By default, RSVP is disabled so that it is backward compatible with systems that do not implement RSVP. To enable RSVP for IP on an interface, perform the following task. This task starts RSVP and sets the bandwidth and single-flow limits.

To configure the RSVP bandwidth, perform the following task. The default maximum bandwidth is up to 75 percent of the bandwidth available on the interface. By default, the amount reservable by a flow can be up to the entire reservable bandwidth.

Reservations on individual circuits that do not exceed 100 kb/s normally succeed. However, if reservations have been made on other circuits adding up to 1.2 Mb/s, and a reservation is made on a subinterface that itself has enough remaining bandwidth, the reservation request will still be refused because the physical interface lacks supporting bandwidth.

Perform this task to configure the maximum bandwidth for single or group flows. As part of the application ID enhancement, maximum bandwidth can be configured for RESV messages. This allows the local policy bandwidth limit to be used by RSVP's admission control process for both shared and nonshared reservations. It also allows a local policy to trigger preemption during the admission control function if there is insufficient policy bandwidth to meet the needs of an incoming RESV message.

If RSVP neighbors are discovered to be using User Datagram Protocol (UDP) encapsulation, the router will automatically generate UDP-encapsulated messages for consumption by the neighbors.

However, in some cases, a host will not originate such a message until it has first heard from the router, which it can do only via UDP. You must instruct the router to generate UDP-encapsulated RSVP multicasts whenever it generates an IP-encapsulated multicast.

To specify multicast destinations that should receive UDP-encapsulated messages, perform the following task:

By default, any RSVP neighbor may offer a reservation request. To control which RSVP neighbors can offer a reservation request, perform the following task. When you perform this task, only neighbors conforming to the access list are accepted. The access list is applied to the IP header.

To enable RSVP to attach itself to NetFlow so that it can receive information about packets in order to update its token bucket and set IP precedence as required, perform the following task. This task is optional for the following reason: When the interface is configured with the ip rsvp svc-required command to use ATM switched virtual circuits (SVCs), RSVP automatically attaches itself to NetFlow to perform packet flow identification. However, if you want to perform IP Precedence-type of service (ToS) bit setting in every packet without using ATM SVCs, then you must use the ip rsvp flow-assist command to instruct RSVP to attach itself to NetFlow.

Note	If you use WFQ, then the ToS and IP Precedence bits will be set only on data packets that RSVP sees, due to congestion.

Note

To configure the IP Precedence and ToS values to be used to mark packets in an RSVP reserved path that either conform to or exceed the RSVP flow specification (flowspec), perform the following task.You must configure the ip rsvp flow-assist command if you want to set IP Precedence or ToS values in every packet and you are not using ATM SVCs; that is, you have not configured the ip rsvp svc-required command.

The ToS byte in the IP header defines the three high-order bits as IP Precedence bits and the five low-order bits as ToS bits.

The router software checks the source and destination addresses and port numbers of a packet to determine if the packet matches an RSVP reservation. If a match exists, as part of its input processing, RSVP checks the packet for conformance to the flowspec of the reservation. During this process, RSVP determines if the packet conforms to or exceeds the flowspec, and it sets the IP header IP Precedence and ToS bits of the packet accordingly. These IP Precedence and ToS bit settings are used by per-VC Distributed Weighted Random Early Detection (DWRED) on the output interface, and they can be used by interfaces on downstream routers.

The combination of scheduling performed by the Enhanced ATM port adapter (PA-A3) and the per-SVC DWRED drop policy ensures that any packet that matches a reservation but exceeds the flowspec (that is, it does not conform to the token bucket for the reservation) is treated as if it were a best-effort packet. It is sent on the SVC for the reservation, but its IP precedence is marked to ensure that it does not interfere with conforming traffic.

To allow a user on a remote management station to monitor RSVP-related information, perform the following task:

Perform this task to verify the resulting RSVP operations, after configuring the RSVP reservations that reflect your network resource policy. You can perform these steps in any order.

This section describes configuration of RSVP on three Cisco 4500 routers for a multicast session.

For information on how to configure RSVP, see the How to Configure RSVP.

The three routers form the router network between an RSVP sender application running on an upstream (end system) host and an RSVP receiver application running on a downstream (end system) host--neither host is shown in this example.

The router network includes three routers: Router A, Router B, and Router C. The example presumes that the upstream High-Speed Serial Interface (HSSI) interface 0 of Router A links to the upstream host. Router A and Router B are connected by the downstream Ethernet interface1 of Router A, which links to the upstream interface Ethernet 1 of Router B. Router B and Router C are connected by the downstream HSSI interface 0 of Router B, which links to the upstream HSSI interface 0 of Router C. The example presumes that the downstream Ethernet interface 2 of Router C links to the downstream host.

