Routing Test

By default, the NetScaler has the ability to participate in Layer 3 routing i.e., learning and advertising routes using routing protocols such as Routing Information Protocol (RIP), Open Shortest Path First (OSPF) and Border Gateway Protocol (BGP). BGP is the de facto standard for routing IP traffic across the global Internet. It is a routing protocol designed to share IP network address groups, or prefixes, between multiple different organizations. Each of these organizations (usually an ISP or a large private network) classify their addressing space as an Autonomous System–a network, or group of networks, that has an addressing and routing structure unique from another organizations. BGP is a very complex and powerful routing protocol, which some characteristics that make it quite unique compared to other protocols like RIP or OSPF. All aspects of its configuration are done manually–there is no “auto-discovery” of neighboring routers. Connections to other BGP neighbors, once configured, use a TCP connection to exchange network prefixes. Because of the possibility of mistakenly sending or receiving route information that could bring down the routing tables for neighboring routers, or even the global Internet, there are many methods of screening and applying routing policies to updates sent or received from BGP peers.

A NetScaler can run BGP as a routing protocol to learn routes from other BGP routers, as well as advertise routes that the NetScaler knows about (networks downstream, vservers, and so on). Configuring NetScaler for BGP routing involves enabling dynamic routing, adding the BGP process to the routing engine, and configuring the BGP process with the essential BGP settings: peer router addresses and Autonomous System numbers, whether to redistribute routes from the kernel and/or defined static routes, and whether to learn routes from connected BGP peers. When a route is advertised, the BGP peers connected to the network, learns those routes. Frequent advertising of routes indicates that the peers are always kept aware of the routes in the network. If there are any errors that occur when a router advertises a route, then the availability of the router may alternate frwuently between up and down. Due to the instability of the router, the network topology is distorted which forces the routes to be withdrawn. If the instability continues, then the routes that are advertised will decrease and the routes that are withdrawn may subsequently go up resulting in high network latency. The Routing test helps administrators to keep a check on the number of routes that are advertised and the routes that are withdrawn over a period of time.

Using this test, administrators can figure out the routes that were advertised and the routes that were relearnt. In addition, this test will help administrators to identify the number of times the routes were withdrawn and the number of times the HA state of the routes was changed.

For this test to run and report metrics, the NetScaler appliance should be configured to create a Syslog file in a remote Syslog server, where the details of all interactions with the NetScaler appliance will be logged. To know how to configure a remote Syslog server for the use of the NetScaler appliance, refer to Creating a Syslog file in a remote Syslog servertopic.

This test is disabled by default. To enable the test, follow the Agents -> Tests -> Enable/Disable menu sequence in the eG administrative interface, pick Citrix NetScaler VPX/MPX as the Component type, select Performance as the Test type, choose this test from the list of disabled tests list, and click on the < button.

Target of the test : A NetScaler VPX/MPX

Agent deploying the test : A remote agent

Outputs of the test : One set of results for the NetScaler appliance being monitored.

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed

Host

The IP address of the host for which the test is being configured.

Port

The port at which the host listens. By default, this is NULL.

Log File Path

This test reports metrics by parsing a Syslog file. Specify the full path to the Syslog file here.

Search String

By default, the Syslog file may contain information relating to a number of servers that are inter linked with the target NetScaler appliance. In order to obtain the metrics of the target NetScaler appliance alone, specify the hostname or the IP address of the target NetScaler appliance for which the logs are to be read from the syslog file, in the Search String text box. Using this search string the information in the Syslog file may be parsed and metrics may be collected.

Search String Index

Here, specify the cursor position after which the eG agent should search for the specified Search String (or the position upto which the eG agent should ignore while searching for the specified Search String) in the syslog file. For example, if the specified Search String appears in the syslog file at the 17th position, then you may need to specify the Search String as 16.

DD Frequency

Refers to the frequency with which detailed diagnosis measures are to be generated for this test. The default is 1:1. This indicates that, by default, detailed measures will be generated every time this test runs, and also every time the test detects a problem. You can modify this frequency, if you so desire. Also, if you intend to disable the detailed diagnosis capability for this test, you can do so by specifying none against DD Frequency.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise suite embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability
  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Route advertised

Indicates the number of routes advertised.

Number

A route advertisement is when a router, using a routing protocol such as RIP or EIGRP, sends information to another router indicating that a specific network is reachable, and what the next "hop" or IP address is to use to get to the final destination. A high value is desired for this measure.

The detailed diagnosis of this measure if enabled lists the routes that were advertised.

Route withdrawn

Indicates the number of routes that were withdrawn.

Number

A route flap occurs when a router alternately advertises a destination network via one route then another, or when there’s an interface error on the router that alternates the availability of the router as up or down. When fluctuations are noticed repeatedly, the routing topology is distorted which in turn forces the router to withdraw the routes. Now, determining the next possible route will take longer than usual for the network thus leading to network latency or downtime. Therefore, the value of this measure should be kept at the least possible value.

The detailed diagnosis of this measure if enabled, lists the routes that were withdrawn.

Route relearnt

Indicates the number of routes that were relearnt.

Number

The detailed diagnosis of this measure if enabled, lists the routes that were relearnt.

HA state changed

Indicates the number of times the HA state to the route was changed.

Number

The detailed diagnosis of this measure if enabled, lists the route for which the HA state changed.