Quality of Service Configuration Guide, Cisco IOS XE 17.x
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The 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.
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
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. The figure below gives an overview of TBAC.
The figure below 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
Enabling RSVP QoS
Perform this task to enable RSVP QoS globally on a device.
SUMMARY STEPS
enable
configureterminal
iprsvpqos
end
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Device> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Device# configure terminal
Enters global configuration mode.
Step 3
iprsvpqos
Example:
Device(config)# ip rsvp qos
Enables RSVP QoS globally on a device.
Step 4
end
Example:
Device(config)# end
(Optional) Returns to privileged EXEC mode.
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
enable
configureterminal
mplstraffic-engtunnels
end
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Router> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Router# configure terminal
Enters global configuration mode.
Step 3
mplstraffic-engtunnels
Example:
Router(config)# mpls traffic-eng tunnels
Enables MPLS TE globally on a router.
Step 4
end
Example:
Router(config)# end
(Optional) Returns to privileged EXEC mode.
Configuring an MPLS TE Tunnel Interface
Before you begin
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
enable
configureterminal
interfacetunnelnumber
end
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Router> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Router# configure terminal
Enters global configuration mode.
Step 3
interfacetunnelnumber
Example:
Router(config)# interface tunnel 1
Specifies a tunnel interface and enters interface configuration mode.
Step 4
end
Example:
Router(config-if)# end
(Optional) Returns to privileged EXEC mode.
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.
The optional interface-kbps and single-flow-kbps arguments specify the amount of bandwidth that can be allocated by RSVP flows or to a single flow, respectively. Values are
from 1 to 10000000.
Note
You must enter a value for the interface-kbpsargument on a tunnel interface.
Step 5
end
Example:
Router(config-if)# end
(Optional) Returns to privileged EXEC mode.
Verifying the TBAC Configuration
Note
You can use the followingshow commands in user EXEC or privileged EXEC
mode, in any order.
Router# show mpls traffic-eng link-management bandwidth-allocation
Displays current local link information.
Step 6
exit
Example:
Router# exit
(Optional) Exits privileged EXEC mode and returns to user EXEC
mode.
Configuration Examples for MPLS TE - Tunnel-Based Admission Control
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 terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)# iprsvpqos
Router(config)# mplstraffic-engtunnels
Router(config)# interfacetunnel1
Router(config-if)# iprsvpbandwidth7500
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 terminal
Enter configuration commands, one per line. End with CNTL/Z.
The figure below shows a network in which TBAC is configured.
The following example verifies that RSVP and MPLS TE are enabled and coexist on the headend router (10.0.0.2 in the figure
above):
Router# show ip rsvp
RSVP: enabled (on 3 interface(s))
RSVP QoS enabled <-------
MPLS/TE signalling enabled <------
Signalling:
Refresh interval (msec): 30000
Refresh misses: 4
.
.
.
The following example verifies that RSVP and MPLS TE are enabled and coexist on the tailend router (10.0.0.3 in the figure
above):
Router# show ip rsvp
RSVP: enabled (on 3 interface(s))
RSVP QoS enabled <-------
MPLS/TE signalling enabled <------
Signalling:
Refresh interval (msec): 30000
Refresh 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 the figure above):
Router# show ip rsvp sender
To From Pro DPort Sport Prev Hop I/F BPS
10.0.0.3 10.0.0.1 UDP 2 2 10.0.0.1 Et0/0 10K <-- IPv4 flow
10.0.0.3 10.0.0.2 0 1 11 none none 100K <-- TE tunnel
Router# show ip rsvp reservation
To From Pro DPort Sport Next Hop I/F Fi Serv BPS
10.0.0.3 10.0.0.1 UDP 2 2 10.0.0.3 Tu1 SE RATE 10K <-- IPv4 flow
10.0.0.3 10.0.0.2 0 1 11 10.1.0.2 Et1/0 SE LOAD 100K <-- TE tunnel
The following examples verify that an IPv4 flow is traveling through a TE tunnel (LSP) on the tailend router (10.0.0.3 in
the figure above):
Router# show ip rsvp sender
To From Pro DPort Sport Prev Hop I/F BPS
10.0.0.3 10.0.0.1 UDP 2 2 10.0.0.2 Et1/0 10K <-- IPv4 flow
10.0.0.3 10.0.0.2 0 1 11 10.1.0.1 Et1/0 100K <-- TE tunnel
Router# show ip rsvp reservation
To From Pro DPort Sport Next Hop I/F Fi Serv BPS
10.0.0.3 10.0.0.1 UDP 2 2 none none SE RATE 10K <-- IPv4 flow
10.0.0.3 10.0.0.2 0 1 11 none none SE LOAD 100K <-- TE tunnel
The following examples display detailed information about the IPv4 flow and the TE tunnel (LSP) on the headend router (10.0.0.2
in the figure above):
Router# show ip rsvp sender detail
PATH: <----------------------------------------------- IPv4 flow information begins here.
