Library: Test Plans

ISIS Testing

The test plans presented here include conformance, functional, and performance tests designed for network and QA engineers testing IS-IS devices and networks, and these tests provide a baseline for achieving network quality.

1. IS-IS Conformance Test
2. IS-IS Convergence Test
3. IS-IS Route Capacity Test
4. IS-IS Real World Performance Test
5. IS-IS Hitless Restart Test

1. IS-IS Conformance Test

Objective
Verify the Device Under Test's (DUT's) compliance with the following capabilities defined in various IS-IS standards:

• IS-IS: ISO/IEC 10589: 1992(E)
• IS-IS for IP Networks: RFC 1195

The primary goal is to validate the major features of the IS-IS protocol, generating pass/fail type results.

Setup
A minimum of two network connections is required from the test tool to the DUT - one for control plane establishment, the other to send a data frame or confirmation frame. Ixia's IxANVL conformance test solution can be used to execute these tests. IxANVL is run from a Linux workstation either connected directly to the DUT or via Ixia test hardware (Figure 1). IxANVL emulates various IS-IS topologies depending on the test case selected.


Figure 1. IS-IS conformance test setup

Input Parameters
Two sets of parameters are required prior to running conformance tests: one for test tool configuration and one for DUT configuration. The test tool inputs describe the interface and protocol-specific characteristics. The DUT configuration stores the matching IS-IS command set for use in Expect scripts (Table 1).

Parameter	Description
Test Tool Configuration	Tester IP addresses, DUT IP addresses, IS-IS protocol parameters (Area, Hello protocol options, Authentication, etc.)
DUT Configuration	IS-IS features (Area, timer values, etc) via Expect scripts.

Table 1. IS-IS conformance test input parameters

Methodology
Conformance testing is an important tool to verify how a DUT complies with specific protocol standards. Packets are sent to the DUT; a response is sent back; and the response is analyzed for validity. This identical process is executed repeatedly for every action paragraph of the specification. Results are provided as pass/fail output. Negative test cases are included to validate, for example, a device's response to "killer" packets.

1. Enter parameters to describe both the Conformance Tester and DUT configuration.
2. Select all or a set of test cases to run (see Figure 2).
3. Run the conformance tests from the user interface or in a batch mode via command scripts. Reconfiguring the DUT is required between test cases to match the test setup.

Figure 2. IS-IS conformance test case selection

Results
Conformance test results indicate the number of test cases passed/failed, including reasons for failed cases. See Figure 3 for an example of IxANVL test results output. IxANVL also maintains the history of each pass or fail test case in the Test Journal (Figure 4). The journal provides the test engineer with the ability to easily recall the results of a particular test that was run. These results can be used to compare proper conformance between different builds of the system being tested.


Figure 3. IS-IS conformance test results


Figure 4. IS-IS conformance test journal

2. IS-IS Convergence Test

Objective
The purpose of this test is to measure convergence time for data traffic traversing multiple paths in an IS-IS network to the same destination. Initiation of a topological change is induced to verify traffic shifts from a primary to secondary path. The test measures the time it takes a device to adjust to the change and begin forwarding traffic down an alternate path.

Setup
This test requires a minimum of three ports. The first port acts as transmitter to the one common prefix, and the other two act as primary and secondary paths maintaining IS-IS adjacencies. Ixia's IxRouter IS-IS Emulation Software can be used to execute this test. Figure 5 highlights the emulated network that can be created by IxRouter to execute this test.


Figure 5. IS-IS convergence test setup

Input Parameters

Parameter	Description
Traffic Rate	The rate at which frames are transmitted.
Input Metric	Metric used to govern the primary and secondary paths using IS-IS.
Advertised Delay per Route	Delay applied to each route prior to executing the topological change.
Number of Routes	Number of advertised routes.

