Hello I find that the graceful restart time number configuration can accept 32bits. bgp_proto GRACEFUL RESTART TIME expr ';' { BGP_CFG->gr_time = $5; } While in the RFC 4724 section 3 it says the graceful restart time is 12bits and restart flags is 4bits. +--------------------------------------------------+ | Restart Flags (4 bits) | +--------------------------------------------------+ | Restart Time in seconds (12 bits) | +--------------------------------------------------+ | Address Family Identifier (16 bits) | +--------------------------------------------------+ | Subsequent Address Family Identifier (8 bits) | +--------------------------------------------------+ | Flags for Address Family (8 bits) | +--------------------------------------------------+ so ,when I set the graceful restart time like 32768.，it will cover the gr_flag. Becasue ,in the bgp_write_capabilites() function ，it first put the gr_time in. Then use "|" to put gr_flags. This will casue the value in gr_time first four bits keep in the gr_flags。 put_u16(buf, caps->gr_time); buf[0] |= caps->gr_flags; Also ，I have find in RFC 4724，it required gr_flag expect the first bit ,the remaining bits are reserved and MUST be set to zero by the sender and ignored by the receiver. gr_time in the configure also can change the remaining bits. Meanwhile, in the bgp_read_capabilites() function, it use "& 0xf0" will remain the wrong 4 bits. caps->gr_flags = pos[2] & 0xf0; caps->gr_time = get_u16(pos + 2) & 0x0fff; I try this on the bird 2.0.7 Thanks Jingting Chen