondary path. 68 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel Traffic flow
TE Path Protection Configuration 69 PE1(config)# interface tunnel 2000 PE1(config-if)# tunnel mpls traffic-eng path-option 10 explicit name MAIN_PE1_PE3 PE1(config-if)# tunnel mpls traffic-eng path-option protect 10 explicit name PRO_PE1_PE3 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel
Check the Path Protection 70 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel PE1#show mpls traffic-eng tunnels protection | begin t2000 PE1_t2000 LSP Head, Tunnel2000, Admin: up, Oper: up Src 172.16.15.2, Dest 172.16.15.4, Instance 10 Fast Reroute Protection: None Path Protection: 0 Common Link(s), 0 Common Node(s) Primary lsp path:172.16.12.1 172.16.12.2 172.16.10.25 172.16.10.26 172.16.15.4 Protect lsp path:172.16.12.14 172.16.12.13 172.16.12.10 172.16.12.9 172.16.12.17 172.16.12.18 172.16.10.34 172.16.10.33 172.16.15.4 ......
Check LSP before Any Failure 71 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel PE1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds ...... Type escape sequence to abort. 0 172.16.12.1 MRU 1512 [Labels: 501 Exp: 0] L 1 172.16.12.2 MRU 1500 [Labels: implicit-null Exp: 0] 5 ms ! 2 172.16.10.26 4 ms
Check LSP when One Link is Down 72 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel PE1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds ...... Type escape sequence to abort. 0 172.16.12.14 MRU 1512 [Labels: 1113 Exp: 0] L 1 172.16.12.13 MRU 1512 [Labels: 811 Exp: 0] 4 ms L 2 172.16.12.9 MRU 1512 [Labels: 619 Exp: 0] 4 ms L 3 172.16.12.18 MRU 1500 [Labels: implicit-null Exp: 0] 3 ms ! 4 172.16.10.33 3 ms
Check Path Protection when One Link is Down 73 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel Router2#show mpls traffic-eng tunnels protection | begin t2000 Router2_t2000 LSP Head, Tunnel2000, Admin: up, Oper: up Src 172.16.15.2, Dest 172.16.15.4, Instance 11 Fast Reroute Protection: None Path Protection: Backup lsp in use.
MPLS TE Services TE Fast Re-Route TE Path Protection TE Tunnel for VRF 74
LDP for VPN Tunnel LSP • In many ISPs, LDP LSP is the tunnel LSP for MPLS L3VPN service. LDP labels are the outer label for traffic forwarding. 75 LD P LD P LD P LD P LD P LD P LD P PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE
TE Tunnel for VPN Tunnel LSP • MPLS TE tunnels also can be used for VPN tunnel LSP. 76 MPLS CORE L3VPN VPNA L2VPN L2VPN PE1 P PE2 PE3 PE4 P P P TE Tunnel from PE1 to PE3 TE Tunnel from PE3 to PE1 1. Set up TE tunnels between PEs
TE Tunnel for VPN Tunnel LSP • MPLS TE tunnels also can be used for VPN tunnel LSP. 77 MPLS CORE L3VPN VPNA L2VPN L2VP N PE1 P PE2 PE3 PE4 P P P TE Tunnel from PE1 to PE3 TE Tunnel from PE3 to PE1 1. Set up TE tunnels between PEs 2. Guide the VPN traffic into the TE tunnel
Configuration of TE Tunnel for VPN Tunnel LSP 78 MPLS CORE L3VPN VPNA L2VPN L2VPN PE1 P PE2 PE3 PE4 P P P TE Tunnel from PE1 to PE3 TE Tunnel from PE3 to PE1 PE1(config)# interface tunnel 1000 PE1(config-if)# tunnel mpls traffic-eng autoroute announce PE1(config)# ip route 172.16.15.4 255.255.255.255 Tunnel1000 OR OR Policy Routing
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In this document
Powered by AI

Introduction to MPLS TE tutorial presented by Jessica Wei, acknowledging Cisco Systems.

Provides an overview of MPLS Traffic Engineering (TE), emphasizing its importance in managing congestion and optimizing bandwidth.

Discusses optimal traffic engineering strategies and MPLS application scenarios, emphasizing L3VPN and L2VPN architectures.

Explains how MPLS TE works, including information distribution, path calculation, and key attributes involved in tunnel management.

