diff options
| -rw-r--r-- | lib/sockopt.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/lib/sockopt.c b/lib/sockopt.c index f1366158..d755746a 100644 --- a/lib/sockopt.c +++ b/lib/sockopt.c @@ -152,10 +152,17 @@ getsockopt_ipv6_ifindex (struct msghdr *msgh) #endif /* HAVE_IPV6 */ -/* Set up a multicast socket options for IPv4 - This is here so that people only have to do their OS multicast mess - in one place rather than all through zebra, ospfd, and ripd - NB: This is a hookpoint for specific OS functionality */ +/* + * Process multicast socket options for IPv4 in an OS-dependent manner. + * Supported options are IP_MULTICAST_IF and IP_{ADD,DROP}_MEMBERSHIP. + * + * Many operating systems have a limit on the number of groups that + * can be joined per socket (where each group and local address + * counts). This impacts OSPF, which joins groups on each interface + * using a single socket. The limit is typically 20, derived from the + * original BSD multicast implementation. Some systems have + * mechanisms for increasing this limit. + */ int setsockopt_multicast_ipv4(int sock, int optname, @@ -200,7 +207,7 @@ setsockopt_multicast_ipv4(int sock, /* Add your favourite OS here! */ #else /* #if OS_TYPE */ - /* default OS support */ + /* standard BSD API */ struct in_addr m; struct ip_mreq mreq; |