Cisco Hoot and Holler over IP
The voice multicasting feature on Cisco 2600 and Cisco 3600 series routers uses Cisco Voice-over-IP
(VoIP) technology to create a permanently connected point-to-multipoint hoot and holler network over
an IP connection.
Four-wire E&M, E1/T1, FXO, and FXS configurations provide continuous VoIP connections across a
packet network using the connection-trunk mechanism. By using the inherent point-to-multipoint
connectivity of IP multicast (IPmc), the routers can take several inbound voice streams from the
traditional hoot devices and forward the packetized voice over the IP network to all parties within a
defined hoot and holler group.
This feature module describes the Cisco Hoot and Holler over IP feature and contains the following
sections:
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•
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•
•
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Feature Overview
Hoot and holler networks provide "always on" multiuser conferences without requiring that users dial
into a conference. These networks came into being more than 40 years ago when local concentrations
of small specialized businesses with common, time-critical informational interests—junkyards, for
example—began to install their own phone wires, speakers (called “squawk boxes”), and microphones
between their businesses to ask each other about parts customers needed. These networks functioned as
crude, do-it-yourself, business-to-business intercom systems.
Hoot and holler broadcast audio network systems have since evolved into the specialized leased-line
networks used by financial and brokerage firms to trade stocks and currency futures and the
accompanying time-critical information such as market updates and morning reports.
Users of various forms of hoot and holler networks now include brokerages, news agencies, publishers,
weather bureaus, transportation providers, power plant operators, manufacturers, collectibles dealers,
talent agencies, and nationwide salvage yard organizations.
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Feature Overview
Hoot and holler networks are typically spread over four to eight sites, although financial retail networks
may have hundreds of sites interconnected. Within a site, bridging (mixing voice signals) is done locally
with a standard analog or digital bridge that may be part of a trading turret system. Between sites, there
are two prevalent methods for providing transport:
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•
Point-to-point leased lines with customer-provided audio bridging at a central site, and
Carrier-provided audio bridging.
When customers provide their own bridging services with point-to-point leased lines, branch offices in
a metropolitan area commonly have 25 to 50 lines or more.
The second method, carrier-provided audio bridging, is prevalent within the United States but rare for
overseas transport. In this scenario, the audio bridges are located at the carrier's central office and the
4-wire lines are terminated at the client's site on a local audio-bridge equipped with 4-wire plug-ins,
which then feed to local PA system speakers. Customer-provided hoot bridging services can now be
replaced with Cisco Hoot and Holler over IP solutions.
An Overview of Cisco Hoot and Holler over IP
Cisco's VoIP technology, which was initially focused on traditional PBX toll-bypass applications, can
be used to combine hoot and holler networks with data networks. While some customers may have done
some level of hoot and data integration in the late 1980s with time-division multiplexing (TDM), this
form of integration does not allow for dynamic sharing of bandwidth that is characteristic of VoIP. This
dynamic sharing of bandwidth is even more compelling with hoot and holler than with a toll-bypass
application, because some hoot circuits may be active for an hour or two for morning reports but might
be dead for the rest of the day—the idle bandwidth can be used by the data applications during these
long periods of inactivity.
Beginning with the Cisco IOS Release 12.1(2)XH, Cisco Hoot and Holler over IP can be implemented
using Cisco's VoIP technology. This solution leverages Cisco's IOS expertise in VoIP, quality of service
(QoS), and IP multicasting (IPmc) and is initially available on Cisco 2600 and 3600 series multiservice
routers.
Figure 2 shows a diagram of the Cisco Hoot and Holler over IP solution connecting legacy hoot
equipment over an IP network.
Note
The "V" on the Cisco router icons signifies that some of the hoot and holler bridging
function is being done by the router's digital signal processors (DSPs).
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Feature Overview
Figure 2
Hoot and Holler over IP using Cisco 2600 and Cisco 3600 Series Routers
PBX
V
FXO
Multicast group 1
E&M phones
V
PBX
PBX
FXO
Multicast group 3
Multicast group 2
V
V
FXS
FXO
V
T1/E1
V
T1/E1
Turret
Turret
Turret
E&M = ear and mouth
Four-wire E&M, E1/T1, FXO, and FXS configurations provide continuous VoIP connections across a
packet network. By using the inherent point-to-multipoint characteristic of IPmc, the routers can take
several inbound voice streams from the traditional hoot devices, and forward the packetized voice over
the IP network to all parties within a defined hoot and holler group.
Voice Multicasting
The voice multicasting feature on Cisco 2600 and Cisco 3600 series routers uses Cisco Voice over IP
(VoIP) technology to create a point-to-multipoint hoot and holler network over an IP connection.
Voice multicasting telephones can be connected to routers in the following ways:
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Connect a 4-wire E&M telephone, which has no dial and is always off-hook, directly to an E&M
voice interface card that is installed in a voice network module. Configure the E&M interface for
four-wire trunk operation. For information about configuring E&M interfaces, see the
Cisco IOS Multiservice Applications Configuration Guide , Release 12.1.
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Connect a conventional telephone to a PBX that is connected to an E&M voice interface card.
Connect a conventional telephone to an FXS voice interface card that is installed in a voice network
module.
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Connect a conventional telephone to a PBX that is connected through a E1/T1 line to a multiflex
trunk interface card that is installed in a high-density voice network module.
Note
The voice multicasting feature supports only one E1/T1 line per high-density voice
network module.
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Feature Overview
IP/TV Access
The Cisco Hoot and Holler over IP feature enables you to access ongoing IP/TV multicasts for listening
to voice content of the IP/TV session. For complete information on IP/TV, see the IP/TV Content
Manager Installation and User Guide .