Addresses bandwidth requirements and tunnel management, highlighting configuration commands and priority settings for tunnels.

Details on configuring tunnel priorities, attribute flags, affinities, and administrative weights for TE tunnels.

Examines link-state protocol extensions (OSPF, IS-IS) for MPLS and discusses how flooding occurs based on link state changes.

Details the steps involved in path calculation, including demand, input from attributes, and output routing through explicit paths.

Distinguishes between strict and loose paths, the RSVP-TE protocol for tunnel setup, and traffic routing mechanisms.

Explains static routes and auto routing in MPLS TE, including how forwarding adjacency impacts IGP calculations.

Explains Fast Re-Route (FRR) mechanisms for protection against link failures in MPLS TE tunnels, ensuring minimal traffic loss.

Describes configurations for link/node protection in MPLS TE and how traffic is rerouted during failures.

Details on path protection strategies that provide backup LSPs for primary tunnels in case of network failures.

Introduces MPLS TE services and integration with VPN tunnels, including service configurations for LDP and VRF.

MPLS Traffic Engineering

  • 1.
    MPLS Traffic Engineering Tutorial APNIC44 14 September 2017 Jessica Wei
  • 2.
  • 3.
  • 4.
    Why MPLS TrafficEngineering? • Handling unexpected congestion • Better utilization of available bandwidth • Route around failed links/nodes • Capacity planning 4
  • 5.
    Optimal Traffic Engineering 5 Tunnel1 Tunnel 2 R1 R2 R3 R4 R5 R6 IP TE MPLS TE Shortest path Determines the path at the source based on additional parameters (available resources and constraints, etc.) Equal cost load balancing Load sharing across unequal paths can be achieved.
  • 6.
    MPLS Application Scenario 6 MPLSCORE Enterprise Enterprise Enterprise L3VPN L2VPN L2VPN Enterprise TE Backup Path for PE1-PE3 PE1 P PE2 PE3 PE4 P P P TE Main Path for PE1-PE3
  • 7.
    How MPLS TEWorks 7 • What is the information? • Dynamically • Manually • RSVP-TE • Autoroute • Static • Policy Information Distribution Path Calculation Path Setup Forward the Traffic Down to the Tunnel
  • 8.
    Terminology—Head, Tail, LSP Upstream R1R2 Downstream R3 TE Tunnel R1 to R4 R4 Head- End Tail-EndMid-Points
  • 9.
  • 10.
    Attributes 10 • Available Bandwidth •Attribute flags (Link Affinity) • Administrative weight (TE-specific link metric) Tunnel Attributes • Tunnel Required Bandwidth • Tunnel Affinity & Mask • Priority TE Tunnel
  • 11.
    Bandwidth on PhysicalLink • Bandwidth – the amount of reservable bandwidth on a physical link 11 R1(Config)# interface gigabitethernet 0/0/5 R1(config-if)# mpls traffic-eng tunnels R1(config-if)# ip rsvp bandwidth 512 R1 Reserved bandwidth is 512 kbps GE0/0/5
  • 12.
    Bandwidth Required byTunnel • Bandwidth required by the tunnel across the network • Not a mandatory command. If not configured, tunnel is requested with zero bandwidth. 12 R1(config)# interface tunnel 1 R1(config-if)# tunnel mpls traffic-eng bandwidth 100 R1 R2 TE Tunnel LSP
  • 13.
    Priority • Each tunnelhas 2 priorities: – Setup priority – Holding priority • Value: 0~7, 0 indicated the highest priority, 7 indicates the lowest priority. 13 TE Tunnel 1 R1 to R4 R1 R2 R3 R4 BW=300 Kbps BW=200 kbps Priority: S1=3 H1=3 TE Tunnel 2 R1 to R3 BW=200 kbps Priority: S2=2 H2=2 S2 < H1
  • 14.
    Priority • Each tunnelhas 2 priorities: – Setup priority – Holding priority • Value: 0~7, 0 indicated the highest priority, 7 indicates the lowest priority. 14 TE Tunnel 1 R1 to R4 R1 R2 R3 R4 BW=300 Kbps BW=200 kbps Priority: S1=3 H1=3 TE Tunnel 2 R1 to R3 BW=200 kbps Priority: S2=2 H2=2 S2 < H1 Tunnel 2 preempts the BW, tunnel 1 has been torn down. Torn down Set up
  • 15.
