Date: Thu, 10 Apr 2008 21:48:07 -0400 From: Jon Radel <jon@radel.com> To: David Allen <the.real.david.allen@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: IP Aliasing Message-ID: <47FEC357.4000709@radel.com> In-Reply-To: <2daa8b4e0804101431q1d5a2ff7me1cfa8a1ff70b801@mail.gmail.com> References: <2daa8b4e0804101431q1d5a2ff7me1cfa8a1ff70b801@mail.gmail.com>
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This is a cryptographically signed message in MIME format. --------------ms060804080703010805000608 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit David Allen wrote: > This may be a dumb question, but I'm puzzled by the following (taken > from the Virtual Hosts section in the Handbook): > > For example, consider the case where the fxp0 interface is connected > to two networks, the 10.1.1.0 network with a netmask of > 255.255.255.0 and the 202.0.75.16 network with a netmask of > 255.255.255.240. > > IP aliasing I get, but two different networks on the same interface? > What would this be plugged into to make that work? Ethernet most likely these days. In a perfect world, where ipv4 addresses flowed like water, everyone managed to forecast everything perfectly, and nobody ever had to renumber a network, I doubt there'd be much call for it. And I'd never want to try make a case for it being terribly elegant. I'm personally acquainted with a couple of cases where it comes up: 1) Multi-homed networks with ipv4 addresses assignments too small to do something "real" like using BGP to advertise >= /24 to multiple ISPs. So to talk via one ISP you use one address and via the other ISP you use the other. 2) You need to migrate to new addresses but can't afford to shut everything down long enough to change everything all at once. There are others. --Jon Radel --------------ms060804080703010805000608 Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIJMTCC AvMwggJcoAMCAQICEG2TkfF/93Sx9LCftry1D3YwDQYJKoZIhvcNAQEFBQAwYjELMAkGA1UE BhMCWkExJTAjBgNVBAoTHFRoYXd0ZSBDb25zdWx0aW5nIChQdHkpIEx0ZC4xLDAqBgNVBAMT I1RoYXd0ZSBQZXJzb25hbCBGcmVlbWFpbCBJc3N1aW5nIENBMB4XDTA4MDMyNDE2NTkyMVoX