Figure 3
Cisco Hoot and Holler over IP Access to IP/ TV Multicast
IP/TV
Content Manager
IP/TV
server
IP/TV
viewer
For the Cisco Hoot and Holler over IP and IP/TV interaction to work correctly:
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Ensure that you have a properly connected and configured network for Voice over IP with the
Cisco Hoot and Holler over IP feature enabled, using the session protocol multicast command.
Ensure that the server configured with the IP/TV Content Manager is in the same Ethernet network
as the Cisco Hoot and Holler over IP functionality.
Ensure that the Cisco Hoot and Holler over IP multicast details are registered with the IP/TV
Content Manager.
Note
IP/TV support for Cisco Hoot and Holler over IP uses only G.711 u-law (mu-law)
encoding.
IP/TV supports one audio stream for Cisco Hoot and Holler over IP.
IP/TV does not support arbitration and mixing.
Content Manager
On the configuration screen (Administration Tool>Scheduled Programs>New
Program>Configuration), provide the following details:
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Multicast address
RTP port—defined by the dial-peer in the router
IP/TV server—IP address or name
From the Settings>Content Manager option:
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Click Add New.
Enter the IP/TV server name.
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Feature Overview
–
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The port number must be 80, because it is HTTP.
Click OK and exit.
Note
In the Content Manager, be sure to specify the multicast IP address and RTP port for the
Cisco Hoot and Holler over IP session.
Interactive Voice Response (IVR)
The Cisco Hoot and Holler over IP feature can support Interactive Voice Response (IVR) as a means of
authentication, authorization, and accounting (AAA) control. See the section “Configuring Interactive
Voice Response (IVR) ” in the Multiservice Applications Configuration Guide and the command
descriptions in the Multiservice Applications Command Reference for more information.
Migration Strategy
To aid troubleshooting and allow for regionalized hoot and holler conferences, most hoot and holler
networks today are structured by interconnecting multiple, regional hoot networks with a centralized
bridge. The regional hoot networks are built using either carrier-based multidrop circuits or point-to-
point circuits bridged by the customer. All of these circuits are connected through patch panels that
allow for these regional bridges to be connected for a larger corporate-wide conference call. This is
typically done for the "morning call" that is broadcast to all locations, advising of market movements,
recommendations, and commentary. Later in the day, the patch panel may be reconfigured to allow for
local or regional conference bridges. This allows for multiple conference calls for various purposes,
without provisioning multiple circuits. By segmenting the network into regions, troubleshooting is also
easier because any audio disturbance, feedback, or level problems can be isolated to a smaller subset of
remote offices for more specific troubleshooting.
The highly segmented nature of existing hoot and holler networks can be leveraged in the migration
from legacy hoot technology to Cisco Hoot and Holler over IP. A small segment of the hoot network
can be converted to Cisco Hoot and Holler over IP while preserving the operational procedures at the
main office.
Note that the migration to Cisco Hoot and Holler over IP does not require replacing end-user equipment
or central bridging equipment. The main impetus for this first phase of migration is to eliminate the
recurring expense of carrier multidrop circuits or dedicated leased lines. By minimizing changes
presented to the end user while realizing an attractive payback period on the capital costs, migration
success is maximized.
As the entire hoot network converges with the data network, additional functionality can be introduced.
Since the hoot and holler connections are now carried in standard multicast RTP packets, hoot channels
can now be received by a soft client such as IP/TV, which can receive an IP multicast RTP stream. An
alternate migration strategy is to use Cisco Hoot and Holler over IP technology initially as a backup for
the existing hoot circuits within a region with a phased plan of cutting over to Cisco Hoot and Holler
over IP as the primary transport while keeping the existing circuits as a backup for a predefined burn-in
period.
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Feature Overview
Technical Details of the Cisco Hoot and Holler over IP Solution
This section describes how Cisco Hoot and Holler over IP works from a technical perspective. It covers
design considerations in terms of IOS configur
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Feature Overview
is handled by the onboard DSPs on each voice-card (NM-1V, NM-2V or NM-HDV). Arbitration
involves identifying the various sources of the voice stream, and mixing involves taking some of those
voice streams and combining them into a single-sourced voice stream. Cisco Hoot and Holler over IP
can handle many inbound voice streams, but it only arbitrates and mixes three streams to be heard
within the Hoot group. This value works fine in most applications, because beyond three streams two
things happen in normal human conversation:
1. People are not able to distinguish the content of more than three streams.
2. People normally stop speaking if they hear others talking ahead of them.
Note
The mixing functionality does not do a summation of the voice streams.
As previously mentioned, the DSPs in Cisco Hoot and Holler over IP do mixing for up to three streams.
This fact is important when network administrators consider how much bandwidth they should plan for
in their Cisco Hoot and Holler over IP network. This is especially crucial when planning WAN
bandwidth, which is often much more expensive and much less available than LAN bandwidth.
The advantage to this functionality is that a network administrator never has to be concerned about
provisioning voice bandwidth for more than three times per call bandwidth for each WAN site, which
helps to simplify overall network planning.
Bandwidth Planning
Four main factors must be considered with regard to bandwidth planning for
Cisco Hoot and Holler over IP:
1. Codecs used for VoIP (G.711, G.726, G.729 and G.729a are currently supported).
2. Bandwidth management techniques.
3. The number of voice streams to be mixed.
4. The amount of guaranteed bandwidth available on the IP network. This includes both LAN and
WAN bandwidth, and should take into consideration things such as Frame Relay CIR.
