GigaTAP-TX configuration

Are there any special configuration steps necessary for the GigaTAP-TX?

Are there any special configuration steps necessary for the GigaTAP-TX?

Answer: Yes, please read the following excerpt from the Users Guide thoroughly.

The GigaTAP-Tx module provides the ability to tap a copper Gigabit Ethernet link, copying traffic to specified tool ports as it flows through the tap. There are two pairs of RJ45 connectors for tapping two different links.

The GigaTAP-Tx Module

Passive Mode vs. Active Mode

By default, the ports in the GigaTAP-Tx module operate in passive mode instead of active mode:

• In passive mode, the relays in the GigaTAP-Tx module are closed. This means that traffic received on one port is repeated out the other port in the pair but is never seen by the GigaVUE – it simply flows between the two ports.
  
  Passive mode protects production links in case of power failure. The tap will always revert to passive mode in the event of power loss.
  
  Note: The Link and Activity LED's are always off when the GigaTAP-Tx is operating in passive mode.
  
  
• In active mode, the relays in the GigaTAP-Tx module are open. Traffic received on one port is actively regenerated out the other port in the port-pair. In addition, it flows through the GigaVUE, making it available to tool ports.

Configuring Tap Connections

There are two main configuration steps when tapping a link with the GigaTAP-Tx:

• Set up the Port-Pair
• Verify End Node Status and Open the Relays

Set up the Port-Pair
A port-pair is a bidirectional connection in which traffic arriving on one port in the pair is actively regenerated out the other (and vice-versa) as a pass-through tap. Without a port-pair in place, traffic arriving on one port will not be regenerated out the other. So, the first step in tapping a link is to set up the port-pair with the config port-pair command:
config port-pair <port-alias1|pid1> <port-alias2|pid2> alias <string>

Notes on Port-Pairs

• Port-pairs can be established between any ports on the same GigaVUE-420.
• On the GigaVUE-MP, paired ports must be in the same module. Because of this restriction, it is not possible to pair a 10Gb port with a 1 Gb port because there is no module with both of these ports.
• Port-pairs support link status propagation – when one port goes down, the other port goes down (and vice-versa).
• Port-pairs between GigaMGMT or GigaPORT ports can be used as an electronic tap for RJ45 or fiber-optical links, although without the fail-over protection provided by the GigaTAP-Tx and GigaTAP-Sx/Lx/Zx.
• Port-pairs can be established between ports using different speeds (for example, from a 100 Mb port to a 1 Gb port).

Note: Depending on traffic volume, port-pairs between ports using different speeds can cause packet loss when going from a faster port to a slower port (for example, from 1 Gb to 100 Mbps, from 10 Gb to 1 Gb (GigaVUE-420 only), and so on).

Verify End Node Status and Open the Relays

The next step is to open the relays for the ports used to tap the link. Before doing so, however, check the link status LED's on both end nodes connected to the port-pair ports to verify that they are operating correctly. The links must be good for fail over protection to function properly.
If the link status on the end nodes is not good (LED's are not green), check the following:

• Verify that the combined cable length is less than 100 meters.
• Verify that auto negotiation settings match. If auto negotiation is not enabled on one of the endpoints, you must manually configure the port-params of the connected tap ports to match, followed by a config save. See config port-params commands in the Users Guide on page 388 for details.
• Most newer Ethernet interfaces support auto sensing (Auto-MDI/MDI-X; part of the 1000BASE-T standard). However, if your equipment does not support this feature (or it is disabled), you may need to use a crossover cable.
• Open the relays for the ports used to tap the link in the GigaTAP-Tx using the config port-params <port-id> taptx active command, followed by a config save. Once you have opened the relays, verify that the green link LED's for both ports in the port-pair have illuminated.

Set up Connections/Maps for Both Ports

Once you have set up a port-pair, make sure to logically connect both ports in the port-pair connection to tool ports. Only the receive traffic is forwarded through the connections, so it’s important to connect both sides of the port-pair to tool ports to see both sides of the traffic.
Example:
For example, consider the tap scenario shown in Figure 5-11 :

1. Example – Tapping a Link with the GigaTAP-Tx
2. The GigaTAP-Tx is installed in the Port 13 - 16 slot in the GigaVUE.
3. The tap is set up between ports 13 and 14.

To set up this tap scenario, you would issue the following commands in the GigaVUE CLI:

Once you have set up the tap, it’s always a good idea to do a show connect in the GigaVUE CLI to review the settings in place. Figure 5-12 shows the results of a show connect once this example has been set up.

Setting up a Tap with the GigaTAP-Tx

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