IP Multicast: IGMP Configuration Guide, Cisco IOS XE Gibraltar 16.12.x
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The Source Specific Multicast (SSM) Mapping feature extends the Cisco suite of SSM transition tools, which also includes
URL Rendezvous Directory (URD) and Internet Group Management Protocol Version 3 Lite (IGMP v3lite). SSM mapping supports SSM
transition in cases where neither URD nor IGMP v3lite is available, or when supporting SSM on the end system is impossible
or unwanted due to administrative or technical reasons. SSM mapping enables you to leverage SSM for video delivery to legacy
set-top boxes (STBs) that do not support IGMPv3 or for applications that do not take advantage of the IGMPv3 host stack.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information,
see Bug Search Tool and 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 table.
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.
Prerequisites for SSM
Mapping
One option available
for using SSM mapping is to install it together with a Domain Name System (DNS)
server to simplify administration of the SSM Mapping feature in larger
deployments.
Before you can configure and use SSM mapping with DNS lookups, you need
to add records to a running DNS server. If you do not already have a DNS server
running, you need to install one.
Restrictions for SSM
Mapping
The SSM Mapping feature does not share the benefit of full SSM. SSM mapping takes a group G join from a host and identifies
this group with an application associated with one or more sources, therefore, it can only support one such application per
group G. Nevertheless, full SSM applications may still share the same group also used in SSM mapping.
Enable IGMPv3 with care on the last hop router when you rely solely
on SSM mapping as a transition solution for full SSM.
Information About SSM Mapping
SSM Components
SSM is a datagram delivery model that best supports one-to-many applications, also known as broadcast applications. SSM is
a core networking technology for the Cisco implementation of IP multicast solutions targeted for audio and video broadcast
application environments and is described in RFC 3569. The following two components together support the implementation of
SSM:
Internet Group Management Protocol Version 3 (IGMPv3)
Protocol Independent Multicast (PIM) SSM, or PIM-SSM, is the routing protocol that supports the implementation of SSM and
is derived from PIM sparse mode (PIM-SM). IGMP is the Internet Engineering Task Force (IETF) standards track protocol used
for hosts to signal multicast group membership to routers. IGMP Version 3 supports source filtering, which is required for
SSM. IGMP For SSM to run with IGMPv3, SSM must be supported in the router, the host where the application is running, and
the application itself.
Benefits of Source Specific Multicast
IP Multicast Address Management Not Required
In the ISM service, applications must acquire a unique IP multicast group address because traffic distribution is based only
on the IP multicast group address used. If two applications with different sources and receivers use the same IP multicast
group address, then receivers of both applications will receive traffic from the senders of both applications. Even though
the receivers, if programmed appropriately, can filter out the unwanted traffic, this situation would cause generally unacceptable
levels of unwanted traffic.
Allocating a unique IP multicast group address for an application is still a problem. Most short-lived applications use mechanisms
like Session Description Protocol (SDP) and Session Announcement Protocol (SAP) to get a random address, a solution that does
not work well with a rising number of applications in the Internet. The best current solution for long-lived applications
is described in RFC 2770, but this solution suffers from the restriction that each autonomous system is limited to only 255
usable IP multicast addresses.
In SSM, traffic from each source is forwarded between routers in the network independent of traffic from other sources. Thus
different sources can reuse multicast group addresses in the SSM range.
Denial of Service Attacks from Unwanted Sources Inhibited
In SSM, multicast traffic from each individual source will be transported across the network only if it was requested (through
IGMPv3, IGMP v3lite, or URD memberships) from a receiver. In contrast, ISM forwards traffic from any active source sending
to a multicast group to all receivers requesting that multicast group. In Internet broadcast applications, this ISM behavior
is highly undesirable because it allows unwanted sources to easily disturb the actual Internet broadcast source by simply
sending traffic to the same multicast group. This situation depletes bandwidth at the receiver side with unwanted traffic
and thus disrupts the undisturbed reception of the Internet broadcast. In SSM, this type of denial of service (DoS) attack
cannot be made by simply sending traffic to a multicast group.
