GENEVE

GENEVE supports all of the capabilities of VXLAN, NVGRE, and STT and was designed to overcome their perceived limitations. Many believe GENEVE could eventually replace these earlier formats entirely.

GENEVE is designed to support network virtualization use cases, where tunnels are typically established to act as a backplane between the virtual switches residing in hypervisors, physical switches, or middleboxes or other appliances. An arbitrary IP network can be used as an underlay although Clos networks - A technique for composing network fabrics larger than a single switch while maintaining non-blocking bandwidth across connection points. ECMP is used to divide traffic across the multiple links and switches that constitute the fabric. Sometimes termed “leaf and spine” or “fat tree” topologies.

Geneve Header:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver|  Opt Len  |O|C|    Rsvd.  |          Protocol Type        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|        Virtual Network Identifier (VNI)       |    Reserved   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Variable Length Options                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Configuration

Common interface configuration

set interfaces geneve <interface> address <address>

Configure interface <interface> with one or more interface addresses.

  • address can be specified multiple times as IPv4 and/or IPv6 address, e.g. 192.0.2.1/24 and/or 2001:db8::1/64

Example:

set interfaces geneve gnv0 address 192.0.2.1/24
set interfaces geneve gnv0 address 2001:db8::1/64
set interfaces geneve <interface> description <description>

Set a human readable, descriptive alias for this connection. Alias is used by e.g. the show interfaces command or SNMP based monitoring tools.

Example:

set interfaces geneve gnv0 description 'This is an awesome interface running on VyOS'
set interfaces geneve <interface> disable

Disable given <interface>. It will be placed in administratively down (A/D) state.

Example:

set interfaces geneve gnv0 disable
set interfaces geneve <interface> disable-flow-control

Ethernet flow control is a mechanism for temporarily stopping the transmission of data on Ethernet family computer networks. The goal of this mechanism is to ensure zero packet loss in the presence of network congestion.

The first flow control mechanism, the pause frame, was defined by the IEEE 802.3x standard.

A sending station (computer or network switch) may be transmitting data faster than the other end of the link can accept it. Using flow control, the receiving station can signal the sender requesting suspension of transmissions until the receiver catches up.

Use this command to disable the generation of Ethernet flow control (pause frames).

Example:

set interfaces geneve gnv0 disable-flow-control
set interfaces geneve <interface> disable-link-detect

Use this command to direct an interface to not detect any physical state changes on a link, for example, when the cable is unplugged.

Default is to detects physical link state changes.

Example:

set interfaces geneve gnv0 disable-link-detect
set interfaces geneve <interface> mac <xx:xx:xx:xx:xx:xx>

Configure user defined MAC address on given <interface>.

Example:

set interfaces geneve gnv0 mac '00:01:02:03:04:05'
set interfaces geneve <interface> mtu <mtu>

Configure MTU on given <interface>. It is the size (in bytes) of the largest ethernet frame sent on this link.

Example:

set interfaces geneve gnv0 mtu 9000
set interfaces geneve <interface> ip arp-cache-timeout

Once a neighbor has been found, the entry is considered to be valid for at least for this specifc time. An entry’s validity will be extended if it receives positive feedback from higher level protocols.

This defaults to 30 seconds.

Example:

set interfaces geneve gnv0 ip arp-cache-timeout 180
set interfaces geneve <interface> ip disable-arp-filter

If set the kernel can respond to arp requests with addresses from other interfaces. This may seem wrong but it usually makes sense, because it increases the chance of successful communication. IP addresses are owned by the complete host on Linux, not by particular interfaces. Only for more complex setups like load-balancing, does this behaviour cause problems.

If not set (default) allows you to have multiple network interfaces on the same subnet, and have the ARPs for each interface be answered based on whether or not the kernel would route a packet from the ARP’d IP out that interface (therefore you must use source based routing for this to work).

In other words it allows control of which cards (usually 1) will respond to an arp request.

Example:

set interfaces geneve gnv0 ip disable-arp-filter
set interfaces geneve <interface> ip disable-forwarding

Configure interface-specific Host/Router behaviour. If set, the interface will switch to host mode and IPv6 forwarding will be disabled on this interface.

set interfaces geneve gnv0 ip disable-forwarding
set interfaces geneve <interface> ip enable-arp-accept

Define behavior for gratuitous ARP frames who’s IP is not already present in the ARP table. If configured create new entries in the ARP table.

Both replies and requests type gratuitous arp will trigger the ARP table to be updated, if this setting is on.

