![]() |
Table Of Contents
MPLS TE—Tunnel-Based Admission Control
Prerequisites for MPLS TE—Tunnel-Based Admission Control
Restrictions for MPLS TE—Tunnel-Based Admission Control
Information About MPLS TE—Tunnel-Based Admission Control
Feature Overview of MPLS TE—Tunnel-Based Admission Control
Benefits of MPLS TE—Tunnel-Based Admission Control
How to Configure MPLS TE—Tunnel-Based Admission Control
Configuring an MPLS TE Tunnel Interface
Configuring RSVP Bandwidth on an MPLS TE Tunnel Interface
Verifying the TBAC Configuration
Configuration Examples for MPLS TE—Tunnel-Based Admission Control
Example: Configuring RSVP Local Policy on a Tunnel Interface
Example: Verifying the TBAC Configuration
Example: Verifying the RSVP Local Policy Configuration
Feature Information for MPLS TE—Tunnel-Based Admission Control
MPLS TE—Tunnel-Based Admission Control
First Published: January 7, 2008Last Updated: February 26, 2010The MPLS TE—Tunnel-Based Admission Control (TBAC) feature enables classic Resource Reservation Protocol (RSVP) unicast reservations that are traveling across a Multiprotocol Label Switching traffic engineering (MPLS TE) core to be aggregated over an MPLS TE tunnel.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for MPLS TE—Tunnel-Based Admission Control" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS XE software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
•
Prerequisites for MPLS TE—Tunnel-Based Admission Control
•
Restrictions for MPLS TE—Tunnel-Based Admission Control
•
Information About MPLS TE—Tunnel-Based Admission Control
•
How to Configure MPLS TE—Tunnel-Based Admission Control
•
Configuration Examples for MPLS TE—Tunnel-Based Admission Control
•
Feature Information for MPLS TE—Tunnel-Based Admission Control
Prerequisites for MPLS TE—Tunnel-Based Admission Control
•
You must configure an MPLS TE tunnel in the network.
•
You must configure RSVP on one or more interfaces on at least two neighboring routers that share a link within the network.
Restrictions for MPLS TE—Tunnel-Based Admission Control
•
Only IPv4 unicast RSVP flows are supported.
•
Primary, one-hop tunnels are not supported. The TE tunnel cannot be a member of a class-based tunnel selection (CBTS) bundle.
•
Multitopology Routing (MTR) is not supported.
•
Only preestablished aggregates are supported. They can be configured statically or dynamically using command-line interface (CLI) commands.
Information About MPLS TE—Tunnel-Based Admission Control
To use the MPLS TE—TBAC feature, you should understand the following concepts:
•
Feature Overview of MPLS TE—Tunnel-Based Admission Control
•
Benefits of MPLS TE—Tunnel-Based Admission Control
Feature Overview of MPLS TE—Tunnel-Based Admission Control
TBAC aggregates reservations from multiple, classic RSVP sessions over different forms of tunneling technologies that include MPLS TE tunnels, which act as aggregate reservations in the core. Figure 1 gives an overview of TBAC.
Figure 1 TBAC Overview
Figure 1 shows three RSVP end-to-end (E2E) flows that originate at routers on the far left, and terminate on routers at the far right. These flows are classic RSVP unicast flows, meaning that RSVP is maintaining a state for each flow. There is nothing special about these flows, except that along their path, these flows encounter an MPLS-TE core, where there is a desire to avoid creating a per-flow RSVP state.
When the E2E flows reach the edge of the MPLS-TE core, they are aggregated onto a TE tunnel. This means that when transiting through the MPLS-TE core, their state is represented by a single state; the TE tunnel is within the aggregation region, and their packets are forwarded (label-switched) by the TE tunnel. For example, if 100 E2E flows traverse the same aggregator and deaggregator, rather than creating 100 RSVP states (PATH and RESV messages) within the aggregation region, a single RSVP-TE state is created, that of the aggregate, which is the TE tunnel, to allocate and maintain the resources used by the 100 E2E flows. In particular, the bandwidth consumed by E2E flows within the core is allocated and maintained in aggregate by the TE tunnel. The bandwidth of each E2E flow is normally admitted into the TE tunnel at the headend, just as any E2E flow's bandwidth is admitted onto an outbound link in the absence of aggregation.
Benefits of MPLS TE—Tunnel-Based Admission Control
To understand the benefits of TBAC, you should be familiar with how Call Admission Control (CAC) works for RSVP and Quality of Service (QoS).
