Verifying the Operation of Load Balancing with Aggregated Interfaces

Purpose

On an M-series or T-series platform, when you configure only the first two labels and the labels vary between traffic flows, traffic may be distributed. However, if there is not much variation between the two labels, traffic may not be distributed equally across aggregated interfaces.

The following output illustrates two situations. The first example output shows a situation in which traffic is not balanced across interfaces because there is not enough variation between the two configured labels. The second example output shows a situation in which traffic is balanced; all three MPLS labels are configured and the third label has enough variation to yield good load-balancing results.

Action

To verify the operation of the hash key, enter the following JUNOS CLI operational mode commands:

user@R2> show configuration forwarding-options

user@R2> show interfaces statistics interface-name detail

user@R2> show mpls lsp statistics

Sample Output

user@R2> show configuration forwarding-options

hash-key {

    family mpls {

        label-1;

        label-2; 

    } # The IP payload option is missing.

}

user@R2> show interfaces statistics ae0 detail

Physical interface: ae0, Enabled, Physical link is Up

  Interface index: 128, SNMP ifIndex: 289, Generation: 129

  Link-level type: Ethernet, MTU: 1514, Speed: 2000mbps, Loopback: Disabled, 
Source filtering: Disabled,

  Flow control: Disabled, Minimum links needed: 1

  Device flags   : Present Running

  Interface flags: SNMP-Traps Internal: 0x4000

  Current address: 00:90:69:0f:07:f0, Hardware address: 00:90:69:0f:07:f0

  Last flapped   : Never

  Statistics last cleared: Never

  Traffic statistics:

   Input  bytes  :               102162                  560 bps

   Output bytes  :            166100728             30744472 bps

   Input  packets:                 1259                    0 pps

   Output packets:              2442317                56515 pps

  Label-switched interface (LSI) traffic statistics:

   Input  bytes  :                    0                    0 bps

   Input  packets:                    0                    0 pps

  Input errors:

    Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Giants: 0, Policed 
discards: 0, Resource errors: 0

  Output errors:

    Carrier transitions: 0, Errors: 0, Drops: 0, MTU errors: 0, Resource errors: 
0

  Ingress queues: 8 supported, 8 in use

  Queue counters:       Queued packets  Transmitted packets      Dropped packets

    0 best-effort                    0                    0                    0

    1 expedited-fo                   0                    0                    0

    2 assured-forw                   0                    0                    0

    3 network-cont                   0                    0                    0

  Egress queues: 8 supported, 8 in use

  Queue counters:       Queued packets  Transmitted packets      Dropped packets

    0 best-effort              2440822              2440822                    0

    1 expedited-fo                   0                    0                    0

    2 assured-forw                   0                    0                    0

    3 network-cont                1225                 1225                    0

  Logical interface ae0.0 (Index 66) (SNMP ifIndex 290) (Generation 131)

    Flags: SNMP-Traps Encapsulation: ENET2

    Statistics        Packets        pps         Bytes          bps

    Bundle:

        Input :          1259          0        102162          560

        Output:       2441888      56515     166056858     30744472

    Link:

      ge-1/1/0.0

        Input :          1259          0        102162          560

        Output:       1488498      56515     101217864     30744272 

      ge-4/3/1.0

        Input :             0          0             0            0

        Output:        953235          0      64822700          200

    Marker Statistics:   Marker Rx     Resp Tx   Unknown Rx   Illegal Rx

      ge-1/1/0.0                 0           0            0            0

      ge-4/3/1.0                 0           0            0            0

    Protocol inet, MTU: 1500, Generation: 128, Route table: 0

      Flags: None

      Addresses, Flags: Is-Preferred Is-Primary

        Destination: 10.35.200.4/30, Local: 10.35.200.5, Broadcast: 10.35.200.7, 
Generation: 147

    Protocol iso, MTU: 1497, Generation: 128, Route table: 0

      Flags: Is-Primary

    Protocol mpls, MTU: 1488, Generation: 128, Route table: 0

      Flags: Is-Primary

What It Means

This sample shows that the hash key at the [edit forwarding-options] hierarchy level does not include the IP payload, indicating that the distribution of traffic is varying only by IP payload. The output for the show interfaces statistics command shows that traffic is not evenly distributed between links ge-1/1/0 and ge-4/3/1 of the aggregated interface ae0, probably due to the missing IP payload label.

