Step 3: Verify That Load Balancing Is Working

Purpose

After configuring load balancing, check that traffic is load-balanced equally across paths. In this section, the command output reflects the load-balancing configuration of the example network shown in Figure 10. The clear commands are used to reset LSP and interface counters to zero so that the values reflect the operation of the load-balancing configuration.

Action

To verify load balancing across interfaces and LSPs, use the following command on the ingress router:

user@host# show configuration

To verify load balancing across interfaces and LSPs, use the following commands on a transit router:

user@host# show route

user@host# show route forwarding-table

user@host# show mpls lsp statistics

user@host# monitor interface traffic

user@host# clear mpls lsp statistics

user@host# clear interface statistics

Sample Output

The following sample output is for the configuration on ingress router R1:

user@R1> show configuration | no-more 

[...Output truncated...]

routing-options {

    [...Output truncated...]

    forwarding-table {

        export lbpp;

    }

}

[...Output truncated...]

policy-options {

    policy-statement lbpp {

        then {

            load-balance per-packet;

        }

    }

}

What It Means

The sample output for the show configuration command on ingress router R1 shows that load balancing is correctly configured with the lbpp policy statement. Also, the lbpp policy is exported into the forwarding table at the [edit routing-options] hierarchy level.

Sample Output

The following sample output is from transit router R2:

user@R2> show route 192.168.0.1 terse 

inet.0: 25 destinations, 27 routes (25 active, 0 holddown, 0 hidden)

+ = Active Route, - = Last Active, * = Both

A Destination        P Prf   Metric 1   Metric 2  Next hop        AS path

* 192.168.0.1/32     O  10          3             so-0/0/1.0   

                                                 >so-0/0/2.0 

[...Output truncated...]

What It Means

The sample output for the show route command issued on transit router R2 shows the two equal-cost paths (so-0/0/1 and so-0/0/2) through the network to the loopback address to R0 (192.168.0.1). Even though the right angle bracket (>) usually indicates the active route, in this instance it does not, as shown in the following four sample outputs.

Sample Output

The following sample output is from transit router R2:

user@R2> monitor interface traffic

R2                                Seconds: 65                  Time: 11:41:14

Interface    Link  Input packets        (pps)     Output packets        (pps)

 so-0/0/0      Up              0          (0)                  0          (0)

 so-0/0/1      Up            126          (0)             164659       (2128)

 so-0/0/2      Up          85219       (1004)             164598       (2128)

 so-0/0/3      Up              0          (0)                  0          (0)

 fe-0/1/0      Up         328954       (4265)              85475       (1094)

 fe-0/1/1      Up              0          (0)                  0          (0)

 fe-0/1/2      Up              0          (0)                  0          (0)

 fe-0/1/3      Up              0          (0)                  0          (0)

[...Output truncated...]

What It Means

The sample output for the monitor interface traffic command issued on transit router R2 shows that output traffic is evenly distributed across the two interfaces so-0/0/1 and so-0/0/2.

Sample Output

The following sample output is from transit router R2:

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: 5 sessions

To              From            State     Packets            Bytes LSPname

192.168.0.1     192.168.1.1     Up          87997         17951388 lsp1

192.168.0.1     192.168.1.1     Up          87997         17951388 lsp2

192.168.0.1     192.168.1.1     Up          87997         17951388 lsp3

192.168.0.1     192.168.1.1     Up          87997         17951388 lsp4

192.168.6.1     192.168.0.1     Up              0                0 r0-r1

Total 5 displayed, Up 5, Down 0

What It Means

The sample output for the show mpls lsp statistics command issued on transit router R2 shows that output traffic is evenly distributed across the four LSPs configured on ingress router R6.

Sample Output

The following sample output is from transit router R2:

user@R2> show route forwarding-table destination 10.0.90.14 

Routing table: inet

Internet:

Destination        Type RtRef Next hop           Type Index NhRef Netif

10.0.90.12/30      user     0                    ulst 262144     6

                                                 ucst   345     5 so-0/0/1.0

                                                 ucst   339     2 so-0/0/2.0

What It Means

The sample output for the show route forwarding-table destination command issued on transit router R2 shows ulst in the Type field, which indicates that load balancing is working. The two unicast (ucst) entries in the Type field are the two next hops for the LSPs.

Sample Output

The following sample output is from transit router R2:

user@R2> show route forwarding-table | find mpls               

Routing table: mpls

MPLS:

Destination        Type RtRef Next hop           Type Index NhRef Netif

default            perm     0                    dscd    38     1

0                  user     0                    recv    37     3

1                  user     0                    recv    37     3

2                  user     0                    recv    37     3

100112             user     0                   Swap 100032       so-0/0/1.0

100128             user     0                   Swap 100048       so-0/0/1.0

100144             user     0 10.0.12.13        Swap 100096       fe-0/1/0.0

100160             user     0                   Swap 100112       so-0/0/2.0

100176             user     0                   Swap 100128       so-0/0/2.0

What It Means

The sample output for the show route forwarding-table | find mpls command issued on transit router R2 shows the MPLS routing table that contains the labels received and used by this router to forward packets to the next-hop router. This routing table is used mostly on transit routers to route packets to the next router along an LSP. The first three labels in the Destination column (Label 0, Label 1, and Label 2) are automatically entered by MPLS when the protocol is enabled. These labels are reserved MPLS labels defined in RFC 3032. Label 0 is the IPv4 explicit null label. Label 1 is the MPLS equivalent of the IP Router Alert label, and Label 2 is the IPv6 explicit null label.

The remaining five labels in the Destination column are nonreserved labels that the router uses to forward traffic, and the last column Netif, shows the interfaces used to send the labeled traffic. For nonreserved labels, the second Type column shows the operation performed on matching packets. In this example, all non-reserved packets are swapped for outgoing packet labels. For example, packets with the label 100112 have their label swapped for 100032 before they are pushed out of interface so-0/0/1.0.