    Configure Priority 15 R1(config)# interfacetunnel 1 R1(config-if)# tunnel mpls traffic-eng priority 3 3 R 1 R 2 TE Tunnel • Recommended that priority S=H; if a tunnel can setup at priority “X”, then it should be able to hold at priority “X” too! • Configuring S > H is illegal; tunnel will most likely be preempted • Default is S = 7, H = 7
  • 16.
    Attribute Flags • Anattribute flag is a 32-bit bitmap on a link that indicate the existence of up to 32 separate properties on that link, also called link affinity or administrative group. 16 R1(config)# interface ethernet 0/1 R1(config-if)# mpls traffic-eng attribute-flags 0x8 R 1
  • 17.
    Tunnel Affinity &Mask • Tunnel affinity helps select which tunnels will go over which links. • For example: a network with OC-12 and Satellite links will use affinities to prevent tunnels with VoIP traffic from taking the satellite links. Tunnel can only go over a link if (Tunnel Mask) && (Attribute Flags) == Tunnel Affinity R1(config)# interface tunnel 1 R1(config-if)# tunnel mpls traffic-eng affinity 0x80 mask 0x80 R 1 R 2 TE Tunnel
  • 18.
    Administrative Weight (TEMetric) • Two costs are associated with a link – TE cost (Administrative weight) – IGP cost • The default TE cost on a link is the same as the IGP cost. We can also configure as following: 18 Router(config)# interface ethernet 0/1 Router(config-if)# mpls traffic-eng administrative-weight 20 R 1 R 2
  • 19.
    Link-State Protocol Extensions/IGP Flooding • TE finds paths other than shortest-cost. To do this, TE must have more info than just per-link cost • OSPF and IS-IS have been extended to carry additional information – Physical bandwidth – RSVP configured bandwidth – RSVP available bandwidth – Link TE metric – Link affinity RFC 3630 OSPF TE RFC 5305 IS-IS TE
  • 20.
    When to Floodthe Information • When a link goes up or down • When a link’s configuration is changed • Periodically reflood the router’s IGP information • When link bandwidth changes significantly 20
  • 21.
    Bandwidth Significant Change •Each time a threshold is crossed, an update message is sent. 21 Ethernet 1/0 Tunnel 1 Tunnel 2 Tunnel 3 Tunnel 4 Update Update 30 50 70 80 90 100 BW%&Threshold
  • 22.
  • 23.
    Tunnel Path Selection •Tunnel has two path options 1. Dynamic 2. Explicit • Path is a set of next-hop addresses (physical or loopbacks) to destination • This set of next-hops is called Explicit Route Object (ERO)
  • 24.
    Path Calculation • ModifiedDijkstra • Often referred to as CSPF – Constrained SPF • Final result is an explicit route meeting desired constraint
  • 25.
    C-SPF • Shortest-cost pathis found that meets administrative constraints • These constraints can be – bandwidth – link attribute (aka color, resource group) – priority • The addition of constraints is what allows MPLS-TE to use paths other than just the shortest one
  • 26.
    Path Computation 26 Demand Input Prune Link ComputeShortest Distance Path Tie-Break Output Operations
  • 27.
    Path Computation -Demand 27 “On demand” by the tunnel’s head-end: 1. for a new tunnel 2. for an existing tunnel whose (current) LSP failed 3. for an existing tunnel when doing re-optimization
  • 28.
    Path Computation -Input 28 Input 1. Configured attributes of tunnels originated at this router 2. Attributes associated with resources 3. Topology state information
  • 29.
    Path Computation -Operation 29 Demand Input Prune Link if: 1. insufficient resources (e.g., bandwidth) 2. violates policy constraints Compute Shortest Distance Path 1. TE uses its own metric Tie-break(Cisco): 1. Path with the highest available bandwidth 2. Path with the smallest hop-count 3. Path found first in TE topology database Output Operations
  • 30.
    Path Computation -Output 30 Output 1. explicit route - expressed as a sequence of router IP addresses • interface addresses • loopback address 2. used as an input to the path setup component
  • 31.