Easy to Install and Manage
SSM is easy to install and provision in a network because it does not require the network to maintain which active sources
are sending to multicast groups. This requirement exists in ISM (with IGMPv1, IGMPv2, or IGMPv3).
The current standard solutions for ISM service are PIM-SM and MSDP. Rendezvous point (RP) management in PIM-SM (including
the necessity for Auto-RP or BSR) and MSDP is required only for the network to learn about active sources. This management
is not necessary in SSM, which makes SSM easier than ISM to install and manage, and therefore easier than ISM to operationally
scale in deployment. Another factor that contributes to the ease of installation of SSM is the fact that it can leverage preexisting
PIM-SM networks and requires only the upgrade of last hop routers to support IGMPv3, IGMP v3lite, or URD.
Ideal for Internet Broadcast Applications
The three benefits previously described make SSM ideal for Internet broadcast-style applications for the following reasons:
The ability to provide Internet broadcast services through SSM without the need for unique IP multicast addresses allows content
providers to easily offer their service (IP multicast address allocation has been a serious problem for content providers
in the past).
The prevention against DoS attacks is an important factor for Internet broadcast services because, with their exposure to
a large number of receivers, they are the most common targets for such attacks.
The ease of installation and operation of SSM makes it ideal for network operators, especially in those cases where content
needs to be forwarded between multiple independent PIM domains (because there is no need to manage MSDP for SSM between PIM
domains).
SSM Transition Solutions
The Cisco IOS suite of SSM transition solutions consists of the following transition solutions that enable the immediate
development and deployment of SSM services, without the need to wait for the availability of full IGMPv3 support in host operating
systems and SSM receiver applications:
Internet Group Management Protocol Version 3 lite (IGMP v3lite)
URL Rendezvous Directory (URD)
SSM mapping
IGMP v3lite is a solution for application developers that allows immediate development of SSM receiver applications switching
to IGMPv3 as soon as it becomes available.
For more information about IGMP v3lite, see the “ Configuring Source Specific Multicast ” module.
URD is an SSM transition solution for content providers and content aggregators that allows them to deploy receiver applications
that are not yet SSM enabled (through support for IGMPv3) by enabling the receiving applications to be started and controlled
through a web browser.
For more information about URD, see the see the “ Configuring Source Specific Multicast ” module.
SSM mapping supports SSM transition in cases where neither URD nor IGMP v3lite are available, or when supporting SSM on the
end system is impossible or unwanted due to administrative or technical reasons.
SSM Mapping Overview
SSM mapping supports
SSM transition
when supporting SSM on the end system is impossible or unwanted due
to administrative or technical reasons. Using SSM to deliver live streaming
video to legacy STBs that do not support IGMPv3
is a typical application of SSM mapping.
In a typical STB
deployment, each TV channel uses one separate IP multicast group and has one
active server host sending the TV channel. A single server may of course send
multiple TV channels, but each to a different group. In this network
environment, if a router receives an IGMPv1 or IGMPv2 membership report for a
particular group G, the report implicitly addresses the well-known TV server
for the TV channel associated with the multicast group.
SSM mapping
introduces a means for the last hop router to discover sources sending to
groups. When SSM mapping is configured, if a router receives an IGMPv1 or
IGMPv2 membership report for a particular group G, the router translates this
report into one or more (S, G) channel memberships for the well-known sources
associated with this group.
When the router
receives an IGMPv1 or IGMPv2 membership report for group G, the router uses SSM
mapping to determine one or more source IP addresses for group G. SSM mapping
then translates the membership report as an IGMPv3 report INCLUDE (G, [S1, G],
[S2, G]...[Sn, G] and continues as if it had received an IGMPv3 report. The
router then sends out PIM joins toward (S1, G) to (Sn, G) and continues to be
joined to these groups as long as it continues to receive the IGMPv1 or IGMPv2
membership reports and as long as
the SSM mapping for the group
remains the same. SSM mapping, thus, enables you to leverage SSM for video
delivery to legacy STBs that do not support IGMPv3 or for applications that do
not take advantage of the IGMPv3 host stack.
