Example: Configuring Aggregated Ethernet High-Speed Uplinks Between an EX4200 Virtual Chassis Access Switch and an EX4200 Virtual Chassis Distribution Switch
EX Series switches allow you to combine multiple Ethernet links into one logical interface for higher bandwidth and redundancy. The ports that are combined in this manner are referred to as a link aggregation group (LAG) or bundle. The number of Ethernet links you can combine into a LAG depends on your EX Series switch model.
This example describes how to configure uplink LAGs to connect a Virtual Chassis access switch to a Virtual Chassis distribution switch:
Requirements
This example uses the following software and hardware components:
Junos OS Release 9.0 or later for EX Series switches
Two EX4200-48P switches
Two EX4200-24F switches
Four XFP uplink modules
Before you configure the LAGs, be sure you have:
Configured the Virtual Chassis switches. See Configuring an EX4200, EX4500, or EX4550 Virtual Chassis (CLI Procedure).
Configured the uplink ports on the switches as trunk ports. See Configuring Gigabit Ethernet Interfaces (CLI Procedure).
Overview and Topology
For maximum speed and resiliency, you can combine uplinks between an access switch and a distribution switch into LAGs. Using LAGs can be particularly effective when connecting a multimember Virtual Chassis access switch to a multimember Virtual Chassis distribution switch.
The Virtual Chassis access switch in this example is composed of two member switches. Each member switch has an uplink module with two 10-Gigabit Ethernet ports. These ports are configured as trunk ports, connecting the access switch with the distribution switch.
Configuring the uplinks as LAGs has the following advantages:
Link Aggregation Control Protocol (LACP) can optionally be configured for link negotiation.
It doubles the speed of each uplink from 10 Gbps to 20 Gbps.
If one physical port is lost for any reason (a cable is unplugged or a switch port fails, or one member switch is unavailable), the logical port transparently continues to function over the remaining physical port.
The topology used in this example consists of one Virtual Chassis access switch and one Virtual Chassis distribution switch. The access switch is composed of two EX4200-48P switches (SWA-0 and SWA-1), interconnected to each other with their Virtual Chassis ports (VCPs) as member switches of Host-A. The distribution switch is composed of two EX4200-24F switches (SWD-0 and SWD-1), interconnected with their VCPs as member switches of Host-D.
Each member of the access switch has an uplink module installed.
Each uplink module has two ports. The uplinks are configured to act
as trunk ports, connecting the access switch with the distribution
switch. One uplink port from SWA-0 and one uplink port from SWA-1
are combined as LAG ae0
to SWD-0. This link is used for one VLAN. The remaining uplink ports
from SWA-0 and from SWA-1 are combined as a second LAG connection
(ae1)
to SWD-1. LAG ae1
is used for another VLAN.
If the remote end of the LAG link is a security device, LACP might not be supported because security devices require a deterministic configuration. In this case, do not configure LACP. All links in the LAG are permanently operational unless the switch detects a link failure within the Ethernet physical layer or data link layers.
Table 1 details the topology used in this configuration example.
| Switch | Hostname and VCID | Base Hardware | Uplink Module | Member ID | Trunk Port |
|---|---|---|---|---|---|
SWA-0 |
Host-A Access switch VCID 1 |
EX4200-48P switch |
One XFP uplink module |
0 |
|
SWA-1 |
Host-A Access switch VCID 1 |
EX4200-48P switch |
One XFP uplink module |
1 |
|
SWD-0 |
Host-D Distribution switch VCID 4 |
EX4200 L-24F switch |
One XFP uplink module |
0 |
|
SWD-1 |
Host-D Distribution switch VCID 4 |
EX4200 L-24F switch |
One XFP uplink module |
1 |
|
Configuration
To configure two uplink LAGs from the Virtual Chassis access switch to the Virtual Chassis distribution switch.
