FEC: Change the default slice size from 1490 to 1472.

1472 is the maximal possible size that does not result in fragmentation
on networks with 1500 MTU size (1500 = 1472 payload + 8 UDP header +
20 IP header).

This can be verified using

	tcpdump -nv -i eth0 udp

The output must contain a zero offset value, and the "Don't Fragment"
IP flag (DF) should be set.

Thanks to Gerrit Renker for pointing this out.

diff --git a/send_common.c b/send_common.c
index 92c9ab3b982aceed323f47c1c760493ab5a4f5b8..f931fdaf75eb3630f52f59b7f5019b16f8aa490b 100644 (file)
--- a/send_common.c
+++ b/send_common.c
@@ -477,7 +477,7 @@ int parse_fec_url(const char *arg, struct sender_command_data *scd)
                goto out;
        }
        /* use default fec parameters. */
-       scd->max_slice_bytes = 1490;
+       scd->max_slice_bytes = 1472;
        scd->slices_per_group = 16;
        scd->data_slices_per_group = 14;
        ret = 0;