Sample Output

user@R2> show configuration forwarding-options

hash-key {

    family mpls {

        label-1;

        label-2;

        payload {

            ip;

        }

    }

}

user@R2> show interfaces statistics ae0 detail

Physical interface: ae0, Enabled, Physical link is Up

  Interface index: 185, SNMP ifIndex: 289, Generation: 186

  Link-level type: Ethernet, MTU: 1514, Speed: 2000mbps, Loopback: Disabled, 
Source filtering: Disabled,

  Flow control: Disabled, Minimum links needed: 1

  Device flags   : Present Running

  Interface flags: SNMP-Traps Internal: 0x4000

  Current address: 00:90:69:0f:07:f0, Hardware address: 00:90:69:0f:07:f0

  Last flapped   : Never

  Statistics last cleared: Never

  Traffic statistics:

   Input  bytes  :              1000775                    0 bps

   Output bytes  :             79662734             30743104 bps

   Input  packets:                13273                    0 pps

   Output packets:              1168916                56512 pps

  Label-switched interface (LSI) traffic statistics:

   Input  bytes  :                    0                    0 bps

   Input  packets:                    0                    0 pps

  Input errors:

    Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Giants: 0, Policed 
discards: 0, Resource errors: 0

  Output errors:

  Carrier transitions: 0, Errors: 0, Drops: 0, MTU errors: 0, Resource errors: 0

  Ingress queues: 8 supported, 8 in use

  Queue counters:       Queued packets  Transmitted packets      Dropped packets

    0 best-effort                    0                    0                    0

    1 expedited-fo                   0                    0                    0

    2 assured-forw                   0                    0                    0

    3 network-cont                   0                    0                    0

  Egress queues: 8 supported, 8 in use

  Queue counters:       Queued packets  Transmitted packets      Dropped packets

    0 best-effort              1186217              1186219                    0

    1 expedited-fo                   0                    0                    0

    2 assured-forw                   0                    0                    0

    3 network-cont               13057                13057                    0

  Logical interface ae0.0 (Index 71) (SNMP ifIndex 292) (Generation 137)

    Flags: SNMP-Traps Encapsulation: ENET2

    Statistics        Packets        pps         Bytes          bps

    Bundle:

        Input :         13273          0       1000775            0

        Output:       1168916      56512      79662734     30743104

    Link:

      ge-1/1/0.0 #Packets are evenly distributed across aggregated interfaces

        Input :         13273          0       1000775            0

        Output:        610927      28256      41716580     15371728

      ge-4/3/1.0

        Input :             0          0             0            0

        Output:        557989      28256      37946154     15371376

    Marker Statistics:   Marker Rx     Resp Tx   Unknown Rx   Illegal Rx

      ge-1/1/0.0                 0           0            0            0

      ge-4/3/1.0                 0           0            0            0

    Protocol inet, MTU: 1500, Generation: 146, Route table: 0

      Flags: None

      Addresses, Flags: Is-Preferred Is-Primary

        Destination: 10.35.200.4/30, Local: 10.35.200.5, Broadcast: 10.35.200.7, 
Generation: 151

    Protocol iso, MTU: 1497, Generation: 147, Route table: 0

      Flags: Is-Primary

    Protocol mpls, MTU: 1488, Generation: 148, Route table: 0

      Flags: Is-Primary

What It Means

This sample output shows the configuration of the hash key and the interface statistics for the aggregated interface ae0. The hash-key configuration specifies the labels used for outbound traffic on different physical links of the aggregated interface. In this case, two labels and IP payload are included in the configuration. The sample output for the show interface statistics command shows the outgoing traffic rate, which is evenly distributed between links ge-1/1/0 and ge-4/3/1 of aggregated interface ae0. However, an even distribution may not always be the case because it depends on a lot of factors, which can be defined at the [edit forwarding-options] hierarchy level.

Sample Output

user@R2> show mpls lsp statistics

Ingress LSP: 0 sessions

Total 0 displayed, Up 0, Down 0

Egress LSP: 0 sessions

Total 0 displayed, Up 0, Down 0

Transit LSP: 9 sessions

To              From            State     Packets          Bytes LSPname

10.255.70.186   10.255.71.199   Up           1430         101943 to_R1_from_R3

10.255.71.199   10.255.70.186   Up          81745        5558550 to_R3_from_R1

10.255.71.199   10.255.70.186   Up          81748        5558768 to_R3_from_R1_1

10.255.71.199   10.255.70.186   Up          81760        5559492 to_R3_from_R1_2

10.255.71.199   10.255.70.186   Up         153259       10421488 to_R3_from_R1_3

10.255.71.199   10.255.70.186   Up         163509       11118573 to_R3_from_R1_4

10.255.71.199   10.255.70.186   Up         163453       11114666 to_R3_from_R1_5

10.255.71.199   10.255.70.186   Up         163450       11114554 to_R3_from_R1_6

10.255.71.199   10.255.70.186   Up         132785        9029356 to_R3_from_R1_7

Total 9 displayed, Up 9, Down 0

What It Means

This sample output shows that there are nine LSPs transiting R2. All are up and passing varying amounts of traffic.