Cost Effective
Real-time traffic is very sensitive to loss and delay. CAC avoids QoS degradation for real-time traffic because CAC ensures that the accepted load always matches the current network capacity. As a result, you do not have to overprovision the network to compensate for absolute worst peak traffic or for reduced capacity in case of failure.
Improved Accuracy
CAC uses RSVP signaling, which follows the same path as the real-time flow, and routers make a CAC decision at every hop. This ensures that the CAC decision is very accurate and dynamically adjusts to the current conditions such as a reroute or an additional link. Also, RSVP provides an explicit CAC response (admitted or rejected) to the application, so that the application can react appropriately and fast; for example, sending a busy signal for a voice call, rerouting the voice call on an alternate VoIP route, or displaying a message for video on demand.
RSVP and MPLS TE Combined
TBAC allows you to combine the benefits of RSVP with those of MPLS TE. Specifically, you can use MPLS TE inside the network to ensure that the transported traffic can take advantage of Fast Reroute protection (50-millisecond restoration), Constraint Based Routing (CBR), and aggregate bandwidth reservation.
Seamless Deployment
TBAC allows you to deploy IPv4 RSVP without any impact on the MPLS part of the network because IPv4 RSVP is effectively tunneled inside MPLS TE tunnels that operate unchanged as per regular RSVP TE. No upgrade or additional protocol is needed in the MPLS core.
Enhanced Scaling Capability
TBAC aggregates multiple IPv4 RSVP reservations ingressing from the same MPLS TE headend router into a single MPLS TE tunnel and egressing from the same MPLS TE tailend router.
How to Configure MPLS TE—Tunnel-Based Admission Control
This section contains the following procedures:
•
Enabling RSVP QoS (required)
•
Enabling MPLS TE (required)
•
Configuring an MPLS TE Tunnel Interface (required)
•
Configuring RSVP Bandwidth on an MPLS TE Tunnel Interface (required)
•
Verifying the TBAC Configuration (optional)
Enabling RSVP QoS
Perform this task to enable RSVP QoS globally on a router.
SUMMARY STEPS
1.
enable
2.
configure terminal
3.
ip rsvp qos
4.
end
DETAILED STEPS
Enabling MPLS TE
Perform this task to enable MPLS TE. This task enables MPLS TE globally on a router that is running RSVP QoS.
SUMMARY STEPS
1.
enable
2.
configure terminal
3.
mpls traffic-eng tunnels
4.
end
DETAILED STEPS
Configuring an MPLS TE Tunnel Interface
Prerequisites
You must configure an MPLS-TE tunnel in your network before you can proceed. For detailed information, see the "MPLS Traffic Engineering (TE)—Automatic Bandwidth Adjustment for TE Tunnels" module.
SUMMARY STEPS
1.
enable
2.
configure terminal
3.
interface tunnel number
4.
end
DETAILED STEPS
Configuring RSVP Bandwidth on an MPLS TE Tunnel Interface
Perform this task to configure RSVP bandwidth on the MPLS TE tunnel interface that you are using for the aggregation.
SUMMARY STEPS
1.
enable
2.
configure terminal
3.
interface tunnel number
4.
ip rsvp bandwidth [interface-kbps] [single-flow-kbps]
5.
end
DETAILED STEPS
Verifying the TBAC Configuration
Note
You can use the following show commands in user EXEC or privileged EXEC mode, in any order.
SUMMARY STEPS
1.
enable
2.
show ip rsvp
3.
show ip rsvp reservation [detail] [filter [destination {ip-address | hostname}] [dst-port port-number] [source {ip-address | hostname}] [src-port port-number]]
4.
show ip rsvp sender [detail] [filter [destination ip-address | hostname] [dst-port port-number] [source ip-address | hostname] [src-port port-number]]
5.
show mpls traffic-eng link-management bandwidth-allocation [summary] [interface-type interface-number]
6.
exit
DETAILED STEPS
Configuration Examples for MPLS TE—Tunnel-Based Admission Control
This section provides the following configuration examples for TBAC:
•
Example: Configuring RSVP Local Policy on a Tunnel Interface
•
Example: Verifying the TBAC Configuration
Example: Configuring TBAC
Note
You must have an MPLS TE tunnel already configured in your network. For detailed information, see the "MPLS Traffic Engineering (TE)—Automatic Bandwidth Adjustment for TE Tunnels" module.
