Optimization of BGP routing

If you have more than one Internet connection, you know that simply using the Boundary Gateway Protocol (Border Gateway PROTOCOL,BGP) makes it difficult to get the optimal routing path. At this point, the 7th signaling system without a telecommunications network is subtle (signaling system 7,SS7). As the control surface of the telecommunications network, SS7 can determine the best path before a call is established. There is no such control surface on the internet, although BGP can also decide the route (this is similar to SS7), but it does not always choose the best path. BGP allows the edge router to transport through a preferred connection without interrupting internal or external users, providing business through a secondary selection connection if the preferred connection fails.

When BGP chooses a route, it is certainly better to consider factors such as the performance of routing pathways that each ISP connection can provide.

Routescience's Pathcontrol is a new product that can measure not only the routing performance of each BGP peer, but also the priority routing through BGP based on this information.

Pathcontrol to pick the heavy task

Pathcontrol 1.1 runs on Linux, providing independent functionality, one for reporting, one for management, and one for core engines, with an interface for each external BGP peer.

Pathcontrol 1.1 provides a robust Java program tool. The next version will allow Pathcontrol to be configured from the GUI (graphical user interface), but in the current release, the device must be managed through a command-line interface based on iOS.

Pathcontrol provides not only internal information such as connectivity performance and their corresponding pathways, but also allows you to configure some variables to control the use of those connections.

Pathcontrol can be placed anywhere after the edge router. The connection to the router can be established through a dedicated port or a channel connection, either way, Pathcontrol needs to access the external world and the edge routers.

Test See performance

Connect Pathcontrol directly to a Cisco CATALYST 6500 switch configured to receive external BGP input data from two Nortel Web switches (one 180e and one AD4). Pathcontrol is set up to peer with Cisco switches, monitoring the routes declared by each Nortel device. Pathcontrol can remain passive, monitor and report the performance of each remote peer, and it can also be placed in declarative mode, which allows it to change the preferred route on the edge router after determining which connection performs better.

Users can configure Pathcontrol to change the frequency of routing so that the user's edge routers are not suppressed. It is best to keep Pathcontrol running for at least a few days in passive mode, use the report generator to observe how often Pathcontrol declares a new route, and then determine the best change frequency for the situation.

Pathcontrol uses a roundtrip time of a TCP handshake as the basis for its performance metrics, sending a 1x1-pixel GIF image to a client via HTTP to passively retrieve the measured performance data, and can also be actively retrieved by probing the Web site that the user has set up. For the latter, Pathcontrol opens a TCP connection to a site and measures the time to complete the three-to-TCP handshake.

To achieve passive measurement, each measurement interface on the device is configured with a virtual IP address (fictitious IP address,vip). Returns an 1x1 pixel GIF image when the address is accessed via HTTP or HTTPS. Pathcontrol provides this GIF directly, measuring the time it took to establish a TCP call with a client computer. As long as the VIP address is embedded in an href on the Web page, the measurement begins once a client requests the page. The key to this is the use of policy-based routing, which is configured on the edge router and transmits communication data coherently based on the source address. This allows the Pathcontrol to continuously measure the performance of each path without regard to the other items in the routing table.

The default state Pathcontrol requires at least 6 measurements for the execution of data. The calculation process gives each path a level that will be used to determine which connection works better. By default, if two or more levels are assigned a value that is no more than 25 points, they are considered "better". If the rank of a connection is 25 points higher than the other, it is considered "best", and Pathcontrol declares the route to the equivalent edge router via the internal boundary Gateway Protocol (interior BGP,IBGP).