Table 2. IS-IS convergence test input parameters

Methodology

1. Test ports 1 and 2 negotiate IS-IS adjacencies and advertise the same set of prefixes, but with different metrics. Test port 1 will contain the best path and be the preferred choice.
2. After the device has synchronized its database and populated the forwarding table from ports 1 and 2, the Tx port 3 initiates traffic flows to all advertised route destinations.
3. A topological change is induced on the primary path. The routes advertised by port 1 should expire or be withdrawn. Traffic should now be re-routed to port 2, which is the secondary path.
4. Measure the timestamp for the first packet to arrive on the secondary path at port 2 for a specific route (T2) and the timestamp for the last packet to arrive on the primary path for same route at port 1 (T1).
5. Calculate the convergence time for the route = T2 - T1.
6. Repeat steps 4 and 5 to obtain the convergence time for all withdrawn routes. Calculate average convergence across all routes.

Figure 6. IS-IS convergence test configuration with metrics

Results
Convergence results for this type of test are reflected in the difference in received timestamps. The difference is the time it took the DUT to stop forwarding to one interface and to start sending to another. The graphical output in Figure 7 demonstrates a typical convergence test result using IxRouter.


Figure 7. IS-IS convergence test result


Figure 8. IS-IS convergence test timestamp measurement

3. IS-IS Route Capacity Test

Objective
Determine the number of routes that an IS-IS DUT can sustain at a single time.

Setup

This test requires at least two test ports - one port to advertise IS-IS adjacencies and routes, and the other to transmit verification traffic to each network prefix. Figure 9 shows the test topology.


Figure 9. IS-IS route capacity test emulated topology

Input Parameters

Parameter	Description
Number of Adjacencies	Number of IS-IS adjacencies with the DUT.
Number of Routes	The number of prefixes to generate at the beginning of the test.
Route Step	Number of routes to increase per iteration.
Number of Ports	Number of IS-IS speaking ports to emulate network scalability. Some DUT may require more than a single port to reach device maximums.
Advertise Delay Per Route	Amount of time to wait for each route to be populated in the DUT's forwarding table.

Table 3. IS-IS route capacity test input parameters

Methodology

1. IS-IS test port 2 builds adjacencies based on the "Number of Adjacencies" parameter and advertises an initial "Number of Routes."
2. After the "Advertised Delay Per Route" has expired for the peer, test port 1 sends traffic with colored frames to each advertised route through the DUT.
3. Verify the colored received frames are received on port 2. Based on this number, either increase or decrease the amount of routes advertised.
4. Re-advertise the new number of routes by adjusting the number of routes advertised on port 1. This is the "Route Step."
5. Repeat steps 3 and 4 until the most optimal number is found for reachable prefixes using IS-IS.

Figure 10. IS-IS route capacity test configuration

Results
The results for this test indicate the maximum number of routes the DUT can successfully support, as verified by data traffic targeting those routes. The optimal method in executing this type of test is using a binary search iteration. Figure 11 presents test results achieved with IxRouter, showing packets received successfully for an optimal IS-IS forwarding table.


Figure 11. IS-IS route capacity test result

4. IS-IS Real World Performance Test

Objective
The purpose of this test is to characterize the performance of an IS-IS DUT connected to a large grid of IS-IS routers. Both stateless and Layer 4-7 stateful traffic are used to target an assorted mix of advertised routes within the grid. Performance measurements such as delay, voice quality, and response time are taken under a certain percentage of network congestion.

Setup
This test is set up with two ports: one to advertise IS-IS intra area routes, and the second port to transmit stateless and stateful traffic. Below is a sample topology for this test. Ixia's IxRouter IS-IS Emulation Software can be used to set up the routing topology. Ixia's IxChariot application can be used to generate both background and stateful Layer 4-7 traffic. The Ixia receive port receives and gauges statistics on Layer 4-7 transactions.


Figure 12. IS-IS real world performance test setup

Input Parameters

Parameter	Description
Number of Adjacencies	Number of IS-IS adjacencies with the DUT.
Traffic Rate (stateless)	The amount of load to put into the bandwidth pipe prior to executing L4-7 test transaction.
Traffic Type	Layer 4-7 type of transactional traffic, e.g. HTTP, FTP, LDAP, VoIP.
Rows and Columns	The size of the emulated IS-IS grid. The number or rows multiplied by the number of columns gives the total number of emulated routers.