Codecs
By default, Cisco IOS sends all VoIP traffic (media, using RTP) at a rate of 50 packets per second. The
packets include not only the voice sample, but also an IP, UDP, and RTP header. The IP/UDP/RTP
header adds an additional 40 bytes to each packet. The amount of bandwidth each VoIP call consumes
depends on the codec selected. The resulting bandwidths can be:
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G.729 or G.729a = 3000bytes * 8 bits = 24Kb/call
G.726 = 6000bytes * 8 bits = 48Kb/call
G.711 = 10000bytes * 8 bits = 80Kb/call
In addition to these calculations, network administrators must consider the Layer 2 headers
(Frame Relay, PPP, Ethernet, and so on.) and add the appropriate number of bytes to each packet.
50 packets per second.
The value of n is equal to the number of voice streams in a session.
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Feature Overview
The uncompressed bandwidth includes IP/UDP/RTP headers (40 bytes) in the bandwidth calculation.
Compressed RTP (cRTP) reduces the IP/UDP/RTP headers to between 2 to 4 bytes per packet. The
calculation of compressed bandwidth below uses 4 bytes for a compressed IP/UDP/RTP header per
packet.
Maximum RTCP bandwidth is five percent of the total RTP traffic in a hoot and holler session. Since
the Cisco Hoot and Holler over IP application supports mixing of a maximum of three voice streams,
the RTCP bandwidth is limited to five percent of three-voice-stream traffic.
In addition to the above, Layer 2 headers (Frame Relay, PPP, Ethernet, and so on) should be considered
and added to the bandwidth calculation.
Table 1
Bandw idth Consideration Table
RTCP Bandwidth per
Payload Size
(byte)
Bandwidth/ Voice Stream
(Kbps)
Cisco Hoot and Holler over IP Example—One Voice Stream in a
Codec
Session (Kbps)
Session (Bandwidth in Kbps)
Uncompressed
Compressed
=(1)*n+(3)
27.6
=(2)*n+(3)
13.2
g.729
g.726
g.711
20
80
24
48
80
9.6
3.6
33.6
65.6
7.2
55.2
40.8
160
12.0
92.0
77.6
cRTP, Variable-Payload Sizes and VAD
Some network administrators may consider this amount of bandwidth per call unacceptable or outside
the limits for which they can provide bandwidth, especially in the WAN. There are several options that
network administrators have for modifying the bandwidth consumed per call:
1. RTP header compression (cRTP)
2. Adjustable byte-size of the voice payload
3. Voice activity detection (VAD)
IP/UDP/RTP headers add an additional 40 bytes to each packet, but each packet header is basically
unchanged throughout the call. cRTP can be enabled for the VoIP calls, which reduces the IP/UDP/RTP
headers to between 2 to 4 bytes per packet.
More detailed documentation on cRTP can be found on CCO at:
In addition to reducing the IP/UDP/RTP headers per packet, the network administrator also has the
option of controlling how much voice payload is included in each packet. This is done using the bytes
keyword and argument in a VoIP dial-peer. The following example shows a dial-peer configuration:
dial-peer voice 1 voip
destination-pattern 4085551234
codec g729r8 bytes 40
session protocol multicast
session target ipv4:239.10.108.252:20102
As the number of bytes per packet is modified, so too is the number of packets per second that are sent.
Voice activity detection (VAD) enables the DSPs to dynamically sense when there are pauses in a
conversation. When these pauses occur, no VoIP packets are sent into the network. This significantly
reduces the amount of bandwidth used per VoIP call, sometimes as much as 40 to 50 percent. When
voice is present, then VoIP packets are again sent. When using Cisco Hoot and Holler over IP, VAD must
be enabled to reduce the amount of processing of idle packets by the DSPs. In basic VoIP, VAD can be
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Feature Overview
enabled or disabled, but since the DSPs also have to do arbitration and mixing, VAD must be disabled
to reduce the DSPs processing load. In addition to enabling VAD (which is on by default), network
administrators should modify the VAD parameters that sense background noise so that idle noise does
not consume bandwidth.
This can be configured as in the following E&M port example:
voice class permanent 1
signal timing oos timeout disabled
signal keepalive 65535
!
voice-port 1/0/0
voice-class permanent 1
connection trunk 111
music-threshold -30
operation 4-wire
The configuration above is used for a voice-port that is in send/receive mode, and only noise above
-30Db is considered voice.
Virtual Interface (Vif)
In all Cisco Hoot and Holler over IP implementations, the routers are configured with an "interface
vif1." This is a virtual interface that is similar to a loopback interface—a logical IP interface that is
always up when the router is active. In addition, it must be configured so the Cisco Hoot and Holler over
IP packets that are locally mixed on the DSPs can be fast-switched along with the other data packets.
This interface must reside on its own unique subnet, and that subnet should be included in the routing
protocol updates (RIP, OSPF, and so on).
Connection Trunk
Cisco Hoot and Holler over IP provides an "always-on" communications bridge—end users do not need
to dial any phone numbers to reach the other members of a hoot group. To simulate this functionality,
Cisco IOS provides a feature called "connection trunk." Connection trunk provides a permanent voice
call, without requiring any input from the end user, because all of the digits are internally dialed by the
router/gateway.
With traditional VoIP usages of connection trunk, the call is mapped to a remote router/gateway, and all
the H.323 signaling is handled dynamically when the trunk is established. With
Cisco Hoot and Holler over IP, the connection trunk is established to the IP address of the IP multicast
(IPmc) group that maps to the hoot group.
