Concept Guide
Example conguration for changing the WEIGHT attribute
DellEMC# configure terminal
DellEMC(conf)# router bgp 400
DellEMC(conf-router_bgp)# neighbor 10.10.10.1 remote-as 500
DellEMC(conf-router_bgp)# neighbor 10.10.10.1 weight 150
DellEMC(conf-router_bgp)# exit
In the above conguration example, the weight attribute for routes received from the neighbor 10.10.10.1 is set to 150.
To view BGP conguration, 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 congure 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 reector.
To allow more than one path, use the following command.
• Enable multiple parallel paths.
CONFIG-ROUTER-BGP mode
maximum-paths {ebgp | ibgp} number
Congure 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 conguration 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 conguration, 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 Reectors
Route reectors reorganize the iBGP core into a hierarchy and allow some route advertisement rules.
NOTE
: Do not use route reectors (RRs) in the forwarding path. In iBGP, hierarchal RRs maintaining forwarding plane RRs could
create routing loops.
Route reection divides iBGP peers into two groups: client peers and nonclient peers. A route reector and its client peers form a route
reection cluster. Because BGP speakers announce only the best route for a given prex, route reector rules are applied after the router
makes its best path decision.
• If a route was received from a nonclient peer, reect the route to all client peers.
• If the route was received from a client peer, reect the route to all nonclient and all client peers.
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Border Gateway Protocol (BGP)