Administrator Guide

1. Allow the advertisement of multiple paths (send, receive or both).
CONFIG-ROUTER-BGP or CONFIG-ROUTER-BGP-AF mode
bgp add-path [both | enable | receive | send] path-count
Configure the following parameters:
•
both: Indicate that the system sends and accepts multiple paths from peers.
• enable: Indicate that the system enables add-path support for the node.
• send: Indicate that the system sends multiple paths to peers.
• receive: Indicate that the system accepts multiple paths from peers.
• path-count: Indicate that the system sends multiple paths to peers. The range is from 2 to 64.
2. Allow the specified neighbor or peer group to allow multiple path advertisements.
CONFIG-ROUTER-BGP or CONFIG-ROUTER-BGP-AF mode
neighbor [ip-address | ipv6–address | peer-group-name] add-path [send | receive | both] path-
count
NOTE: The path-count parameter controls the number of paths that are advertised, not the number of paths that
are received.
DellEMC# configure terminal
DellEMC(conf)# router bgp 400
DellEMC(conf-router_bgp)# neighbor 10.10.10.1 remote-as 500
DellEMC(conf-router_bgp)# bgp add-path both 2
DellEMC(conf-router_bgp)# address-family ipv4 multicast
DellEMC(conf-router_bgp_af)# neighbor 10.10.10.1 activate
DellEMC(conf-router_bgp_af)# neighbor 10.10.10.1 add-path both 3
DellEMC(conf-router_bgp_af)# exit
The above configuration example shows how to enable BGP additional paths to be sent and received with a maximum of two additional
paths to the peers. You can configure the neighbor to send and receive additional paths using the neighbor add-pathcommand at
the address family configuration level.
Configuring IP Community Lists
Within Dell EMC Networking OS, you have multiple methods of manipulating routing attributes.
One attribute you can manipulate is the COMMUNITY attribute. This attribute is an optional attribute that is defined for a group of
destinations. In Dell EMC Networking OS, you can assign a COMMUNITY attribute to BGP routers by using an IP community list. After you
create an IP community list, you can apply routing decisions to all routers meeting the criteria in the IP community list.
IETF RFC 1997 defines the COMMUNITY attribute and the predefined communities of INTERNET, NO_EXPORT_SUBCONFED,
NO_ADVERTISE, and NO_EXPORT. All BGP routes belong to the INTERNET community. In the RFC, the other communities are defined
as follows:
• All routes with the NO_EXPORT_SUBCONFED (0xFFFFFF03) community attribute are not sent to CONFED-EBGP or EBGP peers,
but are sent to IBGP peers within CONFED-SUB-AS.
• All routes with the NO_ADVERTISE (0xFFFFFF02) community attribute must not be advertised.
• All routes with the NO_EXPORT (0xFFFFFF01) community attribute must not be advertised outside a BGP confederation boundary,
but are sent to CONFED-EBGP and IBGP peers.
Dell EMC Networking OS also supports BGP Extended Communities as described in RFC 4360 — BGP Extended Communities Attribute.
To configure an IP community list, use these commands.
1. Create a community list and enter COMMUNITY-LIST mode.
CONFIGURATION mode
ip community-list community-list-name
2. Configure a community list by denying or permitting specific community numbers or types of community.
CONFIG-COMMUNITYLIST mode
{deny | permit} {community-number | local-AS | no-advertise | no-export | quote-regexp
regular-expression-list | regexp regular-expression}
• community-number: use AA:NN format where AA is the AS number (2 Bytes or 4 Bytes) and NN is a value specific to that
autonomous system.
• local-AS: routes with the COMMUNITY attribute of NO_EXPORT_SUBCONFED.
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Border Gateway Protocol (BGP)