Description

On QFX5130 Series devices that are running Junos EVO, users may see the next-hop type as "sftw" in the output of the show route forwarding-table command.

This article explains what the "sftw" next-hop type means.

Symptoms

The next-hop type is indicated as "sftw" in the output of show route forwarding-table as shown below:

jtac-QFX5130-32CD-r002 et-0/0/32 10.10.10.1/24 --------10.10.10.2/24 et-0/0/32 jtac-QFX5130-32CD-r003

[edit]
root@jtac-QFX5130-32CD-r002# run show route forwarding-table | grep sftw
default            user     0                    sftw     7021     1 re0:mgmt-0.0
200.0.0.2/32       user     0                    sftw     7022     1 et-0/0/32.0

[edit]
root@jtac-QFX5130-32CD-r003# run show route forwarding-table | grep sftw
default            user     0                    sftw     5021     1 re0:mgmt-0.0
200.0.0.1/32       user     0                    sftw     5022     1 et-0/0/32.0

Solution

In Junos EVO, "sftw" has been introduced as another type of next-hop. Note that this next-hop type has been introduced only in EVO and not in Junos OS and is therefore expected to be seen in Junos EVO.

A software next-hop can contain a link to another single next-hop, and hence it often works very much like an indirect next-hop. It is seen that this usage helps to reduce churn in Junos EVO objects by providing a common object where topology updates can be reflected. Further MPLS states can also be attached to these software next-hops.

A route that points to a management interface will also use a software next-hop. In this use case, the software next-hop will not point to another next-hop, but will have a flag bit set to indicate that the next-hop is private (in other words, unlike an indirect next-hop, a software next-hop does not need to link to another next-hop).

rpd-agent creates SoftwareNexthop , which contains ip-address that needs to be resolved.

So, when a route is created, an "sftw" next-hop seems to be created whether it is the management port or the loopback interface.

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