    Strict and LoosePath 31 • Paths are configured manually. Each hop is a physical interface or loopback. Strict Path A network node and its preceding node in the path must be adjacent and directly connected. Loose Path A network node must be in the path but is not required to be directly connected to its preceding node. A B C D E A B C D E
  • 32.
    RSVP-TE • After calculatingthe path, tunnel will be set up by using RSVP-TE. • RSVP has three basic functions: – Path setup and maintenance – Path teardown – Error signalling 32
  • 33.
    Setup of TELSP • In following topo, R1 will set up a TE tunnel from R1 to R4: 33 R1 R2 R3 R4 Path 1 Label request Path 2 Label request Path 3 Label request Resv 4 Label= Pop Label Resv 5 Label=300 Resv 6 Label=400 TE Tunnel LSP
  • 34.
  • 35.
    Routing Traffic Downa Tunnel • Once the tunnel is established and operational, it’s ready to forward data traffic. • However, no traffic will enter the tunnel unless the IP routing tables and FIB tables are modified. • How to get traffic down the tunnel? 1. Static route 2. Auto route 3. Policy routing 35
  • 36.
    Example Topology • Inthe following topology, cost=10 for each link. • Tunnel 1 has been created on Router A from A to G. Router F Router C Router D Router A Router B Router E Router I Router H Router G
  • 37.
    Static Route • RouterH is known via the tunnel • Router G is not routed to over the tunnel, even though it’s the tunnel tail! Router F Router H Router B Router C Router E Router D Router G Router A Router I 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 Routing Table of RouterA
  • 38.
    Auto Route • Autoroute allows a TE tunnel to participate in IGP route calculations as a logical link. The tunnel interface is used as the outbound interface of the route. – IGP Shortcut: The command is “autoroute announce” in Cisco IOS. Tunnel interface will be included in SPF tree on the Head-end router. – Forwarding adjacency: allows all nodes in IGP domains to see the TE tunnels and use them in the SPF calculation.
  • 39.
    IGP Shortcut • Everything“behind” the tunnel is routed via the tunnel Router F Router C Router D Router A Router B Router E Router I Router H Router G 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 Routing Table of RouterA
  • 40.
    Forwarding Adjacency • Bidirectionaltunnels: tunnel 1 AtoG, tunnel 2 GtoA • Configure following commands on both Router A and G Router F Router C Router D Router A Router B Router E Router I Router H Router G Enable Forwarding Adjacency on both Router A and G
  • 41.
    Before Configuring ForwardingAdjacency • Assume cost of the tunnels is 5. • Before FA configured, Router H does not include TE tunnel into its SPF calculation. Node Next-Hop Cost A G 40 … … ... Routing Table of RouterH Router F Router C Router D Router A Router B Router E Router I Router H Router G
  • 42.
    After Configuring ForwardingAdjacency • After FA configured, Router G advertised as a link in an IGP network with the link's cost associated with it. • Router H can see the TE tunnel and use it to compute the shortest path for routing traffic throughout the network. Router F Router C Router D Router A Router B Router E Router I Router H Router G Node Next-Hop Cost A G 15 … … ... Routing Table of RouterH
  • 43.
    Policy Routing • Routingtable isn’t affected by policy routing • Cisco IOS Need (12.0(23)S or 12.2T) or higher for ‘set interface tunnel’ to work Router F Router H Router B Router C Router E Router D Router G Router A Router 1 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 of RouterA
  • 44.
  • 45.
    MPLS TE Services TEFast Re-Route TE Path Protection TE Tunnel for VRF 45
  • 46.
    MPLS TE FastRe-Route • Traffic engineering fast reroute (TE FRR) provides protection for MPLS TE tunnels. • If a link or a node fails, FRR locally repairs the protected LSPs by rerouting them over backup tunnels that bypass failed links or node, minimizing traffic loss. 1. Link Protection 2. Node Protection 46