The following example enables RSVP and MPLS TE globally on a router and then configures a tunnel interface and bandwidth of 7500 kbps on the tunnel interface traversed by the RSVP flows:
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# ip rsvp qos
Router(config)# mpls traffic-eng tunnels
Router(config)# interface tunnel 1
Router(config-if)# ip rsvp bandwidth 7500
Router(config-if)# end
Example: Configuring RSVP Local Policy on a Tunnel Interface
The following example configures an RSVP default local policy on a tunnel interface:
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface tunnel 1
Router(config-if)# ip rsvp policy local default
Router(config-rsvp-local-if-policy)# max bandwidth single 10
Router(config-rsvp-local-if-policy)# forward all
Router(config-rsvp-local-if-policy)# end
Example: Verifying the TBAC Configuration
Figure 2 shows a network in which TBAC is configured.
Figure 2 Sample TBAC Network
The following example verifies that RSVP and MPLS TE are enabled and coexist on the headend router (10.0.0.2 in Figure 2):
Router# show ip rsvpRSVP: enabled (on 3 interface(s))RSVP QoS enabled <-------MPLS/TE signalling enabled <------Signalling:Refresh interval (msec): 30000Refresh misses: 4...The following example verifies that RSVP and MPLS TE are enabled and coexist on the tailend router (10.0.0.3 in Figure 2):
Router# show ip rsvpRSVP: enabled (on 3 interface(s))RSVP QoS enabled <-------MPLS/TE signalling enabled <------Signalling:Refresh interval (msec): 30000Refresh misses: 4...The following examples verify that an IPv4 flow is traveling through a TE tunnel (a label-switched path [LSP]) on the headend router (10.0.0.2 in Figure 2):
Router# show ip rsvp senderTo From Pro DPort Sport Prev Hop I/F BPS10.0.0.3 10.0.0.1 UDP 2 2 10.0.0.1 Et0/0 10K <-- IPv4 flow10.0.0.3 10.0.0.2 0 1 11 none none 100K <-- TE tunnelRouter# show ip rsvp reservationTo From Pro DPort Sport Next Hop I/F Fi Serv BPS10.0.0.3 10.0.0.1 UDP 2 2 10.0.0.3 Tu1 SE RATE 10K <-- IPv4 flow10.0.0.3 10.0.0.2 0 1 11 10.1.0.2 Et1/0 SE LOAD 100K <-- TE tunnelThe following examples verify that an IPv4 flow is traveling through a TE tunnel (LSP) on the tailend router (10.0.0.3 in Figure 2):
Router# show ip rsvp senderTo From Pro DPort Sport Prev Hop I/F BPS10.0.0.3 10.0.0.1 UDP 2 2 10.0.0.2 Et1/0 10K <-- IPv4 flow10.0.0.3 10.0.0.2 0 1 11 10.1.0.1 Et1/0 100K <-- TE tunnelRouter# show ip rsvp reservationTo From Pro DPort Sport Next Hop I/F Fi Serv BPS10.0.0.3 10.0.0.1 UDP 2 2 none none SE RATE 10K <-- IPv4 flow10.0.0.3 10.0.0.2 0 1 11 none none SE LOAD 100K <-- TE tunnelThe following examples display detailed information about the IPv4 flow and the TE tunnel (LSP) on the headend router (10.0.0.2 in Figure 2):
Router# show ip rsvp sender detailPATH: <----------------------------------------------- IPv4 flow information begins here.Destination 10.0.0.3, Protocol_Id 17, Don't Police , DstPort 2Sender address: 10.0.0.1, port: 2Path refreshes:arriving: from PHOP 10.0.0.10 on Et0/0 every 30000 msecs. Timeout in 189 secTraffic params - Rate: 10K bits/sec, Max. burst: 10K bytesMin Policed Unit: 0 bytes, Max Pkt Size 2147483647 bytesPath ID handle: 02000412.Incoming policy: Accepted. Policy source(s): DefaultStatus:Output on Tunnel1, out of band. Policy status: Forwarding. Handle: 0800040E <--- TE tunnel verifiedPolicy source(s): DefaultPath FLR: Never repairedPATH: <------------------------------------------------ TE tunnel information begins here.Tun Dest: 10.0.0.3 Tun ID: 1 Ext Tun ID: 10.0.0.2Tun Sender: 10.0.0.2 LSP ID: 11Path refreshes:sent: to NHOP 10.1.0.2 on GigabitEthernet1/0/0...
