Hello, I have a question regarding the subject. In the old threads it seemed to have concluded that ignoring preferred source in local route was a bug and a pacth was proposed.
See, http://marc.theaimsgroup.com/?l=linux-netdev&m=99985580920599&w=2 There, the following patch is proposed, --- net/ipv4/route.c.x Fri Sep 7 02:30:54 2001 +++ net/ipv4/route.c Fri Sep 7 02:30:54 2001 @@ -1795,14 +1795,13 @@ if (res.type == RTN_LOCAL) { if (!key.src) - key.src = key.dst; + key.src = res.fi->fib_prefsrc ? : key.dst; if (dev_out) dev_put(dev_out); dev_out = &loopback_dev; dev_hold(dev_out); key.oif = dev_out->ifindex; - if (res.fi) - fib_info_put(res.fi); + fib_info_put(res.fi); res.fi = NULL; flags |= RTCF_LOCAL; goto make_route; However, in the relatively recent kernel (2.6.17.9) it seems that the patch hasn't been applied. net/ipv4/route.c 2508 if (res.type == RTN_LOCAL) { 2509 if (!fl.fl4_src) 2510 fl.fl4_src = fl.fl4_dst; 2511 if (dev_out) 2512 dev_put(dev_out); 2513 dev_out = &loopback_dev; 2514 dev_hold(dev_out); 2515 fl.oif = dev_out->ifindex; 2516 if (res.fi) 2517 fib_info_put(res.fi); 2518 res.fi = NULL; 2519 flags |= RTCF_LOCAL; 2520 goto make_route; 2521 } And actually the source IP of the comunication between two local interfaces is always that of destination. So the questions is why the patch hasn't been applied to the main line kernel, although deciding the souce IP for local route based on routing table seemed more natural than makeing it IP of the destination. The actual problem I have is the following, (if you are interested,) We have a nfs server whose IP address is shared among two hosts using vrrp and those two hosts also act as nfs clients. When the following host1 is a nfs server, the two hosts have following IPs. host1 IP1, VRIP(nfs server's IP shared using vrrp) host2 IP2 The nfs server and clients IP becomes as follows, because on host1 the source IP of nfs packet becomes that of destination i.e. VRIP. nfs server IP nfs client IP on host1 VRIP VRIP on host2 VRIP IP2 We also share the content of the rmtab which is something like VRIP:/filesystem:0x00000001 IP2:/filesystem:0x00000001 (the first colummn is nfs client, the second is shared file system and the third column is the mount count.) When something happens to host1, the failover is triggered and the VRIP is moved to the host2, host1 IP1 host2 IP2, VRIP(nfs server's IP shared using vrrp) nfs server IP nfs client IP on host1 VRIP IP1 on host2 VRIP VRIP Accesses to the nfs mounted filesystem on host1 will be denied, if the content of the rmtab dosen't change, because the nfs server on host2 thinks the clients are only VRIP and IP2. Of course, it can be avoided, if we unmount and remount the files system on the client, or if we appropriately change the content of the rmtab when the failover occurs. However I think, it would be much nicer if the source IP of the client was always the primary IP of a interface. This is realized if the source IP is determined by the preferred source in routing table. Then the IPs of the nfs server and the clients are always like this, and this dosen't cause any problem when the failover happens. nfs server IP nfs client IP on host1 VRIP IP1 on host2 VRIP IP2 Thanks in advance, Kimitoshi Takahashi, Cluster Computing Inc., Japan - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
