Chassis Chain (Hardware)
For daisy chain, the Ixia hardware can be structured as a chain of different types of chassis, up to 256 units. For a star topology, the Ixia hardware can be structured as a chain of different types (with restrictions) of chassis, up to 5. The following table describes the chassis available for the two types of chains:
Chassis | Number of Load Modules Supported | Daisy chain | Star |
---|---|---|---|
XG/XGS |
12 high density modules |
Yes |
Yes |
XM12 |
12 high density modules |
Yes |
Yes (slave only) |
XM2 |
Two high density modules |
Yes |
Yes (slave only) |
All non-Optixia chassis support load modules that each may contain one to 8 ports. Up to 16 ports per load module are supported on Optixia XM2 and XM12 chassis, which can result in a very large number of ports for the overall system.
Multiple Ixia chassis are chained together through special Sync-out/Sync-in cables that allow for port-to-port synchronization across locally connected chassis in accordance with the specification mentioned in the Chassis Chain Timing Specification section.
Note: Windows and Native chassis are not supported in the same chain.
Daisy Chain
There are several rules that must be observed when connecting chassis in daisy chains. If a rule is violated, chassis timing may not meet the specification.
- Sync cable length between two chassis in a chain should be less than or equal to 6 feet.
- In a physical chassis chain, the Optixia chassis must be grouped together, and the non-Optixia chassis must be grouped together; that is, the two types can be on the same chassis chain, but cannot be intermingled. In a virtual chain that consists of several physical chains, each physical chain must obey this rule.
- Sequence numbers must be unique in a chain. Within a chain, there cannot be duplicate sequence numbers.The master chassis must have the smallest sequence value in the physical chain. The order of sequence numbers must match the order of chassis (up to 99999). The numbers do not have to be sequentially contiguous (1, 2, 3, and so on.) but they must be sequentially increasing in value (1, 5, 8, and so on.)
- Certain load modules must be used in only the first 3 chassis in a chain. These include LM100TXS8, LM100TXS2, LM100TX8, and LM100TX1. If these boards are used in the fourth or later chassis in a chain, the network ports may not operate reliably.
The following figure is a representation of an independent Ixia chassis chain and control network. Chassis are chained together through their sync cables. The first chassis in a chain has a Sync-out connection (but no Sync-in unless it is the AFD1 GPS receiver), and is called the master chassis. All other chassis in the chain are termed subordinates.
Figure: Ixia Chassis chain and Control Workstation
Star Topology
There are several rules that must be observed connecting chassis in star topology. If a rule is violated, chassis timing may not meet the specification.
- Sync cable length between two chassis in a chain should be less than or equal to 6 feet.
- Only XG/XGS chassis can be the master of the chain.
- Only Optixia chassis (XG/XGS, XM2, XM12) chassis can be slaves.
All four sync out ports on the XG12 and XGS12 chassis shall be available for synchronization connection to slave chassis.
Figure: XG12 chassis sync-out ports
Figure: XGS12 chassis sync-out ports
In current deployment of these chassis, one sync-out port is available, and 3 additional sync-out ports are covered. There shall be a maximum of 5 synchronized chassis per system when deployed in the Star Topology with one slave connected to each of the 4 sync-out ports on the master. When there are fewer than 5 chassis, slaves may be connected to any sync-out port on the master.
You can choose to daisy chain chassis, or use star topology, but cannot combine the two.
Figure: Ixia Daisy Chain and Star Topology
Figure: Ixia Star Topology chassis chain
Multiple, geographically-separated, independent chassis may be synchronized with a high degree of accuracy by using an Ixia chassis. Specific chassis include an integral GPS or CDMA receiver which is used for worldwide chassis synchronization. See Chassis Synchronization for a complete discussion of chassis timing.
Note: Plugging-in or removing the sync cable while IxServer is starting or running can cause the IxServer to detect the change in the sync-in connection and shut down. If this occurs, restart IxServer, then restart all Ixia applications.
Ports from the chassis are connected to the Device Under Test (DUT) using cables appropriate for the media. Ports from any chassis may be connected to the similar ports on the DUT. It is even possible to connect multiple independent DUTs to different ports on different chassis.
Each chassis is driven by an Intel Pentium-based computer running Windows XP Professional and Ixia-supplied software. Each chassis may be directly connected to a monitor, keyboard, and mouse to create a standalone system, but it is typical to connect all chassis through an Ethernet network and run the IxExplorer client software or Tcl client software on one or more external control PC workstations. IxExplorer client software runs on any Windows 2000/XP based system or Windows Server 2003 (console usage or simultaneous remote terminal access for multiple users). Tcl client software runs on Windows 2000/XP based systems and several Unix-based systems.
Chassis Chain Timing Specification
Depending on the chassis topology, there are different timing skews between chassis.
For daisy chain:
- Chassis timing skew between similar XG/XGS chassis <= +/- 5ns.
- Chassis timing skew between similar chassis (except XG and XGS) <= +/- 40ns.
- Chassis timing skew between different chassis <= +/- 80ns.
Based on the above numbers:
- Maximum latency error between similar XG/XGS chassis due to the chassis <= +/- 5ns.
- Maximum latency error between similar chassis (except XG and XGS) due to the chassis <= +/- 40ns.
- Maximum latency error between different chassis due to the chassis <= +/- 80ns.
For star topology:
- Chassis timing skew between similar XG/XGS chassis one master and one slave <= +/- 5ns.
- Chassis timing skew between similar XG/XGS chassis both slaves <= +/- 10ns.
- Chassis timing skew between similar chassis (except XG and XGS) both slaves <= +/- 160ns.
- Chassis timing skew between different chassis (XG master, XM slave) <= +/- 80ns.
- Chassis timing skew between different chassis (XG slave, XM slave) <= +/- 85ns.
Based on the above numbers:
- Maximum latency error between similar XG/XGS chassis due to the chassis <= +/- 10ns.
- Maximum latency error between similar chassis (except XG and XGS) due to the chassis <= +/- 160ns.
- Maximum latency error between different chassis due to the chassis <= +/- 85ns.