Re: network dropouts

["Jan Kundrát" <jan.kundrat@fzu.cz>]

Keir Fraser wrote:
>>no, I'm setting it manually via `ifconfig` in init script. Notice the 
>>following lines in kernel log:
>>
>>Dec 12 20:33:23 zirafa xen-br0: port 1(eth0) entering disabled state
>>Dec 12 20:34:23 zirafa xen-br0: port 1(eth0) entering learning state
>>
>>Why is eth0 (the only physical device in xen-br0) getting into disabled 
>>state?
> 
> 
> My guess would be that the bridge code is receiving carrier-change
> events from eth0. This causes it to put eth0 in disabled state for a
> while. 
> 
> One way to check this would be to add some printk()'s to
> net/bridge/br_notify.c and see whether you are getting NETDEV_CHANGE
> or NETDEV_DOWN events. If so, it may be that your physical connection,
> or your router/switch/hub, is a bit dodgy.
> 
> None of the other paths via which the interface may get disabled seem
> very likely to occur, but we can look at those if it doesn't appear
> that you are getting NETDEV events.

Hi, I finally managed to get it. Here is my patch to net/bridge/br_notify.c:

--- br_notify.c.original        2004-11-14 15:31:58.000000000 +0100
+++ br_notify.c 2004-12-17 13:57:19.000000000 +0100
@@ -45,37 +45,58 @@
         switch (event) {
         case NETDEV_CHANGEMTU:
                 dev_set_mtu(br->dev, br_min_mtu(br));
+               printk("NETDEV_CHANGEMTU\n");
                 break;

         case NETDEV_CHANGEADDR:
                 br_fdb_changeaddr(p, dev->dev_addr);
                 br_stp_recalculate_bridge_id(br);
+               printk("NETDEV_CHANGEADDR\n");
                 break;

         case NETDEV_CHANGE:     /* device is up but carrier changed */
-               if (!(br->dev->flags & IFF_UP))
+               printk("NETDEV_CHANGE ");
+               if (!(br->dev->flags & IFF_UP)) {
+                       printk("- !(br->dev->flags & IFF_UP)==true\n");
                         break;
+               }

                 if (netif_carrier_ok(dev)) {
-                       if (p->state == BR_STATE_DISABLED)
+                       printk("- netif_carrier_ok(dev)==true ");
+                       if (p->state == BR_STATE_DISABLED) {
+                               printk("- calling br_stp_enable_port(p)");
                                 br_stp_enable_port(p);
+                       }
                 } else {
-                       if (p->state != BR_STATE_DISABLED)
+                       printk("- netif_carrier_ok(dev)!=true ");
+                       if (p->state != BR_STATE_DISABLED) {
+                               printk(" - calling br_stp_disable_port(p)");
                                 br_stp_disable_port(p);
+                       }
                 }
+               printk("\n");
                 break;

         case NETDEV_DOWN:
-               if (br->dev->flags & IFF_UP)
+               printk("NETDEV_DOWN ");
+               if (br->dev->flags & IFF_UP) {
+                       printk("- calling br_stp_disable_port(p)");
                         br_stp_disable_port(p);
+               }
+               printk("\n");
                 break;

         case NETDEV_UP:
-               if (netif_carrier_ok(dev) && (br->dev->flags & IFF_UP))
+               printk("NETDEV_UP ");
+               if (netif_carrier_ok(dev) && (br->dev->flags & IFF_UP)) {
+                       printk("- calling br_stp_enable_port(p)");
                         br_stp_enable_port(p);
+               }
+               printk("\n");
                 break;

         case NETDEV_UNREGISTER:
+               printk("NETDEV_UNREGISTER\n");
                 spin_unlock_bh(&br->lock);
                 br_del_if(br, dev);
                 goto done;

and messages from syslog (obviously my patch is wrong as it'ss putting 
several messages together (missing "\n")):

Dec 17 18:37:02 zirafa NETDEV_CHANGE - netif_carrier_ok(dev)!=true  - 
calling br_stp_disable_port(p)<6>xen-br0: port 1(eth0) entering disabled 
state
Dec 17 18:37:02 zirafa
Dec 17 18:38:02 zirafa NETDEV_CHANGE - netif_carrier_ok(dev)==true - 
calling br_stp_enable_port(p)<6>xen-br0: port 1(eth0) entering learning 
state
Dec 17 18:38:02 zirafa
Dec 17 18:38:02 zirafa xen-br0: topology change detected, propagating
Dec 17 18:38:02 zirafa xen-br0: port 1(eth0) entering forwarding state

However, `ifconfig` says 0 for carrier:

eth0      Link encap:Ethernet  HWaddr 00:10:4B:B6:BD:0E
           inet addr:10.18.6.60  Bcast:10.18.6.63  Mask:255.255.255.192
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:3382 errors:0 dropped:0 overruns:0 frame:0
           TX packets:3164 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:312112 (304.7 Kb)  TX bytes:334955 (327.1 Kb)
           Interrupt:11 Base address:0xe400
xen-br0   Link encap:Ethernet  HWaddr 00:10:4B:B6:BD:0E
           inet addr:10.18.6.60  Bcast:10.18.6.63  Mask:255.255.255.255
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:3186 errors:0 dropped:0 overruns:0 frame:0
           TX packets:2971 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:246738 (240.9 Kb)  TX bytes:307288 (300.0 Kb)

Xen box has 3c590 card which is connected by cat5 1m long patch cable 
into TP-Link TL-SL3210 managable switch (which has 8*100Mbps, 1*1Gbps 
and 1 GBIC slot) which was quite expensive, so I don't think it's such a 
piece of s*** :-), but I might be mistaken (hope I am not).

Possible workaround could be setting up routing between domain0 and 
other domains, but it won't be a simple task.

TIA,
jkt

-- 
cd /local/pub && more beer > /dev/mouth



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