Dell N3200-ON Networking N-Series Switches User Guide version 6.8.0 - Page 1374

Figure 38-3. Combining iBGP Routes R100 eBGP AS1 R1 OSPF OSPF R2 iBGP R3 OSPF R4 eBGP OSPF R5 R200 R300 Address Aggregation Dell Networking BGP supports address aggregation. The network administrator can configure up to 128 aggregate addresses. BGP compares active prefixes in the local RIB to the set of aggregate addresses. To be considered a match for an aggregate address, a prefix must be more specific (i.e., have a longer prefix length) than the aggregate address. A prefix whose prefix length equals the length of the aggregate address is not considered for aggregation. If one or more prefixes fall within an aggregate, the aggregate is considered active. A prefix must be used for forwarding to be considered for inclusion in an aggregate address (unless it is a locally-originated prefix). Aggregate addresses may overlap (for example, 10.1.0.0/16 and 10.0.0.0/8). A prefix that matches overlapping aggregates is considered to match only the aggregate with the longest mask. When an aggregate address becomes active (that is, when the first contained route is matched to the aggregate), BGP 1374 BGP