Using Bird 1.3.1 OSPF with 'rx buffer large' in the config. This test system is a couple of bird instances talking to each other. I've noticed that when LSA updates get above 4000 the checksum system seems to break. Before: Jul 1 18:39:21 acer-aspire-5536 bird: cloudtest: Scheduling routing table calculation Jul 1 18:39:21 acer-aspire-5536 bird: cloudtest: LSUPD packet received from 192.168.0.201 via eth0 Jul 1 18:39:21 acer-aspire-5536 bird: cloudtest: length 3964 Jul 1 18:39:21 acer-aspire-5536 bird: cloudtest: router 192.168.0.201 Jul 1 18:39:21 acer-aspire-5536 bird: cloudtest: LSA Type: 0001, Id: 192.168.0.201, Rt: 192.168.0.201, Age: 0, Seq: 8000000a, Sum: 7113 Jul 1 18:39:21 acer-aspire-5536 bird: cloudtest: LSACK packet sent via eth0 Jul 1 18:39:21 acer-aspire-5536 bird: cloudtest: length 44 Jul 1 18:39:21 acer-aspire-5536 bird: cloudtest: router 192.168.0.20 Jul 1 18:39:21 acer-aspire-5536 bird: cloudtest: LSA Type: 0001, Id: 192.168.0.201, Rt: 192.168.0.201, Age: 0, Seq: 8000000a, Sum: 7113 After: Jul 1 18:39:26 acer-aspire-5536 bird: cloudtest: LSUPD packet received from 192.168.0.201 via eth0 Jul 1 18:39:26 acer-aspire-5536 bird: cloudtest: length 4192 Jul 1 18:39:26 acer-aspire-5536 bird: cloudtest: router 192.168.0.201 Jul 1 18:39:26 acer-aspire-5536 bird: cloudtest: LSA Type: 0001, Id: 192.168.0.201, Rt: 192.168.0.201, Age: 1, Seq: 8000000a, Sum: b77a Jul 1 18:39:26 acer-aspire-5536 bird: Received bad lsa checksum from 192.168.0.201: 7ab7 4f5b The two processes then get stuck in a loop constantly requesting, updating and failing. Any ideas where the issue might lie? Rgs Neil Wilson