nanog mailing list archives
Re: two interfaces one subnet
From: Per Heldal <heldal () eml cc>
Date: Tue, 12 May 2009 10:30:18 +0200
David Devereaux-Weber wrote:
I work with iHDTV <http://ihdtv.org>, a project that sends uncompressed high definition television (1.5 Gbps) as UDP over two 1 Gbps interfaces. If both interfaces are on the same subnet, the OS sees the same router (gateway) address on both interfaces, and the results are sub-optimal ... around 50% packet loss.
Check closes and you may discover that the loss isn't on the path host->router, but on the reverse. Some hosts/interfaces are optimised for L2 link-aggregation, in which case they by default present the same MAC (host MAC-address) on multiple interfaces. Those will fail when configured with separate IP-addresses on the same VLAN/subnet. L2 switches that support link-aggregation will try to spread the traffic across the available ports on one VLAN on which it sees the same MAC. 2 ports gives 50% loss, 3 ports 67% and so on. Most host interfaces will not pick up IP-packets which destination doesn't match it's assigned address. //per
Current thread:
- Re: two interfaces one subnet, (continued)
- Re: two interfaces one subnet David Coulson (May 11)
- Re: two interfaces one subnet Chris Adams (May 11)
- Re: two interfaces one subnet Patrick W. Gilmore (May 11)
- Re: two interfaces one subnet Ben Scott (May 11)
- Re: two interfaces one subnet Patrick W. Gilmore (May 11)
- Re: two interfaces one subnet Martin Hannigan (May 12)
- Two interfaces one subnet (summary) Ivan Pepelnjak (May 14)
- Re: two interfaces one subnet Curtis Maurand (May 12)
- Re: two interfaces one subnet Chris Meidinger (May 12)
- Re: two interfaces one subnet David Devereaux-Weber (May 11)
- Re: two interfaces one subnet Chris Meidinger (May 11)
- Re: two interfaces one subnet Ben Scott (May 11)
- Re: two interfaces one subnet Chris Meidinger (May 11)
- Re: two interfaces one subnet Patrick W. Gilmore (May 11)
- Re: two interfaces one subnet Scott Howard (May 12)
- Re: two interfaces one subnet Patrick McManus (May 13)