Connecting to an Ethernet Switch

Problem

The router connects to an Ethernet switch, and you want to aggregate a number of the switch's Ethernet interfaces onto a single JUNOS Ethernet interface.

Solution

There are three steps to setting up an aggregated Ethernet interface. First, enable Ethernet aggregation on the router:

[edit chassis] aviva@router1# set aggregated-devices ethernet device-count 24

Second, enable aggregation on the Ethernet interface:

[edit interfaces fe-0/0/3 ] aviva@router1# set fastether-options 802.3ad ae0

Finally, configure the aggregated Ethernet interface:

[edit interfaces ae0] aviva@router1# set vlan-tagging aviva@router1# set unit 0 vlan-id 1 aviva@router1# set unit 0 family inet address 10.10.10.1/24

Discussion

Link aggregation of Ethernet interfaces, defined in the IEEE 802.3ad standard, is a way to aggregate multiple connections from a switch into a single logical interface on a Fast Ethernet or Gigabit Ethernet interface on an M-series or T-series router. (J-series boxes do not support Ethernet aggregation). The JUNOS software balances traffic across all member links within an aggregated Ethernet bundle.

This recipe configures a bundle of 24 aggregated logical interfaces. The set aggregated-devices ethernet command tells the router chassis process to treat the Ethernet logical interfaces configured for aggregation as separate virtual devices. On the Fast Ethernet interface, the set fastether-options 802.3ad ae0 command turns on aggregation on the interface and associates the interface with aggregated Ethernet interface 0. Because the aggregation creates virtual links on the interface, do not configure a logical interface on the Fast Ethernet interface.

To set up the aggregated Ethernet interface itself, configure VLAN tagging and a logical interface with an IP address on interface ae0.

Verify the configuration by looking at the Fast Ethernet and aggregated Ethernet interfaces. On the Fast Ethernet interface, you see the logical interface points to the aggregated Ethernet bundle:

aviva@router1> show interfaces fe-0/0/3 Physical interface: fe-0/0/3, Enabled, Physical link is Up Interface index: 131, SNMP ifIndex: 82 Description: to nutmeg fe-003 Link-level type: Ethernet, MTU: 1518, Speed: 100mbps, Loopback: Disabled, Source filtering: Disabled, Flow control: Enabled Device flags : Present Running Interface flags: SNMP-Traps 16384 Link flags : 4 CoS queues : 4 supported Current address: 00:05:85:02:a7:f0, Hardware address: 00:05:85:02:a4:03 Last flapped : 2005-05-26 03:10:25 PDT (05:39:39 ago) Input rate : 0 bps (0 pps) Output rate : 0 bps (0 pps) Active alarms : None Active defects : None Logical interface fe-0/0/3.0 (Index 72) (SNMP ifIndex 87) Flags: SNMP-Traps 16384 VLAN-Tag [ 0x8100.1 ] Encapsulation: ENET2 Input packets : 0 Output packets: 0 Protocol aenet, AE bundle: ae0.0 Logical interface fe-0/0/3.32767 (Index 73) (SNMP ifIndex 88) Flags: SNMP-Traps 16384 VLAN-Tag [ 0x0000.0 ] Encapsulation: ENET2 Input packets : 0 Output packets: 0

The first logical interface points to the ae0.0 aggregated Ethernet bundle. The JUNOS software creates a second logical interface, fe-0/0/3.32767, for handling traffic that is not part of the aggregate, such as the Link Aggregation Control Protocol (LACP) traffic exchanged by the aggregated partners.

On the aggregated Ethernet interface, you see information about the bundle and traffic statistics:

aviva@router1> show interfaces ae0 Physical interface: ae0, Enabled, Physical link is Up Interface index: 302, SNMP ifIndex: 89 Link-level type: Ethernet, MTU: 1518, Speed: 100mbps, Loopback: Disabled, Source filtering: Disabled, Flow control: Disabled, Minimum links needed: 1 Device flags : Present Running Interface flags: SNMP-Traps 16384 Current address: 00:05:85:02:a7:f0, Hardware address: 00:05:85:02:a7:f0 Last flapped : Never Input rate : 0 bps (0 pps) Output rate : 0 bps (0 pps) Logical interface ae0.0 (Index 69) (SNMP ifIndex 211) Flags: SNMP-Traps 16384 VLAN-Tag [ 0x8100.1 ] Encapsulation: ENET2 Statistics Packets pps Bytes bps Bundle: Input : 0 0 0 0 Output: 0 0 0 0 Protocol inet, MTU: 1500 Flags: None Addresses, Flags: Is-Preferred Is-Primary Destination: 10.10.10/24, Local: 10.10.10.1, Broadcast: 10.10.10.255

Notice that the VLAN tag on the aggregated Ethernet interface matches that of the fe-0/0/3.0 logical interface.