Concept Guide

To view BGP conguration, use the show config command in CONFIGURATION ROUTER BGP mode or the show running-
config bgp command in EXEC Privilege mode.
Enabling Multipath
By default, the software allows one path to a destination. You can enable multipath to allow up to 64 parallel paths to a destination.
You can congure the maximum number of parallel routes (multipath support) to a destination in BGP.
NOTE: Dell EMC Networking recommends not using multipath and add path simultaneously in a route reector.
To allow more than one path, use the following command.
• Enable multiple parallel paths.
CONFIG-ROUTER-BGP mode
maximum-paths {ebgp | ibgp} number
Congure the following parameters:
– ebgp: Enable multipath support for external BGP routes.
– ibgp: Enable multipath support for internal BGP routes.
– number: Maximum number of parallel paths. The range is from 2 to 64.
Example conguration for enabling multipath
DellEMC# configure terminal
DellEMC(conf)# router bgp 400
DellEMC(conf-router_bgp)# maximum-paths ibgp 5
DellEMC(conf-router_bgp)# exit
In the above example conguration, the maximum number of parallel internal BGP routes is set to 5, so that only 5 routes can be installed in
a routing table.
The show ip bgp network command includes multipath information for that network.
Route Reectors
Route reectors reorganize the iBGP core into a hierarchy and allow some route advertisement rules.
NOTE
: Do not use route reectors (RRs) in the forwarding path. In iBGP, hierarchal RRs maintaining forwarding plane RRs could
create routing loops.
Route reection divides iBGP peers into two groups: client peers and nonclient peers. A route reector and its client peers form a route
reection cluster. Because BGP speakers announce only the best route for a given prex, route reector rules are applied after the router
makes its best path decision.
• If a route was received from a nonclient peer, reect the route to all client peers.
• If the route was received from a client peer, reect the route to all nonclient and all client peers.
To illustrate how these rules aect routing, refer to the following illustration and the following steps. Routers B, C, D, E, and G are members
of the same AS (AS100). These routers are also in the same Route Reection Cluster, where Router D is the Route Reector. Router E and
H are client peers of Router D; Routers B and C and nonclient peers of Router D.
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Border Gateway Protocol (BGP)