Date: Thu, 19 Jan 2017 22:04:49 -0500 From: Jon Radel <jon@radel.com> To: dweimer@dweimer.net, FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: Tuning Route Cache Message-ID: <28d24a44-9e1c-7c12-d7e8-6f243a350510@radel.com> In-Reply-To: <ae39bbc53f3e2f2b1afa3afa93b43fa4@dweimer.net> References: <ae39bbc53f3e2f2b1afa3afa93b43fa4@dweimer.net>
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This is a cryptographically signed message in MIME format. --------------ms040306020205080504010206 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 1/18/17 11:55 AM, Dean E. Weimer wrote: > I have been searching, but so far unsuccessfully found any hints. I hav= e > a situation that occurred with a FreeBSD server that is running 11.0 > that is in a DMZ with its default router directing traffic to other > routers in the same subnet. we had one of those routers get swapped out= > last night. however the FreeBSD server still had the old router in its > cache, and couldn't communicate with the remote sites. >=20 You don't seem to have gotten any responses, at least on the list, so I'll take a stab at this. I'm handicapped by a complete lack of knowledge as to how you're getting those routes into the routing table in the first place. You don't really appear to say. It appears that you're not using static routes, as you expect things to happen automatically. Are you using a routing protocol (RIP, etc.). Are you counting on Router Discovery working? Are you depending on ICMP Redirects? Have you confirmed that the appropriate routing daemon is actually running? Have you confirmed that the routers are actually advertising routes correctly? As far as I recall, the *longest* time that you should have stale routes hanging around is 30 minutes if you use Router Discovery with the default settings. Everything else should, unless you really break it, converge much faster than that. See man 8 routed for more on some of that, including reducing the 30 minutes. > I need to find a way to shorten this cache, I understand why its there > to prevent repeated lookups, this doesn't happen all the time but I am > thinking if I could change this cache length to a couple of hours this > would have saved me a lot of trouble. As the routes would have cleared > out over night and when users got back on the network in the morning > everything would have been working. The routing table really doesn't work like that. If you're using static routing, nothing changes until you tell it to. If you're using a routing protocol then a daemon is responsible for adding and removing routes based on what it learns, and routes that are no longer advertised by a router go away pretty quickly. Even if you want routes learned from an ICMP Redirect to be cleaned up automatically, you'll need routed to do it for you. See the above referenced man page. --=20 --Jon Radel jon@radel.com --------------ms040306020205080504010206 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCC Cq8wggSvMIIDl6ADAgECAhEA4CPLFRKDU4mtYW56VGdrITANBgkqhkiG9w0BAQsFADBvMQsw CQYDVQQGEwJTRTEUMBIGA1UEChMLQWRkVHJ1c3QgQUIxJjAkBgNVBAsTHUFkZFRydXN0IEV4 dGVybmFsIFRUUCBOZXR3b3JrMSIwIAYDVQQDExlBZGRUcnVzdCBFeHRlcm5hbCBDQSBSb290 MB4XDTE0MTIyMjAwMDAwMFoXDTIwMDUzMDEwNDgzOFowgZsxCzAJBgNVBAYTAkdCMRswGQYD VQQIExJHcmVhdGVyIE1hbmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNP TU9ETyBDQSBMaW1pdGVkMUEwPwYDVQQDEzhDT01PRE8gU0hBLTI1NiBDbGllbnQgQXV0aGVu dGljYXRpb24gYW5kIFNlY3VyZSBFbWFpbCBDQTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCC AQoCggEBAImxDdp6UxlOcFIdvFamBia3uEngludRq/HwWhNJFaO0jBtgvHpRQqd5jKQi3xdh 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