SSM mapping enables
the last hop router to determine the source addresses either by a statically
configured table on the router or by consulting a DNS server. When the
statically configured table is changed, or when the DNS mapping changes, the
router will leave the current sources associated with the joined groups.
Static SSM Mapping
SSM static mapping
enables you to configure the last hop router to use a static map to determine
the sources sending to groups. Static SSM mapping requires that you configure
access lists (ACLs) to define group ranges. The groups permitted by those ACLs
then can be mapped to sources using the
ipigmpstaticssm-map global configuration command.
You can configure
static SSM mapping in smaller networks when a DNS is not needed or to locally
override DNS mappings that may be temporarily incorrect. When configured,
static SSM mappings take precedence over DNS mappings.
DNS-Based SSM Mapping
DNS-based SSM mapping
enables you to configure the last hop router to perform a reverse DNS lookup to
determine sources sending to groups (see the figure below). When DNS-based SSM
mapping is configured, the router constructs a domain name that includes the
group address G and performs a reverse lookup into the DNS. The router looks up
IP address resource records (IP A RRs) to be returned for this constructed
domain name and uses the returned IP addresses as the source addresses
associated with this group. SSM mapping supports up to 20 sources for each
group. The router joins all sources configured for a group.
Figure 1. DNS-Based
SSM-Mapping
The SSM mapping
mechanism that enables the last hop router to join multiple sources for a group
can be used to provide source redundancy for a TV broadcast. In this context,
the redundancy is provided by the last hop router using SSM mapping to join two
video sources simultaneously for the same TV channel. However, to prevent the
last hop router from duplicating the video traffic, it is necessary that the
video sources utilize a server-side switchover mechanism where one video source
is active while the other backup video source is passive. The passive source
waits until an active source failure is detected before sending the video
traffic for the TV channel. The server-side switchover mechanism, thus, ensures
that only one of the servers is actively sending the video traffic for the TV
channel.
To look up one or
more source addresses for a group G that includes G1, G2, G3, and G4, the
following DNS resource records (RRs) must be configured on the DNS server:
G4.G3.G2.G1
[multicast-domain] [timeout]
IN A
source-address-1
IN Asource-address-2
IN Asource-address-n
The
multicast-domain argument is a configurable DNS
prefix. The default DNS prefix is in-addr.arpa. You should only use the default
prefix when your installation is either separate from the internet or if the
group names that you map are global scope group addresses (RFC 2770 type
addresses that you configure for SSM) that you own.
The
timeout
argument configures the length of time for which the router performing SSM
mapping will cache the DNS lookup. This argument is optional and defaults to
the timeout of the zone in which this entry is configured. The timeout
indicates how long the router will keep the current mapping before querying the
DNS server for this group. The timeout is derived from the cache time of the
DNS RR entry and can be configured for each group/source entry on the DNS
server. You can configure this time for larger values if you want to minimize
the number of DNS queries generated by the router. Configure this time for a
low value if you want to be able to quickly update all routers with new source
addresses.
Note
Refer to your DNS
server documentation for more information about configuring DNS RRs.
To configure
DNS-based SSM mapping in the software, you must configure a few global commands
but no per-channel specific configuration is needed. There is no change to the
configuration for SSM mapping if additional channels are added. When DNS-based
SSM mapping is configured, the mappings are handled entirely by one or more DNS
servers. All DNS techniques for configuration and redundancy management can be
applied to the entries needed for DNS-based SSM mapping.
SSM Mapping Benefits
The SSM Mapping feature provides almost the same ease of network installation and management as a pure SSM solution based
on IGMPv3. Some additional configuration is necessary to enable SSM mapping.
