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This module describes how to configure IP multicast over ATM, including point-to-multipoint virtual circuits (VCs) and ATM bundle.
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
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.
Protocol Independent Multicast (PIM) nonbroadcast multiaccess (NBMA) mode allows the software to replicate packets for each neighbor on the NBMA network. Traditionally, the software replicates multicast and broadcast packets to all broadcast configured neighbors. This action might be inefficient when not all neighbors want packets for certain multicast groups. NBMA mode enables you to reduce bandwidth on links leading into the NBMA network, and to reduce the number of CPU cycles in switches and attached neighbors.
It is appropriate to configure PIM NBMA mode on ATM, Frame Relay, Switched Multimegabit Data Service (SMDS), PRI ISDN, or X.25 networks only, especially when these media do not have native multicast available. Do not use PIM NBMA mode on multicast-capable LANs (such as Ethernet or FDDI).
You should use PIM sparse mode with this feature. Therefore, when each Join message is received from NBMA neighbors, PIM stores each neighbor IP address and interface in the outgoing interface list for the group. When a packet is destined for the group, the software replicates the packet and unicasts (data-link unicasts) it to each neighbor that has joined the group.
Consider the following two factors before enabling PIM NBMA mode:
IP Multicast over ATM Point-to-Multipoint VCs is a feature that dynamically creates ATM point-to-multipoint switched virtual circuits (SVCs) to handle IP multicast traffic more efficiently.
This feature can enhance router performance and link utilization because packets are not replicated and sent multiple times over the ATM interface.
Traditionally, over NBMA networks, Cisco routers would perform a pseudobroadcast to get broadcast or multicast packets to all neighbors on a multiaccess network. For example, assume in the figure that Routers A, B, C, D, and E were running the Open Shortest Path First (OSPF) protocol. Router A must deliver to Routers D and E. When Router A sends an OSPF Hello packet, the data link layer replicates the Hello packet and sends one to each neighbor (this procedure is known as pseudobroadcast), which results in four copies being sent over the link from Router A to the multiaccess WAN.
With the advent of IP multicast, where high-rate multicast traffic can occur, the pseudobroadcast approach does not scale. Furthermore, in the preceding example, Routers B and C would get data traffic they do not need. To handle this problem, PIM can be configured in NBMA mode using the ip pim nbma-mode command. PIM in NBMA mode works only for sparse mode groups. Configuring PIM in NBMA mode would allow only Routers D and E to get the traffic without distributing to Routers B and C. However, two copies are still delivered over the link from Router A to the multiaccess WAN.
If the underlying network supported multicast capability, the routers could handle this situation more efficiently. If the multiaccess WAN were an ATM network, IP multicast could use multipoint VCs.
To configure IP multicast using multipoint VCs, Routers A, B, C, D, and E in the figure must run PIM sparse mode. If the Receiver directly connected to Router D joins a group and Router A is the PIM RP, the following sequence of events occurs:
If a host sends an IGMP report over an ATM interface to a router, the router adds the host to the multipoint VC for the group.
This feature can also be used over ATM subinterfaces.
An idling policy uses the ip pim vc-count command to limit the number of VCs created by PIM. When the router stays at or below the number configured, no idling policy is in effect. When the next VC to be opened will exceed the value, an idling policy is exercised. An idled VC does not mean that the multicast traffic is not forwarded; the traffic is switched to VC 0. VC 0 is the broadcast VC that is open to all neighbors listed in the map list. The name VC 0 is unique to PIM and the mroute table.
The idling policy works as follows:
By default, all VCs are eligible for idling. You can configure a minimum rate required to keep VCs from being idled.
Perform this task to configure IP multicast over ATM point-to-multipoint VCs. All of the steps in the task can be used in an ATM network. This feature can also be used over ATM subinterfaces. PIM NBMA mode could be used in an ATM, Frame Relay, SMDS, PRI ISDN, or X.25 network.
