Netgear XCM8810 - 8800 SERIES 10-SLOT CHASSIS SWITCH ユーザーズマニュアル
Chapter 20. IPv4 Unicast Routing
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NETGEAR 8800 User Manual
final hop router, when IP subnet directed broadcast forwarding is enabled on an IP VLAN via
the command line, the following happens:
the command line, the following happens:
•
Some basic validity checks are performed (for example, checking to see if the VLAN has
IP enabled)
•
A subnet broadcast route entry for the subnet is installed. For example, consider a
system with the following configuration:
VLAN-A = 10.1.1.0/24, ports 1:1, 1:2, 1:3, 1:4
VLAN-B = 20.1.1.0/24, ports 1:5, 1:6, 1:7, 1:8
VLAN-C = 30.1.1.0/24, ports 1:9, 1:10, 1:11
If you enable IP directed broadcast forwarding on VLAN-A, you should install a route
entry for 10.1.1.1.255 on this system.
entry for 10.1.1.1.255 on this system.
•
A packet arriving on port 1:5 VLAN-B with destination IP (DIP) set to 10.1.1.255, the
source IP (SIP) set to 20.1.1.3, the DMAC set to the router MAC, and the SMAC set to
the originating system MAC, arrives at the installed route entry and is sent out on all the
ports of VLAN-A, with DMAC set to be all FF and the SMAC set to the router's system
MAC.
the originating system MAC, arrives at the installed route entry and is sent out on all the
ports of VLAN-A, with DMAC set to be all FF and the SMAC set to the router's system
MAC.
•
An IP packet arriving on port 1:1 VLAN-A with the DIP set to 10.1.1.255, the SIP set to
10.1.1.3, the DMAC set to all FF, and the SMAC set to the originator’s MAC, causes the
L2 to be flooded out of all the ports of VLAN-A.
L2 to be flooded out of all the ports of VLAN-A.
When IP subnet directed broadcast is disabled on an IP VLAN, on each port of the VLAN, all
IP subnet directed broadcast entries are deleted.
IP subnet directed broadcast entries are deleted.
Note:
IP subnet directed broadcast uses fast-path forwarding.
Command-line Support for IP Broadcast Handling
The
enable ipforwarding
and
disable ipforwarding
commands are enhanced to support
the enhanced IP broadcast handling functionality on BlackDiamond 10808, 12800, and
20800 platforms. Specifically, the following two keywords were added to the commands:
20800 platforms. Specifically, the following two keywords were added to the commands:
•
fast-direct-broadcast, which specifies to forward IP broadcast packets in the hardware
and send a copy to the CPU
•
ignore-broadcast, which specifies to forward IP broadcast packets in the hardware but
not send a copy to the CPU
For further details, see the appropriate command reference pages in the NETGEAR 8800
Chassis Switch CLI Manual.
Chassis Switch CLI Manual.
Note:
These two keywords are available on BlackDiamond 10808 and
20800 series switches only.