quagga and frr，from The Linux Foundation

FRRouting (FRR) is an IP routing protocol suite for Linux and Unix platforms which includes protocol daemons for BGP, IS-IS, LDP, OSPF, PIM, and RIP.

FRR’s seamless integration with the native Linux/Unix IP networking stacks makes it applicable to a wide variety of use cases including connecting hosts/VMs/containers to the network, advertising network services, LAN switching and routing, Internet access routers, and Internet peering.

支援的協定清單：

Protocol 　　　　IPv4　　　　 IPv6

OSPF　　　　OSPFv2 　　OSPFv3

ISIS 　　　　ISIS IPv4 　　ISIS IPv6

RIP 　　　　RIP 　　　　RIPng

BGP 　　　　BGP IPv4 　　BGP IPv6

BGP 4-byte AS BGP 　　IPv4 4-byte AS BGP 　　IPv6 4-byte AS

LDP 　　　　LDP IPv4

每個守護程序使用socket收發封包，以RIP為例：

1、static int rip_create(void)

/* Create read and timer thread. */

rip_event(RIP_READ, rip->sock);

rip_event(RIP_UPDATE_EVENT, 1);

2、void rip_event(enum rip_event event, int sock)

thread_add_read(master, rip_read, NULL, sock, &rip->t_read);

thread_add_timer(master, rip_update, NULL,

sock ? 2 : rip->update_time + jitter,

&rip->t_update);

3、static int rip_read(struct thread *t)

len = recvfrom(sock, (char *)&rip_buf.buf, sizeof(rip_buf.buf), 0,

(struct sockaddr *)&from, &fromlen);

4、static int rip_send_packet(u_char *buf, int size, struct sockaddr_in *to, struct connected *ifc)

ret = sendto(rip->sock, buf, size, 0, (struct sockaddr *)&sin,

sizeof(struct sockaddr_in));