Routing – How to get multiple uplinks on Juniper EX switch to work

juniperjuniper-exjuniper-junosrouting

We have a Juniper EX4200. Ports 0, 2, 4 and 6 are connected to another Juniper switch. These ports are our network uplinks. All other ports are connected to our servers. We want traffic to use all 4 uplinks (total capacity 4 Gbps), but it seems like only the first port (0) is every used, all other show no or little traffic, even under heavy load.

Our switch :

# show interfaces
ge-0/0/0 {
    unit 0 {
        family ethernet-switching;
    }
}

...

# show interfaces vlan
unit 401 {
    family inet {
        address e.f.g.2/29;
    }
}
unit 101 {
    family inet {
        address a.b.c.1/29;
    }
}
unit 102 {
    family inet {
        address a.b.c.9/29;
    }
} 
...

#show vlans
server-1 {
    vlan-id 101;
    interface {
        ge-0/0/1.0;
    }
    l3-interface vlan.101;
}
server-2 {
    vlan-id 103;
    interface {
        ge-0/0/3.0;
    }
    l3-interface vlan.103;
}
default {
    vlan-id 401;
    l3-interface vlan.401;
}
v401;

...

show routing-options
static {
    route 0.0.0.0/0 next-hop e.f.g.1;
}

Our switch ports 0, 2, 4 and 6 connects to ports 0, 1, 2 and 3 of the upstream switch. The upstream switch is configured like :

set routing-options static route a.b.c.1/24 next-hop e.f.g.2

set interfaces ge-0/0/0 unit 0 family ethernet-switching
set interfaces ge-0/0/1 unit 0 family ethernet-switching
set interfaces ge-0/0/2 unit 0 family ethernet-switching
set interfaces ge-0/0/3 unit 0 family ethernet-switching

set vlans v401 vlan-id 401
set vlans v401 interface ge-0/0/3.0
set vlans v401 interface ge-0/0/2.0
set vlans v401 interface ge-0/0/1.0
set vlans v401 interface ge-0/0/0.0
set vlans v401 l3-interface vlan.401

Why aren't we seeing traffic flowing through the 3 other uplinks?

Best Answer

As Ron has mentioned, this is most likely the result of spanning-tree blocking the remaining three interfaces, as you have created a loop in your network.

To achieve what you're after (load-sharing/flow-hasing), configure the following on BOTH switches to form an aggregated ethernet link:

set chassis aggregated-devices ethernet device-count 8

wildcard range delete interfaces ge-0/0/[0-3]
wildcard range delete vlans v401 interface ge-0/0/[0-3]

set interfaces interface-range AE0-MEMBERS ether-options 802.3ad ae0
wildcard range set interfaces interface-range AE0-MEMBERS member ge-0/0/[0-3]
set interfaces ae0 aggregated-ether-options lacp active

set interfaces ae0 unit 0 family ethernet-switching
set vlans v401 interface ae0

I'm not a fan of assigning interfaces to the VLAN, so you can replace the last line with:

set interfaces ae0 unit 0 family ethernet-switching members v401

I liken Junos VLAN assignment to the eternal struggle over which side of the roll toilet paper should be hung.

Related Topic