H3C Technologies H3C SecBlade LB Cards - Manual (Page 31)

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Item Description
Enable Forced LB
When you select UDP as the protocol, set whether to enable the mechanism of
distributing services based on packets.
Packet exchange for some UDP-based services, such as DNS, RADIUS, and so on,
can be completed in one exchanging process, and in some specific scenarios, the
quintuple of packets is the same. In this case, load balancing cannot be
implemented on service packets based on the session-based load balancing mode.
Therefore, forced load balancing needs to be enabled to implement load balancing
of service packets according to the mechanism of distributing services based on
packets.
IMPORTANT:
Forced load balancing of fragmented packets is implemented based on virtual
fragment reassembly. Therefore, you must enable virtual fragment reassembly on the
zone to which the interfaces that process LB packets belong. For more information, see
Security Configuration Guide.
Port Set the port number used by the cluster to provide services.
Forwarding Mode
Load balancing mode adopted:
• NAT—NAT-mode server load balancing.
• Direct Routing—DR-mode server load balancing.
• Firewall—Firewall load balancing.
IMPORTANT:
For NAT-mode server load balancing, to implement NAT internal server on the LB
product's interface attached to the user network, do not configure the VSIP as the
external IP address of the internal server. Otherwise, the two functions may conflict
with each other.
Enable SNAT
Enable source address NAT translation, which changes the source address of a
packet during load balancing.
This option can be set only when the forwarding mode is NAT.
IMPORTANT:
After you enable SNAT for the virtual service, do not configure NAT on the LB
product's interface connecting the real server for traffic matching the virtual service.
Otherwise, the two functions may conflict with each other.
SNAT IP Pool
Configure an SNAT IP address pool.
The option can be set when Enable SNAT is selected. Its default value is the virtual
service IP address.
The start IP address and end IP address must be both configured or both empty, and
the end IP address must be greater than the start IP address.
IMPORTANT:
The SNAT address pool cannot have overlapping address spaces with the address
pool configured for dynamic NAT on the interface that connects the device to the real
server. Otherwise, TCP packet checksum calculation error may occur.