Typically, an RSVP-capable application running on an end system host on one side of a router network sends either unicast or multicast RSVP PATH (Set Up) messages to the destination end system or host on the other side of the router network with which it wants to communicate. The initiating application is referred to as the sender; the target or destination application is called the receiver. In this example, the sender runs on the host upstream from Router A and the receiver runs on the host downstream from Router C. The router network delivers the RSVP PATH messages from the sender to the receiver. The receiver replies with RSVP RESV messages in an attempt to reserve across the network the requested resources that are required between itself and the sender. The RSVP RESV messages specify the parameters for the requisite QoS that the router network connecting the systems should attempt to offer.

This example does not show the host that would run the sender application and the host that would run the receiver application. Normally, the first router downstream from the sender in the router network--in this case, Router A--would receive the RSVP PATH message from the sender. Normally, the last router in the router network--that is, the next hop upstream from the host running the receiver application, in this case, Router C--would receive an RSVP RESV message from the receiver.

Because this example does not explicitly include the hosts on which the sender and receiver applications run, the routers have been configured to act as if they were receiving PATH messages from a sender and RESV messages from a receiver. The commands used for this purpose, allowing RSVP to be more fully illustrated in the example, are the ip rsvp sender command and the ip rsvp reservation command. On Router A, the following command has been issued:

ip rsvp sender 225.1.1.1 10.1.2.1 UDP 7001 7000 10.1.2.1 Hs0 20 1

This command causes the router to act as if it were receiving PATH messages destined to multicast address 225.1.1.1 from a source 10.1.2.1. The previous hop of the PATH message is 10.1.2.1, and the message was received on HSSI interface 0.

On Router C, the following command has been issued:

ip rsvp reservation 225.1.1.1 10.1.2.1 UDP 7001 7000 10.1.3.1 Et2 FF LOAD 8 1

This command causes the router to act as if it were receiving RESV messages for the session with multicast destination 225.1.1.1. The messages request a Fixed Filter reservation to source 10.1.2.1, and act as if they had arrived from a receiver on Ethernet interface 2 with address 10.1.3.1.

In the example, the RSVP PATH messages flow in one direction: downstream from the sender, which in this example is Router A. (If the host were to initiate the RSVP PATH message, the message would flow from the host to Router A.) Router A sends the message downstream to Router B, and Router B sends it downstream to Router C. (If the downstream host were the actual receiver, Router C would send the RSVP PATH message downstream to the receiver host.) Each router in the router network must process the RSVP PATH message and route it to the next downstream hop.

The RSVP RESV messages flow in one direction: upstream from the receiver (in this example, Router C), upstream from Router C to Router B, and upstream from Router B to Router A. If the downstream host were the receiver, the message would originate with the host, which would send it to Router C. If the upstream host were the sender, the final destination of the RSVP RESV message would be the upstream host. At each hop, the router receiving the RSVP RESV message must determine whether it can honor the reservation request.

The ip rsvp bandwidth command both enables RSVP on an interface and specifies the amount of bandwidth on the interface that can be reserved (and the amount of bandwidth that can be allocated to a single flow). To ensure QoS for the RSVP reservation, WFQ is configured on the interfaces enabled for the reservation.

If the router network is capable of offering the specified (QoS) level of service, then an end-to-end reserved path is established. If not, the reservation attempt is rejected and a RESV ERROR message is sent to the receiver. The ability of each router in the network to honor the requested level of service is verified, link by link, as the RSVP RESV messages are sent across the router network to the sender. However, the data itself for which the bandwidth is reserved travels one way only: from the sender to receiver across an established PATH. Therefore, the QoS is effective in only one direction. This is the common case for one-to-many multicast data flows.

After the three routers in the example are configured, the show ip rsvp sender and show ip rsvp reservation commands will make visible the PATH and RESV state.

Router A Configuration

On Router A, RSVP is enabled on Ethernet interface 1 with 10 kb/s to be reserved for the data transmission. A weighted fair queue is reserved on this interface to ensure RSVP QoS. (On Router A, RSVP is also enabled on HSSI interface 0 with 1 kb/s reserved, but this bandwidth is used simply for passing messages.)