In addition, all negotiation of UDP ports for the audio stream is manually configured. The following
example shows an E&M voice port connection trunk set up for Cisco Hoot and Holler over IP:
voice-port 1/0/0
connection trunk 111
music-threshold -30
operation 4-wire
!
dial-peer voice 1 voip
destination-pattern 111
voice-class permanent 1
session protocol multicast
session target ipv4:237.111.0.0:22222
ip precedence 5
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In this example, the digits in the connection trunk 111 string match the destination pattern of the VoIP
dial peer. Also, the session protocol is set to multicast and the session target is pointing to the IPmc
group number with the UDP port (22222) predefined.
Benefits
Cisco Hoot and Holler over IP provides the following benefits:
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Eliminates yearly reoccurring circuit-switched telecom charges (toll-bypass).
Eliminates the need for leased-lines and the accompanying charges.
Reduces the need for Hoot and Holler bridges.
Improves Hoot and Holler network manageability.
Reduces the time to troubleshoot a problem from hours to minutes.
Reduces the time to provision bandwidth from days to a few hours.
Increases productivity through future applications (such as IP/TV and turret support).
Ability to integrate voice, video, and data signaling capabilities.
Related Documents
For information about installing voice network modules and voice interface cards in Cisco 2600 and
Cisco 3600 series routers, see the following publications:
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Cisco Network Module Hardware Installation Guide
WAN Interface Card Hardware Installation Guide
For information about configuring Voice over IP features, see the following publications:
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Software Configuration Guide for Cisco 3600 Series and Cisco 2600 Series Routers
Voice over IP Quick Start Guide
Cisco IOS Multiservice Applications Configuration Guide , Release 12.1
For further information about IP multicasting, go to this site:
IP Multicast Site (http://www.cisco.com/ipmulticast)
For further information about IP/TV, see the following publication:
IP/TV Content Manager User Guide
For further information about interactive voice response (IVR), see the following document:
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Configuring Interactive Voice Response for Cisco Access Platforms
Restrictions
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Cisco Hoot and Holler over IP supports the mixing of only three voice streams.
IP/TV does not support the mixing of audio streams.
IP/TV supports only G.711 u-law (mu-law).
Voice Interface Card Basic Rate Interface (VIC-BRI) is not supported.
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Supported Platforms
Supported Platforms
Router Platforms:
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Cisco 2600
Cisco 3600 series
Network Modules:
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NM-HDV
NM-1V
NM-2V
Supported Standards, MIBs, and RFCs
Standards
No new or modified standards are supported by this feature.
MIBs
No new or modified MIBs are supported by this feature.
To obtain lists of MIBs supported by platform and Cisco IOS release and to download MIB modules,
go to the Cisco MIB web site on Cisco Connection Online (CCO) at
RFCs
No new or modified RFCs are supported by this feature.
Configuration Tasks
See the following sections for configuring Cisco Hoot and Holler over IP:
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Configuration Tasks
Configuring Multicast Routing (Required)
To enable multicast routing on the platform, perform the following steps:
Command
Purpose
Router(config)# ip multicast-routing
Step 1
Enables multicast routing.
Configuring the Virtual Interface (Required)
To configure the virtual interface for multicast fast switching, perform the following steps:
Command
Purpose
Router(config)# interface vif1
Step 1
Defines a virtual interface for multicast fast
switching. Routers joining the same session must
have their virtual interfaces on different subnets.
Otherwise, packets are not switched to the IP
network.
Router(config-if)# ip address address subnet-mask
Step 2
Step 3
Assigns the IP address and subnet mask for the
virtual interface.
Router(config-if)# ip pim { sparse mode | dense-mode |
sparse-dense-mode }
Specifies Protocol Independent Multicast (PIM).
Whatever mode you choose should match all the
interfaces in all the routers of your network.
Configuring VoIP Dial Peers (Required)
To configure the VoIP dial peers on the router, perform the following steps:
Command
Purpose
Router(config)# dial-peer voice tag voip
Step 1
Step 2
Assigns a variable number (tag) to the VoIP dial
peer.
Router(config-dial-peer)# destination-pattern
multicast-session-number
The destination pattern for the VoIP dial peer must
match the value of the multicast-session-number
string for the corresponding voice port.
Router(config-dial-peer)# session protocol multicast
Step 3
Step 4
This step is mandatory for voice multicasting and
is the command introduced specifically for the
Cisco Hoot and Holler over IP application.
Router(config-dial-peer)# session target
ipv4:address:port
Assigns the session target for voice multicasting
dial peers. This is a multicast address in the range
224.0.1.0 to 239.255.255.255 and must be the
same for all ports in a session.
The audio RTP port is an even number in the range
16384 to 32767, and must also be the same for all
ports in a session. An odd-numbered port
(UDP port number + 1) is used for the RTCP
traffic for that session.
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Command
Purpose
Router(config-dial-peer)# ip precedence number
Step 5
Step 6
(Optional) Specifies the IP precedence.
Router(config-dial-peer)# codec (codec-type}
Configures the codec. You must configure the
same codec on all dial peers in a session.
When the default codec, g729r8, is used, it does
not appear in the configuration when the show
running command is used.
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Configuration Tasks
Configuring E&M Voice Ports (Required, if used)
If using E&M voice ports, configure them by performing the following steps:
Command
Purpose
Router(config)# voice class permanent tag1
Step 1
Step 2
Defines voice class for transmit-receive mode.
Disables signaling loss detection.
Router(config-class)# signal timing oos timeout
disabled
Router(config-class)# signal keepalive number
Step 3
Step 4
Step 5
Specifies keepalive signaling packet interval.
Returns to global configuration mode.
Selects the voice port to configure.
