Watch Mode Overview

Packeteer's watch mode is used when you don’t want the PacketShaper to be cabled into the main data path — when your situation requires that the unit monitor the traffic non-inline. This type of deployment is sometimes required for data centers that have restrictions on the introduction of inline elements into the network.

Note: The watch mode feature is not available on the PacketShaper 1200 or 1400 Lite models.

This feature works with PacketShaper and PacketShaper ISP units. When a unit is in watch mode, it passively monitors the traffic on your network and performs all the traffic classification and reporting tasks that PacketShapers typically do: identify your network traffic, measure response times, track bandwidth utilization, notify you of conditions of interest, and report on the performance of your applications and network. It can provide you with insight into what applications are being used on your network and highlight performance issues. Consistent with its role as a passive watcher, a PacketShaper in watch mode will not perform traffic shaping; any existing policies and partitions will be ignored.

In watch mode, the PacketShaper’s OUTSIDE port(s) are used for monitoring network traffic and the MGMT port (on a PacketShaper 1700, 3500, or 7500) or INSIDE port(s) can be used for managing the unit itself. PacketWise decides which port to use for management access by looking at which ports are connected. If an INSIDE or MGMT port isn’t connected to a network, the OUTSIDE port can be used for management. If more than one INSIDE port is connected, only one will be active and pass traffic; the other connected ports will provide redundant management access. PacketWise decides which port to use for management access according to the following order: MGMT (if available), built-in INSIDE, upper/right LEM INSIDE, lower/left LEM INSIDE.

Note: If the Dedicated Management Port feature is enabled on the PacketShaper 1700, 3500, or 7500 models, you will only be able to access the unit through the MGMT port; you cannot manage via any other port.

Watch mode is supported in a variety of network configurations. One example is shown above; see Connect PacketShapers into Redundant Topologies for other supported topologies.

A PacketShaper in watch mode includes the following features:

• Is compatible with SPAN ports, mirrored switch ports, and hubs connecting multiple routers
• Can monitor traffic to/from up to 256 WAN routers
• Can receive traffic from up to three network segments (if LAN Expansion Modules are installed)
• Can be managed from a separate network than the one being monitored

Non-Inline Deployment Requirements and Limitations

Packeteer's non-inline deployment has the following requirements and limitations:

• Packeteer has tested and certified watch mode compatibility with the Cisco Catalyst 4000/5000 series and the Dell PowerConnect 5212.
• Packeteer has tested and certified tap compatibility with the following NetOptics taps: 10/100 Ethernet, Gigabit 1000BaseTX, and fiber-optic splitter.
• Packeteer's watch mode and direct standby features cannot be used together.
• Watch mode can be enabled in legacy tunnel mode, but not in migration or enhanced mode.
• The host show command will not display output if both of the main LEM ports are disconnected and watch mode is enabled.
  
• Device classification cannot be used in watch mode. Because PacketWise performs classification by device (LEM) when a packet exits the Packeteer unit, and watch mode drops all packets, the packets do not exit on any interface and thus cannot be classified by interface. If you are using watch mode and want to classify and/or control traffic by device, you can create classes based on the MAC address of the watch mode routers.
• VoIP latency cannot be measured by a PacketShaper in watch mode.

Compression Estimator Mode

Another useful application of the watch mode feature is to evaluate Packeteer’s Xpress compression feature, using a single PacketShaper. When a PacketShaper is deployed non-inline with compression and watch mode enabled, PacketWise will estimate the amount of compression that would have occurred on outbound data if the unit had been deployed inline. All the compression statistics, graphs, and reports are accessible and reflect an estimation of compression benefits. To come up with these estimates, Xpress does not compress the live data; it compresses the packets in the outbound direction (those that are destined to routers on the router watch list) and then drops the compressed data.

Packeteer's Compression Estimator capability provides you with a simple way to project compression gains from PacketShaper's Xpress option with a single unit evaluation. Deployed using mirrored switch ports, taps, or SPAN ports, Compression Estimator allows the PacketShaper to monitor traffic and estimate the bytes saved for different application traffic types and produce overall compression savings estimation for the entire link.

See Compression Estimator.

Compression Estimator Limitations

Compression Estimator mode has the following limitations:

• Works on outbound traffic only. An outbound data center traffic installation represents a good proxy for traffic mixes. Due to the asymmetric nature of traffic, the majority of traffic is served outbound from data center servers and represents a suitable proxy for overall network traffic.
• Available only in legacy tunnel mode; does not work in enhanced or migration mode.
• Offers statistics on byte savings and bandwidth increases, but doesn't provide differences in response times. (An inline deployment of PacketShaper with the compression module offers this capability.)
• Is not applicable where existing PacketShapers are deployed inline. This mode is targeted for new customers. Existing customers with inline deployments can enable compression evaluation keys on two PacketShapers to enable a real-world test.

See also:

Configure Watch Mode