Dell PowerSwitch S4128F-ON OS10 Enterprise Edition User Guide Release 10.4.0ER - Page 264

If you configure the bgp bestpath as-path ignore command and the bestpath as-path multipath-relax command at the same time, an error message displays-only enable one command at a time. More path support More path (Add-Path) reduces convergence times by advertising multiple paths to its peers for the same address prefix without replacing existing paths with new ones. By default, a BGP speaker advertises only the best path to its peers for a given address prefix. If the best path becomes unavailable, the BGP speaker withdraws its path from its local router information base (RIB) and recalculates a new best path. This situation requires both IGP and BGP convergence and is a lengthy process. BGP add-path also helps switch over to the next new best path when the current best path is unavailable. The Add-Path capability to advertise more paths is supported only on IBGP peers-it is not supported on EBGP peers and BGP peer groups. Ignore router ID calculations Avoid unnecessary BGP best path transitions between external paths under certain conditions. The bestpath router-id ignore command reduces network disruption caused by routing and forwarding plane changes and allows for faster convergence. Advertise cost As the default process for redistributed routes, OS10 supports IGP cost as MED. Both auto-summarization and synchronization are disabled by default. BGPv4 and BGPv6 support • Deterministic MED, default • A path with a missing MED is treated as worst path and assigned an 0xffffffff MED value • Delayed configuration at system boot - OS10 reads the entire configuration file BEFORE sending messages to start BGP peer sessions 264 Layer 3