Date: Sun, 27 Oct 2002 14:54:38 -0800 From: Lars Eggert <larse@ISI.EDU> To: Lars Eggert <larse@ISI.EDU> Cc: Luigi Rizzo <rizzo@icir.org>, net@FreeBSD.ORG Subject: Re: Bridging when one interface has no carrier Message-ID: <3DBC6EAE.8090301@isi.edu> In-Reply-To: <3D61224B.2020902@isi.edu> References: <3D61224B.2020902@isi.edu> <20020819102951.A38869@iguana.icir.org> <3DB885BD.8010203@isi.edu>
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This is a cryptographically signed message in MIME format. --------------ms060601020507050408040900 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Lars Eggert wrote: > This causes the problem decribed in PR kern/41632 > (http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/41632), where dhcpd > "listens" on interface A which is bridged to interface B. When A has no > carrier, DHCP requests arriving on B are ignored. When A has a carrier, > dhcp will get a copy of the packet when it is bridge-forwarded out A, so > the problem doesn't occur then. > > Attached is a rough patch to if_ethersubr.c that fixes the problem. That patch (new version attached) turned out to only fix part of the problem. When bridge-forwarding packets to an interface without a carrier, they start to fill up its outbout queue. Once the queue is full, new packets that are routed to that interfaces won't be bridged anymore. This happens in the example above with dhcpd. DHCP requests come in on B and get bridge-forwarded to A (filling up A's outbound queue). dhcpd generates responses, which are sent via A and then bridge-forwarded to B. Once A's outbound queue is full, those responses fall on the floor. Attached is an ugly hack that fixes this in my setup. The next issue is bridge interactions with IPv6 stateless autoconf. IPv6 doesn't like link-local addresses appearing on (apparently) different interfaces... Lars -- Lars Eggert <larse@isi.edu> USC Information Sciences Institute --------------ms060601020507050408040900 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 MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIJtjCC AzgwggKhoAMCAQICEGZFcrfMdPXPY3ZFhNAukQEwDQYJKoZIhvcNAQEEBQAwgdExCzAJBgNV BAYTAlpBMRUwEwYDVQQIEwxXZXN0ZXJuIENhcGUxEjAQBgNVBAcTCUNhcGUgVG93bjEaMBgG A1UEChMRVGhhd3RlIENvbnN1bHRpbmcxKDAmBgNVBAsTH0NlcnRpZmljYXRpb24gU2Vydmlj ZXMgRGl2aXNpb24xJDAiBgNVBAMTG1RoYXd0ZSBQZXJzb25hbCBGcmVlbWFpbCBDQTErMCkG CSqGSIb3DQEJARYccGVyc29uYWwtZnJlZW1haWxAdGhhd3RlLmNvbTAeFw0wMDA4MzAwMDAw MDBaFw0wNDA4MjcyMzU5NTlaMIGSMQswCQYDVQQGEwJaQTEVMBMGA1UECBMMV2VzdGVybiBD YXBlMRIwEAYDVQQHEwlDYXBlIFRvd24xDzANBgNVBAoTBlRoYXd0ZTEdMBsGA1UECxMUQ2Vy dGlmaWNhdGUgU2VydmljZXMxKDAmBgNVBAMTH1BlcnNvbmFsIEZyZWVtYWlsIFJTQSAyMDAw 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