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diff --git a/zarb-ml/mageia-discuss/20101025/002619.html b/zarb-ml/mageia-discuss/20101025/002619.html new file mode 100644 index 000000000..c546876af --- /dev/null +++ b/zarb-ml/mageia-discuss/20101025/002619.html @@ -0,0 +1,154 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<HTML> + <HEAD> + <TITLE> [Mageia-discuss] network balancing by default + </TITLE> + <LINK REL="Index" HREF="index.html" > + <LINK REL="made" HREF="mailto:mageia-discuss%40mageia.org?Subject=Re%3A%20%5BMageia-discuss%5D%20network%20balancing%20by%20default&In-Reply-To=%3C201010250000.46478.maarten.vanraes%40gmail.com%3E"> + <META NAME="robots" CONTENT="index,nofollow"> + <META http-equiv="Content-Type" content="text/html; charset=us-ascii"> + + <LINK REL="Next" HREF="002630.html"> + </HEAD> + <BODY BGCOLOR="#ffffff"> + <H1>[Mageia-discuss] network balancing by default</H1> + <B>Maarten Vanraes</B> + <A HREF="mailto:mageia-discuss%40mageia.org?Subject=Re%3A%20%5BMageia-discuss%5D%20network%20balancing%20by%20default&In-Reply-To=%3C201010250000.46478.maarten.vanraes%40gmail.com%3E" + TITLE="[Mageia-discuss] network balancing by default">maarten.vanraes at gmail.com + </A><BR> + <I>Mon Oct 25 00:00:46 CEST 2010</I> + <P><UL> + + <LI>Next message: <A HREF="002630.html">[Mageia-discuss] network balancing by default +</A></li> + <LI> <B>Messages sorted by:</B> + <a href="date.html#2619">[ date ]</a> + <a href="thread.html#2619">[ thread ]</a> + <a href="subject.html#2619">[ subject ]</a> + <a href="author.html#2619">[ author ]</a> + </LI> + </UL> + <HR> +<!--beginarticle--> +<PRE>Op zondag 24 oktober 2010 22:39:29 schreef Luca Berra: +><i> On Sun, Oct 24, 2010 at 11:43:28AM +0200, Maarten Vanraes wrote: +</I>><i> >I would propose the following: +</I> +First off, the timing of this proposal is probably too soon, i just wanted to +get it out there, in case i forgot later. + +><i> >A.) by default, add for every interface, a little advanced routing which +</I>><i> >makes packets return from the same way they came. +</I>><i> >This usually is only useful with incoming packets, but can still be useful +</I>><i> >if laptops have for example 2 gateways because the wifi is still on and +</I>><i> >the cable is too. That would mean that from both interfaces it'd be +</I>><i> >possible to use ssh or vnc or whatever. +</I>><i> +</I>><i> this is possible with incoming packets, but, how do you select the +</I>><i> source of a new one? +</I> +this step is only for the replies of incoming packets and never has any effect +on new outgoing packets; this step doesn't change anything for new outgoing +packets. and this can even be used on interfaces that aren't used as default +gateway. + +><i> >B.) if we have multiple gateways (like in that case), have them use both +</I>><i> >balancedly. ie: start a small daemon which checks which of the gateways is +</I>><i> >up or down; and change the default gateway accordingly, or even both in +</I>><i> >some kind of balanced mode. (with advanced routing.) +</I>><i> +</I>><i> This could go wrong in so many ways i would not even try: +</I>><i> i.e. how do you determine if a gateway is up? dont tell me icmp, many +</I>><i> firewall refuse it, and vrrp standard says the backup gateway should not +</I>><i> answer icmp echo. +</I> +there are alot of different aspects to what we consider as a "working" isp +connection. + +this isn't about having perfection; it's about improving what we have now. + + +Consider a laptop user; the user has a network connection and also has his wifi +up. + +You will notice that there are in fact 2 default gateways (possibly with +different metric, but we cannot be sure). + +what i propose is to use both together balanced by default. + +this in itself is an improvement; the parts about detection of "up" or "down" +(except the interface itself) are extras, after all, the same issues can even +happen with one gateway. + + +Balancing is even more usefull if there are ways of automatically detecting +which interfaces are unwanted for routing. + +(TBH you assumed icmp is what would be used; we all know icmp can be blocked +and is never relied on..) + +possible problems: +A) interface down +B) DHCP expired +C) gateway down +D) further routing down +E) DNS down + +A is trivial, so we'll just skip that one. + +B seems easy to do too; however, reusing the last DHCP lease could still be +usefull, it might well be only a dhcp failure; we should try with the current +lease if possible. + +E is a bit of an extra (it's not really routing, but a DNS that's down (does +not answer) could well be eliminated (not sure if this should be done +separately or not)) OTOH, failure of the recursive DNS of the ISP seems to be +somewhat frequent in my experience. + +C+D are tricky: D is even a bit of a grey area; my ISP frequently has a few +routes broken. icmp can definately not be relied on in all cases. and even if +you ping your gateway, you don't know if it goes any further. + +This could be circumvented by putting known servers that actually echo icmp in +a list and ping those. but for that matter, it doesn't have to be icmp; we +could easily have a list of public services that can be connected to. but is +this really what we want? + +We could even just monitor how much packets are unreplied to per interface and +choose that. + +Or we could try to have each retry of unreplied packet go through the next +default route. + +Or we could just not handle that (like it is now). + +remember that right now only A(+B) is used; and having balanced default routes +would probably mean that there is 50% packet loss, instead of 100% in most +cases. + + +also remember that if the metrics are the same for some reason, you will get +much stranger things when both are working perfectly. +</PRE> + + + +<!--endarticle--> + <HR> + <P><UL> + <!--threads--> + + <LI>Next message: <A HREF="002630.html">[Mageia-discuss] network balancing by default +</A></li> + <LI> <B>Messages sorted by:</B> + <a href="date.html#2619">[ date ]</a> + <a href="thread.html#2619">[ thread ]</a> + <a href="subject.html#2619">[ subject ]</a> + <a href="author.html#2619">[ author ]</a> + </LI> + </UL> + +<hr> +<a href="https://www.mageia.org/mailman/listinfo/mageia-discuss">More information about the Mageia-discuss +mailing list</a><br> +</body></html> |