Router(config-class)# exit
Router(config)# voice-port
router-slot/voice-slot/VIC-port
Router(config-voice-port)# voice-class permanent tag1
Step 6
Uses voice class tag1 for the port that is allowed to
speak.
Router(config-voice-port)# connection trunk
multicast-session-number
Step 7
Step 8
Ties the voice port to a multicast-session number.
Router(config-voice-port)# music-threshold threshold
(Optional) Sets the music threshold to make VAD
less sensitive.
Router(config-voice-port)# operation 4-wire
Step 9
Specifies 4-wire operation. (2-wire is the default.)
Router(config-voice-port)# type { 1 | 2 | 3 | 5 }
Step 10
Selects the appropriate E&M interface type
(depending on the end connection—such as PBX):
•
Type 1 indicates the following lead
configuration (default—this is the
recommended option):
–
–
E—Output, relay to ground
M—Input, referenced to ground
•
Type 2 indicates the following lead
configuration:
–
–
–
–
E—Output, relay to SG
M—Input, referenced to ground
SB—Feed for M, connected to -48V
SG—Return for E, galvanically isolated
from ground
•
Type 3 indicates the following lead
configuration:
–
–
–
–
E—Output, relay to ground
M—Input, referenced to ground
SB—Connected to -48V
SG—Connected to ground
•
Type 5 indicates the following lead
configuration:
–
–
E—Output, relay to ground
M—Input, referenced to -48V
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Configuration Tasks
Command
Purpose
Router(config-voice-port)# signal { wink-start |
immediate | delay-dial }
Step 11
Configures the signaling type for E&M voice
ports. The default is wink-start. Select
immediate for the Cisco Hoot and Holler over IP
application. In the immediate-start protocol, the
originating side does not wait for a wink before
sending addressing information. After receiving
addressing digits, the terminating side then goes
off-hook for the duration of the call. The
originating endpoint maintains off-hook for the
duration of the call.
Router(config-voice-port)# voice-port
router-slot/voice-slot/VIC-port
Step 12
Selects another voice port.
Router(config-voice-port)# voice-class permanent tag2
Step 13
Step 14
Uses voice class tag2 for the receive-only port.
Router(config-voice-port)# connection trunk
multicast-session-number
Ties the voice port to the same multicast-session
number as in Step 12.
Router(config-voice-port)# music-threshold threshold
Step 15
Step 16
(Optional) Sets the music threshold to make VAD
less sensitive.
Router(config-voice-port)# operation 4-wire
Specifies 4-wire operation. (2-wire is the default.)
Configuring for Receive Only Mode (Optional)
To configure Cisco Hoot and Holler over IP as receive-only mode, perform the following steps:
Command
Purpose
Router(config-class)# voice class permanent tag2
Step 1
Step 2
Step 3
Defines voice class for receive-only mode.
Specifies the received signal pattern.
Router(config-class)# signal pattern oos receive 0000
Router(config-class)# signal timing oos suppress-all
seconds
If the transmit out-of-service pattern (from the
PBX to the network) matches for the time
specified, the router stops sending packets to the
network.
Router(config-class)# signal keepalive number
Step 4
Specifies keepalive signaling packet interval.
Configuring Relevant Interface (Serial/Ethernet) (Required)
To configure either the serial or Ethernet interface, perform the following steps:
Command
Purpose
Router(config)# interface { ethernet | serial }
slot/port
Step 1
Step 2
Configures the physical interface (serial/Ethernet)
for transmitting multicast packets.
Router(config-if)# ip address address subnet-mask
Assigns the IP address and subnet mask for the
interface.
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Configuration Examples
Note
In all of the following configuration examples, the routers are configured with an
interface vif1 command. This is a virtual interface that is similar to a loopback
interface—it is a logical IP interface that is always up when the router is active. In
addition, it must be configured so that the Cisco Hoot and Holler over IP packets that are
locally mixed on the DSPs can be fast-switched along with the other data packets. This
interface needs to reside on its own unique subnet, and that subnet should be included in
the routing protocol updates (RIP, OSPF, and so on).
Voice Multicasting over an Ethernet LAN
Figure 4 shows the simplest configuration for voice multicasting over an Ethernet LAN. Two routers
are connected to each other over the Ethernet LAN. One E&M phone is connected to each router.
Figure 4
Voice Multicasting over a LAN
E&M VIC
3/1/1
IP cloud
E&M VIC
2/0/0
Router 2
Router 1
router-slot/voice-slot/VIC-port numbering convention. This router is configured as in the following
example:
hostname Abbott
!
ip multicast-routing
!
voice class permanent 1
signal timing oos timeout disabled
signal keepalive 65535
!
interface Vif1
ip address 1.1.1.1 255.0.0.0
ip pim sparse-dense-mode
!
interface Ethernet0/0
ip address 3.3.3.1 255.0.0.0
ip pim sparse-dense-mode
!
ip route 2.0.0.0 255.0.0.0 3.3.3.2
!
voice-port 2/0/0
voice-class permanent 1
connection trunk 111
operation 4-wire
!
dial-peer voice 1 voip
destination-pattern 111
session protocol multicast
session target ipv4:237.111.0.111:22222
!
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Note
Note
The connection-trunk connection type is a point-to-point connection, similar to a tie-line
on a PBX network. All voice traffic—including signaling—placed at one end is
immediately transferred to the other.
The E&M voice port must be configured for 4-wire operation.
Configuring the Second Router
In router Costello (Figure 4), the E&M phone is connected to voice port 3/1/1. Router Costello uses the
same configuration as Abbott, except for the following differences:
•
•
•
The virtual interface must be on a different subnet from the first router.
