Extreme Networks ExtremeWare 7.7, Command Reference Manual

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mtrace
ExtremeWare 7.7 Command Reference Guide 2075
mtrace
mtrace source <ip address> {destination <ip address>} {group <ip address>}
{from <ip address>} {gateway <ip address >} {timeout <seconds>}
{maximum-hops <number>}
Description
Initiates a request to trace the path of multicast traffic from the source to the destination of a multicast
group.
Syntax Description
Defaults
• destination—current system
• group—0.0.0.0
• from—outgoing interface to reach the source or destination
• gateway—destination 224.0.0.2
• timeout—three seconds
• maximum-hops—255
Usage Guidelines
This command relies on a feature of multicast routers that is accessed using the IGMP protocol. Since
multicast uses reverse path forwarding, a multicast trace is run from the destination to the source. A
query packet is sent to the last-hop multicast router. This router builds a trace response packet, fills in a
report for its hop, and forwards the packet to the next upstream router. As the request is forwarded,
each router in turn adds its own report to the trace response. When the request reaches the first-hop
router, the filled in request is sent back to the system requesting the trace. The request will also be
returned if the maximum hop limit is reached.
If a router does not support the mtrace functionality, it will silently drop the request packet and no
information will be returned. For this situation, you would send the trace with a small number of
maximum hops allowed, increasing the number of hops as the stream is traced.
<ip address> Specifies an IP address.
source Specifies the unicast address of the multicast source.
destination Specifies the unicast address of the destination to which the path of the
multicast traffic will be traced.
group Specifies the multicast IP address of the group for which the traffic will be
traced.
from Specifies the unicast address of an interface in the system to use as the
response address in the request.
gateway Specifies the unicast address of a first hop router to which the query will be
directed.
timeout Specifies the time to wait before indicating a failure.
maximum-hops Specifies the maximum number of hops the mtrace request can traverse.