From 4a163b016333e58fee9d6ec6b53a09e0160b3213 Mon Sep 17 00:00:00 2001 From: Christian Breunig Date: Wed, 22 Nov 2023 10:52:40 +0100 Subject: vxlan: T5759: change default MTU from 1450 -> 1500 bytes Found an odd behavior on Linux and the VyOS CLI implementation. If adding VXLAN interfaces using iproute2 the MTU differs depending on the creation syntax: ip -4 link add vxlan100 type vxlan dstport 4789 external df unset tos inherit \ ttl 16 nolearning vnifilter local 172.16.33.201 ip -4 link add vxlan200 type vxlan id 200 dstport 4789 local 172.16.33.201 dev eth0 ip -6 link add vxlan300 type vxlan id 300 dstport 4789 local 2001:db8:1::1 dev eth0 132: vxlan300: mtu 1430 qdisc noop state DOWN group default qlen 1000 link/ether 4e:fb:e3:f5:d9:59 brd ff:ff:ff:ff:ff:ff 133: vxlan200: mtu 1450 qdisc noop state DOWN group default qlen 1000 link/ether 0e:4e:f4:76:59:3f brd ff:ff:ff:ff:ff:ff 134: vxlan100: mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether ba:b6:b7:0c:b1:37 brd ff:ff:ff:ff:ff:ff VyOS always sets a default MTU of 1450 bytes which is correct for IPv4 p2p links or multicast, but invalid for IPv6 p2p. Also this will break EVPN deployments as ethernet bridges with MTU < 1500 bytes are less fun. Increase default MTU to 1500 bytes. Migrate old configurations to use 1450 bytes if not specified otherwise on the CLI. --- smoketest/scripts/cli/base_interfaces_test.py | 3 +-- smoketest/scripts/cli/test_interfaces_vxlan.py | 15 +++++++++------ 2 files changed, 10 insertions(+), 8 deletions(-) (limited to 'smoketest') diff --git a/smoketest/scripts/cli/base_interfaces_test.py b/smoketest/scripts/cli/base_interfaces_test.py index da196133a..3f42196f7 100644 --- a/smoketest/scripts/cli/base_interfaces_test.py +++ b/smoketest/scripts/cli/base_interfaces_test.py @@ -412,10 +412,9 @@ class BasicInterfaceTest: for intf in self._interfaces: base = self._base_path + [intf] - self.cli_set(base + ['mtu', self._mtu]) - for option in self._options.get(intf, []): self.cli_set(base + option.split()) + self.cli_set(base + ['mtu', self._mtu]) # check validate() - can not set low MTU if 'no-default-link-local' # is not set on CLI diff --git a/smoketest/scripts/cli/test_interfaces_vxlan.py b/smoketest/scripts/cli/test_interfaces_vxlan.py index be1fa9d7f..18676491b 100755 --- a/smoketest/scripts/cli/test_interfaces_vxlan.py +++ b/smoketest/scripts/cli/test_interfaces_vxlan.py @@ -18,6 +18,7 @@ import unittest from vyos.configsession import ConfigSessionError from vyos.ifconfig import Interface +from vyos.ifconfig import Section from vyos.utils.network import get_bridge_fdb from vyos.utils.network import get_interface_config from vyos.utils.network import interface_exists @@ -32,12 +33,13 @@ class VXLANInterfaceTest(BasicInterfaceTest.TestCase): cls._base_path = ['interfaces', 'vxlan'] cls._options = { 'vxlan10': ['vni 10', 'remote 127.0.0.2'], - 'vxlan20': ['vni 20', 'group 239.1.1.1', 'source-interface eth0'], + 'vxlan20': ['vni 20', 'group 239.1.1.1', 'source-interface eth0', 'mtu 1450'], 'vxlan30': ['vni 30', 'remote 2001:db8:2000::1', 'source-address 2001:db8:1000::1', 'parameters ipv6 flowlabel 0x1000'], 'vxlan40': ['vni 40', 'remote 127.0.0.2', 'remote 127.0.0.3'], 'vxlan50': ['vni 50', 'remote 2001:db8:2000::1', 'remote 2001:db8:2000::2', 'parameters ipv6 flowlabel 0x1000'], } cls._interfaces = list(cls._options) + cls._mtu = '1450' # call base-classes classmethod super(VXLANInterfaceTest, cls).setUpClass() @@ -139,7 +141,7 @@ class VXLANInterfaceTest(BasicInterfaceTest.TestCase): def test_vxlan_vlan_vni_mapping(self): bridge = 'br0' interface = 'vxlan0' - source_interface = 'eth0' + source_address = '192.0.2.99' vlan_to_vni = { '10': '10010', @@ -152,8 +154,7 @@ class VXLANInterfaceTest(BasicInterfaceTest.TestCase): } self.cli_set(self._base_path + [interface, 'parameters', 'external']) - self.cli_set(self._base_path + [interface, 'parameters', 'vni-filter']) - self.cli_set(self._base_path + [interface, 'source-interface', source_interface]) + self.cli_set(self._base_path + [interface, 'source-address', source_address]) for vlan, vni in vlan_to_vni.items(): self.cli_set(self._base_path + [interface, 'vlan-to-vni', vlan, 'vni', vni]) @@ -189,11 +190,12 @@ class VXLANInterfaceTest(BasicInterfaceTest.TestCase): def test_vxlan_neighbor_suppress(self): bridge = 'br555' interface = 'vxlan555' - source_interface = 'eth0' + source_interface = 'dum0' + + self.cli_set(['interfaces', Section.section(source_interface), source_interface, 'mtu', '9000']) self.cli_set(self._base_path + [interface, 'parameters', 'external']) self.cli_set(self._base_path + [interface, 'source-interface', source_interface]) - self.cli_set(self._base_path + [interface, 'parameters', 'neighbor-suppress']) # This must fail as this VXLAN interface is not associated with any bridge @@ -223,6 +225,7 @@ class VXLANInterfaceTest(BasicInterfaceTest.TestCase): self.assertTrue(tmp['linkinfo']['info_slave_data']['learning']) self.cli_delete(['interfaces', 'bridge', bridge]) + self.cli_delete(['interfaces', Section.section(source_interface), source_interface]) def test_vxlan_vni_filter(self): interfaces = ['vxlan987', 'vxlan986', 'vxlan985'] -- cgit v1.2.3