On 06/25/2012 12:02 PM, Mike Christie wrote: > You sent the mail below to the wrong guy. You only sent the mail below > to me and it was not my idea. Can I post on the list and to Ulrich that > he was right. >
Ignore that. I see it also went to the list. > > On 06/24/2012 10:12 PM, Spike White wrote: >> MTU!!! That was the problem. >> >> As we've always previously done layer 2 (flat) network and our iSCSI >> switches are configured for jumbo frames, we always set MTU to 9000. >> >> So when we flipped over to layer 3, I didn't even think about MTU. I just >> flipped over the IP address, set netmask, added the gw per iSCSI NIC. >> >> What confused me was how I could ping, traceroute, discover down the iSCSI >> NICs. But not login. >> >> Since these are TCP connections, I'm surprised path MTU discovery didn't >> save me. >> >> I'm sure it's that one hop that's the culprit -- when I was layer 2 that >> same iSCSI box was working fine w/ jumbo frames. >> >> Thanks for responding. Wireshark was an excellent idea BTW -- I would have >> been the problem immediately w/ wireshark. I'm guessing my discover >> packets were <1500 bytes, but my login packets must be >1500 bytes. >> >> Spike >> >> >> On Fri, Jun 22, 2012 at 1:29 AM, Ulrich Windl < >> ulrich.wi...@rz.uni-regensburg.de> wrote: >> >>> Hi! >>> >>> Did you check for MTU problems? Like: The router cannot handle MTUs that >>> are sent, and does not fragment, but discard them? Anyway tcpdump or >>> wireshark might help. >>> >>> Regards, >>> Ulrich >>> >>> >>>>>> Spike White <spikewhit...@gmail.com> schrieb am 21.06.2012 um 04:41 in >>> Nachricht >>> <CAO2Co24d=lc29vxtxmoa0n2wdk3lhoq+cp2q7avefzekv3t...@mail.gmail.com>: >>> > Hi. >>>> >>>> I have dual redundant dedicated iSCSI NICs with RHEL5.7. So I'm running >>>> the iscsi-initiator-utils--6.2.0.872-10.0.1.el5 that comes w/ RHEL 5.7. >>>> It's based directly on open-iscsi. >>>> >>>> Using CHAP authentication. No iSCSI off-loading. >>>> >>>> When I do layer 2 (flat routing) where the iSCSI target portal and iSCSI >>>> NICs are on the same subnet, all works great. >>>> >>>> When I move the NICs one subnet over (one hop to the iSCSI target >>> portal), >>>> then ping to portal works. Discovery of iSCSI targets works. But logins >>>> to all targets hang and ultimately fail. Why? >>>> >>>> I've defined the gw for each iSCSI NIC in the >>>> /etc/sysconfig/network/ifcfg-eth* files. (That's why ping and traceroute >>>> works). >>>> >>>> Why did I move one subnet over? Because my network guy wants me to >>> measure >>>> the increased latency introduced by going from zero hops to one hop. >>>> (They're not a fan of flat networks, too inflexible in large env's). >>>> >>>> Spike >>> >>> >>> >>> >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "open-iscsi" group. >>> To post to this group, send email to open-iscsi@googlegroups.com. >>> To unsubscribe from this group, send email to >>> open-iscsi+unsubscr...@googlegroups.com. >>> For more options, visit this group at >>> http://groups.google.com/group/open-iscsi?hl=en. >>> >>> >> > -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To post to this group, send email to open-iscsi@googlegroups.com. To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