  • 47.
    Link Failure • Ifthe link between P1 to P3 is down, the TE tunnel LSP will be torn down and take time to recompute a new path if autoroute. 47 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4
  • 48.
    Fast Re-Route ----Link Protection • In link protection, the bypass tunnel has been set up to bypass only a single link of the LSP's path. 48 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel Set up a bypass tunnel from P1 to PE3 (P1-P2-PE4- PE3) to protect the link from P1 to PE3
  • 49.
    Fast Re-Route ----Link Protection • The bypass tunnel protects LSP if the protected link along their path fails by rerouting the LSP's traffic to the next hop (bypassing the failed link). 49 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel Traffic flow
  • 50.
    Configuration of LinkProtection(1) - Primary Tunnel 50 interface tunnel 100 ip unnumbered loopback0 tunnel mode mpls traffic-eng tunnel destination 3.3.3.3 tunnel mpls traffic-eng bandwidth 256 tunnel mpls traffic-eng path-option 1 explicit name PRIMARY tunnel mpls traffic-eng autoroute announce PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Cisco IOS
  • 51.
    Configuration of LinkProtection(2) ---- Backup Tunnel 51 interface tunnel 1000 ip unnumbered loopback0 tunnel mode mpls traffic-eng tunnel destination 3.3.3.3 tunnel mpls traffic-eng bandwidth 256 tunnel mpls traffic-eng path-option 1 explicit name LINK_PRO_P1_P3 tunnel mpls traffic-eng autoroute announce PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel
  • 52.
    Configuration of LinkProtection(3) ---- Fast Re-Route 52 P1(config)# interface te 0/0/12 P1(config-if)# mpls traffic-eng backup-path tunnel 1000 PE1(config)# interface tunnel 100 PE1(config-if)# tunnel mpls traffic-eng fast-reroute PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel TE0/0/12
  • 53.
    Configuration of LinkProtection(4) ---- RSVP Signalling Hello 53 P1(config)# ip rsvp signalling hello P1(config)# interface te 0/0/12 P1(config-if)# ip rsvp signalling hello PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel TE0/0/12 P3(config)# ip rsvp signalling hello P3(config)# interface te 0/0/12 P3(config-if)# ip rsvp signalling hello TE0/0/12
  • 54.
    Check Fast Reroute 54 PE1 PE2 MPLSNetwork PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel TE0/0/12 TE0/0/12 P1#show mpls traffic-eng tunnels backup Router2_t1000 LSP Head, Admin: up, Oper: up Tun ID: 1000, LSP ID: 134, Source: 172.16.15.2 Destination: 172.16.15.5 Fast Reroute Backup Provided: Protected i/fs: Te0/0/12 Protected LSPs/Sub-LSPs: 1, Active: 0 Backup BW: any pool unlimited; inuse: 256 kbps Backup flags: 0x0
  • 55.
    When the ProtectedLink is UP 55 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 TE0/0/12 TE0/0/12 Router1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds Type escape sequence to abort. 0 172.16.10.2 MRU 1512 [Labels: 201 Exp: 0] L 1 172.16.10.1 MRU 1512 [Labels: 521 Exp: 0] 3 ms L 2 172.16.12.2 MRU 1500 [Labels: implicit-null Exp: 0] 3 ms ! 3 172.16.10.26 3 ms
  • 56.
    When the ProtectedLink is Down 56 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 TE0/0/12 TE0/0/12 Router1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds Type escape sequence to abort. 0 172.16.10.2 MRU 1512 [Labels: 201 Exp: 0] L 1 172.16.10.1 MRU 1512 [Labels: 1108/521 Exp: 0/0] 4 ms L 2 172.16.12.13 MRU 1512 [Labels: 816/521 Exp: 0/0] 3 ms L 3 172.16.12.9 MRU 1512 [Labels: 521 Exp: 0] 3 ms D 4 172.16.10.26 3 ms ! 5 172.16.10.26 3 ms Bypass Tunnel
  • 57.
