Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 750)

720 Multi-Service IronWare Switching Configuration Guide
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Multicast over GRE tunnel
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Syntax: show interface tunnel tunnel-no
Multicast over GRE tunnel
NOTE
MTU fragmentation for multicast traffic is not enabled over a GRE tunnel. Packets are transmitted
without MTU fragmentation. This behavior is applicable on Brocade MLX series, Brocade NetIron
XMR, Brocade NetIron CER, and Brocade NetIron CES devices.
Multi-Service IronWare software supports Multicast over a point-to-point GRE tunnel. Multicast over
a GRE tunnel allows multicast packets to be transported through a GRE tunnel across an IP cloud
towards its receiver. A GRE tunnel is provisioned at each end of the IP cloud. A GRE tunnel is a
virtual IP tunnel; the IP tunnel source can also be a VE interface. The IP cloud sitting in between the
two GRE endpoints serves as a PIM enabled logical link. As bidirectional control messages are sent
over the GRE tunnel, the multicast distribution tree is established across the IP cloud. Multicast
data is encapsulated with a predefined GRE header at the ingress node. The GRE packet is routed
within the IP cloud using the outer unicast GRE destination address. As the packet reaches the
egress node of the tunnel, the packet is decapsulated. The multicast packet continues on its way to
the multicast distribution tree to reach its receivers.
Configuring PIM GRE tunnel
The Brocade device PIM GRE tunnel configuration allows you to enable PIM Sparse (PIM-SM) and
PIM Dense (PIM-DM) on a GRE tunnel.
Enabling PIM-SM on a GRE tunnel interface
To enable PIM-SM on a GRE Tunnel Interface, enter the following command.
Brocade(config)#interface tunnel 20
Brocade
(
config-tnif-20)#ip pim-sparse
Syntax: [no] ip pim-sparse
Enabling PIM-DM on a GRE tunnel interface
To enable PIM-DM on a GRE Tunnel Interface, enter the following command.
Brocade(config)#interface tunnel 20
Brocade
(
config-tnif-20)#ip pim
Syntax: [no] ip pim
Configuring PIM GRE tunnel using the strict RPF check
The Brocade PIM GRE tunnel configuration allows you to enforce strict rpf check rules on (s,g) entry
on a GRE tunnel interface. The (s,g) entry uses the GRE tunnel as a RPF interface. During unicast
routing transit, GRE tunnel packets may arrive at different physical interfaces. The ip pim tunnel
rpf-strict command allows you to limit a specific port to accept the (s,g) GRE tunnel traffic.