Guidelines For Multicast Access Policies - Avaya 8800 Planning And Engineering, Network Design

Multicast network design
multicast traffic, you can use the Multicast MAC Filtering feature to forward traffic to a configured
subset of the ports in the VLAN. This multicast MAC address is not an IP multicast MAC address.
At a minimum, map the multicast MAC address to a set of ports within the VLAN. In addition, if traffic
is routed on the local Avaya Ethernet Routing Switch 8800/8600, you must configure an Address
Resolution Protocol (ARP) entry to map the shared unicast IP address to the shared multicast MAC
address. You must configure an ARP entry because the hosts can also share a virtual IP address,
and packets addressed to the virtual IP address need to reach each host.
Avaya recommends that you limit the number of such configured multicast MAC addresses to a
maximum of 100. This number is related to the maximum number of possible VLANs you can
configure because for every multicast MAC filter that you configure the maximum number of
configurable VLANs reduces by one. Similarly, configuring large numbers of VLANs reduces the
maximum number of configurable multicast MAC filters downwards from 100.
Although you can configure addresses starting with 01.00.5E, which are reserved for IP multicast
address mapping, do not enable IP multicast with streams that match the configured addresses.
This may result in incorrect IP multicast forwarding and incorrect multicast MAC filtering.

Guidelines for multicast access policies

Use the following guidelines when you configure multicast access policies:
• Use masks to specify a range of hosts. For example, 10.177.10.8 with a mask of
255.255.255.248 matches hosts addresses 10.177.10.8 through 10.177.10.15. The host
subnet address and the host mask must be equal to the host subnet address. An easy way to
determine this is to ensure that the mask has an equal or fewer number of trailing zeros than
the host subnet address. For example, 3.3.0.0/255.255.0.0 and 3.3.0.0/255.255.255.0 are
valid. However, 3.3.0.0/255.0.0.0 is not.
• Receive access policies should apply to all eligible receivers on a segment. Otherwise, one
host joining a group makes that multicast stream available to all.
• Receive access policies are initiated when reports are received with addresses that match the
filter criteria.
• Transmit access policies are applied when the first packet of a multicast stream is received by
the switch.
Multicast access policies can be applied to a DVMRP or PIM routed interface if IGMP reports the
reception of multicast traffic. In the case of DVMRP routed interfaces where no IGMP reports are
received, some access policies cannot be applied. The static receivers work properly on DVMRP or
PIM switch-to-switch links.
With the exception of the static receivers that work in these scenarios, and the other exceptions
noted at the end of this section,
page 187 illustrates where access policies can and cannot be applied. On VLAN 4, access policies
can be applied and take effect because IGMP control traffic can be monitored for these access
policies. The access policies do not apply on the ports connecting switches together on V1, V2, or
V3 because multicast data forwarding on these ports depends on DVMRP or PIM and does not use
IGMP.
June 2016
Figure 86: Applying IP multicast access policies for DVMRP
Planning and Engineering — Network Design
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