!
version 12.0
service config
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service udp-small-servers
service tcp-small-servers
!
hostname routerA
!
ip subnet-zero
no ip domain-lookup
ip multicast-routing
ip dvmrp route-limit 20000
!
!
interface Ethernet0
 ip address 172.0.0.193 255.0.0.0
 no ip directed-broadcast
 no ip route-cache
 no ip mroute-cache
 media-type 10BaseT
!
interface Ethernet1
 ip address 172.1.1.2 255.0.0.0
 no ip directed-broadcast
 ip pim dense-mode
 ip rsvp bandwidth 10 10
 fair-queue 64 256 1000
 media-type 10BaseT
!
interface Hssi0
 ip address 10.1.1.1 255.0.0.0
 no ip directed-broadcast
 ip pim dense-mode
 ip rsvp bandwidth 1 1
!
interface ATM0
 no ip address
 no ip directed-broadcast
 shutdown
!
router ospf 100
 network 10.0.0.0 0.255.255.255 area 10
 network 172.0.0.0 0.255.255.255 area 10
!
ip classless
ip rsvp sender 225.1.1.1 12.1.2.1 UDP 7001 7000 10.1.2.1 Hs0 20 1
!
line con 0
 exec-timeout 0 0
 length 0
 transport input none
line aux 0
line vty 0 4
 login
!
end

Router B Configuration

On Router B, RSVP is enabled on HSSI interface 0 with 20 kb/s to be reserved for the data transmission. A weighted fair queue is reserved on this interface to ensure RSVP QoS. (On Router B, RSVP is also enabled on Ethernet interface 1 with 1 kb/s reserved, but this bandwidth is used simply for passing messages.)

!
version 12.0
service config
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service udp-small-servers
service tcp-small-servers
!
hostname routerB
!
ip subnet-zero
no ip domain-lookup
ip multicast-routing
ip dvmrp route-limit 20000
clock calendar-valid
!
interface Ethernet0
 ip address 172.0.0.194 255.0.0.0
 no ip directed-broadcast
 no ip route-cache
 no ip mroute-cache
 media-type 10BaseT
!
interface Ethernet1
 ip address 10.1.1.1 255.0.0.0
 no ip directed-broadcast
 ip pim dense-mode
 ip rsvp bandwidth 1 1
 media-type 10BaseT
!
interface Hssi0
 ip address 10.1.1.2 255.0.0.0
 no ip directed-broadcast
 ip pim dense-mode
 ip rsvp bandwidth 20 20
 fair-queue 64 256 1000
 hssi internal-clock
!
interface ATM0
 no ip address
 no ip directed-broadcast
 shutdown
!
router ospf 100
 network 10.0.0.0 0.255.255.255 area 10
 network 172.0.0.0 0.255.255.255 area 10
!
ip classless
!
line con 0
 exec-timeout 0 0
 length 0
 transport input none
line aux 0
line vty 0 4
 login
!
end

Router C Configuration

On Router C, RSVP is enabled on Ethernet interface 2 with 20 kb/s to be reserved for the data transmission. A weighted fair queue is reserved on this interface to ensure RSVP QoS. (On Router C, RSVP is also enabled on HSSI interface 0 with 1 kb/s reserved, but this bandwidth is used simply for passing messages.)

!
version 12.0
service config
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service udp-small-servers
service tcp-small-servers
!
hostname routerC
!
ip subnet-zero
no ip domain-lookup
ip multicast-routing
ip dvmrp route-limit 20000
!
interface Ethernet0
 ip address 172.0.0.195 255.0.0.0
 no ip directed-broadcast
 no ip route-cache
 no ip mroute-cache
 media-type 10BaseT
!
interface Ethernet1
 no ip address
 no ip directed-broadcast
 shutdown
 media-type 10BaseT
!
interface Ethernet2
 ip address 10.1.3.2 255.0.0.0
 no ip directed-broadcast
 ip pim dense-mode
 ip rsvp bandwidth 20 20
 fair-queue 64 256 1000
 media-type 10BaseT
!
interface Ethernet3
 no ip address
 no ip directed-broadcast
 shutdown
 media-type 10BaseT
!
interface Ethernet4
 no ip address
 no ip directed-broadcast
 shutdown
 media-type 10BaseT
!
interface Ethernet5
 no ip address
 no ip directed-broadcast
 shutdown
 media-type 10BaseT
!
interface Hssi0
 ip address 10.1.1.1 255.0.0.0
 no ip directed-broadcast
 ip pim dense-mode
 ip rsvp bandwidth 1 1
 hssi internal-clock
!
interface ATM0
 no ip address
 no ip directed-broadcast
 shutdown
!
router ospf 100
 network 10.0.0.0 0.255.255.255 area 10
 network 172.0.0.0 0.255.255.255 area 10
!
ip classless
ip rsvp reservation 225.1.1.1 10.1.2.1 UDP 7001 7000 10.1.3.1 Et2 FF LOAD 8 1
!
line con 0
 exec-timeout 0 0
 length 0
 transport input none
line aux 0
line vty 0 4
 login
!
end

