Concept Guide

Example conguration for enabling additional paths
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 conguration 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 congure the neighbor to send and receive additional paths using the neighbor add-pathcommand at the
address family conguration level.
Conguring 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 dened 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 denes the COMMUNITY attribute and the predened 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 dened 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 congure 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 Congure a community list by denying or permitting specic 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 specic to that
autonomous system.
• local-AS: routes with the COMMUNITY attribute of NO_EXPORT_SUBCONFED.
• no-advertise: routes with the COMMUNITY attribute of NO_ADVERTISE.
• no-export: routes with the COMMUNITY attribute of NO_EXPORT.
• quote-regexp: then any number of regular expressions. The software applies all regular expressions in the list.
• regexp: then a regular expression.
Example of the show ip community-lists Command
To view the conguration, use the show config command in CONFIGURATION COMMUNITY-LIST or CONFIGURATION
EXTCOMMUNITY LIST mode or the show ip {community-lists | extcommunity-list} command in EXEC Privilege mode.
DellEMC#show ip community-lists
ip community-list standard 1
224
Border Gateway Protocol (BGP)