Destination 10.0.0.3, Protocol_Id 17, Don't Police , DstPort 2
Sender address: 10.0.0.1, port: 2
Path refreshes:
arriving: from PHOP 10.0.0.10 on Et0/0 every 30000 msecs. Timeout in 189 sec
Traffic params - Rate: 10K bits/sec, Max. burst: 10K bytes
Min Policed Unit: 0 bytes, Max Pkt Size 2147483647 bytes
Path ID handle: 02000412.
Incoming policy: Accepted. Policy source(s): Default
Status:
Output on Tunnel1, out of band. Policy status: Forwarding. Handle: 0800040E <--- TE tunnel verified
Policy source(s): Default
Path FLR: Never repaired
PATH: <------------------------------------------------ TE tunnel information begins here.
Tun Dest: 10.0.0.3 Tun ID: 1 Ext Tun ID: 10.0.0.2
Tun Sender: 10.0.0.2 LSP ID: 11
Path refreshes:
sent: to NHOP 10.1.0.2 on GigabitEthernet1/0/0
.
.
.
Router# show ip rsvp reservation detail
RSVP 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 2
Next Hop: 10.0.0.3 on Tunnel1, out of band <-------------------- TE tunnel verified
Reservation 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: 10.0.0.2
Tun Sender: 10.0.0.2 LSP ID: 11
Next Hop: 10.1.0.2 on GigabitEthernet1/0/0
Label: 0 (outgoing)
Reservation Style is Shared-Explicit, QoS Service is Controlled-Load
.
.
.
Router# show ip rsvp installed detail
RSVP: GigabitEthernet0/0/0 has no installed reservations
RSVP: GigabitEthernet1/0/0 has the following installed reservations
RSVP Reservation. Destination is 10.0.0.3. Source is 10.0.0.2,
Protocol is 0 , Destination port is 1, Source port is 11
Traffic Control ID handle: 03000405
Created: 04:46:55 EST Fri Oct 26 2007 <------ IPv4 flow information
Admitted flowspec:
Reserved bandwidth: 100K bits/sec, Maximum burst: 1K bytes, Peak rate: 100K bits/sec
Min Policed Unit: 0 bytes, Max Pkt Size: 1500 bytes
Resource provider for this flow: None
.
.
.
RSVP: Tunnel1 has the following installed reservations <------ TE tunnel verified
RSVP Reservation. Destination is 10.0.0.3. Source is 10.0.0.1,
Protocol is UDP, Destination port is 2, Source port is 2
Traffic Control ID handle: 01000415
Created: 04:57:07 EST Fri Oct 26 2007 <----- IPv4 flow information
Admitted flowspec:
Reserved bandwidth: 10K bits/sec, Maximum burst: 10K bytes, Peak rate: 10K bits/sec
Min Policed Unit: 0 bytes, Max Pkt Size: 0 bytes
Resource provider for this flow: None
.
.
.
The following examples display detailed information about the IPv4 flow and the TE tunnel (LSP) on the tailend router (10.0.0.3
in the figure above):
Router# show ip rsvp sender detail
PATH: <----------------------------------------------- IPv4 flow information begins here.
