Bgp4+ Route Reflection; Bgp4+ Route Aggregation; Bgp4+ Multipath - Brocade Communications Systems FastIron SX 800 Configuration Manual

BGP4+ route reflection

A BGP device can act as a route-reflector client or as a route reflector. You can configure a BGP peer as a route-reflector client from the
device that is going to reflect the routes and act as the route reflector using the neighbor route-reflector-client command.
When there is more than one route reflector, they should all belong to the same cluster. By default, the value for cluster-id is used as the
device ID. The device ID can be changed using the cluster-id command.
The route-reflector server reflects the routes as follows:
• Routes from the client are reflected to the client as well as to nonclient peers.
• Routes from nonclient peers are reflected only to client peers.
If route-reflector clients are connected in a full IBGP mesh, you can disable client-to-client reflection on the route reflector using the no
client-to-client-reflection command.
A BGP device advertises only those routes that are preferred ones and are installed into the Routing Table Manager (RTM). When a route
cannot be installed into the RTM because the routing table is full, the route reflector may not reflect that route. In cases where the route
reflector is not placed directly in the forwarding path, you can configure the route reflector to reflect routes even though those routes are
not in the RTM using the always-propagate command.

BGP4+ route aggregation

A device can be configured to aggregate routes in a range of networks into a single IPv6 prefix.
By default, a device advertises individual BGP4+ routes for all the networks. The aggregation feature allows you to configure a device to
aggregate routes in a range of networks into a single IPv6 prefix. For example, without aggregation, a device will individually advertise
routes for networks 2001:db8:0001:0000::/64, 2001:db8:0002:0000::/64, 2001:db8:0003:0000::/64, and so on. You can
configure the device to send a single, aggregate route for the networks instead so that the aggregate route would be advertised as
2001:db8::/32 to BGP4 neighbors.

BGP4+ multipath

The BGP4+ multipath feature can be used to enable load-balancing across different paths.
BGP4+ selects only one best path for each IPv6 prefix it receives before installing it in the IP routing table. If you need load-balancing
across different paths, you must enable BGP4+ multipath using the maximum-paths command under IPv6 address family configuration
mode.
IBGP paths and EBGP paths can be exclusively selected, or a combination of IBGP and EBGP paths can be selected.
The following attributes of parallel paths must match for them to be considered for multipathing:
• Weight
• Local Preference
• Origin
• AS-Path Length
• MED
• Neighbor AS (EBGP multipath)
• AS-PATH match (for IBGP multipath)
FastIron Ethernet Switch Layer 3 Routing
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