Procedure
CLI Quick Configuration
To quickly configure aggregated Ethernet high-speed uplinks between a Virtual Chassis access switch and a Virtual Chassis distribution switch, copy the following commands and paste them into the switch terminal window:
[edit]
set chassis aggregated-devices ethernet device-count 2
set interfaces ae0 aggregated-ether-options minimum-links 1
set interfaces ae0 aggregated-ether-options link-speed 10g
set interfaces ae1 aggregated-ether-options minimum-links 1
set interfaces ae1 aggregated-ether-options link-speed 10g
set interfaces ae0 unit 0 family inet address 192.0.2.0/25
set interfaces ae1 unit 0 family inet address 192.0.2.128/25
set interfaces xe-0/1/0 ether-options 802.3ad ae0
set interfaces xe-1/1/0 ether-options 802.3ad ae0
set interfaces xe-0/1/1 ether-options 802.3ad ae1
set interfaces xe-1/1/1 ether-options 802.3ad ae1 Step-by-Step Procedure
To configure aggregated Ethernet high-speed uplinks between a Virtual Chassis access switch and a Virtual Chassis distribution switch:
Specify the number of LAGs to be created on the chassis:
[edit chassis] user@Host-A# set aggregated-devices ethernet device-count 2
Specify the number of links that need to be present for the
ae0LAG interface to beup:[edit interfaces] user@Host-A# set ae0 aggregated-ether-options minimum-links 1
Specify the number of links that need to be present for the
ae1LAG interface to beup:[edit interfaces] user@Host-A# set ae1 aggregated-ether-options minimum-links 1
Specify the media speed of the
ae0link:[edit interfaces] user@Host-A# set ae0 aggregated-ether-options link-speed 10g
Specify the media speed of the
ae1link:[edit interfaces] user@Host-A# set ae1 aggregated-ether-options link-speed 10g
Specify the interface ID of the uplinks to be included in LAG
ae0:[edit interfaces] user@Host-A# set xe-0/1/0 ether-options 802.3ad ae0 user@Host-A# set xe-1/1/0 ether-options 802.3ad ae0
Specify the interface ID of the uplinks to be included in LAG
ae1:[edit interfaces] user@Host-A# set xe-0/1/1 ether-options 802.3ad ae1 user@Host-A# set xe-1/1/1 ether-options 802.3ad ae1
Specify that LAG
ae0belongs to the subnet for the employee broadcast domain:[edit interfaces] user@Host-A# set ae0 unit 0 family inet address 192.0.2.0/25Specify that LAG
ae1belongs to the subnet for the guest broadcast domain:[edit interfaces] user@Host-A# set ae1 unit 0 family inet address 192.0.2.128/25
Results
Display the results of the configuration:
[edit]
chassis {
aggregated-devices {
ethernet {
device-count 2;
}
}
}
interfaces {
ae0 {
aggregated-ether-options {
link-speed 10g;
minimum-links 1;
}
unit 0 {
family inet {
address 192.0.2.0/25;
}
}
}
ae1 {
aggregated-ether-options {
link-speed 10g;
minimum-links 1;
}
unit 0 {
family inet {
address 192.0.2.128/25;
}
}
xe–0/1/0 {
ether-options {
802.3ad ae0;
}
}
xe–1/1/0 {
ether-options {
802.3ad ae0;
}
}
xe–0/1/1 {
ether-options {
802.3ad ae1;
}
}
xe–1/1/1 {
ether-options {
802.3ad ae1;
}
}
}
Verification
To verify that switching is operational and two LAGs have been created, perform these tasks:
Verifying That LAG ae0 Has Been Created
Purpose
Verify that LAG ae0
has been created on the switch.
Action
show interfaces ae0 terse
Interface Admin Link Proto Local Remote ae0 up up ae0.0 up up inet 192.0.2.0/25
Meaning
The output confirms that the ae0
link is up and shows the family
and IP address assigned to this link.
Troubleshooting
Troubleshooting a LAG That Is Down
Problem
The show interfaces terse command shows
that the LAG is down
Solution
Check the following:
Verify that there is no configuration mismatch.
Verify that all member ports are up.
Verify that a LAG is part of family ethernet switching (Layer 2 LAG) or family inet (Layer 3 LAG).
Verify that the LAG member is connected to the correct LAG at the other end.
Verify that the LAG members belong to the same switch (or the same Virtual Chassis).