Destination 10.0.0.3, Protocol_Id 17, Don't Police , DstPort 2
Sender address: 10.0.0.1, port: 2
Path refreshes:
arriving: from PHOP 10.0.0.2 on Et1/0 every 30000 msecs, out of band. Timeout in 188 sec
Traffic params - Rate: 10K bits/sec, Max. burst: 10K bytes
Min 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: 10.0.0.2
Tun Sender: 10.0.0.2 LSP ID: 11
Path refreshes:
arriving: from PHOP 10.1.0.1 on Et1/0 every 30000 msecs. Timeout in 202 sec
.
.
.
Router# show ip rsvp reservation detail
RSVP 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 2
Next Hop: none
Reservation 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: 10.0.0.2
Tun Sender: 10.0.0.2 LSP ID: 11
Next Hop: none
Label: 1 (outgoing)
Reservation Style is Shared-Explicit, QoS Service is Controlled-Load
.
.
.
Router# show ip rsvp request detail
RSVP Reservation. Destination is 10.0.0.3, Source is 10.0.0.1,
Protocol is UDP, Destination port is 2, Source port is 2
Prev Hop: 10.0.0.2 on GigabitEthernet1/0/0, out of band <-------------- TE tunnel verified
Reservation Style is Shared-Explicit, QoS Service is Guaranteed-Rate
Average 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: 10.0.0.2
Tun Sender: 10.0.0.2 LSP ID: 11
Prev Hop: 10.1.0.1 on GigabitEthernet1/0/0
Label: 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:
Device# show run interface tunnnel 1
Building configuration...
Current configuration : 419 bytes
!
interface Tunnel1
bandwidth 3000
ip unnumbered Loopback0
tunnel destination 10.0.0.3
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng autoroute announce
tunnel mpls traffic-eng priority 1 1
tunnel mpls traffic-eng bandwidth 100
tunnel mpls traffic-eng path-option 1 dynamic
tunnel mpls traffic-eng fast-reroute
ip rsvp policy local default <---------------- Local policy information begins here.
max bandwidth single 10
forward all
ip rsvp bandwidth 3000
end
The following example provides additional information about the default local policy configured on tunnel interface 1:
Device# show ip rsvp policy local detail
Tunnel1:
Default policy:
Preemption Scope: Unrestricted.
Local Override: Disabled.
Fast ReRoute: Accept.
Handle: BC000413.
Accept Forward
Path: Yes Yes
Resv: Yes Yes
PathError: Yes Yes
ResvError: Yes Yes
Setup Priority Hold Priority
TE: N/A N/A
Non-TE: N/A N/A
Current Limit
Senders: 0 N/A
Receivers: 1 N/A
Conversations: 1 N/A
Group bandwidth (bps): 10K N/A
Per-flow b/w (bps): N/A 10K
Generic policy settings:
Default policy: Accept all
Preemption: Disabled
Additional References
The following sections provide references related to the RSVP--VRF Lite Admission Control feature.
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.
--
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Feature Information for MPLS TE - Tunnel-Based Admission Control
The following table provides release information about the feature or features described in this module. This table 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.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco
Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1. Feature Information for MPLS TE--Tunnel-Based Admission Control (TBAC)
Feature Name
Releases
Feature Information
MPLS TE Tunnel-Based Admission Control
Cisco IOS XE Release 2.6
The MPLS TE--Tunnel-Based Admission Control feature enables classic Resource Reservation Protocol (RSVP) unicast reservations
that are traveling across an MPLS TE core to be aggregated over an MPLS TE tunnel. The following commands were introduced
or modified:
iprsvpqos,
showiprsvp,
showiprsvpreservation,
showiprsvpsender,
showmplstraffic-englink-managementbandwidth-allocation.
Glossary
admissioncontrol--The process by which an RSVP reservation is accepted or rejected on the basis of end-to-end available network resources.
QoS--quality of service. A measure of performance for a transmission system that reflects its transmission quality and service
availability. Quality of service focuses on achieving appropriate network performance for networked applications; it is superior
to best effort performance.
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.
VRF--virtual routing and forwarding. An extension of IP routing that provides multiple routing instances. A VRF consists of an
IP routing table, a derived forwarding table, a set of interfaces that use the forwarding table, and a set of rules and routing
protocols that determine what goes into the forwarding table. In general, a VRF includes the routing information that defines
a customer VPN site that is attached to a provider edge (PE) device.