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Home > Archive > CCNP > December 2001 > EtherChannel
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| Peakey 2001-12-13, 5:48 pm |
| Hi All!!!
I know this is slightly off exam topic, but i was hoping someone would be able to answer my question.
I have two cisco 2948g switches both are running cat4000.6-3-3.bin with cat4000-promupgrade.6-1-4.bin.
I want to be able to etherchannel 3 ports on each switch (6 in total), into the same group. The idea being that these 6 ports connect to 1 Server with 6x100meg NICs, all using the same IP address for redundancy purposes. (so if one switch dies, the server will still be able to communicate with the other 3 NICs through the other switch.
FYI, server is a Compaq Proliant 8500.
I am unsure if you can etherchannel the same group across 2 different switches.
Any ideas?
Thanks
Glen | |
| sidodgers 2001-12-13, 7:52 pm |
| quote:
Originally posted by Peakey
Hi All!!!
I know this is slightly off exam topic, but i was hoping someone would be able to answer my question.
I have two cisco 2948g switches both are running cat4000.6-3-3.bin with cat4000-promupgrade.6-1-4.bin.
I want to be able to etherchannel 3 ports on each switch (6 in total), into the same group. The idea being that these 6 ports connect to 1 Server with 6x100meg NICs, all using the same IP address for redundancy purposes. (so if one switch dies, the server will still be able to communicate with the other 3 NICs through the other switch.
FYI, server is a Compaq Proliant 8500.
I am unsure if you can etherchannel the same group across 2 different switches.
Any ideas?
Thanks
Glen
As far as I'm aware, you can't etherchannel an odd number of ports. I'm not sure if the 4000 series firmware is different, but this is definitely the case on 5000s. | |
| Peakey 2001-12-13, 9:04 pm |
| Thanks for your reply.
If i can't have an odd number of etherchannel ports on the one switch.... Can i then user 4 ports on one switch and 2 ports on the other switch, and somehow group them together to form the one etherchannel?? | |
| MadChef 2001-12-14, 5:06 am |
| quote:
Originally posted by Peakey
If i can't have an odd number of etherchannel ports on the one switch.... Can i then user 4 ports on one switch and 2 ports on the other switch, and somehow group them together to form the one etherchannel??
No. You can't form a single etherchannel from one host to two switches. You could, however, create two seperate etherchannels and run each channel in a fault tolerent mode on the host. That would work from the Cisco side, but I don't know if your host software will allow such a setup.
MadChef | |
| sidodgers 2001-12-14, 5:10 am |
| quote:
Originally posted by MadChef
No. You can't form a single etherchannel from one host to two switches. You could, however, create two seperate etherchannels and run each channel in a fault tolerent mode on the host. That would work from the Cisco side, but I don't know if your host software will allow such a setup.
MadChef
Yea, that would have been my advice... it depends entirely on what software you're using, and also the willingness of the switches to age out their CAM tables or you could wind up losing data.
In a unix-based OS it would actually be quite simple to hack together something which channel-bonded a couple ethernet cards and monitored their link state, and transferred the properties of the bundle to another bundle if the first one died.
Not sure at all with NT. YMMV.
Sid  | |
| strikeattack 2001-12-14, 12:43 pm |
| quote:
No. You can't form a single etherchannel from one host to two switches. You could, however, create two seperate etherchannels and run each channel in a fault tolerent mode on the host. That would work from the Cisco side, but I don't know if your host software will allow such a setup.
Agreed. The difference, is of course that you will probably end up with two addresses in the subnet, one for each adapter. This may or not be the desired configuration that you want.
I do understand what you are trying to do. You want to be able to account for switch failure, link failure, and NIC failure. WHAT YOU CAN DO is split the Etherchannel bundles between switch blades, so as to account for blade failure. In ther words, you run half of the cables to Blade1 and half to Blade2. This provides for blade failure, link failure, and NIC failure. | |
| Peakey 2001-12-16, 3:30 pm |
| Thank you all for your replies!!!
I will probably set the server up with just 2 nics with a fail on fault configuration (via the the Compaq Teaming software), i was just hoping i might be able to etherchannel the six nics together and have some redundancy in place across multiple switches.
Regards
Glen | |
| sidodgers 2001-12-16, 3:56 pm |
| quote:
Originally posted by strikeattack
Agreed. The difference, is of course that you will probably end up with two addresses in the subnet, one for each adapter. This may or not be the desired configuration that you want.
I do understand what you are trying to do. You want to be able to account for switch failure, link failure, and NIC failure. WHAT YOU CAN DO is split the Etherchannel bundles between switch blades, so as to account for blade failure. In ther words, you run half of the cables to Blade1 and half to Blade2. This provides for blade failure, link failure, and NIC failure.
yeah, but he's running 2900s, which don't have blades | |
| Peakey 2001-12-18, 9:03 pm |
| I thought i'd post a follow up just to let everyone know what i've done.
I've configured my server with an etherchannel of 6 NICs.
I then configured SWITCH-A with a 4-port etherchannel, i then configured SWITCH-B with a 2-port etherchannel.
When i do a SH ARP on either switch it tells me that to get to my server, go through the 4-port etherchannel on SWITCH-A, no probs there!!! (it appears to ignore the 2-port etherchannel, even though all 6 nics are teamed into the same etherchannel on my server)..... i then did a bit of testing, i.e. powered SWITCH-A off.... my server was still pingable... i then did a SH ARP on SWITCH-B (SWITCH-A is powered off at the moment), it tells me that to get to my server, go through SWITCH-B via the 2-port etherchannel. ccccooollll, it appears to have 'failed over' to SWITCH-B..... I then powered SWITCH-A back on, once it was alive again, SH ARP was telling me that to get to my server go through SWITCH-A (my 4-port etherchannel, my preferred method).....
Going through the reply posts, i was under the impression that this was not going to be possible, but for same strange reason (and this has to be a first), things seem to be working ok...... it appears i don't have a fully blown 6 NIC etherchannel (no probs as 4-port is sufficient), all working similtaneously, but a primary 4-port etherchannel and a 'hot standby' 2-port etherchannel.
The Compaq NIC teaming software that i'm using, doesn't seem to mind talking to 2 switches, and when my SWITCH-A fails, SWITCH-B seems quite happy to takeover the control of handling the communication to the Compaq server via the 2-port etherchannel on SWITCH-B.
I've still got a bit of testing to do, but all seems to be working quite nicely at this stage.
Go figure!?!?!?!?
Peakey |
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