The SSM benefit of inhibition of DoS attacks applies when SSM mapping is configured. When SSM mapping is configured the only
segment of the network that may still be vulnerable to DoS attacks are receivers on the LAN connected to the last hop router.
Since those receivers may still be using IGMPv1 and IGMPv2, they are vulnerable to attacks from unwanted sources on the same
LAN. SSM mapping, however, does protect those receivers (and the network path leading towards them) from multicast traffic
from unwanted sources anywhere else in the network.
Address assignment within a network using SSM mapping needs to be coordinated, but it does not need assignment from outside
authorities, even if the content from the network is to be transited into other networks.
How to Configure SSM Mapping
Configuring Static SSM
Mapping
Perform this task
to configure the last hop router in an SSM deployment to use static SSM mapping
to determine the IP addresses of sources sending to groups.
Before you begin
Enable IP multicast routing, enable PIM sparse mode, and configure SSM before performing this task. For more information,
see the “Configuring Basic Multicast ”module.
Before you configure static SSM mapping, you must configure ACLs that define the group ranges to be mapped to source addresses.
SUMMARY STEPS
enable
configureterminal
ipigmpssm-mapenable
noipigmpssm-mapquerydns
ipigmpssm-mapstaticaccess-listsource-address
Repeat Step 5
to configure additional static SSM mappings, if required.
end
show running-config
copy running-config start-up config
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
ipigmpssm-mapenable
Example:
Device(config)# ip igmp ssm-map enable
Enables SSM
mapping for groups in the configured SSM range.
Note
By default,
this command enables DNS-based SSM mapping.
Step 4
noipigmpssm-mapquerydns
Example:
Device(config)# no ip igmp ssm-map query dns
(Optional)
Disables DNS-based SSM mapping.
Note
Disable
DNS-based SSM mapping if you only want to rely on static SSM mapping. By
default, the
ipigmpssm-map command
enables DNS-based SSM mapping.
Step 5
ipigmpssm-mapstaticaccess-listsource-address
Example:
Device(config)# ip igmp ssm-map static 11 172.16.8.11
Configures
static SSM mapping.
The ACL
supplied for the
access-list
argument defines the groups to be mapped to the source IP address entered for
the
source-address
argument.
Note
You can configure additional static SSM mappings. If additional SSM mappings are configured and the router receives an IGMPv1
or IGMPv2 membership report for a group in the SSM range, the Cisco IOS XE software determines the source addresses associated
with the group by walking each configured ipigmpssm-mapstatic command. The Cisco IOS XE software associates up to 20 sources per group.
Step 6
Repeat Step 5
to configure additional static SSM mappings, if required.
--
Step 7
end
Example:
Device(config)# end
Ends the
current configuration session and returns to privileged EXEC mode.
Step 8
show running-config
Example:
Device# show running-config
Verifies your entries.
Step 9
copy running-config start-up config
Example:
Device# copy running-config start-up config
(Optional) Saves your entries in the configuration file.
Perform this task
to configure the last hop router to perform DNS lookups to learn the IP
addresses of sources sending to a group.
Before you begin
Enable IP multicast routing, enable PIM sparse mode, and configure SSM before performing this task. For more information,
see the "Configuring Basic Multicast"module.
Before you can configure and use SSM mapping with DNS lookups, you need to be able to add records to a running DNS server.
If you do not already have a DNS server running, you need to install one.
Specifies the address of one or more name servers to use for name and address resolution.
Step 7
Repeat Step 6 to configure additional DNS servers for redundancy, if required.
--
Step 8
end
Example:
Device(config-if)# end
Returns to
privileged EXEC mode.
Step 9
show running-config
Example:
Device# show running-config
Verifies your entries.
Step 10
copy running-config startup-config
Example:
Device# copy running-config startup-config
(Optional) Saves your entries in the configuration file.
