Dell N3200-ON Networking N-Series Switches User Guide version 6.8.0 - Page 1371

default learned by other means, either from default-information originate or a default learned from a peer. This type of default origination is not conditioned on the presence of a default route in the routing table. Equal Cost Multipath (ECMP) By default, Dell Networking BGP selects a single next hop for each BGP route. Dell Networking BGP can be configured to install BGP routes with up to 16 next hops in the common routing table (RTO). The network administrator can independently configure the maximum number of next hops for routes through internal and external peers. Paths can be used to form an ECMP route when they are both internal or both external, the resolved next hop is different, and the following attributes are the same: • local preference • AS path length • origin • MED • IGP distance to the BGP next hop Dell Networking BGP does not require ECMP next hops to be in a common AS. This behavior is enabled by default. To disable this behavior, use the no bgp always-compare-med command. When advertising to neighbors, BGP always advertises the single best path to each destination prefix, even if BGP has an ECMP route to a destination. NOTE: The maximum ECMP width is limited by the chosen SDM template. All Dell Networking N3200-ON Series switches can support 16-wide ECMP when using a non-default SDM template. BGP Next-Hop Resolution BGP UPDATE messages specify a NEXT_HOP attribute for each prefix. The NEXT_HOP attribute may be on an attached subnet for the receiver when the UPDATE is received from an external peer. But the NEXT_HOP on routes from internal peers or a multihop external peer is not always on a local subnet. Thus, BGP has to resolve the BGP NEXT_HOP to one or more local next hops (similar to how a router resolves a tunnel endpoint to a local next BGP 1371