Date: Fri, 02 Nov 2001 17:35:40 -0600 From: Randall Stewart <randall@stewart.chicago.il.us> To: Lars Eggert <larse@ISI.EDU> Cc: Barney Wolff <barney@databus.com>, freebsd-net@FreeBSD.ORG, xbone@ISI.EDU Subject: Re: SCTP and multiple default routes Message-ID: <3BE32DCC.22A84E28@stewart.chicago.il.us> References: <3BE30097.C02C828D@stewart.chicago.il.us> <3BE303EA.1040506@isi.edu> <20011102162701.A38190@tp.databus.com> <3BE317B8.3040108@isi.edu>
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Lars: I will add my 2cents to Barney's reply to this as well.. Lars Eggert wrote: > > Barney Wolff wrote: > > > Whether or not multiple default routes is a good idea, SCTP-style > > multihoming makes a tremendous difference for small organizations > > that cannot justify getting a block of addresses big enough to be > > routed by multiple providers. With SCTP I can have a host with > > an address from a cable-modem provider and another from a dsl provider > > and my peers can treat both as addresses of my one machine, so > > connections will not break if one link goes down. The big payoff > > for the Internet as a whole is I don't need a separate route to me > > in the global routing tables. > > The big drawback is that it requires a completely new protocol... Which is currently beginning to be deployed. Sun, Aix, Linux and other O/S's which I refuse to name are putting forward SCTP.. > > It also requires both peers to speak SCTP, and applications in question > > must be changed to run over SCTP as well. In other words, it doesn't The change is a very very simple one instead of fd = socket(AF_INET,SOCK_STREAM, IPPROTO_TCP); you od fd = socket(AF_INET,SOCK_STREAM, IPPROTO_SCTP); Not a big deal for the TCP compatibility model. You don't get to use streams if you do the above only .. but hey you get the multiple interface... Not a big deal... > > work yet, and it will be some time before it does, and then only for modified apps. Not as long as you think.. IMHO > > > I would gladly pay for two such links if there were an automatic way > > to switch away from a broken link. Without asking cable or dsl > > providers to talk bgp to me (which they will surely refuse to do) > > this is not easy. > > You can get the exact same behavior toady, with existing Internet > protocols: Create an IP tunnel to the peer over one interface pair, > switch the tunnel over to the other pair in case of failure. This is > transparent to the application (it uses the virtual addresses of the > tunnel), uses existing protocols (TCP/UDP over IP in IP), works now. > > Only new piece is reconfiguring your tunnel, which is trivial (one or > two system commands, and can be easily automated.) > And to add to Barney's issue... you also must wait for a routing convergence to know to move the tunnel. In the case of SCTP the first timeout moves you to the alternate. R > -- > Lars Eggert <larse@isi.edu> Information Sciences Institute > http://www.isi.edu/larse/ University of Southern California > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message -- Randall R. Stewart randall@stewart.chicago.il.us 815-342-5222 (cell phone) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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