What to Do Next
Configuring Static Traffic Forwarding with SSM Mapping
Perform this task to configure static traffic forwarding with SSM mapping on the last hop router. Static traffic forwarding
can be used in conjunction with SSM mapping to statically forward SSM traffic for certain groups. When static traffic forwarding
with SSM mapping is configured, the last hop router uses DNS-based SSM mapping to determine the sources associated with a
group. The resulting (S, G) channels are then statically forwarded.
Before you begin
This task does not include the steps for configuring DNS-based SSM mapping. See the Configuring DNS-Based SSM Mapping (CLI) task for more information about configuring DNS-based SSM mapping.
SUMMARY STEPS
enable
configureterminal
interfacetypenumber
ipigmpstatic-groupgroup-addresssourcessm-map
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
interfacetypenumber
Example:
Router(config)# interface gigabitethernet 1/0/0
Selects an interface on which to statically forward traffic for a multicast group using SSM mapping and enters interface configuration
mode.
Note
Static forwarding of traffic with SSM mapping works with either DNS-based SSM mapping or statically-configured SSM mapping.
Step 4
ipigmpstatic-groupgroup-addresssourcessm-map
Example:
Router(config-if)# ip igmp static-group 232.1.2.1 source ssm-map
Configures SSM mapping to be used to statically forward a (S, G) channel out of the interface.
Use this command if you want to statically forward SSM traffic for certain groups, but you want to use DNS-based SSM mapping
to determine the source addresses of the channels.
Enables
privileged EXEC mode. Enter your password if prompted.
Example:
> enable
Step 2
showipigmpssm-mapping
(Optional)
Displays information about SSM mapping.
The following
example shows how to display information about SSM mapping configuration. In
this example, SSM static mapping and DNS-based SSM mapping are enabled.
Example:
# show ip igmp ssm-mapping
SSM Mapping : Enabled
DNS Lookup : Enabled
Mcast domain : ssm-map.cisco.com
Name servers : 10.0.0.3
10.0.0.4
Step 3
showipigmpssm-mappinggroup-address
(Optional)
Displays the sources that SSM mapping uses for a particular group.
The following
example shows how to display information about the configured DNS-based SSM
mapping. In this example, the router has used DNS-based mapping to map group
232.1.1.4 to sources 172.16.8.5 and 172.16.8.6. The timeout for this entry is
860000 milliseconds (860 seconds).
Example:
# show ip igmp ssm-mapping 232.1.1.4
Group address: 232.1.1.4
Database : DNS
DNS name : 4.1.1.232.ssm-map.cisco.com
Expire time : 860000
Source list : 172.16.8.5
: 172.16.8.6
(Optional)
Displays the multicast groups with receivers that are directly connected to the
router and that were learned through IGMP.
The following
is sample output from the
showipigmpgroups command with the
group-address
argument and
detail keyword.
In this example the “M” flag indicates that SSM mapping is configured.
Example:
# show ip igmp group 232.1.1.4 detail
Interface: GigabitEthernet2/0/0
Group: 232.1.1.4 SSM
Uptime: 00:03:20
Group mode: INCLUDE
Last reporter: 0.0.0.0
CSR Grp Exp: 00:02:59
Group source list: (C - Cisco Src Report, U - URD, R - Remote,
S - Static, M - SSM Mapping)
Source Address Uptime v3 Exp CSR Exp Fwd Flags
172.16.8.3 00:03:20 stopped 00:02:59 Yes CM
172.16.8.4 00:03:20 stopped 00:02:59 Yes CM
172.16.8.5 00:03:20 stopped 00:02:59 Yes CM
172.16.8.6 00:03:20 stopped 00:02:59 Yes CM
Step 5
showhost
(Optional)
Displays the default domain name, the style of name lookup service, a list of
name server hosts, and the cached list of hostnames and addresses.
The following
is sample output from the
showhostcommand. Use this command to display DNS
entries as they are learned by the router.
