Configuring Ip Community Lists - Dell S4820T Configuration Manual

CONFIG-ROUTER-BGP mode
bgp add-path [both|received|send] path-count count
The range is from 2 to 64.
2. Allow the specified neighbor/peer group to send/ receive multiple path advertisements.
CONFIG-ROUTER-BGP mode
neighbor add-path
NOTE: The path-count parameter controls the number of paths that are advertised, not the
number of paths that are received.

Configuring IP Community Lists

Within Dell 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 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 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.
• no-advertise: routes with the COMMUNITY attribute of NO_ADVERTISE.
• no-export: routes with the COMMUNITY attribute of NO_EXPORT.
Border Gateway Protocol IPv4 (BGPv4)
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