Date: Sun, 15 Sep 2002 18:22:29 +0200 (CEST) From: Oliver Fromme <olli@secnetix.de> To: freebsd-stable@FreeBSD.ORG, Andrew Stesin <stesin@breaker.tormoz.net> Subject: Re: Bug? VLANs, fxp, Catalyst and link0 story Message-ID: <200209151622.g8FGMTLH075351@lurza.secnetix.de> In-Reply-To: <20020915182028.O1070-100000@chour.hostmaster.net.ua>
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Andrew Stesin <stesin@breaker.tormoz.net> wrote: > On Sun, 15 Sep 2002, Oliver Fromme wrote: > > You don't need "mtu 1500" either, because fxp supports jumboframes > > natively (and the vlan driver knows about it). > > This one is problematic. Does it *really* know? I feel I need mtu 1500 > flag just to be safe. :) "Feeling" is not enough to get a system to work reliably. ;-) This is from the vlan(4) manpage: | fxp(4) supports long frames for the vlan natively. | [...] | Except for fxp(4), sis(4) and tx(4), none of the above | drivers inform the vlan driver about their support for | long frames. That implies that the fxp driver _does_ inform the vlan driver about its support for long frames. So the manual setting of the MTU is not needed. > This flag does no harm anyway, doesn't it? :) No, it doesn't. On the other hand, I tend not to try to "fix" things that are not broken, and to specify only things that are really necessary. The simpler, the better (and the less risk to have typos sneaking in). Another thing to take into account is the fact that such settings are also some kind of documentation for themselves. When you (or someone else) look at your config half a year later, the specification of "mtu 1500" might look like it is really necessary (why would it be there otherwise?). So it might be misleading to leave superfluous stuff in there. But of course, if it makes you "feel" better, by all means, don't change it. ;-) > As for me, I'd note that maybe it would be nice to somewhat update > manpages - so dumb people like me will recognize the abovementioned > difference more easily. I think reading the _whole_ manpage should be sufficient in most cases. Everything you need to know is in there. It is certainly not a tutorial on VLANs (neither is it intended to be one). > The only visible (for now) difference is appearance of lines: > > fxp0: Microcode loaded, int_delay: 1000 usec bundle_max: 6 The following was added to the fxp(4) manpage recently: | link0 Some chip revisions have loadable microcode which | can be used to reduce the interrupt load on the | host cpu. Not all boards have support microcode | support. Setting the link0 flag with ifconfig(8) | will download the microcode to the chip if it is | available. That description sounds like it is completely optional, i.e. it _should_ work fine without the link0 flag. > Thanks, I got the idea. Anyway, I prefer static vlanXX allocation and > numbering - it's much more convenient with regard to setting IP filtering > up. (You may be sure you apply say NAT to vlan12 and this *really* is an > external interface ;) Yes, dynamic and static numbering have both advantages and disadvantages. For a certain setup, I need dynamic numbering because the number and addresses of vlan interfaces change dynamically, depending on the services assigned to a server within a farm cluster. > > I'm also doing the vlan/vlandev assignment and the actual configuration > > in two separate steps, because it seemed that it didn't always work > > reliably when I tried to do both things at once. > > Some microtimeout needed for actual vlan clone creation, maybe? No, I got an error message from ifconfig. :-) But that was on an older version of 4.6-stable, maybe it is different now (but I still do it in separate steps). Regards Oliver -- Oliver Fromme, secnetix GmbH & Co KG, Oettingenstr. 2, 80538 München Any opinions expressed in this message may be personal to the author and may not necessarily reflect the opinions of secnetix in any way. "All that we see or seem is just a dream within a dream" (E. A. Poe) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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