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Need 'nopmtudisc' option for tunnel interface
Closed, ResolvedPublicFEATURE REQUEST

Description

Need 'nopmtudisc' option for tunnel interface. This is required for MPLS over gre or Ethernet over gre applications. This option is described in the iproute2 manuals (ip-tunnel).

Details

Difficulty level
Normal (likely a few hours)
Version
-
Why the issue appeared?
Will be filled on close
Is it a breaking change?
Perfectly compatible

Related Objects

Event Timeline

daniil created this object in space S1 VyOS Public.
daniil mentioned this in T915: MPLS Support.

Proposed CLI

set interfaces tunnel tun0 parameters ip disable-pmtu-discovery

or

set interfaces tunnel tun0 parameters ip pmtu-discovery-disable

I'd personally recommend "pmtu-discovery-disable", but either would be fine.

As far as i know all our other "disable" commands starts wirh "disable-"

@runar we also added no- in the 1.3 series, so I'd prefer: set interfaces tunnel tun0 parameters ip disable-pmtu-discovery or set interfaces tunnel tun0 parameters ip no-pmtu-discovery

PR https://github.com/vyos/vyos-1x/pull/676

It is difficult to do in this performance this option as "valueless" because all tunnel options defined in tunnel.py interfaces-tunnel.py "IP route" format "ip tunnel add ttl/tos/key/etc"
When an option has already been passed to the tunnel.py script, it checks its value anyway.
So I should use enable/disable style

set interfaces tunnel tun0 address '10.5.2.1/30'
set interfaces tunnel tun0 encapsulation 'gre'
set interfaces tunnel tun0 local-ip '192.168.122.15'
set interfaces tunnel tun0 multicast 'enable'
set interfaces tunnel tun0 parameters ip ttl '0'
set interfaces tunnel tun0 remote-ip '192.168.122.1'
set interfaces tunnel tun0 parameters ip pmtu-discovery 'disable'

Check

vyos@r5-roll# sudo ip -d tunnel show tun0
tun0: gre/ip remote 192.168.122.1 local 192.168.122.15 ttl inherit tos inherit nopmtudisc
[edit]
vyos@r5-roll#

CLI command will be: set interfaces tunnel tun10 parameters ip no-pmtu-discovery, Also PMTU can not be changed in IPv6 sourced tunnels, a validation check has been added.

Should be backported to 1.3 equuleus branch after it's confirmed properly working.

c-po changed the task status from Open to Needs testing.Jan 15 2021, 6:37 PM
c-po claimed this task.
c-po triaged this task as Low priority.
c-po changed Difficulty level from Easy (less than an hour) to Normal (likely a few hours).
c-po changed Is it a breaking change? from Unspecified (possibly destroys the router) to Perfectly compatible.

'nopmtudisc' option still not present

set interfaces tunnel tun0 address '10.0.0.1/30'
set interfaces tunnel tun0 encapsulation 'gre'
set interfaces tunnel tun0 local-ip '192.0.2.55'
set interfaces tunnel tun0 parameters ip no-pmtu-discovery
set interfaces tunnel tun0 remote-ip '192.0.2.254'

Check

vyos@r5-roll# sudo ip -d tunnel show tun0
tun0: gre/ip remote 192.0.2.254 local 192.0.2.55 ttl inherit
c-po reopened this task as Backport candidate.
c-po edited projects, added VyOS 1.4 Sagitta; removed VyOS 1.2 Crux.
c-po moved this task from Need Triage to Finished on the VyOS 1.4 Sagitta board.
c-po removed a project: VyOS 1.3 Equuleus.