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'Redundant Switch'
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'Redundant Switch'

FreekFreek Member
edited July 2012 in Help

Suppose I have a simple network connection between two computers using a switch. That would make the switch my Single Point of Failure. Both computers have 2 network cards, but can only use 1 static IP.
How can I make the switch redundant without giving the two computers extra IPs? I am asking this because I have a piece of software which can only listen to one IP..
This solution won't work, as I need extra IPs if I am correct:
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What I am looking for is a setup in which one switch can fail and the other switch will continue working automatically.. Is this even possible with just 1 IP available per PC?

Thanks

Linux noob willing to learn.

Comments

  • This should be possible using nic bonding/teaming. Configure in ALB or SFT with two switches.

  • FreekFreek Member

    Thanks for the reply, @ShardHost.
    Should this setting be enabled in the Switch (e.g. managed switch?) or on the computer side(s)? Both computers run Windows 7 Professional.

    Linux noob willing to learn.

  • KuJoeKuJoe Member, Provider
    edited July 2012

    If your switchs support LACP and stacking then that is the best route. I personally set the bonding on the NICs (1 IP, 2 NICs) but that's in CentOS and not sure if Windows supports it. Also don't forget to get switches that support Spanning Tree if you stack them.

    -Joe @ SecureDragon - LEB's Powered by Wyvern in FL, CO, CA, IL, NJ, GA, OR, TX, and AZ
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  • FreekFreek Member

    @KuJoe, Thanks for your reply.
    I haven't bought any hardware yet, so all options are still open. So you suggest me to buy a switch that supports LACP, Stacking and Spanning Tree? Could you give me an example if possible?

    I think Windows will complain about IP conflicts, but I am not sure...

    Linux noob willing to learn.

  • MaouniqueMaounique Member
    edited July 2012

    Windows can have nic bonding in software, I think it is vendor specific for their nics. You will also NEED a special switch if you want to do aggregation, but you wont if you only need a spare link. All in all looks like a bit expensive.

    If you can install some small VMs with a virtualization of your choice, you could setup this via 3 VMs each end. For example with pfsense and 2 IPCops. The idea is that the 2 IPCops will be bridged each to one NIC (can be any, no matter) and the pfsense will be doing failover over those 2 ipcops (just examples of easy to configure firewall small footprint distros). That will be at both ends, 2 pairs of IPCops talking to each other and aggregated by the pfsense. In this case any nic and cheap ass switch will do as long as you have the necessary throughput. IPCops need 1 GB virtual drive and 64 mb ram, pfsense will be happier with 128 ram and 3 gb virtual hdd, but they can work in less resources.
    M

    Extremist conservative user, I wish to preserve human and civil rights, free speech, freedom of the press and worship, rule of law, democracy, peace and prosperity, social mobility, etc. Now you can draw your guns.

  • Go59954Go59954 Member
    edited July 2012

    It might be possible to do it through NATing?

    But in either case I'd (and I might be wrong) go with a single switch from a durable type given that I can fully access it remotely, restart or configure when needed, also that I can call someone in place to restart it through power or to check the power if it's down, and in worst case I can go there by myself to reconfigure it. And btw, if you had a power outage both switches will go down anyway if they use same power source, and it's possible that both of them gets an error and need a restart for both.

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  • ALB does not require any switch support. It will work with standard switches. The only thing I am not sure about is windows support; however this should be driver specific

    What Nics are you running?

  • prometeusprometeus Member, Provider

    All active/standby bonding/teaming/whatever I know not require any switch support (required for some active/active setups). So if the aim is to provide redundancy/failover then use an active/standby configuration and you should be fine...

    IperWeb & Prometeus, Hosting Provider since 1997. iwStack cloud infrastructure
  • KuJoeKuJoe Member, Provider

    The only bonding that requires switch support is 802.1ax/802.3ad (LACP). The other 6 options do not require special switches. We currently use Adaptive transmit load balancing but will be switching to Active-backup policy this week with our new network (2 routers + 2 switches).

    -Joe @ SecureDragon - LEB's Powered by Wyvern in FL, CO, CA, IL, NJ, GA, OR, TX, and AZ
    Need backup space? Check out BackupDragon
  • @prometeus said: (required for some active/active setups

    Yep, the ones that increase bw, not those that are for redundancy only. I think that using some VMs is free and highly configurable, as such should be tried before investing in equipment (hardware with specific drivers at least) if it is enough (can handle the load, mostly, since I cant see other problems).
    M

    Extremist conservative user, I wish to preserve human and civil rights, free speech, freedom of the press and worship, rule of law, democracy, peace and prosperity, social mobility, etc. Now you can draw your guns.

  • miTgiBmiTgiB Member

    @KuJoe said: not sure if Windows supports it

    Most cards provide support in their driver to do LACP in Windows. I have done this with Intel and Realtech, and you then configure networking on the new bonded device. One fails, the other is still going.

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  • FreekFreek Member
    edited July 2012

    Thanks for the replies guys, I know enough for now :)
    The aim was to provide a fallover/backup in case one switch goes down.
    Apparently most Intel dual-NIC cards can do this without using any fancy switches.
    Thanks again for pointing me into the right direction!

    Linux noob willing to learn.

  • rds100rds100 Member
    edited July 2012

    Realistically switch failures are so rare that you are going to introduce much more chance of downtime by adding unnecessary complexity and it is not worth it to do two nics for failover in most cases. Unless you are doing it for load balancing too, i.e. if 1Gbit is not enough for you and you want 2 Gigabits, but then you have to know that there are gotchas too.

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  • You will need to connect the switches to each other if you are using the same subnet for for both NIC's (as per your applicaiton requirements. You dont need to worry about spanning tree with two switches as you wont be introducing any loops - unless you are conencting these to other switches then you will have to worry about this.

    LACP (802.3ad) is over rated for host conenctions. Each established connection will only use one uplink anyway so in most cases it would be very difficult to exceed the badwidth of one port, unless you have an application making lots of connections. This always gets overlooked, it simply doesnt work how you would expect it to. A single file copy for example from one server to the other with 2X1Gb uplinks will only result in 1Gbps throughput.

    LACP has benefits if you have lots of hosts connecting to single point and the switch will help balance the established connections across both ports meaning the total amount of bandwidth to one host is increased.

    Also the switches dont often support LACP across two switches so both of the uplinks form each switch will need to go to the same switch deffeating the whole purpose.

    If your using Windows hosts buy some HP NIC's and get the HP teaming software, it is very easy to use. I usaully just set them up for failover with preference order so the preffered NIC's always use the same switch.

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