Coyote Point Systems E350GX, Installation And Administration Manual

Page: 88 / 344

Chapter 5: Configuring Equalizer Operation
88 Equalizer Installation and Administration Guide
stale timeout
The length of time that a partially open or closed Layer 4 connection is
maintained. If a client fails to complete the TCP connection termination
handshake sequence or sends a SYN packet but does not respond to the
server’s SYN/ACK, Equalizer marks the connection as incomplete. See
“Layer 4 Connection Timeouts” on page 263.
sticky netmask
Enables sticky network aggregation for a subnet. Sticky network
aggregation is applicable only for Layer 4 TCP and UDP clusters.
Sticky network aggregation enables Equalizer to correctly handle sticky
connections from ISPs that use multiple proxy servers to direct user
connections. When you enable sticky network aggregation, all the
connections coming from a particular network are directed to the same
server. (Typically, all the servers in a proxy farm are on the same
network.)
The
sticky netmask
value indicates which portion of the address
Equalizer should use to identify particular networks. The mask
corresponds to the number of bits in the network portion of the
address:
8 bits corresponds to a Class A network
16 bits corresponds to a Class B network
24 bits corresponds to a Class C network
A potential drawback of using sticky network aggregation is that all
users connecting through a particular proxy farm might be directed to
the same server. In practice, this has not been a problem. Equalizer’s
load-balancing algorithms direct other visitors to different servers to
keep the load balanced.
Note – If you are using two Equalizers in a failover configuration, you must set the
sticky network aggregation mask identically on both Equalizers.
enable outbound NAT
When outbound NAT (Network Address Translation) is enabled, Equalizer
modifies all packets
originating from the servers behind it, substituting
either the Default VLAN IP address or the address specified in the
server’s
Outbound NAT tab for the source (server) IP address before
forwarding the packets on to the recipient. [On the E250GX and legacy
‘si’ systems, the External Interface IP is used instead of the Default
VLAN IP.] This option applies to both Layer 4 and Layer 7 and is disabled
by default.
See “Configuring Outbound NAT” on page 145 for a description of the
server
Outbound NAT
tab.
Outbound NAT is usually necessary when you are using reserved (i.e.,
non-routable) IP addresses for your servers on one VLAN and cluster IP
addresses on another VLAN. NAT ensures that external hosts won’t see
packets originating from non-routable IP addresses. There is a
performance cost for using NAT, since Equalizer must modify every
outbound packet’s source address.
If your cluster and server IPs are all on the same subnet (sometimes
called
single network mode ), outbound NAT should be disabled . Because
the clusters and servers are all on the same subnet, NAT may interfere
with other features (such as
spoof ). In this case, NAT should be
configured on the network gateway device.