Example:
# show host
Default domain is cisco.com
Name/address lookup uses domain service
Name servers are 10.48.81.21
Codes: UN - unknown, EX - expired, OK - OK, ?? - revalidate
temp - temporary, perm - permanent
NA - Not Applicable None - Not defined
Host Port Flags Age Type Address(es)
10.0.0.0.ssm-map.cisco.c None (temp, OK) 0 IP 172.16.8.5
172.16.8.6
172.16.8.3
172.16.8.4
Step 6
debugipigmpgroup-address
(Optional)
Displays the IGMP packets received and sent and IGMP host-related events.
The following
is sample output from the
debugipigmpcommand when SSM static mapping is enabled.
The following output indicates that the router is converting an IGMPv2 join for
group G into an IGMPv3 join:
Example:
IGMP(0): Convert IGMPv2 report (*,232.1.2.3) to IGMPv3 with 2 source(s) using STATIC.
The following
is sample output from the
debugipigmp command when DNS-based SSM mapping is
enabled. The following output indicates that a DNS lookup has succeeded:
Example:
IGMP(0): Convert IGMPv2 report (*,232.1.2.3) to IGMPv3 with 2 source(s) using DNS.
The following
is sample output from the
debugipigmp command when DNS-based SSM mapping is enabled
and a DNS lookup has failed:
IGMP(0): DNS
source lookup failed for (*, 232.1.2.3), IGMPv2 report failed
Configuration Examples for SSM Mapping
SSM Mapping Example
The following configuration example shows a router configuration for SSM mapping. This example also displays a range of other
IGMP and SSM configuration options to show compatibility between features. Do not use this configuration example as a model
unless you understand all of the features used in the example.
Note
Address assignment in the global SSM range 232.0.0.0/8 should be random. If you copy parts or all of this sample configuration,
make sure to select a random address range but not 232.1.1.x as shown in this example. Using a random address range minimizes
the possibility of address collision and may prevent conflicts when other SSM content is imported while SSM mapping is used.
!
no ip domain lookup
ip domain multicast ssm.map.cisco.com
ip name-server 10.48.81.21
!
!
ip multicast-routing distributed
ip igmp ssm-map enable
ip igmp ssm-map static 10 172.16.8.10
ip igmp ssm-map static 11 172.16.8.11
!
!
.
.
.
!
interface GigabitEthernet0/0/0
description Sample IGMP Interface Configuration for SSM-Mapping Example
ip address 10.20.1.2 255.0.0.0
ip pim sparse-mode
ip igmp last-member-query-interval 100
ip igmp static-group 232.1.2.1 source ssm-map
ip igmp version 3
ip igmp explicit-tracking
ip igmp limit 2
ip igmp v3lite
ip urd
!
.
.
.
!
ip pim ssm default
!
access-list 10 permit 232.1.2.10
access-list 11 permit 232.1.2.0 0.0.0.255
!
This table describes the significant commands shown in the SSM mapping configuration example.
Table 1. SSM Mapping Configuration Example Command Descriptions
Command
Description
noipdomainlookup
Disables IP DNS-based hostname-to-address translation.
Note
The
noipdomain-list command is shown in the configuration only to demonstrate that disabling IP DNS-based hostname-to-address translation does
not conflict with configuring SSM mapping. If this command is enabled, the Cisco IOS XE software will try to resolve unknown
strings as hostnames.
ipdomainmulticastssm-map.cisco.com
Specifies ssm-map.cisco.com as the domain prefix for SSM mapping.
ipname-server10.48.81.21
Specifies 10.48.81.21 as the IP address of the DNS server to be used by SSM mapping and any other service in the software
that utilizes DNS.
ipmulticast-routing
Enables IP multicast routing.
ipigmpssm-mapenable
Enables SSM mapping.
ipigmpssm-mapstatic10172.16.8.10
Configures the groups permitted by ACL 10 to use source address 172.16.8.10.