DTA5MDMyNDE2NTkyMVowXjEOMAwGA1UEBBMFUmFkZWwxEzARBgNVBCoTCkpvbiBUaG9tYXMx GTAXBgNVBAMTEEpvbiBUaG9tYXMgUmFkZWwxHDAaBgkqhkiG9w0BCQEWDWpvbkByYWRlbC5j b20wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDPdCxQufreHHDAI9YN2axx87Rf 0TK1PYFMlJHi4y1ebdAMPqR6M44bz+3m8YnKn1bmIf7dWyisWyAIQYCOhW/2r66o4MdF9qJ9 z5uhMy+28zaJP/Glg64C3WPM0VfveCgvu+ApEyf2JDbjc/hUomw8KpppgOcn1wX6PZGbhHVv eAvDTWJ0ugqo08Ny6GR0bsGvePmxdWSQq+0aGTHqA1I2EozJBZ8W5xlUtKe22j56i1Uw1ujk Rlosdu2PTs8QOY1OUHuLPnEV9EWtYF7g6bXDUDsJxypXZy9qTipPplYXjdWgkLVRvezri+BN kgin8UKhKLQ99vS25zrMFKu80g31AgMBAAGjKjAoMBgGA1UdEQQRMA+BDWpvbkByYWRlbC5j b20wDAYDVR0TAQH/BAIwADANBgkqhkiG9w0BAQUFAAOBgQAR4u9o4CFvztyo0sZb3tCQIWYb 5U4jW9da3goVwWIkMz+qeCb2kiTQfsSmOdF9YJ8VTRdYW0l0fQbqL5JikVhaYeX85cpqZ3iA /PPJpfPtJw8g5jJOAROVAvxydMZXQYxyIBMV4HNG3qir44YnyfmJXkBtRFYWdxBc7bQpoZSZ jzCCAvMwggJcoAMCAQICEG2TkfF/93Sx9LCftry1D3YwDQYJKoZIhvcNAQEFBQAwYjELMAkG A1UEBhMCWkExJTAjBgNVBAoTHFRoYXd0ZSBDb25zdWx0aW5nIChQdHkpIEx0ZC4xLDAqBgNV BAMTI1RoYXd0ZSBQZXJzb25hbCBGcmVlbWFpbCBJc3N1aW5nIENBMB4XDTA4MDMyNDE2NTky MVoXDTA5MDMyNDE2NTkyMVowXjEOMAwGA1UEBBMFUmFkZWwxEzARBgNVBCoTCkpvbiBUaG9t YXMxGTAXBgNVBAMTEEpvbiBUaG9tYXMgUmFkZWwxHDAaBgkqhkiG9w0BCQEWDWpvbkByYWRl bC5jb20wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDPdCxQufreHHDAI9YN2axx 87Rf0TK1PYFMlJHi4y1ebdAMPqR6M44bz+3m8YnKn1bmIf7dWyisWyAIQYCOhW/2r66o4MdF 9qJ9z5uhMy+28zaJP/Glg64C3WPM0VfveCgvu+ApEyf2JDbjc/hUomw8KpppgOcn1wX6PZGb hHVveAvDTWJ0ugqo08Ny6GR0bsGvePmxdWSQq+0aGTHqA1I2EozJBZ8W5xlUtKe22j56i1Uw 1ujkRlosdu2PTs8QOY1OUHuLPnEV9EWtYF7g6bXDUDsJxypXZy9qTipPplYXjdWgkLVRvezr i+BNkgin8UKhKLQ99vS25zrMFKu80g31AgMBAAGjKjAoMBgGA1UdEQQRMA+BDWpvbkByYWRl bC5jb20wDAYDVR0TAQH/BAIwADANBgkqhkiG9w0BAQUFAAOBgQAR4u9o4CFvztyo0sZb3tCQ IWYb5U4jW9da3goVwWIkMz+qeCb2kiTQfsSmOdF9YJ8VTRdYW0l0fQbqL5JikVhaYeX85cpq Z3iA/PPJpfPtJw8g5jJOAROVAvxydMZXQYxyIBMV4HNG3qir44YnyfmJXkBtRFYWdxBc7bQp oZSZjzCCAz8wggKooAMCAQICAQ0wDQYJKoZIhvcNAQEFBQAwgdExCzAJBgNVBAYTAlpBMRUw EwYDVQQIEwxXZXN0ZXJuIENhcGUxEjAQBgNVBAcTCUNhcGUgVG93bjEaMBgGA1UEChMRVGhh d3RlIENvbnN1bHRpbmcxKDAmBgNVBAsTH0NlcnRpZmljYXRpb24gU2VydmljZXMgRGl2aXNp b24xJDAiBgNVBAMTG1RoYXd0ZSBQZXJzb25hbCBGcmVlbWFpbCBDQTErMCkGCSqGSIb3DQEJ ARYccGVyc29uYWwtZnJlZW1haWxAdGhhd3RlLmNvbTAeFw0wMzA3MTcwMDAwMDBaFw0xMzA3 MTYyMzU5NTlaMGIxCzAJBgNVBAYTAlpBMSUwIwYDVQQKExxUaGF3dGUgQ29uc3VsdGluZyAo UHR5KSBMdGQuMSwwKgYDVQQDEyNUaGF3dGUgUGVyc29uYWwgRnJlZW1haWwgSXNzdWluZyBD QTCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEAxKY8VXNV+065yplaHmjAdQRwnd/p/6Me 7L3N9VvyGna9fww6YfK/Uc4B1OVQCjDXAmNaLIkVcI7dyfArhVqqP3FWy688Cwfn8R+RNiQq E88r1fOCdz0Dviv+uxg+B79AgAJk16emu59l0cUqVIUPSAR/p7bRPGEEQB5kGXJgt/sCAwEA AaOBlDCBkTASBgNVHRMBAf8ECDAGAQH/AgEAMEMGA1UdHwQ8MDowOKA2oDSGMmh0dHA6Ly9j cmwudGhhd3RlLmNvbS9UaGF3dGVQZXJzb25hbEZyZWVtYWlsQ0EuY3JsMAsGA1UdDwQEAwIB BjApBgNVHREEIjAgpB4wHDEaMBgGA1UEAxMRUHJpdmF0ZUxhYmVsMi0xMzgwDQYJKoZIhvcN AQEFBQADgYEASIzRUIPqCy7MDaNmrGcPf6+svsIXoUOWlJ1/TCG4+DYfqi2fNi/A9BxQIJNw PP2t4WFiw9k6GX6EsZkbAMUaC4J0niVQlGLH2ydxVyWN3amcOY6MIE9lX5Xa9/eH1sYITq72 6jTlEBpbNU1341YheILcIRk13iSx0x1G/11fZU8xggNkMIIDYAIBATB2MGIxCzAJBgNVBAYT AlpBMSUwIwYDVQQKExxUaGF3dGUgQ29uc3VsdGluZyAoUHR5KSBMdGQuMSwwKgYDVQQDEyNU aGF3dGUgUGVyc29uYWwgRnJlZW1haWwgSXNzdWluZyBDQQIQbZOR8X/3dLH0sJ+2vLUPdjAJ BgUrDgMCGgUAoIIBwzAYBgkqhkiG9w0BCQMxCwYJKoZIhvcNAQcBMBwGCSqGSIb3DQEJBTEP Fw0wODA0MTEwMTQ4MDdaMCMGCSqGSIb3DQEJBDEWBBT5JDMAfKPEUSBVttYTEUn+O3cOozBS BgkqhkiG9w0BCQ8xRTBDMAoGCCqGSIb3DQMHMA4GCCqGSIb3DQMCAgIAgDANBggqhkiG9w0D AgIBQDAHBgUrDgMCBzANBggqhkiG9w0DAgIBKDCBhQYJKwYBBAGCNxAEMXgwdjBiMQswCQYD VQQGEwJaQTElMCMGA1UEChMcVGhhd3RlIENvbnN1bHRpbmcgKFB0eSkgTHRkLjEsMCoGA1UE AxMjVGhhd3RlIFBlcnNvbmFsIEZyZWVtYWlsIElzc3VpbmcgQ0ECEG2TkfF/93Sx9LCftry1 D3YwgYcGCyqGSIb3DQEJEAILMXigdjBiMQswCQYDVQQGEwJaQTElMCMGA1UEChMcVGhhd3Rl IENvbnN1bHRpbmcgKFB0eSkgTHRkLjEsMCoGA1UEAxMjVGhhd3RlIFBlcnNvbmFsIEZyZWVt YWlsIElzc3VpbmcgQ0ECEG2TkfF/93Sx9LCftry1D3YwDQYJKoZIhvcNAQEBBQAEggEAK2BT P4cKCCZvTZwPW6XRD+97xZ/yvYjFd8+GhceKbjlQIi9qgZoKD4DgQ1KNC7esCNTjm4xHdVqK SCRdsJRh5wOCAZDNsr5wPYkVXFhDz7Bwgqwd4BkaMwmK4YSZ6aSvRmmV9NGOS+ixojW/zGEM kqZ+8hqsEoOYeF2tK6qLjPCuc6F2WuyX57VK5gFeQbLW2Ta2F2j2xk+0IVM0nwqCy2ym9C14 3C+fz3r/RuVBLPRb3rH1BtU22KkJrHoI35tTinZ32o02xGsnRzMobJ+o/lHi01M9xVKNh0FJ qlWFPH/sQ8nLTM8MnzJJ8GPyZVszRXixRTzB6q3xgYzNbeIx/AAAAAAAAA== --------------ms060804080703010805000608--
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