Enabling 4-byte AS number suppression
BGP supports 4-byte AS numbers. The 4-byte AS number occupies four bytes, in the range of 1 to 4294967295. By default, a device sends an Open message to the peer device for session establishment. The Open message indicates that the device supports 4-byte AS numbers. If the peer device supports 2-byte AS numbers instead of 4-byte AS numbers, the session cannot be established. To resolve this issue, enable the 4-byte AS number suppression function. The device then sends an Open message to inform the peer that it does not support 4-byte AS numbers, so the BGP session can be established.
If the peer device supports 4-byte AS numbers, do not enable the 4-byte AS number suppression function. Otherwise, the BGP session cannot be established.
To enable 4-byte AS number suppression (IPv4):
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter BGP view or BGP-VPN instance view. |
| N/A |
3. Enable 4-byte AS number suppression. | peer { group-name | ip-address [ mask-length ] } capability-advertise suppress-4-byte-as | By default, 4-byte AS number suppression is not enabled. |
To enable 4-byte AS number suppression (IPv6):
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter BGP view or BGP-VPN instance view. |
| N/A |
3. Enable 4-byte AS number suppression. | peer { group-name | ipv6-address [ prefix-length ] } capability-advertise suppress-4-byte-as | By default, 4-byte AS number suppression is not enabled. |