    When the ProtectedLink is Down 57 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 TE0/0/1 2 TE0/0/1 2 Bypass Tunnel P1#show mpls traffic-eng tunnels property fast-reroute P2P TUNNELS/LSPs: LSP Tunnel PE1_t100 is signalled, connection is up InLabel : GigabitEthernet0/0/0, 201 Prev Hop : 172.16.10.2 OutLabel : TenGigabitEthernet0/0/12, 521 Next Hop : 172.16.12.2 FRR OutLabel : Tunnel1000, 521 (in use) RSVP Signalling Info: Src 172.16.15.1, Dst 172.16.15.4, Tun_Id 100, Tun_Instance 3649 RSVP Path Info: My Address: 172.16.12.1 Explicit Route: 172.16.15.5 172.16.10.25 172.16.10.26 172.16.15.4 Record Route: NONE Tspec: ave rate=256 kbits, burst=1000 bytes, peak rate=256 kbits RSVP Resv Info: Record Route: 172.16.15.5(521) 172.16.15.4(3) Fspec: ave rate=256 kbits, burst=1000 bytes, peak rate=256 kbits
  • 58.
    Node Failure • Ifone node on the LSP fails, TE tunnel also will be torn down. 58 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4
  • 59.
    Fast Re-Route ----Node Protection • Node protection is similar to link protection in most ways, the backup tunnel is set up to bypass the protected node. 59 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel Set up a bypass tunnel from P1 to PE3 to protect the node P3 and also the links.
  • 60.
    Fast Re-Route ----Node Protection • The backup tunnel can reroute the traffic to bypass the failure node. • Backup tunnels also provide protection from link failures, because they bypass the failed link and the node. 60 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel Traffic flow
  • 61.
    Primary LSP BeforeAny Failure 61 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel PE1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds Type escape sequence to abort. 0 172.16.10.2 MRU 1512 [Labels: 203 Exp: 0] L 1 172.16.10.1 MRU 1512 [Labels: 522 Exp: 0] 3 ms L 2 172.16.12.2 MRU 1500 [Labels: implicit-null Exp: 0] 3 ms ! 3 172.16.10.26 3 ms
  • 62.
    Bypass LSP BeforeAny Failure 62 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel P1#traceroute mpls traffic-eng tunnel 1500 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds Type escape sequence to abort. 0 172.16.12.14 MRU 1512 [Labels: 1113 Exp: 0] L 1 172.16.12.13 MRU 1512 [Labels: 804 Exp: 0] 4 ms L 2 172.16.12.9 MRU 1512 [Labels: 616 Exp: 0] 3 ms L 3 172.16.12.18 MRU 1500 [Labels: implicit-null Exp: 0] 4 ms ! 4 172.16.10.33 4 ms
  • 63.
    Check Fast Rerouteafter the Node is Down 63 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel P1#show mpls traffic-eng tunnels property fast-reroute P2P TUNNELS/LSPs: LSP Tunnel PE1_t100 is signalled, connection is up InLabel : GigabitEthernet0/0/0, 202 Prev Hop : 172.16.10.2 OutLabel : TenGigabitEthernet0/0/12, 502 Next Hop : 172.16.12.2 FRR OutLabel : Tunnel1500, implicit-null (in use) RSVP Signalling Info: Src 172.16.15.1, Dst 172.16.15.4, Tun_Id 100, Tun_Instance 3684 RSVP Path Info: My Address: 172.16.12.1 Explicit Route: 172.16.15.4 172.16.15.4 Record Route: NONE Tspec: ave rate=256 kbits, burst=1000 bytes, peak rate=256 kbits RSVP Resv Info: Record Route: 172.16.15.5(502) 172.16.15.4(3) Fspec: ave rate=256 kbits, burst=1000 bytes, peak rate=256 kbits
  • 64.
    Check LSP afterthe Node is Down 64 PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE TE Tunnel from PE1 to PE3 P3 P4 Bypass Tunnel PE1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds Type escape sequence to abort. 0 172.16.10.2 MRU 1512 [Labels: 202 Exp: 0] L 1 172.16.10.1 MRU 1512 [Labels: implicit-null Exp: 0] 4 ms L 2 172.16.12.13 MRU 1512 [Labels: 804 Exp: 0] 3 ms L 3 172.16.12.9 MRU 1512 [Labels: 616 Exp: 0] 4 ms L 4 172.16.12.18 MRU 1500 [Labels: implicit-null Exp: 0] 4 ms ! 5 172.16.10.33 4 ms
  • 65.
    MPLS TE Services TEFast Re-Route TE Path Protection TE Tunnel for VRF 65
  • 66.
    MPLS TE PathProtection • Path protection provides an end-to-end failure recovery mechanism for MPLS TE tunnels. • If the ingress node detects a failure of the primary LSP, it switches traffic to a backup LSP. After the primary LSP recovers, traffic switches back to the primary LSP. • Path protection reduces the time required to recalculate a route in case of a failure within the MPLS tunnel. 66
