Question about UBNT Bridge Performance vs SFP



  • When using any Ubnt router, and using one of the bridged ports to connect to my switch, does this in itself create a performance bottleneck vs using a separate SFP to connect to said switch? I've read that enabled the "virtual bridge" drops performance by about half.



  • Why would you bridge the ports? If you need switch functionality, there are few Edgerouters that have switch chip so no bridging required. And to answer your question, yes, bridging adds a lot of overhead since it's done in software, and router hardware is rather limited and designed to deal with routing.



  • A connection between a router/firewall and a switch doesn't have to be a bridged connection, it can just be an uplink.

    @scottalanmiller or someone else can probably explain what a bridge is specifically - I'm sure my explanation would just be wrong.



  • @krisleslie said in Question about UBNT Bridge Performance vs SFP:

    When using any Ubnt router, and using one of the bridged ports to connect to my switch, does this in itself create a performance bottleneck vs using a separate SFP to connect to said switch? I've read that enabled the "virtual bridge" drops performance by about half.

    Why would you create a bridge on your router? Are you using the right term here?



  • Isn't a virtual bridge just turning the other ports into a switch?



  • @wrx7m said in Question about UBNT Bridge Performance vs SFP:

    Isn't a virtual bridge just turning the other ports into a switch?

    Yes, that is basically what a bridge would do.



  • @dbeato said in Question about UBNT Bridge Performance vs SFP:

    @wrx7m said in Question about UBNT Bridge Performance vs SFP:

    Isn't a virtual bridge just turning the other ports into a switch?

    Yes, that is basically what a bridge would do.

    That slows the ER down? I know the ER-X has a Switch chip, so that shouldn't actually be slower... I suppose doing that in other ER's could be the issue the OP mentions.

    To that end - yeah, don't do that, don't bridge other ports on the router into a single network. Just use a single line from the configured port to switch, and go from there.



  • @Dashrender I don't think that it slows it down.



  • @dbeato said in Question about UBNT Bridge Performance vs SFP:

    @Dashrender I don't think that it slows it down.

    It does. Throughput drops rather drastically, I've seen 50% drop, others reported even more, up to 80%.



  • @marcinozga said in Question about UBNT Bridge Performance vs SFP:

    @dbeato said in Question about UBNT Bridge Performance vs SFP:

    @Dashrender I don't think that it slows it down.

    It does. Throughput drops rather drastically, I've seen 50% drop, others reported even more, up to 80%.

    yeah, while these drops seem super drastic (I'm curious why it's so bad) the ERs that don't have switch chips have to use software to make switching happen, and clearly there is a performance hit doing so.

    So just don't do it. why do you need more than one port per network going to the switch?



  • All of you need to learn to use the right terms.

    Setting up a bridge will 100% slow shit down because all of the traffic is software routed (aka CPU). Setting up a bridge is not a switch, but yes it makes all of the ports that are part of the bridge pass traffic like a switch.

    A switch is hardware chips that handle connecting the ports.

    Certain models of Ubiquiti gear have hardware switching built in. These are the ERX and ERX-SFP and a few others.

    The ERL does not. A lot of people that think Ubiquiti gear should act like a $5 Linksys get confused when they cannot just plug everything into the ports on the ERL and have magic. So those people all end up setting up a bridge on 2 of the ERL ports.



  • This is an ERL with a bridge.

    The site is a home office. The site needed exactly 1 ethernet port (desk phone) and 1 ethernet port (wireless AP).

    The user had no desire for extra devices to be plugged in to fail. This is a good use case for a bridged port. Also speed is not an issue on site, the limitations of the bridge are not slowing the user's speed.

    That said, this was also put in place before the ER-X existed. Today I would use an ER-X for this. There is not good use case for a bridge on a router now.

    [email protected]# show interfaces 
     bridge br0 {
         address 10.202.199.1/24
         aging 300
         bridged-conntrack disable
         description LAN
         firewall {
             in {
                 name LAN_IN
             }
             local {
                 name LAN_LOCAL
             }
         }
         hello-time 2
         max-age 20
         priority 0
         promiscuous enable
         stp false
     }
     ethernet eth0 {
         bridge-group {
             bridge br0
         }
         duplex auto
         speed auto
     }
     ethernet eth1 {
         bridge-group {
             bridge br0
         }
         duplex auto
         speed auto
     }
     ethernet eth2 {
         address dhcp
         description WAN
         dhcp-options {
             default-route update
             default-route-distance 210
             name-server no-update
         }
         duplex auto
         firewall {
             in {
                 name WAN_IN
             }
             local {
                 name WAN_LOCAL
             }
         }
         speed auto
     }
     loopback lo {
     }
    

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