RFC 2918 (rfc2918) - Page 2 of 4
Route Refresh Capability for BGP-4
Alternative Format: Original Text Document
RFC 2918 Route Refresh for BGP-4 September 2000
2. Route Refresh Capability
To advertise the Route Refresh Capability to a peer, a BGP speaker
uses BGP Capabilities Advertisement [BGP-CAP]. This capability is
advertised using the Capability code 2 and Capability length 0.
By advertising the Route Refresh Capability to a peer, a BGP speaker
conveys to the peer that the speaker is capable of receiving and
properly handling the ROUTE-REFRESH message (as defined in Section 3)
from the peer.
3. Route-REFRESH Message
The ROUTE-REFRESH message is a new BGP message type defined as
follows:
Type: 5 - ROUTE-REFRESH
Message Format: One encoded as
0 7 15 23 31
+-------+-------+-------+-------+
| AFI | Res. | SAFI |
+-------+-------+-------+-------+
The meaning, use and encoding of this field is the
same as defined in [BGP-MP, sect. 7]. More specifically,
AFI - Address Family Identifier (16 bit).
Res. - Reserved (8 bit) field. Should be set to 0 by the
sender and ignored by the receiver.
SAFI - Subsequent Address Family Identifier (8 bit).
4. Operation
A BGP speaker that is willing to receive the ROUTE-REFRESH message
from its peer should advertise the Route Refresh Capability to the
peer using BGP Capabilities advertisement [BGP-CAP].
A BGP speaker may send a ROUTE-REFRESH message to its peer only if it
has received the Route Refresh Capability from its peer. The carried in such a message should be one of the that
the peer has advertised to the speaker at the session establishment
time via capability advertisement.
Chen Standards Track