2-1. auto-summary
Syntax Description:
This command has no arguments. auto-summary is enabled by default.
Purpose: When auto-summary is enabled, routes injected into BGP via redistribution are summarized on a classful boundary. A 32-bit IP address consists of a network address and a host address. The subnet mask determines the number of bits used for the network address and the number of bits used for the host address. The IP address classes have a natural or standard subnet mask, as shown in Table 2-1.
| Class | Address Range | Natural Mask |
|---|---|---|
| A | 1.0.0.0 to 126.0.0.0 | 255.0.0.0 or /8 |
| B | 128.1.0.0 to 191.254.0.0 | 255.255.0.0 or /16 |
| C | 192.0.1.0 to 223.255.254.0 | 255.255.255.0 or /24 |
| Reserved addresses include 128.0.0.0, 191.255.0.0, ... | ||
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