Brocade Virtual ADX Switch and Router Guide (Supporting ADX v03.1.00) - Manual (Page 80)

66 Brocade Virtual ADX Switch and Router Guide
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Configuring IP parameters
4
Disabling forwarding of IP source-routed packets
A source-routed packet specifies the exact router path for the packet. The packet specifies the path
by listing the IP addresses of the router interfaces through which the packet must pass on its way to
the destination. The Virtual ADX running router code supports both types of IP source routing:
• Strict source routing – requires the packet to pass through only the listed routers. If the Virtual
ADX (running router code) receives a strict source-routed packet but cannot reach the next hop
interface specified by the packet, the Virtual ADX (running router code) discards the packet
and sends an ICMP Source-Route-Failure message to the sender.
NOTE
The Virtual ADX (running router code) allows you to disable sending of the Source-Route-Failure
messages. Refer to
“Disabling ICMP messages” on page 67.
• Loose source routing – requires that the packet pass through all of the listed routers but also
allows the packet to travel through other routers, which are not listed in the packet.
The Virtual ADX (running router code) forwards both types of source-routed packets by default. To
disable the feature, use either of the following methods. You cannot enable or disable strict or
loose source routing separately.
To disable forwarding of IP source-routed packets, enter the following command.
Virtual ADX(config)# no ip source-route
Syntax: [no] ip source-route
To re-enable forwarding of source-routed packets, enter the following command.
Virtual ADX(config)# ip source-route
Enabling support for zero-based IP subnet broadcasts
By default, the Virtual ADX (running router code) treats IP packets with all ones in the host portion
of the address as IP broadcast packets. For example, the Virtual ADX treats IP packets with
10.157.22.255/24 as the destination IP address as IP broadcast packets and forwards the packets
to all IP hosts within the 10.157.22.x subnet (except the host that sent the broadcast packet to the
Virtual ADX).
Most IP hosts are configured to receive IP subnet broadcast packets with all ones in the host
portion of the address. However, some older IP hosts instead expect IP subnet broadcast packets
that have all zeros instead of all ones in the host portion of the address. To accommodate this type
of host, you can enable the Virtual ADX to treat IP packets with all zeros in the host portion of the
destination IP address as broadcast packets.
NOTE
When you enable the Virtual ADX (running router code) for zero-based subnet broadcasts, the Virtual
ADX (running router code) still treats IP packets with all ones the host portion as IP subnet
broadcasts too. Thus, the Virtual ADX (running router code) can be configured to support all ones
only (the default) or all ones and all zeroes.
NOTE
This feature applies only to IP subnet broadcasts, not to local network broadcasts. The local network
broadcast address is still expected to be all ones.