Date: Mon, 12 Mar 2018 20:42:20 +0000 From: Grzegorz Junka <list1@gjunka.com> To: freebsd-net@freebsd.org Subject: Re: Incorrect route interface Message-ID: <f619ee3a-8af0-9aaa-b377-5dad83d3d70a@gjunka.com> In-Reply-To: <201803122013.w2CKDwSH080298@pdx.rh.CN85.dnsmgr.net> References: <201803122013.w2CKDwSH080298@pdx.rh.CN85.dnsmgr.net>
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On 12/03/2018 20:13, Rodney W. Grimes wrote: >> On 12/03/2018 18:04, Rodney W. Grimes wrote: >>>> On 11/03/2018 20:57, Marek Zarychta wrote: >>>>> On Sun, Mar 11, 2018 at 05:46:52PM +0000, Grzegorz Junka wrote: >>>>>> On 11/03/2018 06:04, Eugene Grosbein wrote: >>>>>>> 11.03.2018 7:01, Grzegorz Junka wrote: >>>>>>> >>>>>>>>> Just do not assign addresses from same network 10.20.0.0/16 to different network interfaces >>>>>>>>> and you will be fine. Assign them all to right interface: >>>>>>>>> >>>>>>>>> ifconfig_em0="inet 10.20.2.14 netmask 255.255.0.0" >>>>>>>>> ifconfig_em0_alias0="inet 10.20.2.15/32" >>>>>>>>> ifconfig_igb0_alias0="inet 10.20.2.16/32" >>>>>>> Interfaces meant to be all equal, last line should be: >>>>>>> >>>>>>> ifconfig_em0_alias1="inet 10.20.2.16/32" >>>>>>> >>>>>> OK, I see. So this is in case I want many IPs assigned to the same >>>>>> interface. What if I want one IP assigned to multiple interfaces (i.e. >>>>>> so that the additional igb0-3 effectively work as a 4-port switch)? >>>>>> >>>>> Please consider bonding all NICs as one bridge(4) interface. Then >>>>> multiple IPs could be assigned to such interface. >>>>> >>>> Many thanks Eugene and Marek for your suggestions. I will now need to >>>> decide if I want to fragment the network into subnets or bridge the >>>> interfaces. >>>> GregJ >>> I believe some of the problem you are experincing is addressed >>> in this differential: >>> https://reviews.freebsd.org/D14547 >>> >>> Your original configuration was(is) valid, just not common, >>> and I have not seen this done in more than a decade, but it >>> seems as if rstone@ also has someone doing this "multiple IP's >>> into same subnet on seperate interfaces". >>> >> Thanks for the link. That's interesting. According to this post that >> configuration shouldn't be valid: >> >> https://forums.freenas.org/index.php?threads/multiple-network-interfaces-on-a-single-subnet.20204/ > I'll disagree with the claims it is not valid. I shall however support > the claims that it is non-standard, and non-trivial to understand just > what it is that occurs in *BSD when you do this. I have seen this > "claimed to be invalid" coniguration in use several times over the > past 30 years. > > Where people seem to get this "invalid" from is expecting the traffic > to be bound to an IP to go both in and OUT that interface is what is > not invalid, but a wrong assertion. Traffic WELL come in that interface, > as that is how ethernet macs, arp's an IP work. However it WELL go > out the interface that is selected by the routing table. If you > can seperate in your mind that this is how IN and OUT interfaces > are decided the rest becomes simply mechanical. > > Simple typical *BSD installs end up with all traffic going out just > one of the interfaces, but I can write route rules that change that > artifact. And this is where the usage of this odd configuration > sometimes comes about. > > With modern implimentations of *BSD that now have multiple fib's, > and things like netgraph, and ipfw one can get very creative in > what actually happens. And none of it is invalid, just often > miss understood. I can actually casue that traffic bound to > a specific IP to go in and out that specific interface. Ipfw's > ability to cause a packet to use an alternate fib is how. > > ipfw add allow ip from ${ip_of_nicX} to any setfib ${fib_for_nicX} I don't know much about the network stack in FreeBSD but I would assume that I should be able to configure specific traffic (based on the destination subnet, so nothing fancy) to go out of a specific interface. Not only I wasn't able to do that, I was told my approach was wrong. So I think I agree with you. GregJ
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