BGP toolkit
Test Cisco-style AS-path regular expressions against real paths, decode standard, large and extended communities (no-export, blackhole, route targets…), and convert and classify AS numbers.
AS-path regex tester
Common
_ matches a space, comma, brace, parenthesis or the start or end of the path. ^ is the neighbour side, $ the origin.
Result
In config
Common filters and their Junos equivalents
| Cisco-style regex | Matches | Junos |
|---|---|---|
| Routes from your own AS (empty path) | "()" | |
| Learned from neighbour AS 65001 | "65001 .*" | |
| Originated by AS 65001 | ".* 65001" | |
| Passed through AS 65001 anywhere in the path | ".* 65001 .*" | |
| Originated by neighbour 65001, prepends included | "65001+" | |
| Originated by a directly connected AS (one hop) | "." | |
| Contains a 16-bit private ASN (64512–65534) | — |
Junos expressions work on whole AS numbers (. is any one AS) and are not interchangeable with the Cisco style.
Community decoder
AS numbers
| AS | asdot | Size | Kind | Notes |
|---|
Only 2-byte AS numbers fit a standard community (AS:value); 4-byte networks use large communities.