VLAN joys (by alaric)

Well, having eliminated the VLANs from my network problems, I've been busily taking advantage of them again, and working around the fact that daapd and samba don't seem to talk very well to iTunes and MacOS X's smbfs.

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Not VLAN woes (by alaric)

Ok, having eliminated all VLANs from the equation, I still see iTunes connecting to daapd giving up a few tens of seconds into each song. So it looks like the latest release of iTunes doesn't like daapd for some reason.

However, SMB performance is still dreadful, with common "server disconnected" error messages.

I've confirmed it's not the LAN at fault (unless subtly so) by doing HTTP, SCP, and telnet-to-chargen and getting good rates.

Right now I'm trying an experiment with smbclient rather than the smbfs that comes with Mac OS X - and it seems to be running fine... so it looks like there's some problem between OS X's smbfs and the version of samba I have, which is just bizarre.

Perhaps I ought to set up Appletalk sharing - at least that way Sarah can access the household music collection, anyway...

HTTP caching (by alaric)

Yesterday I configured Squid on my internal network; machines on the office LAN can use it if configured to use an HTTP proxy, while machines on the wifi LAN are forced to use it as a transparent proxy via port forwarding on the router (I'm slowly making the wifi LAN more and more like a cheap ISP's network - it's an open wifi, so I'm keen to force its users to be well-behaved).

The thing is, watching Squid's logs, I was horrified at just how few pages it felt it could cache. I'd always imagined, when developing Web apps, that anything fetched with GET could be cached for a while (and might even be prefetched). So when I actually dug a little deeper, I found that just about anything dynamically generated (including quite static pages that just use a bit of PHP to automatically include the same navigation in every page, with the currently selected option highlighted, for example) is, unless the script author has made special effort, generally not cacheable.

You can check the cacheability of pages with this useful cacheability testing tool.

Blog software is terrible at this, for example, despite generally having very cacheable pages

Rather than explain the rules in detail here, I'll link to somebody who already has. In particular, read the section on writing cache-aware scripts.

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VLAN update (by alaric)

Ok, suspecting that the MTUs might be a problem, I put an fxp ethernet card into the single PCI slot in my home server (ousting the SCSI card), since that card can support the large Ethernet frames required to have a standard 1500 MTU plus 802.1Q VLAN tags.

But, alas, things were little better. From a desktop machine wired into the same switch as the server I still can't do DAAP without iTunes randomly closing the connection in mid-stream, and from Sarah's laptop on the wireless LAN, she still can't do DAAP or reliable SMB file sharing (the connection keeps getting dropped). SMB seems OK from the desktop machine, however.

So I wondered if NetBSD's 802.1Q implementation might be the problem; since the old vr interface is built into the server's motherboard, I now have two NICs, so just put the server on both internal VLANs independently (with no 802.1Q). And it's no better.

I can imagine that iTunes might just be fussy about its DAAP implementation and not like something daapd (an open-source implementation of the DAAP music sharing in iTunes) is doing; but why should SMB also be unreliable? I tried SMB from my own laptop over the wifi link, and found it workable but oddly slow. I'm going to experiment further with connecting my laptop directly to the switch (on either wifi or internal VLAN) and seeing how it responds, I think... something's fishy!

VLAN woes (by alaric)

At our house, we have three LANs; the external one, which is connected to the ADSL router and has a range of six public IPs; the internal one, which is joined to the external one via a NAT router (so using a single public IP) and contains my workstations and the fileserver; and the guest one, which is bridged to wireless Ethernet - and also joined to the external network via the NAT router.

Now, since I've not cabled the place yet, the physical layout of the network is dictated by the lengths of the cables I have. The ADSL router is at one end of the building, near the phone sockets, while the workstations are right at the very other end of the building. Therefore, the NAT router is in the airing cupboard, roughly in the middle of the building; my longest cables reach from the ADSL router to the NAT router, and from the NAT router to a switch in the office from with the workstations and server connect; and the wireless bridge sits in the airing cupboard along with the NAT router.

Even when I have structured cabling in place, I don't want to be having to cable three separate LANs around the house anyway; the natural solution is to use VLANs. That way, you can have switches joined by single-cable trunks, and those trunks carry all of the LANs in one; at each switch, you can either configure a port to connect to a specified VLAN, or configure the port to use IEEE 802.1Q tagging to connect a machine that understands it, in which case that machine can join whichever VLANs it is allowed using the single cable. This saves on the cabling a great deal.