Date: Wed, 26 Jun 1996 09:49:04 -0700 From: bmah@cs.berkeley.edu (Bruce A. Mah) To: "Ron G. Minnich" <rminnich@sarnoff.com> Cc: hackers@freebsd.org Subject: Re: Frame relay and ATM support: virtual interface per vpi? Message-ID: <199606261649.JAA18110@premise.CS.Berkeley.EDU> In-Reply-To: Your message of "Wed, 26 Jun 1996 12:06:12 EDT." <Pine.SUN.3.91.960626120017.2433A-100000@terra>
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"Ron G. Minnich" writes: > > Doesn't it seem that if you do the VIF per VCI model, you're > > restricting yourself to having only a single VC to any given > > destination? In other words, it seems that this model would preclude > > my being able to have multiple VCs to another host. > not at all. you can have lots of vc's per destination. The reason we've > set up to support so many VCs is to support many VCs per host. Again, you > have to move your thinking around a bit from the current networking > model. Once you start doing that, however, the particular way to plug ATM > into the BSD networking architecture is not as obvious as it first seems. > We're even looking at having user-mode striped ATM connections between > applications, and boy does this make for some changes ... Hmmm. So I guess, w.r.t the BSD networking implementation, one would (for example) associate a TCP connection with a route through the appropriate VIF for that connection's VC? Something like that? The way I've been looking at things is more from a router perspective, in which you have to route packets for flows that don't necessarily originate locally (thus the method I had in mind above doesn't work). In this case, you need a packet classifier in the router (my implementation was in the ATM device driver) to help with the multiplexing. It really violates layering because link-layer code is looking at network and transport layer headers. But there's no other way to get all the information needed. Bruce.
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