Re: Problem with VLANs
On 2007/08/03 15:27, Hugo van Niekerk wrote: [...] pcn(4) can be persuaded to send frames large enough to hold vlan tags and a 1500-byte packet with the diff below, but on the vmware I just tried, I can't get it to receive frames that size. Then again, neither does em(4) with Ethernet0.virtualDev = e1000, or vic(4) with Ethernet0.virtualDev = vmxnet, so it's likely to be a problem with the NIC on the vmware I just tried it on (nfe on a junk windows box). If anyone wants to try their luck with a real pcn (rare beast that it is ..) or a better vmware installation here's the diff (against -current) to test. A test is only successful if you can send *and receive* large packets over a vlan interface over the wire (e.g. ping -s1472 some.other.host.on.the.vlan). Features table for the AMD chip says 'software vlan support' and there's nothing specific to enable large frame reception mentioned in the data sheet that I could find, but there could be some reason (other than they didn't think of it) why it seems not to be done in other OS. Index: if_pcn.c === RCS file: /cvs/src/sys/dev/pci/if_pcn.c,v retrieving revision 1.15 diff -u -p -r1.15 if_pcn.c --- if_pcn.c9 Nov 2006 14:25:23 - 1.15 +++ if_pcn.c3 Aug 2007 10:40:49 - @@ -805,6 +805,8 @@ pcn_attach(struct device *parent, struct IFQ_SET_MAXLEN(ifp-if_snd, PCN_NTXDESC -1); IFQ_SET_READY(ifp-if_snd); + ifp-if_capabilities = IFCAP_VLAN_MTU; + /* Attach the interface. */ if_attach(ifp); ether_ifattach(ifp); @@ -1128,7 +1130,8 @@ pcn_ioctl(struct ifnet *ifp, u_long cmd, break; case SIOCSIFMTU: - if (ifr-ifr_mtu ETHERMTU || ifr-ifr_mtu ETHERMIN) + if (ifr-ifr_mtu ETHERMTU + ETHER_VLAN_ENCAP_LEN || + ifr-ifr_mtu ETHERMIN) error = EINVAL; else if (ifp-if_mtu != ifr-ifr_mtu) ifp-if_mtu = ifr-ifr_mtu;
Re: Problem with VLANs
Stuart Henderson [EMAIL PROTECTED] wrote: case SIOCSIFMTU: - if (ifr-ifr_mtu ETHERMTU || ifr-ifr_mtu ETHERMIN) + if (ifr-ifr_mtu ETHERMTU + ETHER_VLAN_ENCAP_LEN || + ifr-ifr_mtu ETHERMIN) error = EINVAL; else if (ifp-if_mtu != ifr-ifr_mtu) ifp-if_mtu = ifr-ifr_mtu; This isn't the idea. The MTU is not supposed to be set to 1504, it stays at 1500 and if_vlan sees IFCAP_VLAN_MTU and knows that the chip actually supports MTU + EVL_ENCAPLEN. With this change, then on several chips, if the user expected to set 1504 and then use if_vlan on top of that (say, to pass packets that are alreay tagged by another device) then it would fail.
Re: Problem with VLANs
On 2007/08/03 16:18, Chris Cappuccio wrote: Stuart Henderson [EMAIL PROTECTED] wrote: case SIOCSIFMTU: - if (ifr-ifr_mtu ETHERMTU || ifr-ifr_mtu ETHERMIN) + if (ifr-ifr_mtu ETHERMTU + ETHER_VLAN_ENCAP_LEN || + ifr-ifr_mtu ETHERMIN) error = EINVAL; else if (ifp-if_mtu != ifr-ifr_mtu) ifp-if_mtu = ifr-ifr_mtu; This isn't the idea. The MTU is not supposed to be set to 1504, it stays at 1500 and if_vlan sees IFCAP_VLAN_MTU and knows that the chip actually supports MTU + EVL_ENCAPLEN. damn, yes you're right. Scrub this bit of the diff then. With this change, then on several chips, if the user expected to set 1504 and then use if_vlan on top of that (say, to pass packets that are alreay tagged by another device) then it would fail. btw, you can stack tags (e.g. vlanYYY vlandev vlanXXX), at least on some nics.
Re: Problem with VLANs
Redirected as this is a misc@ question not a tech@ question. On Thu, 2007-08-02 at 11:48 +0930, Hugo van Niekerk wrote: Hey Everybody Im running OpenBSD 3.9. At startup during vlan initialization I get an error that the vlan initiated with a nonstandard mtu of 1946 (parent pcn1). Of course I understand that a vlan header has to be sent and that provision has to be made for this. Ive done a lot of searching on the web around this and everything is pointing to the fact that the network driver does not support / has not been set for a larger mtu. This is where I get stuck. There is a component SIOCIFMTU that reports that the mtu value I use is incorrect for a specific interface when I try to increase the mtu from the command line using ifconfig. This component, according to my research sets the mtu value automatically at startup based on the information that is fed to it by the network card driver. Anything above what is set at startup would be invalid. Can anybody please give me some advise as to where I can more resources that I can research to resolve this problem or point me in the right direction. I would really appreciated this! Also, I've been looking for a guide or good book / resource around configuring vlans on OpenBSD, I thought maybe I made a mistake in the hostname.if and pf.conf files. Again any assistance here will be greatly appreciated. regards Hugo If your interface is initializing with a MTU of 1496 then the card that you are using is not capable of supporting a MTU over 1500 which is required by the 802.1q spec to do VLAN tagging. A full size ethernet frame with the 802.1q encapsulation is actually 1504 bytes. This is not a configuration issue, unless you have specified a smaller packet size. There is no configuration needed, if the card is capable of doing vlan trunking with the full packet size, it will otherwise it will automatically decrease the MTU to allow for the 4 byte header that will be added. Unfortunately not all the ethernet cards/drivers are able to support this over-sized packet. To check which drivers are capable of supporting it you can grep for IFCAP_VLAN_MTU in the /usr/src/sys/dev/pci/if_driver.c files. I personally have had the best luck with the fxp, sis, and em drivers when I am doing vlan trunking. Tim Donahue
Re: Problem with VLANs
On 2007/08/02 10:54, Tim Donahue wrote: Redirected as this is a misc@ question not a tech@ question. On Thu, 2007-08-02 at 11:48 +0930, Hugo van Niekerk wrote: Im running OpenBSD 3.9. At startup during vlan initialization I get Unfortunately lacking a dmesg... an error that the vlan initiated with a nonstandard mtu of 1946 (parent pcn1). Of course I understand that a vlan header has to be If this is a real machine, swapping the card is probably the best idea. If it's vmware, you may be able to change settings and use Intel emulation and em(4) or vmxnet and vic(4) (with newer OpenBSD). Unfortunately not all the ethernet cards/drivers are able to support this over-sized packet. To check which drivers are capable of supporting it you can grep for IFCAP_VLAN_MTU in the /usr/src/sys/dev/pci/if_driver.c files. I personally have had the best luck with the fxp, sis, and em drivers when I am doing vlan trunking. sk and bge work fine too. I think re and dc as well, but I'm not actively using them (re - machine's blown up, dc - my znyx card is too long to fit into anything I have handy). xl works sometimes but is not a great choice.