In this example, ACL 10 permits all groups in the 232.1.2.0/25 range except 232.1.2.10.
ipigmpssm-mapstatic11172.16.8.11
Configures the groups permitted by ACL 11 to use source address 172.16.8.11.
In this example, ACL 11 permits group 232.1.2.10.
ippimsparse-mode
Enables PIM sparse mode.
ipigmplast-member-query-interval100
Reduces the leave latency for IGMPv2 hosts.
Note
This command is not required for configuring SSM mapping; however, configuring this command can be beneficial for IGMPv2
hosts relying on SSM mapping.
ipigmpstatic-group232.1.2.1sourcessm-map
Configures SSM mapping to be used to determine the sources associated with group 232.1.2.1. The resulting (S, G) channels
are statically forwarded.
ipigmpversion3
Enables IGMPv3 on this interface.
Note
This command is shown in the configuration only to demonstrate that IGMPv3 can be configured simultaneously with SSM mapping;
however, it is not required.
ipigmpexplicit-tracking
Minimizes the leave latency for IGMPv3 host leaving a multicast channel.
Note
This command is not required for configuring SSM mapping.
ipigmplimit2
Limits the number of IGMP states resulting from IGMP membership states on a per-interface basis.
Note
This command is not required for configuring SSM mapping.
ipigmpv3lite
Enables the acceptance and processing of IGMP v3lite membership reports on this interface.
Note
This command is shown in the configuration only to demonstrate that IGMP v3lite can be configured simultaneously with SSM
mapping; however, it is not required.
ipurd
Enables interception of TCP packets sent to the reserved URD port 465 on an interface and processing of URD channel subscription
reports.
Note
This command is shown in the configuration only to demonstrate that URD can be configured simultaneously with SSM mapping;
however, it is not required.
ippimssmdefault
Configures SSM service.
The default keyword defines the SSM range access list as 232/8.
Configures the ACLs to be used for static SSM mapping.
Note
These are the ACLs that are referenced by the
ipigmpssm-mapstatic commands in this configuration example.
DNS Server Configuration Example
To configure DNS-based SSM mapping, you need to create a DNS server zone or add records to an existing zone. If the routers
that are using DNS-based SSM mapping are also using DNS for other purposes besides SSM mapping, you should use a normally-configured
DNS server. If DNS-based SSM mapping is the only DNS implementation being used on the router, you can configure a fake DNS
setup with an empty root zone, or a root zone that points back to itself.
The following example shows how to create a zone and import the zone data using Network Registrar:
Router> zone 1.1.232.ssm-map.cisco.com. create primary file=named.ssm-map
100 Ok
Router> dns reload
100 Ok
The following example shows how to import the zone files from a named.conf file for BIND 8:
Router> ::import named.conf /etc/named.conf
Router> dns reload
100 Ok:
Note
Network Registrar version 8.0 and later support import BIND 8 format definitions.
Additional References
Related Documents
Related Topic
Document Title
SSM concepts and configuration
“Configuring Basic IP Multicast” module
Cisco IOS IP multicast commands: complete command syntax, command mode, defaults, command history, usage guidelines, and
examples
Cisco IOS IP Multicast Command Reference
Standards
Standards
Title
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this
feature.
--
MIBs
MIBs
MIBs Link
No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.
To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found
at the following URL:
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and
resolving technical issues with Cisco products and technologies.
To receive security and technical information about your products, you can subscribe to various services, such as the Product
Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.
Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.
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 2. Feature Information for SSM Mapping
Feature Name
Releases
Feature Information
Source Specific Multicast (SSM) Mapping
12.3(2)T
12.2(18)S
12.2(18)SXD3
12.2(27)SBC
15.0(1)S
Cisco IOS XE 3.1.0SG
This feature was introduced.
The following commands were introduced or modified:
debugipigmp,ipdomainmulticast,ipigmpssm-mapenable,ipigmpssm-mapquerydns,ipigmpssm-mapstatic,ipigmpstatic-group,showipigmpgroups,showipigmpssm-mapping.
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