Avaya P880 User Manual

Page 21

610-0184-095

June 14, 2001

Example:

The unicast routing protocol in use on all connected routers is OSPF,
and all ports are on the same VLAN. An endstation joins the IP
multicast group 226.128.0.5 on port 1. The MAC address for the
group is 01:00:5E:00:00:05. IGMP snooping creates a session for this
MAC address, with port 1 as the client port. There is a non-multicast
OSPF router attached to port 2. OSPF uses the IP multicast
link scoped group 224.0.0.5, which also maps to a MAC address of
01:00:5E:00:00:05. Because port 2 is not considered a router port,
and it is not part of the 01:00:5E:00:00:05 session, the switch only
passes OSPF messages out port 1. Other protocols, such as the
Service Location Protocol (RFC 2608), use 224.0.1.22 and
224.0.1.35, which can be blocked by endstations joining sessions
that map to the same MAC address.

Note: This is the same problem that is discussed in the Microsoft
Product Support Article Q223136 that can be found at:

http://support.microsoft.com/support/kb/articles/Q223/1/ 36.asp

involving RRAS setup. This specific issue, however, should not break
routing protocols as suggested in this article because the Cajun
switch ignores joins for local multicast groups (224.0.0.x).

Workaround:

Check that all ports that are connected to the router are configured
as router ports. This prevents all router-to-router messages from
being blocked.

If other non-router protocols, such as the Server Location Service,
are in use, create static sessions as needed. Do not create static
sessions that conflict with the protocols used on your network.

Refer to the following web site for a complete list of internet
multicast addresses recognized by the IANA:

http://www.isi.edu/in-notes/iana/assignments/ multicast-addresses

Note: Enable is the default state for “Rate Limiting” on 10/100
Mbps ports. Multicast traffic and broadcast traffic is rate-limited (to
20%) on 10/100 Mbps ports.

Multicast traffic is rate-limited unless Intelligent Multicasting is
enabled. Multicast traffic for which the Intelligent Multicast session
was created is not subject to rate limiting unless the rate limiting