Aggregating Routes; Configuring Bgp Confederations - Dell S4820T Configuration Manual

When you enable a route reflector, Dell Networking OS automatically enables route reflection to all
clients. To disable route reflection between all clients in this reflector, use the no bgp client-to-
client reflection command in CONFIGURATION ROUTER BGP mode. All clients must be fully
meshed before you disable route reflection.
To view a route reflector configuration, use the show config command in CONFIGURATION ROUTER
BGP mode or the show running-config bgp in EXEC Privilege mode.

Aggregating Routes

Dell Networking OS provides multiple ways to aggregate routes in the BGP routing table. At least one
specific route of the aggregate must be in the routing table for the configured aggregate to become
active.
To aggregate routes, use the following command.
AS_SET includes AS_PATH and community information from the routes included in the aggregated route.
• Assign the IP address and mask of the prefix to be aggregated.
CONFIG-ROUTER-BGP mode
aggregate-address ip-address mask [advertise-map map-name] [as-set]
[attribute-map map-name] [summary-only] [suppress-map map-name]
Example of Viewing Aggregated Routes
In the show ip bgp command, aggregates contain an 'a' in the first column (shown in bold) and routes
suppressed by the aggregate contain an 's' in the first column.
Dell#show ip bgp
BGP table version is 0, local router ID is 10.101.15.13
Status codes: s suppressed, d damped, h history, * valid, > best
Path source: I - internal, a - aggregate, c - confed-external, r -
redistributed, n - network
Origin codes: i - IGP, e - EGP, ? - incomplete
Network
*> 7.0.0.0/29
*> 7.0.0.0/30
*>a 9.0.0.0/8
*> 9.2.0.0/16
*> 9.141.128.0/24 10.114.8.33
Dell#

Configuring BGP Confederations

Another way to organize routers within an AS and reduce the mesh for IBGP peers is to configure BGP
confederations.
As with route reflectors, BGP confederations are recommended only for IBGP peering involving many
IBGP peering sessions per router. Basically, when you configure BGP confederations, you break the AS
into smaller sub-AS, and to those outside your network, the confederations appear as one AS. Within the
confederation sub-AS, the IBGP neighbors are fully meshed and the MED, NEXT_HOP, and LOCAL_PREF
attributes are maintained between confederations.
To configure BGP confederations, use the following commands.
• Specifies the confederation ID.
CONFIG-ROUTER-BGP mode
246
Next Hop Metric LocPrf Weight Path
10.114.8.33 0
10.114.8.33 0
192.0.0.0
10.114.8.33
0 18508 ?
0 18508 ?
32768 18508 701 {7018 2686 3786} ?
0 18508 701 i
0 18508 701 7018 2686 ?
Border Gateway Protocol IPv4 (BGPv4)