D-Link DGS-3620-28TC-SI Product Manual - Page 243

xStack® DGS-3620 Series Managed Switch Web UI Reference Guide BGP State Use the drop-down menu to enable or disable the Border Gateway Protocol state. By disabling the BGP protocol, all peers will be disconnected and dynamic routes will be deleted. All the static configurations however will be reserved. If BGP is enabled again, the previous configurations can be re-applied. Synchronization Usually, a BGP speaker does not advertise a route to an external neighbor unless that route is local or exists in the IGP. By default, synchronization between BGP and the IGP is turned off to allow the BGP to advertise a network route without waiting for route validation from the IGP. This feature allows routers and access servers within an Autonomous System to have the route before BGP makes it available to other autonomous systems. Enforce First AS This command is used to enforce the neighbor's AS as the first AS in the AS list. When the setting is Enabled, any updates received from an external neighbor that do not have the neighbor's configured Autonomous System (AS) at the beginning of the AS_PATH in the received update, will be denied and the neighbor will be closed. Enabling this feature adds to the security of the BGP network by not allowing traffic from unauthorized systems. Always compare MED Enable or disable the comparison of the Multi Exit Discriminator (MED) for paths from the neighbors in different Autonomous Systems. By default this setting is Disabled. Deterministic MED Enable or disable to enforce the deterministic comparison of the Multi Exit Discriminator (MED) for paths received from the neighbors within the same Autonomous System. By default this setting is Disabled. Best Path Option Choose from AS Path Ignore, Compare Router ID, Med Confed, MED Missing As Worst, and Compare Confed Aspath. AS Path Ignore - If selected, the BGP process will ignore the AS path in the path selection process. Compare Router ID - If selected, the BGP process will include the router ID in the path selection process. Similar routes are compared and the route with the lowest router ID is selected. Med Confed - If selected, the BGP process will compare the MED for the routes that are received from confederation peers. For routes that have an external AS in the path, the comparison does not occur. MED Missing As Worst - If selecteded, the BGP process will assign a value of infinity to routes that are missing the Multi Exit Discriminator (MED) attribute. If disabled, the BGP process will assign a value of zero to routes that are missing the Multi Exit Discriminator (MED) attribute, causing this route to be chosen as the best path. Compare Confed Aspath - If selected, the BGP process will compare the confederation AS path length of the routes received. The shorter the confederation AS path length, the better the route is. Best Path Option State Used the drop-down menu to enable or disable AS Path Ignore, Compare Router ID, Med Confed, MED Missing As Worst, and Compare Confed Aspath. The default is Disabled. Default Local Preference (0-4294967295) Enter a default local preference between 0 and 4294967295. The default value is 100. Router Identifier This field is used to set BGP router ID. An ID to identify a BGP router. If it is set to zero the router ID will be automatically determined. User must specify a unique router ID within the network. Hold Time (0-65535) The valid values are from 0 to 65535. The system will declare a peer as dead if a keepalive message is received that is more than the hold time. The default value is 180 seconds. If the holdtime is set to zero, then the holdtime will never expire. If the two routers that build a BGP connection have a different hold time, then the smaller hold time will be used. If the timer is specified for specific neighbors, then the neighbor specific timer will take effect. The hold time needs to be at least three times that of the keepalive timer. 233