Cisco APIC Layer 3 Networking Configuration Guide, Release 6.2(x)

Route summarization at the L3Out external EPG level

Updated: April 17, 2026

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Explains how route summarization policies are applied at the L3Out External EPG level to achieve route summarization towards L3Out peers only.

Route summarization at the L3Out external EPG level is a routing policy that

applies BGP, OSPF, or EIGRP route summarization policies to a bridge domain or transit subnet
achieves route summarization towards L3Out peers only and not within the ACI fabric, and
advertises aggregate prefixes to external L3Out peers while preventing more-specific prefixes from being advertised to the L3Out peers.

Route summarization characteristics

Route summarization at the L3Out External EPG level has these characteristics:

For OSPF, inter-area and external route summarization are supported.
Summary routes are exported; they are not advertised within the fabric.
To achieve summarization of routes into the ACI fabric as well as towards external L3Out peers, see Route filtering and aggregation at the VRF level.

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