router
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... multicast traffic to ports where at least one
multicast router is connected. It must instead flood multicast
traffic to these ports ...
... through IGMP which traffic flows need to be received by router ports
to be routed because routers ...
... IGMP.
In situations where multiple multicast routers are connected to a
switched backbone, IGMP ...
... In switched backbone networks or exchange points, where predominantly
routers are connected with each other, a large amount of multicast
traffic may lead to unexpected congestion. It also leads to more
...
... multicast
traffic may lead to unexpected congestion. It also leads to more
resource consumption in the routers because they must discard the
unwanted multicast traffic.
...
... The RGMP protocol described in this document restricts multicast
traffic to router ports. To effectively restrict traffic, it must be
...
... For this reason, RGMP only supports a single RGMP enabled router to
be connected directly to a port of an RGMP ...
... There are four types of RGMP messages of concern to the
router-switch interaction. The type codes are defined to be the
highest values in an octet to avoid the re-use of already assigned
...
... RGMP Router side Protocol Description ...
... groups are desired at each
of their ports. Multicast routers use RGMP to pass such information
to the switches ...
... RGMP to pass such information
to the switches. Only routers send RGMP messages. They ignore
received RGMP ...
... indicate that it is RGMP enabled. When RGMP is disabled on a routers
interface, it will send out an RGMP ...
... When an interface is RGMP enabled, a router sends an RGMP Join
message out through this interface ...
... receive traffic for from the interface. The router needs to
periodically [Join Interval] re-send an RGMP ...
... RGMP Leave message for the group. For robustness,
the router MAY send more than one such message.
If IPv4 ...
... multicast packets for an undesired group are received at a
router from a switch, the router MAY send a RGMP ...
... switch. These messages are called data-triggered
RGMP Leave messages and the router SHOULD rate-limit them. The
router MAY suppress sending a data triggered RGMP ...
... RGMP Leave messages and the router SHOULD rate-limit them. The
router MAY suppress sending a data triggered RGMP Leave message if it
has a desired group ...
... IPv4 multicast traffic
towards these routers. Black holing occurs when a RGMP Leave is
received from one router ...
... routers. Black holing occurs when a RGMP Leave is
received from one router while the other router is still joined.
...
... RGMP Leave is
received from one router while the other router is still joined.
This malfunction is not only easily recognized by the actual users
...
...
This malfunction is not only easily recognized by the actual users
connected through the routers, but it also adheres to the principle
that a failure situation causes less traffic than more. Reverting to
...
... correlated with the cause anymore.
Because routers supporting RGMP are not required to send RGMP Join ...
... switch SHOULD recognize a
port connected to a router by other appropriate protocol packets or
dedicated IPv4 multicast router discovery ...
... router by other appropriate protocol packets or
dedicated IPv4 multicast router discovery mechanisms such as MRDISC
[11]. The manual configuration ...
... [11]. The manual configuration is required to support routers not
supporting PIM or other methods ...
... links may be required if non-PIM
routers are being used, depending on the other capabilities of the
switch.
...
... ports to make
it look like an RGMP enabled router to a potential switch at the
other end of the link ...
... traffic restriction is applied there only.
RGMP-incapable routers will receive multicast traffic for all
multicast groups ...
... a few known restrictions.
A router running RGMP on a switched network will not receive traffic ...
... ports are dedicatedly connected to one system which
acts as an RGMP capable router. This is also the recommended
configuration to best leverage the benefits of the RGMP protocol
...
... multicast data towards a
non-RGMP enabled router on the same port. This effectively
introduces a blackholing DoS attack ...
... affect a port if there officially is only one RGMP enabled router
connected to it (i.e., if the port is RGMP ...
... port only if there officially
is only one RGMP enabled router connected to it (i.e., if the port
is RGMP ...
... RGMP
for the purpose of constraining multicast traffic towards router
ports. This appendix will explain the motivation not to rely on
...
... IGMP (version 2) and is
as such easy to add to router and switch platforms that already
support IGMP ...
... port which is one reason for its complexity. In RGMP, this
configuration is explicitly not supported: More than one router
per switched port is not only not a common scenario in today's
...
... switches can easily be the
aggregate required bandwidth to routers on either sides. For
this reason, inter-switch bandwidth ...
... over provisioned. In addition, the likelihood for receiving
routers to be only on the sources side of an inter-switch link
is in general deployments ...
... PIM-SSM, it does not have explicit messages
for the router to selectively join to (S,G) channels individually.
...
... join to (S,G) channels individually.
Instead the router must RGMP join to all (Si,G) channels ...
... As discussed in Appendix B. This is probably one extension that
should be avoided. Multiple RGMP router per port are
inappropriate for efficient multicast traffic ...
... routers,
additional RGMP messages may be added to allow routers to indicate
that certain group (ranges ...
... Multicast Exchange Points (MIXes) environments situations exist
where different downstream routers for policy reasons need to
receive the same traffic flow from different upstream ...
... receive the same traffic flow from different upstream routers.
This problem could be solved by actually providing an upstream ...
... router only to those
downstream routers who want to have the traffic from exactly this
upstream ...
... traffic from exactly this
upstream router. This extension would best go in hand with
changes to the layer 3 routing protocol ...
... changes to the layer 3 routing protocol run between the routers.
As previously mentioned, RGMP ...