The IP address in the Ethernet configuration must be different from that of the first router.
The voice port and slot should match the router’s hardware configuration.
hostname Costello
!
ip multicast-routing
!
voice class permanent 1
signal timing oos timeout disabled
signal keepalive 65535
!
!
interface Vif1
ip address 2.2.2.2 255.0.0.0
ip pim sparse-dense-mode
!
interface Ethernet0/0
ip address 3.3.3.2 255.0.0.0
ip pim sparse-dense-mode
!
ip route 1.0.0.0 255.0.0.0 3.3.3.1
!
voice-port 3/1/1
voice-class permanent 1
timeouts wait-release 3
connection trunk 222
music-threshold -30
operation 4-wire
!
dial-peer voice 1 voip
destination-pattern 111
session protocol multicast
session target ipv4:237.111.0.111:22222
!
Note
The multicast session for this port, shown in the session target command, must match the
multicast session configured on the first router.
The codec configured for this dial peer must match the codec for the dial peer on the first
router.
Both routers must be configured to use the same connection trunk and destination pattern.
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Verifying the Configuration
If you have configured your routers by following these examples, you should now be able to talk over
the telephones. You can also use the show dial-peer voice command on each router to verify that the
data you configured is correct.
To verify that an audio path has been established, use the show call active voice command. This
command displays all active voice calls traveling through the router.
High-Density Voice Modules
A multiflex trunk interface card in a high-density voice network module requires special voice-port
configuration. First, select the card to configure:
voice-card 6
codec complexity high
!
Note
Codec complexity must be high. Voice multicasting does not support medium complexity,
which is the default.
The following commands show how to define the T1 channel and signaling method, and map each DS0
to voice port slot/port:ds0-group:
controller T1 6/0
ds0-group 1 timeslots 1 type e&m-immediate-start
ds0-group 2 timeslots 2 type e&m-immediate-start
ds0-group 3 timeslots 3 type e&m-immediate-start
…
ds0-group 22 timeslots 22 type e&m-immediate-start
ds0-group 23 timeslots 23 type e&m-immediate-start
The following commands show how to configure the voice ports on the multiflex trunk interface card:
!
voice-port 6/0:1
connection trunk 111
!
voice-port 6/0:2
connection trunk 111
!
voice-port 6/0:3
connection trunk 111
…
voice-port 6/0:22
connection trunk 111
!
voice-port 6/0:23
connection trunk 111
Dial Peer Configuration
Cisco IOS software uses objects called dial peers to tie together telephone numbers, voice ports, and
other call parameters. Configuring dial peers is similar to configuring static IP routes—you are
instructing the router what path to follow to route the call.
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Dial peers are identified by numbers, but to avoid confusing these numbers with telephone numbers,
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Voice Multicasting over a WAN
The configuration for voice multicasting sessions over IP on Frame Relay is the same as for the Ethernet
LAN in the previous example. Configure the WAN interface on each router with the ip address and ip
Quality of Service
Voice traffic is much more sensitive to timing variations than data traffic. For good voice performance,
configure your data network so that voice packets are not lost or delayed. The following example shows
one way to improve quality of service (QoS) for voice multicasting over a Frame Relay connection:
!Configure physical interface for transmitting multicast packets.
!Listen to packets of Session Announcement Protocol (SAP).
!This example uses a subinterface
!
interface serial0/0
encapsulation frame-relay
frame-relay traffic-shaping
no frame-relay broadcast-queue
!
interface serial0/0.1 point-to-point
ip address 5.5.5.5 255.255.255.0
ip pim sparse-dense-mode
frame-relay class hootie
frame-relay interface-dlci 100
frame-relay ip rtp header-compression
!
!Frame relay class commands.
!
map-class frame-relay hootie
frame-relay cir 64000
frame-relay bc 2000
frame-relay mincir 64000
no frame-relay adaptive-shaping
frame-relay fair-queue
frame-relay fragment 80
frame-relay ip rtp priority 16384 16383 64
Note
In the frame-relay ip rtp priority command, the first number is the audio port. The
second number is the number of consecutive audio ports to which the IP RTP priority
queuing applies. The third number is the bandwidth, which should equal the bandwidth
needed for each call multiplied by the number of calls.
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Cisco Hoot and Holler over IP with Ethernet Topology (Two Hoot Groups)
Figure 5
Cisco Hoot and Holler over IP w ith Ethernet Topology
E&M
4-wire
FXS
Router 2
Router 1
Router 3
FXO
Group 1
Group 2
FXO
PBX
PBX
E&M = ear and mouth
In this configuration, two hoot and holler groups are set up by defining two multicast groups
(237.111.0.111 and 237.111.0.112) and mapping the connection trunk 111 and connection trunk 112
commands from the voice ports to the VoIP dial peers associated with each group. Each router is
connected to a dedicated switch port, and IP precedence is set to 5 for all Cisco Hoot and Holler over
IP packets.
Router-1 (E&M 4-Wire Ports)
hostname Router-1
!
ip multicast-routing
!
voice class permanent 1
signal timing oos timeout disabled
signal keepalive 65535
!
interface Vif1
ip address 1.1.1.1 255.255.255.0
ip pim sparse-dense-mode
!