1. enable
2. configure terminal
3. interface atm number
4. ip pim nbma-mode
5. ip pim multipoint-signalling
6. atm multipoint-signalling
7. ip pim vc-count number
8. ip pim minimum-vc-rate pps
9. show ip pim vc
Note |
The following task is for configuring PIM sparse mode on the ATM bundle. However, this feature is supported with PIM sparse mode, PIM dense mode, and PIM sparse-dense mode. |
1. enable
2. configure terminal
3. interface atm number
4. ip pim sparse-mode
5. end
The following example shows how to enable IP multicast over ATM point-to-multipoint VCs:
interface ATM2/0 ip address 171.69.214.43 255.255.255.248 ip pim sparse-mode ip pim multipoint-signalling ip ospf network broadcast atm nsap-address 47.00918100000000410B0A1981.333333333333.00 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi atm multipoint-signalling map-group mpvc router ospf 9 network 171.69.214.0 0.0.0.255 area 0 ! ip classless ip pim rp-address 171.69.10.13 98 ! map-list mpvc ip 171.69.214.41 atm-nsap 47.00918100000000410B0A1981.111111111111.00 broadcast ip 171.69.214.42 atm-nsap 47.00918100000000410B0A1981.222222222222.00 broadcast ip 171.69.214.43 atm-nsap 47.00918100000000410B0A1981.333333333333.00 broadcast
The following examples show how to configure IP multicast over ATM PVC bundle for the following topology:
multicast sender —> Device1 — ATM bundle — Device2 —> multicast receiver
Configure ATM bundle on Device1
interface ATM0/0/0.1 point-to-point ip address 100.1.1.1 255.255.255.0 bundle test encapsulation aal5snap oam-bundle manage pvc-bundle 0/32 vbr-rt 19000 15000 5000 precedence 7 pvc-bundle 1/33 ubr 2480 precedence 6 pvc-bundle 1/34 ubr 4890 precedence 3-5 pvc-bundle 1/35 !
Configure ATM bundle on Device2
interface ATM0/1/0.1 point-to-point ip address 100.1.1.2 255.255.255.0 bundle test encapsulation aal5snap oam-bundle manage pvc-bundle 0/32 vbr-rt 19000 15000 5000 precedence 7 pvc-bundle 1/33 ubr 2480 precedence 6 pvc-bundle 1/34 ubr 4890 precedence 3-5 pvc-bundle 1/35 !
Configure IP multicast on Device1 and Device2
The following example is for configuring static RP on each device:
ip multicast-routing distributed ip pim rp-address 100.1.1.1
Enable PIM on ATM bundle on Device1 and Device2
The following example is for configuring PIM sparse mode on each device:
interface ATM0/0/0.1 ip pim sparse-mode
The following example shows how to configure ATM PVC on an ATM sub interface:
interface ATM0/1/0.1 point-to-point ip address 100.1.1.2 255.255.255.0 ip pim sparse-mode pvc 1/32 encapsulation aal5snap
The following example shows how to configure ATM PVC under PVP:
interface ATM0/1/0.2 multipoint ip address 100.1.2.2 255.255.255.0 ip pim sparse-mode atm pvp 10 pvc 10/32 encapsulation aal5snap
Related Topic |
Document Title |
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Cisco IOS commands |
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IP multicast commands |
MIB |
MIBs Link |
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To locate and download MIBs for selected platforms, Cisco IOS XE software releases, and feature sets, use Cisco MIB Locator found at the following URL: |
Description |
Link |
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The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation 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.
Feature Name |
Releases |
Description |
---|---|---|
P Multicast over ATM Point-to-Multipoint VCs |
This feature was added before Cisco IOS XE Release 2.1. |
This feature dynamically creates ATM point-to-multipoint switched virtual circuits (SVCs) to handle IP multicast traffic more efficiently. It can enhance router performance and link utilization because packets are not replicated and sent multiple times over the ATM interface. |
IP Multicast over ATM PVC Bundle |
Cisco IOS XE Release 3.7.1S |
IP multicast features supported on IP interfaces are also supported on ATM PVC Bundle and Layer3 ATM PVC interfaces. |