Mailing List Archive

ChangeSet 1.1159.258.139, 2005/05/19 15:03:42+01:00, kaf24@firebug.cl.cam.ac.uk

Do not set jumbo MTU on the fake netfront/back loopback device. It
causes packet loss at the Ethernet bridge (since bridges do not
fragment IP packets).
Signed-off-by: Keir Fraser <keir@xensource.com>



loopback.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletion(-)


diff -Nru a/linux-2.6.11-xen-sparse/drivers/xen/netback/loopback.c b/linux-2.6.11-xen-sparse/drivers/xen/netback/loopback.c
--- a/linux-2.6.11-xen-sparse/drivers/xen/netback/loopback.c 2005-05-19 11:06:06 -04:00
+++ b/linux-2.6.11-xen-sparse/drivers/xen/netback/loopback.c 2005-05-19 11:06:06 -04:00
@@ -94,7 +94,15 @@
dev->get_stats = loopback_get_stats;

dev->tx_queue_len = 0;
- dev->mtu = 16*1024;
+
+ /*
+ * We do not set a jumbo MTU on the interface. Otherwise the network
+ * stack will try to send large packets that will get dropped by the
+ * Ethernet bridge (unless the physical Ethernet interface is configured
+ * to transfer jumbo packets). If a larger MTU is desired then the system
+ * administrator can specify it using the 'ifconfig' command.
+ */
+ /*dev->mtu = 16*1024;*/
}

static int __init loopback_init(void)

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