!
interface Ethernet0/0
ip address 1.5.13.1 255.255.255.0
ip pim sparse-dense-mode
!
router rip
network 1.1.1.0
network 1.5.13.0
!
voice-port 1/0/0
voice-class permanent 1
connection trunk 111
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music-threshold -30
operation 4-wire
!
voice-port 1/0/1
voice-class permanent 1
connection trunk 112
music-threshold -30
operation 4-wire
!
dial-peer voice 111 voip
destination-pattern 111
session protocol multicast
session target ipv4:237.111.0.111:22222
ip precedence 5
!
dial-peer voice 112 voip
destination-pattern 112
session protocol multicast
session target ipv4:239.194.0.10:22224
ip precedence 5
!
end
Router-2 (FXS Ports)
hostname Router-2
!
ip multicast-routing
!
voice class permanent 1
signal timing oos timeout disabled
signal keepalive 65535
!
interface Vif1
ip address 2.2.2.2 255.255.255.0
ip pim sparse-dense-mode
!
interface Ethernet0/0
ip address 1.5.13.2 255.255.255.0
ip pim sparse-dense-mode
!
router rip
network 2.2.2.0
network 1.5.13.0
!
dial-peer voice 111 voip
destination-pattern 111
session protocol multicast
session target ipv4:237.111.0.111:22222
ip precedence 5
!
dial-peer voice 112 voip
destination-pattern 112
session protocol multicast
session target ipv4:239.194.0.10:22224
ip precedence 5
!
end
Note
If you want to join the hoot and holler session directly without having to dial any session
numbers, use the command connection plar, followed by the multicast-session number.
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Router-3 (FXO Ports)
hostname Router-3
!
ip multicast-routing
!
voice class permanent 1
signal timing oos timeout disabled
signal keepalive 65535
!
interface Vif1
ip address 3.3.3.3 255.255.255.0
ip pim sparse-dense-mode
!
interface Ethernet0/0
ip address 1.5.13.3 255.255.255.0
ip pim sparse-dense-mode
!
router rip
network 3.3.3.0
network 1.5.13.0
!
dial-peer voice 111 voip
destination-pattern 111
session protocol multicast
session target ipv4:237.111.0.111:22222
ip precedence 5
!
dial-peer voice 112 voip
destination-pattern 112
session protocol multicast
session target ipv4:239.194.0.10:22224
ip precedence 5
!
end
Cisco Hoot and Holler over IP with Frame-Relay Topology (One Hoot Group)
Figure 6
Cisco Hoot and Holler over IP w ith Fram e-Relay Topology
Router 1
IP multicast
network
Router 2
Router 3
In this topology, three routers are connected using 64K Frame-Relay PVCs in a hub and spoke topology,
with Router 1 being the hub. We have defined one hoot and holler group. All three routers have been
configured to traffic-shape their data and voice on the WAN to CIR, and all three routers are using IP
RTP priority to guarantee QoS for the Cisco Hoot and Holler over IP packets. In addition, the
frame-relay broadcast-queue is disabled on the serial interfaces. This occurs because, by default, the
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broadcast-queue is only 40 packets deep and Cisco Hoot and Holler over IP transmits packets at 50
packets per second. Unless the queue is disabled, some packets would be dropped and voice QoS would
be degraded.
Router-1
hostname Router-1
!
ip multicast-routing
!
voice class permanent 1
signal timing oos timeout disabled
signal keepalive 65535
!
interface Vif1
ip address 1.1.1.1 255.255.255.0
ip pim sparse-dense-mode
!
router rip
network 1.1.1.0
network 5.5.5.0
network 5.5.6.0
!
interface Serial0/0
no ip address
ip pim sparse-dense-mode
encapsulation frame-relay
frame-relay traffic-shaping
no frame-relay broadcast-queue
!
interface Serial0/0.1 point-to-point
ip address 5.5.5.1 255.255.255.0
ip pim sparse-dense-mode
frame-relay class hoot-n-holler
frame-relay interface-dlci 100
frame-relay ip rtp header-compression
!
interface Serial0/0.2 point-to-point
ip address 5.5.6.1 255.255.255.0
ip pim sparse-dense-mode
frame-relay class hoot-n-holler
frame-relay interface-dlci 101
frame-relay ip rtp header-compression
!
map-class frame-relay hoot-n-holler
frame-relay cir 128000
frame-relay bc 1280
frame-relay mincir 128000
frame-relay fragment 160
frame-relay ip rtp priority 16384 16384 128
no frame-relay adaptive-shaping
!
voice-port 1/0/0
voice-class permanent 1
connection trunk 111
music-threshold -30
operation 4-wire
!
dial-peer voice 1 voip
destination-pattern 111
session protocol multicast
session target ipv4:237.111.0.0:22222
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ip precedence 5
Router-2
hostname Router-2
!
ip multicast-routing
!
voice class permanent 1
signal timing oos timeout disabled
signal keepalive 65535
!
interface Vif1
ip address 2.2.2.2 255.255.255.0
ip pim sparse-dense-mode
!
router rip
network 2.2.2.0
network 5.5.5.0
!
interface Serial0/0
no ip address
ip pim sparse-dense-mode
encapsulation frame-relay
frame-relay traffic-shaping
no frame-relay broadcast-queue
!
interface Serial0/0.1 point-to-point
ip address 5.5.5.2 255.255.255.0
ip pim sparse-dense-mode
frame-relay class hoot-n-holler
frame-relay interface-dlci 100
frame-relay ip rtp header-compression
!
map-class frame-relay hoot-n-holler
frame-relay cir 128000
frame-relay bc 1280
frame-relay mincir 128000
frame-relay fragment 160
frame-relay ip rtp priority 16384 16383 128
no frame-relay adaptive-shaping
!
voice-port 1/0/0
voice-class permanent 1
connection trunk 111
music-threshold -30
operation 4-wire
!
dial-peer voice 1 voip
destination-pattern 111
session protocol multicast
session target ipv4:237.111.0.0:22222
ip precedence 5
Router-3
hostname Router-3
!
