IDEAL INDUSTRIES UniPRO MGig1, Руководство пользователя

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152810 UniPRO
Page 18 User Guide
Connection Establishment
To make a connection between a tester and a loopback device, or between two testers becomes
progressively more complicated the higher the Layer used.
Layer 1 is sufficient to test a physical medium, such as a copper or fiber cable, or a radio link. Higher
layers can be used, and their settings, such as addresses and VLAN/MPLS tags, have no effect apart
from reducing the amount of frame space available for the payload. The only requirement is that the
tester is set to use the attached loopback device (or slave tester) as its target.
Layer 2 is required in a LAN environment to connect via Layer 2 switches. The tester can be commanded
to DETECT all compatible IDEAL devices (loopback units or testers) on the network. The detected
devices can be added to the tester’s Target list and one of them selected as the target for tests. The test
frames will have the target’s MAC address in their destination field. Higher layer information that may be
present in the frames will have no effect on the communication between the tester and the target.
Layer 3 must be used when tests are run over a routed environment in the WAN outside of the local LAN.
The tester needs to identify its target by a public IP address. When the target is located in the WAN, it will
need to be assigned a known address so that the tester can be set up to communicate with it. It is not
possible to automatically DETECT compatible IDEAL devices/targets that are outside of the LAN. The
test frames will have the target’s IP address in the destination field. Frames retransmitted by the loopback
device will have the tester’s IP address in their destination field. The destination MAC will be replaced by
the MAC of the gateway.
Layer 4 is used when the target is located in another LAN that is connected to the tester’s LAN by a WAN
connection, on the far side of an edge router. The target will not have a public IP address, but instead a
private one assigned, either automatically or manually, by its local network. The test frames will have the
public IP address of the edge router in their Destination fields, and in addition the port number of the port
to which the target is connected. The router will need to be set up with port forwarding to forward the
frames to the target using the correct port number. The frames retransmitted by the loopback device will
have the LAN address of the router in their destination field. This will be translated by the router using its
Network Address Translation (NAT) table so that the frames eventually arrive back at the originating
tester.
In addition to the increased complexity of the setup at the higher layers, the issues that follow can arise
and must be overcome before testing can proceed.
Firewalls in LAN edges are designed specifically to block the type of traffic that testers generate. Test
traffic can only pass through a firewall that has an open port, or a Demilitarized Zone (DMZ), to which the
target is connected.
Ethernet transmission tests can generate large amounts of traffic and are designed to stress networks to
the point of failure. This must be taken into account when setting up the tests in order to avoid disrupting
other network traffic or causing network elements to block the overload situation.
Loopback devices that are configured to Layer 1 (Physical) loop cannot be automatically detected or
remote controlled because they do not receive or respond to Ethernet frames. They only retransmit them.
Targets and Services
Targets are destinations for test traffic. They can be (a) loopback units that retransmit the traffic back to
the source or, (b) other testers that receive and check the traffic and also generate and send traffic back
the other way.
A service is a stream of traffic with specific characteristics. Up to eight services, each with different
characteristics, can be used simultaneously for testing a network’s ability to carry multiple types of traffic,
to different destinations and, for example, over different VLANs. Each service is sent to a defined target.
This may be a common target for all services, selected from the Targets list, or the destination addresses
(MAC & IP) may be set individually for each service. By default a service will use the destination MAC
and IP of the target and source MAC and IP of the tester.