10
Steelhead Appliance Installation and Configuration Guide
Overview of the Steelhead EX
WAN Optimization
–
Deny
- Drop the SYN packet and send a message back to its source.
–
Discard
- Drop the SYN packet silently.
Peering rules
- Peering rules determine how a
Steelhead appliance
reacts when it sees a probe query.
Peering rules are an ordered list of fields a Steelhead appliance uses to match with incoming SYN
packet fields: for example, source or destination subnet, IP address, VLAN, or TCP port, as well as the
IP address of the probing
Steelhead appliance
. This is especially useful in complex networks. There are
the following types of peering rule actions:
–
Pass
- The receiving
Steelhead appliance
does not respond to the probing
Steelhead appliance
, and
allows the SYN+ probe packet to continue through the network.
–
Accept
- The receiving
Steelhead appliance
responds to the probing
Steelhead appliance
and becomes
the remote-side
Steelhead appliance
(that is, the peer
Steelhead appliance
) for the optimized
connection.
–
Auto
- If the receiving
Steelhead appliance
is not using enhanced auto-discovery, this has the same
effect as the Accept peering rule action. If enhanced auto-discovery is enabled, the
Steelhead
appliance
only becomes the optimization peer if it is the last
Steelhead appliance
in the path to the
server.
For detailed information about in-path and peering rules and how to configure them, see the
Steelhead
Appliance Management Console User’s Guide
.
Fail-to-Wire (Bypass) Mode
All
Steelhead appliance
models and in-path network interface cards support a fail-to-wire mode. In the event
of a failure or loss of power, the Steelhead appliance goes into bypass mode and the traffic passes through
uninterrupted.
If the Steelhead appliance is in bypass mode, you are notified in the following ways:
The Intercept/Bypass status light on the bypass card is triggered. For detailed information about
bypass card status lights, see the appendix.
The Home page of the Management Console displays Critical in the Status bar.
SNMP traps are sent (if you have set this option).
The event is logged to system logs (syslog).
Email notifications are sent (if you have set this option).
When the fault is corrected, new connections receive optimization; however, connections made during the
fault do not. To force all connections to be optimized, enable the
kickoff
feature. Generally, connections are
short-lived and kickoff is not necessary. For detailed information about enabling the kickoff feature, see the
Steelhead Appliance Management Console User’s Guide
.
When the Steelhead appliance is in bypass mode the traffic passes through uninterrupted. Traffic that was
optimized might be interrupted, depending on the behavior of the application-layer protocols. When
connections are restored, they succeed, even though without optimization.
In an out-of-path deployment, if the server-side Steelhead appliance fails, the first connection from the
client fails. After detecting that the Steelhead appliance is not functioning, a ping channel is set up from the
client-side Steelhead appliance to the server-side Steelhead appliance. Subsequent connections are passed
through unoptimized. When the ping succeeds, processing is restored and subsequent connections are
intercepted and optimized.
For detailed information about the
ping
command, see the
Riverbed Command-Line Interface Reference
Manual
.