Router# show ip rsvp reservation detailRSVP Reservation. Destination is 10.0.0.3, Source is 10.0.0.1,<--- IPv4 flow information begins here.Protocol is UDP, Destination port is 2, Source port is 2Next Hop: 10.0.0.3 on Tunnel1, out of band <-------------------- TE tunnel verifiedReservation Style is Shared-Explicit, QoS Service is Guaranteed-Rate...Reservation: <--------------------------------------- TE Tunnel information begins here.Tun Dest: 10.0.0.3 Tun ID: 1 Ext Tun ID: 10.0.0.2Tun Sender: 10.0.0.2 LSP ID: 11Next Hop: 10.1.0.2 on GigabitEthernet1/0/0Label: 0 (outgoing)Reservation Style is Shared-Explicit, QoS Service is Controlled-Load...Router# show ip rsvp installed detailRSVP: GigabitEthernet0/0/0 has no installed reservationsRSVP: GigabitEthernet1/0/0 has the following installed reservationsRSVP Reservation. Destination is 10.0.0.3. Source is 10.0.0.2,Protocol is 0 , Destination port is 1, Source port is 11Traffic Control ID handle: 03000405Created: 04:46:55 EST Fri Oct 26 2007 <------ IPv4 flow informationAdmitted flowspec:Reserved bandwidth: 100K bits/sec, Maximum burst: 1K bytes, Peak rate: 100K bits/secMin Policed Unit: 0 bytes, Max Pkt Size: 1500 bytesResource provider for this flow: None...RSVP: Tunnel1 has the following installed reservations <------ TE tunnel verifiedRSVP Reservation. Destination is 10.0.0.3. Source is 10.0.0.1,Protocol is UDP, Destination port is 2, Source port is 2Traffic Control ID handle: 01000415Created: 04:57:07 EST Fri Oct 26 2007 <----- IPv4 flow informationAdmitted flowspec:Reserved bandwidth: 10K bits/sec, Maximum burst: 10K bytes, Peak rate: 10K bits/secMin Policed Unit: 0 bytes, Max Pkt Size: 0 bytesResource provider for this flow: None...Router# show ip rsvp interface detailEt0/0:RSVP: EnabledInterface State: UpBandwidth:Curr allocated: 0 bits/secMax. allowed (total): 3M bits/secMax. allowed (per flow): 3M bits/sec...Et1/0:RSVP: EnabledInterface State: UpBandwidth:Curr allocated: 0 bits/secMax. allowed (total): 3M bits/secMax. allowed (per flow): 3M bits/sec...Tu1: <--------------------------------- TE tunnel information begins here.RSVP: EnabledRSVP aggregation over MPLS TE: EnabledInterface State: UpBandwidth:Curr allocated: 20K bits/secMax. allowed (total): 3M bits/secMax. allowed (per flow): 3M bits/sec...The following examples display detailed information about the IPv4 flow and the TE tunnel (LSP) on the tailend router (10.0.0.3 in Figure 2):
Router# show ip rsvp sender detailPATH: <----------------------------------------------- IPv4 flow information begins here.Destination 10.0.0.3, Protocol_Id 17, Don't Police , DstPort 2Sender address: 10.0.0.1, port: 2Path refreshes:arriving: from PHOP 10.0.0.2 on Et1/0 every 30000 msecs, out of band. Timeout in 188 secTraffic params - Rate: 10K bits/sec, Max. burst: 10K bytesMin Policed Unit: 0 bytes, Max Pkt Size 2147483647 bytes...PATH: <------------------------------------------------ TE tunnel information begins here.Tun Dest: 10.0.0.3 Tun ID: 1 Ext Tun ID: 10.0.0.2Tun Sender: 10.0.0.2 LSP ID: 11Path refreshes:arriving: from PHOP 10.1.0.1 on Et1/0 every 30000 msecs. Timeout in 202 sec...Router# show ip rsvp reservation detailRSVP Reservation. Destination is 10.0.0.3, Source is 10.0.0.1, <--- IPv4 flow information begins here.Protocol is UDP, Destination port is 2, Source port is 2Next Hop: noneReservation Style is Shared-Explicit, QoS Service is Guaranteed-Rate...Reservation: <--------------------------------------- TE tunnel information begins here.Tun Dest: 10.0.0.3 Tun ID: 1 Ext Tun ID: 10.0.0.2Tun Sender: 10.0.0.2 LSP ID: 11Next Hop: noneLabel: 1 (outgoing)Reservation Style is Shared-Explicit, QoS Service is Controlled-Load...Router# show ip rsvp request detailRSVP Reservation. Destination is 10.0.0.3, Source is 10.0.0.1,Protocol is UDP, Destination port is 2, Source port is 2Prev Hop: 10.0.0.2 on GigabitEthernet1/0/0, out of band <-------------- TE tunnel verifiedReservation Style is Shared-Explicit, QoS Service is Guaranteed-RateAverage Bitrate is 10K bits/sec, Maximum Burst is 10K bytes...Request: <------------------------------------ TE tunnel information begins here.Tun Dest: 10.0.0.3 Tun ID: 1 Ext Tun ID: 10.0.0.2Tun Sender: 10.0.0.2 LSP ID: 11Prev Hop: 10.1.0.1 on GigabitEthernet1/0/0Label: 0 (incoming)Reservation Style is Shared-Explicit, QoS Service is Controlled-Load...Example: Verifying the RSVP Local Policy Configuration
The following example verifies that a default local policy has been configured on tunnel interface 1:
Router# show run interface tunnnel 1Building configuration...Current configuration : 419 bytes!interface Tunnel1bandwidth 3000ip unnumbered Loopback0tunnel destination 10.0.0.3tunnel mode mpls traffic-engtunnel mpls traffic-eng autoroute announcetunnel mpls traffic-eng priority 1 1tunnel mpls traffic-eng bandwidth 100tunnel mpls traffic-eng path-option 1 dynamictunnel mpls traffic-eng fast-rerouteip rsvp policy local default <---------------- Local policy information begins here.max bandwidth single 10forward allip rsvp bandwidth 3000endThe following example provides additional information about the default local policy configured on tunnel interface 1:Router# show ip rsvp policy local detailTunnel1:Default policy:Preemption Scope: Unrestricted.Local Override: Disabled.Fast ReRoute: Accept.Handle: BC000413.Accept ForwardPath: Yes YesResv: Yes YesPathError: Yes YesResvError: Yes YesSetup Priority Hold PriorityTE: N/A N/ANon-TE: N/A N/ACurrent LimitSenders: 0 N/AReceivers: 1 N/AConversations: 1 N/AGroup bandwidth (bps): 10K N/APer-flow b/w (bps): N/A 10KGeneric policy settings:Default policy: Accept allPreemption: DisabledAdditional References
The following sections provide references related to the MPLS TE Tunnel-Based Admission Control feature.
Related Documents
Related Topic Document TitleCisco IOS commands
RSVP commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples
QoS features including signaling, classification, and congestion management
MPLS tunnels
"MPLS Traffic Engineering (TE)—Automatic Bandwidth Adjustment for TE Tunnels" module
Standards
Standard TitleNo new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.
—
MIBs
RFCs
Technical Assistance
Feature Information for MPLS TE—Tunnel-Based Admission Control
Table 1 lists the release history for this feature.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note
Table 1 lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Glossary
admission control—The process by which an RSVP reservation is accepted or rejected on the basis of end-to-end available network resources.
aggregate—An RSVP flow that represents multiple E2E flows; for example, an MPLS-TE tunnel may be an aggregate for many E2E flows.
aggregation region—An area where E2E flows are represented by aggregate flows, with aggregators and deaggregators at the edge; for example, an MPLS-TE core, where TE tunnels are aggregates for E2E flows. An aggregation region contains a connected set of nodes that are capable of performing RSVP aggregation.
aggregator—The router that processes the E2E PATH message as it enters the aggregation region. This router is also called the TE tunnel headend router; it forwards the message from an exterior interface to an interior interface.
bandwidth—The difference between the highest and lowest frequencies available for network signals. The term is also used to describe the rated throughput capacity of a given network medium or protocol.
deaggregator—The router that processes the E2E PATH message as it leaves the aggregation region. This router is also called the TE tunnel tailend router; it forwards the message from an interior interface to an exterior interface.
E2E—end-to-end. An RSVP flow that crosses an aggregation region and whose state is represented in aggregate within this region; for example, a classic RSVP unicast flow that crosses an MPLS-TE core.
LSP—label switched path. A configured connection between two routers in which label switching is used to carry the packets. The purpose of an LSP is to carry data packets.
MPLS—Multiprotocol Label Switching. Packet-forwarding technology, used in the network core, that applies data link layer labels to tell switching nodes how to forward data, resulting in faster and more scalable forwarding than network layer routing normally can do.
QoS—quality of service. A measure of performance for a transmission system that reflects its transmission quality and service availability.
RSVP—Resource Reservation Protocol. A protocol that supports the reservation of resources across an IP network. Applications that run on IP end systems can use RSVP to indicate to other nodes the nature (bandwidth, jitter, maximum burst, and so on) of the packet streams that they want to receive.
state—Information that a router must maintain about each LSP. The information is used for rerouting tunnels.
TE—traffic engineering. The techniques and processes that are used to cause routed traffic to travel through the network on a path other than the one that would have been chosen if standard routing methods had been used.
tunnel—Secure communications path between two peers, such as two routers.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
© 2008-2010 Cisco Systems, Inc. All rights reserved.