ip multicast-routing
!
voice class permanent 1
signal timing oos timeout disabled
signal keepalive 65535
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!
interface Vif1
ip address 3.3.3.3 255.255.255.0
ip pim sparse-dense-mode
!
router rip
network 3.3.3.0
network 5.5.6.0
!
interface Serial0/0
no ip address
ip pim sparse-dense-mode
encapsulation frame-relay
frame-relay traffic-shaping
no frame-relay broadcast queue
!
interface Serial0/0.1 point-to-point
ip address 5.5.6.2 255.255.255.0
ip pim sparse-dense-mode
frame-relay class hoot-n-holler
frame-relay interface-dlci 101
frame-relay ip rtp header-compression
!
map-class frame-relay hoot-n-holler
frame-relay cir 128000
frame-relay bc 1280
frame-relay mincir 128000
frame-relay fragment 160
frame-relay ip rtp priority 16384 16383 128
no frame-relay adaptive-shaping
!
voice-port 1/0/0
voice-class permanent 1
connection trunk 111
music-threshold -30
operation 4-wire
!
dial-peer voice 1 voip
destination-pattern 111
session protocol multicast
session target ipv4:237.111.0.0:22222
ip precedence 5
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session protocol multicast
session protocol multicast
To set the session protocol as multicast, use the session protocol multicast dial-peer configuration
command. To negate this command and return to the cisco default session protocol, use the no version
of this command.
session protocol multicast
no session protocol multicast
Syntax Description
Defaults
There are no keywords or arguments.
When this command is not implemented, the default session protocol is cisco.
Dial-peer configuration
Command Modes
Command History
Release
Modification
12.1(2)XH
This command was introduced on Cisco 2600 and Cisco 3600 series routers
for the Cisco Hoot and Holler over IP application.
Usage Guidelines
Examples
Use the session protocol multicast dial-peer configuration command for voice conferencing in a Hoot
and Holler networking implementation. This command allows more than two ports to join the same
session simultaneously. It is supported on Cisco 2600 and Cisco 3600 series routers.
The following example shows the use of the the session protocol multicast dial-peer configuration
command in context with its accompanying commands:
Router(config)# dial-peer voice 111 voip
Router(config-dial-peer)# destination-pattern 111
Router(config-dial-peer)# session protocol multicast
Router(config-dial-peer)# session target ipv4:237.111.0.111:22222
Router(config-dial-peer)# ip precedence 5
Router(config-dial-peer)# codec g711ulaw
Related Commands
Command
Description
session target ipv4
Assigns the session target for voice-multicasting dial peers.
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Glossary
Glossary
CIR—Committed information rate. The average rate of information transfer a subscriber (for example,
the network administrator) has stipulated for a Frame-Relay PVC.
Codec—Coder-decoder. Device that typically uses pulse-code modulation (PCM) to transform analog
signals into a digital bit stream and digital signals back into analog signals. In Voice over IP, it specifies
the voice-coder rate of speech for a dial peer.
Dial peer—An addressable call endpoint that contains configuration information including voice
protocol, a codec type, and a telephone number associated with the call. There are five kinds of dial
peers: POTS, VoIP, VoFR, VoATM, and VoHDLC. In Voice over IP, there are two kinds of dial peers:
•
POTS—Connected through a traditional telephony network and points to a particular voice port on
a voice network device.
•
VoIP—Connected through a packet network (IP network for VoIP) and points to specific VoIP
device.
DSP—Digital signal processor.
DTMF—Dual tone multifrequency. Uses two simultaneous voice-band tones for dial such as
touch-tone.
E&M—Ear and mouth. Stands for the 2-wire or 4-wire interface with separate signaling paths for the
receiving and transmitting signals—a type of signaling traditionally used in the telecommunications
industry. Indicates the use of a handset that corresponds to the ear (receiving) and mouth (transmitting)
component of a telephone. E&M is a trunking arrangement generally used for two-way switch-to-switch
or switch-to-network connecting. The Cisco analog E&M interface is an RJ-48 connector that allows
connections to PBX trunk lines (tie lines). E&M is also available on E1 and T1 digital interfaces.
FXO—Foreign Exchange Office. An FXO interface connects to the Public Switched Telephone
Network (PSTN) central office and is the interface offered on a standard telephone. The Cisco FXO
interface is an RJ-11 connector that allows an analog connection at the PSTN's central office or to a
station interface on a PBX.
FXS—Foreign Exchange Station. An FXS interface connects directly to a standard telephone and
supplies ring, voltage, and dial tone. Cisco's FXS interface is an RJ-11 connector that allows
connections to basic telephone service equipment, keysets, and PBXs.
Hoot and holler—A broadcast audio network used extensively by the brokerage industry for market
updates and trading. Similar networks are used in publishing, transportation, power plants, and
manufacturing.
IVR—Interactive voice response. When someone dials in, IVR responds with a prompt to get a personal
identification number (PIN), and so on.
PBX—Private branch exchange. Digital or analog telephone switchboard or switching facility located
on the subscriber premises and used to connect private and public telephone networks.
PVC—Permanent virtual circuit.
QoS—Quality of service. QoS refers to the measure of service quality provided to the user.
TDM—Time-division multiplexing.
Trunk—Service that allows quasi-transparent connections between two PBXs, a PBX and a local
extension, or some other combination of telephony interfaces to be permanently conferenced together
by the session application and signaling passed transparently through the IP network.
VAD—Voice activity detection.
VIC—Voice interface card.
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Glossary
VNM—Voice network module.
VoIP—Voice over Internet Protocol.
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