The following example shows how to configure an absolute value for the RSVP bandwidth and percentage of interface as the flow bandwidth:

configure terminal
 interface multilink 2
  ip rsvp bandwidth 1000 percent 50

The following example shows how to configure a percentage of interface as the RSVP bandwidth and an absolute value for the flow bandwidth:

configure terminal
 interface multilink 2
  ip rsvp bandwidth percent 50 1000

The following example shows how to configure an absolute value for the RSVP bandwidth and the flow bandwidth:

configure terminal
 interface multilink 2
  ip rsvp bandwidth 23 34

The following example shows how to configure a percentage of RSVP bandwidth of an interface that should be the limit for a group of flows in an interface level RSVP policy:

configure terminal
 interface multilink 2
 ip rsvp policy local identity id1 
 maximum bandwidth percent group 80
 maximum bandwidth percent single 5
 end

The following example shows how to verify the configuration of percentage of RSVP bandwidth that should be the limit for a group of flows:

Router# show running interface multilink 2
Building configuration...
Current configuration : 298 bytes
!
interface Multilink2
 ip address 30.30.30.1 255.255.255.0
 ip ospf cost 100
 ppp multilink
 ppp multilink group 2
 ppp multilink endpoint ip 30.30.30.2
 ip rsvp policy local identity id1
  maximum bandwidth percent group 80
  maximum bandwidth percent single 5
 ip rsvp bandwidth percent 50 percent 10
end

The following example shows how to configure RSVP ingress bandwidth for an interface:

enable
 configure terminal
  interface tunnel 0
   ip rsvp bandwidth ingress 200

The following example shows how to configure the maximum ingress bandwidth for a group of reservations and for a single reservation respectively, in a global-based RSVP policy:

enable
 configure terminal
  ip rsvp local identity rsvp-video
   maximum bandwidth ingress group 200
   maximum bandwidth ingress single 100
The following example shows how to configure the maximum percentage of RSVP ingress bandwidth of an interface for a group of reservations and for a single reservation, respectively:
enable
 configure terminal
  interface tunnel 0
   ip rsvp local identity rsvp-video
    maximum bandwidth ingress percent group 50
    maximum bandwidth ingress single 50

The following example shows how to verify the ingress CAC parameters on an interface:

Router# show ip rsvp ingress interface detail ethernet 1/0
interface    rsvp  in-allocated  in-i/f max  in-flow max  VRF            
Et1/0        ena   0             7500K       7500K        0 

The following example shows how to configure tunnel bandwidth overhead:

configure terminal
 interface tunnel 0
  ip rsvp overhead-percent 25

end

You can use the show ip rsvp interface, show ip rsvp interface detailand show ip rsvp reservationcommands to verify the RSVP configuration parameters:

Router# show ip rsvp interface detail
Tu0:
   RSVP: Enabled
   Interface State: Up
   Bandwidth:
     Curr allocated: 10K bits/sec
     Max. allowed (total): 75K bits/sec
     Max. allowed (per flow): 75K bits/sec
     Max. allowed for LSP tunnels using sub-pools: 0 bits/sec
     Set aside by policy (total): 0 bits/sec
   Admission Control:
     Header Compression methods supported:
       rtp (36 bytes-saved), udp (20 bytes-saved)
     Tunnel IP Overhead percent:
       4
     Tunnel Bandwidth considered:
       Yes
   Traffic Control:
     RSVP Data Packet Classification is ON via CEF callbacks
   Signalling:
     DSCP value used in RSVP msgs: 0x3F
     Number of refresh intervals to enforce blockade state: 4
   Authentication: disabled
     Key chain:   <none>
     Type:        md5
     Window size: 1
     Challenge:   disabled 
   Hello Extension:
     State: Disabled

Router# show ip rsvp interface
interface    rsvp       allocated  i/f max  flow max sub max  VRF            
Et0/0        ena        10400      7500K    7500K    0   
Et1/0        ena        20K        7500K    7500K    0   

Tu0 ena 10400 750K 750K 0

Router# show ip rsvp reservation
To            From          Pro DPort Sport Next Hop      I/F      Fi Serv BPS
192.168.2.2   192.168.1.2   TCP 10    10    192.168.2.2   Tu0      SE RATE 10K