  • 67.
    TE Path ProtectionExample • Under on tunnel, both main path and secondary path are created. 67 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3 CE CE CE CESecondary Path for Tunnel One tunnel has been created on PE1, to PE3
  • 68.
    TE Path ProtectionExample • When main path is not available, secondary path will be active. Traffic will go via secondary path. 68 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel Traffic flow
  • 69.
    TE Path ProtectionConfiguration 69 PE1(config)# interface tunnel 2000 PE1(config-if)# tunnel mpls traffic-eng path-option 10 explicit name MAIN_PE1_PE3 PE1(config-if)# tunnel mpls traffic-eng path-option protect 10 explicit name PRO_PE1_PE3 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel
  • 70.
    Check the PathProtection 70 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel PE1#show mpls traffic-eng tunnels protection | begin t2000 PE1_t2000 LSP Head, Tunnel2000, Admin: up, Oper: up Src 172.16.15.2, Dest 172.16.15.4, Instance 10 Fast Reroute Protection: None Path Protection: 0 Common Link(s), 0 Common Node(s) Primary lsp path:172.16.12.1 172.16.12.2 172.16.10.25 172.16.10.26 172.16.15.4 Protect lsp path:172.16.12.14 172.16.12.13 172.16.12.10 172.16.12.9 172.16.12.17 172.16.12.18 172.16.10.34 172.16.10.33 172.16.15.4 ......
  • 71.
    Check LSP beforeAny Failure 71 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel PE1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds ...... Type escape sequence to abort. 0 172.16.12.1 MRU 1512 [Labels: 501 Exp: 0] L 1 172.16.12.2 MRU 1500 [Labels: implicit-null Exp: 0] 5 ms ! 2 172.16.10.26 4 ms
  • 72.
    Check LSP whenOne Link is Down 72 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel PE1#traceroute mpls traffic-eng tunnel 100 Tracing MPLS TE Label Switched Path on Tunnel100, timeout is 2 seconds ...... Type escape sequence to abort. 0 172.16.12.14 MRU 1512 [Labels: 1113 Exp: 0] L 1 172.16.12.13 MRU 1512 [Labels: 811 Exp: 0] 4 ms L 2 172.16.12.9 MRU 1512 [Labels: 619 Exp: 0] 4 ms L 3 172.16.12.18 MRU 1500 [Labels: implicit-null Exp: 0] 3 ms ! 4 172.16.10.33 3 ms
  • 73.
    Check Path Protectionwhen One Link is Down 73 PE1 PE2 MPLS Network PE3 PE4 P1 P2 TE Tunnel Main Path from PE1 to PE3CE CE CE CESecondary Path for Tunnel Router2#show mpls traffic-eng tunnels protection | begin t2000 Router2_t2000 LSP Head, Tunnel2000, Admin: up, Oper: up Src 172.16.15.2, Dest 172.16.15.4, Instance 11 Fast Reroute Protection: None Path Protection: Backup lsp in use.
  • 74.
    MPLS TE Services TEFast Re-Route TE Path Protection TE Tunnel for VRF 74
  • 75.
    LDP for VPNTunnel LSP • In many ISPs, LDP LSP is the tunnel LSP for MPLS L3VPN service. LDP labels are the outer label for traffic forwarding. 75 LD P LD P LD P LD P LD P LD P LD P PE1 PE2 MPLS Network PE3 PE4 P1 P2 CE CE CE CE
  • 76.
    TE Tunnel forVPN Tunnel LSP • MPLS TE tunnels also can be used for VPN tunnel LSP. 76 MPLS CORE L3VPN VPNA L2VPN L2VPN PE1 P PE2 PE3 PE4 P P P TE Tunnel from PE1 to PE3 TE Tunnel from PE3 to PE1 1. Set up TE tunnels between PEs
  • 77.
    TE Tunnel forVPN Tunnel LSP • MPLS TE tunnels also can be used for VPN tunnel LSP. 77 MPLS CORE L3VPN VPNA L2VPN L2VP N PE1 P PE2 PE3 PE4 P P P TE Tunnel from PE1 to PE3 TE Tunnel from PE3 to PE1 1. Set up TE tunnels between PEs 2. Guide the VPN traffic into the TE tunnel
  • 78.
    Configuration of TETunnel for VPN Tunnel LSP 78 MPLS CORE L3VPN VPNA L2VPN L2VPN PE1 P PE2 PE3 PE4 P P P TE Tunnel from PE1 to PE3 TE Tunnel from PE3 to PE1 PE1(config)# interface tunnel 1000 PE1(config-if)# tunnel mpls traffic-eng autoroute announce PE1(config)# ip route 172.16.15.4 255.255.255.255 Tunnel1000 OR OR Policy Routing
  • 79.