Table 4. IS-IS intra-area test input parameters

Methodology

1. An IS-IS topology is emulated between the DUT and Test Port 2 with a given "Number of Adjacencies."
2. Test Port 2 emulates the intra-area grid of IS-IS routers based on the "Rows and Columns" parameter.
3. Layer 4-7 endpoints are established on both test ports.
4. Stateless background traffic is generated from Test Port 1 into the DUT to produce congestion to a certain percentage indicated by "Traffic Rate."
5. Layer 4-7 stateful traffic is generated on Test Port 1 targeted to endpoints in Test Port 2 located within the virtual IS-IS topology.
6. Adjustment of the background traffic percentage is made based on changing the "Traffic Rate" parameter to observe any changes in test results.

Figure 13. IS-IS real world performance test configuration


Figure 14. IS-IS real world performance test configuration - IxChariot

Results
Results for this test provide Layer 4-7 data throughput, latency, response time, and/or MOS (Mean Opinion Score) metrics.

An sample IxChariot results file is shown below. Test success is determined based on criteria required for Layer 4-7 traffic characteristics. Introduction of the background traffic is meant to achieve real world congestion over the network interfaces. The sample results that follow show raw numbers for two VoIP sessions that were run to a remote destination emulated by an IS-IS grid.


Figure 15. IS-IS real world performance test results

5. IS-IS Hitless Restart Test

Objective
Verify the DUT's functional ability to support an IS-IS Hitless Restart. Multiple paths are established to the DUT, and traffic will flow to the advertised best path route. Traffic flow should remain unchanged if a peer is reset and the DUT properly supports IS-IS Hitless Restart. Metrics such as frames received, rate, and consistency are verified on the primary and secondary paths.

Setup
This test requires three test ports: two to advertise IS-IS adjacencies with hitless restart enabled and the other port to transmit a continuous rate of traffic. This test presents the DUT with more than one path to a destination, and initiates a peer flap to confirm that the device is still forwarding to the stale peer. This test can be executed using Ixia's IxRouter IS-IS Emulation Software in conjunction with IxExplorer for traffic generation and analysis. Figure 16 shows an example of the test topology.


Figure 16. IS-IS hitless restart test topology

Input Parameters
The DUT and tester should both reflect similar timers and feature sets. Restarting modes and restarting times are key to the configuration.

Parameter	Description
Restart mode	Restart mode is reflected in the IIH hellos and can be modified for assorted sub-modes.
Restart time	The time allotted for the peer to reset before completely stopping the traffic.
Area	The area ID reflected in the IS-IS NET id.
Metric	Cost assigned to the primary and secondary paths advertised by IS-IS.

Table 5. IS-IS hitless restart test input parameters

Methodology

1. Rx Port 1 advertises an IPv4 prefix reachable via IS-IS. The DUT and tester are configured for IS-IS Hitless Restart. This path from Rx Port 1 is the optimal forwarding path.
2. Rx Port 2 advertises the same prefix as Rx Port 1, except with a higher metric. This sub-optimal path must not be used in a Hitless Restart topology.
3. Traffic is sent from the Tx Port to the IS-IS route advertised by the Rx Ports 1 and 2.
4. Confirm that frames are received on Rx Port 1 - the optimal IS-IS path.
5. Reset the IS-IS neighbor. Inducing a reset of the neighbor will trigger the Hitless Restart feature. The DUT should continue to transmit traffic to the restarting peer for the timers specified.

Figure 17. IS-IS hitless restart test configuration

Results
Success of this test is based on the ability of the DUT to maintain forwarding to a reset peer, no alternate route selection, and that the timers are precise. IxRouter can reflect the correct results by graphing the assorted traffic rates on the primary path and secondary path. No frames should be received on the alternate path when using Hitless Restart.


Figure 18. IS-IS hitless restart test results

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