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dhcp-relay doesn't need multiple interfaces
Open, Requires assessmentPublicBUG


The configuration of dhcp-relay expects multiple interface names to be listed. This is not required, doesn't work as specified in the documentation, and gives misleading error messages.

Specification of multiple interfaces causes isc-dhcp-relay to listen for DHCP client broadcast requests on those interfaces and has nothing to do with where those broadcasts are then sent.

When specifying a single interface, commit gives an error message:

user@router# commit
[ service dhcp-relay ]
WARNING: At least two interfaces are required for DHCP relay
to work

Work to be done:


Difficulty level
Easy (less than an hour)
Why the issue appeared?
Will be filled on close
Is it a breaking change?
Unspecified (possibly destroys the router)

Event Timeline

danfoster2 added a comment.EditedJan 21 2020, 3:24 PM

I've created a PR in the vyos/vyos-documentation repo for the documentation fix:

I've created a PR in the vyos/vyos-1x repy for the config verification fix:

pasik added a subscriber: pasik.Jan 21 2020, 8:07 PM

@dmbaturin @c-po
Not sure why did we merge these PRs. The isc-dhcp-relay does require at least two interfaces to work. This was discussed in details in T1276 and T2408.
As result the latest documentation is inaccurate what could make users confused.

Can you double check it?