ip-mroute
Display IP multicast routing cache information
SYNOPSIS
ip mroute [ show | add | del | flush ] [ dev IFACE ] [ from ADDRESS ] [ group ADDRESS ] [ to ADDRESS ] [ iif IFACE ] [ oif IFACE ] [ ttl TTL ]
PARAMETERS
show
Display the multicast routing cache.
add
Add a new multicast routing entry.
del
Delete an existing multicast routing entry.
flush
Flush all multicast routing entries.
Use with caution!
dev IFACE
Specifies the interface to use for querying the mroute cache. If omitted, all interfaces are considered.
from ADDRESS
Specifies the source address of the multicast traffic.
group ADDRESS
Specifies the multicast group address.
to ADDRESS
Specifies the destination address (relevant for PIM-SM).
iif IFACE
Specifies the incoming interface for the multicast traffic.
oif IFACE
Specifies the outgoing interface for the multicast traffic.
ttl TTL
Specifies the TTL (Time-To-Live) for the multicast packets.
DESCRIPTION
The ip-mroute
command in Linux is used to manage the multicast routing cache in the kernel. Multicast routing is a mechanism for efficiently sending data to multiple recipients simultaneously. The ip-mroute
command allows you to view, add, and delete multicast routes. This is crucial for applications and services that rely on multicast communication, such as video streaming, IPTV, and some network protocols. It provides tools for inspecting the multicast routing table, enabling administrators to configure and troubleshoot multicast forwarding. Proper configuration ensures efficient multicast delivery, preventing unnecessary network traffic and optimizing resource utilization. The command interacts directly with the kernel's multicast routing functionality, offering fine-grained control over multicast packet forwarding. Different options allow listing existing entries, or modifying or deleting those entries.
CAVEATS
Modifying the multicast routing table incorrectly can disrupt network communication. Understanding multicast routing protocols (e.g., PIM-SM, PIM-DM) is essential before making changes.
MULTICAST FORWARDING CACHE
The multicast forwarding cache is a kernel-level data structure that stores information about active multicast streams. The ip mroute
command interacts with this cache to manage multicast routing decisions.
PIM (PROTOCOL INDEPENDENT MULTICAST)
Multicast protocols like PIM-SM (Sparse Mode) and PIM-DM (Dense Mode) influence how the mroute cache is populated and managed. The `ip mroute` command can be used to observe and configure routes learned and installed by PIM daemons.
HISTORY
The iproute2
suite, including ip-mroute
, replaced the older net-tools
. It was developed to provide a more modern and feature-rich interface for network configuration. It became prevalent with the wider adoption of Linux for networking and routing roles.