If the ARP table already contains the IP address of the gratuitous arp frame, the arp table will be updated regardless if this setting is on or off.

set interfaces geneve gnv0 ip enable-arp-accept
set interfaces geneve <interface> ip enable-arp-announce

Define different restriction levels for announcing the local source IP address from IP packets in ARP requests sent on interface.

Use any local address, configured on any interface if this is not set.

If configured, try to avoid local addresses that are not in the target’s subnet for this interface. This mode is useful when target hosts reachable via this interface require the source IP address in ARP requests to be part of their logical network configured on the receiving interface. When we generate the request we will check all our subnets that include the target IP and will preserve the source address if it is from such subnet. If there is no such subnet we select source address according to the rules for level 2.

set interfaces geneve gnv0 ip enable-arp-announce
set interfaces geneve <interface> ip enable-arp-ignore

Define different modes for sending replies in response to received ARP requests that resolve local target IP addresses:

If configured, reply only if the target IP address is local address configured on the incoming interface.

If this option is unset (default), reply for any local target IP address, configured on any interface.

set interfaces geneve gnv0 ip enable-arp-ignore
set interfaces geneve <interface> ip enable-proxy-arp

Use this command to enable proxy Address Resolution Protocol (ARP) on this interface. Proxy ARP allows an Ethernet interface to respond with its own MAC address to ARP requests for destination IP addresses on subnets attached to other interfaces on the system. Subsequent packets sent to those destination IP addresses are forwarded appropriately by the system.

Example:

set interfaces geneve gnv0 ip enable-proxy-arp
set interfaces geneve <interface> ip proxy-arp-pvlan

Private VLAN proxy arp. Basically allow proxy arp replies back to the same interface (from which the ARP request/solicitation was received).

This is done to support (ethernet) switch features, like RFC 3069, where the individual ports are NOT allowed to communicate with each other, but they are allowed to talk to the upstream router. As described in RFC 3069, it is possible to allow these hosts to communicate through the upstream router by proxy_arp’ing.

Note

Does not need to be used together with proxy_arp.

This technology is known by different names:

  • In RFC 3069 it is called VLAN Aggregation
  • Cisco and Allied Telesyn call it Private VLAN
  • Hewlett-Packard call it Source-Port filtering or port-isolation
  • Ericsson call it MAC-Forced Forwarding (RFC Draft)
set interfaces geneve <interface> ip source-validation <strict | loose | disable>

Enable policy for source validation by reversed path, as specified in RFC 3704. Current recommended practice in RFC 3704 is to enable strict mode to prevent IP spoofing from DDos attacks. If using asymmetric routing or other complicated routing, then loose mode is recommended.

  • strict: Each incoming packet is tested against the FIB and if the interface is not the best reverse path the packet check will fail. By default failed packets are discarded.
  • loose: Each incoming packet’s source address is also tested against the FIB and if the source address is not reachable via any interface the packet check will fail.
  • disable: No source validation
set interfaces geneve <interface> ipv6 address autoconf

SLAAC RFC 4862. IPv6 hosts can configure themselves automatically when connected to an IPv6 network using the Neighbor Discovery Protocol via ICMPv6 router discovery messages. When first connected to a network, a host sends a link-local router solicitation multicast request for its configuration parameters; routers respond to such a request with a router advertisement packet that contains Internet Layer configuration parameters.

Note

This method automatically disables IPv6 traffic forwarding on the interface in question.

Example:

set interfaces geneve gnv0 ipv6 address autoconf
set interfaces geneve <interface> ipv6 address eui64 <prefix>

EUI-64 as specified in RFC 4291 allows a host to assign iteslf a unique 64-Bit IPv6 address.

Example:

set interfaces geneve gnv0 ipv6 address eui64 2001:db8:beef::/64
set interfaces geneve <interface> ipv6 address no-default-link-local

Do not assign a link-local IPv6 address to this interface.

Example:

set interfaces geneve gnv0 ipv6 address no-default-link-local
set interfaces geneve <interface> ipv6 disable-forwarding

Configure interface-specific Host/Router behaviour. If set, the interface will switch to host mode and IPv6 forwarding will be disabled on this interface.

Example:

set interfaces geneve gnv0 ipv6 disable-forwarding
set interfaces geneve <interface> vrf <vrf>

Place interface in given VRF instance.

See also

There is an entire chapter about how to configure a VRF, please check this for additional information.

Example:

set interfaces geneve gnv0 vrf red

GENEVE options

set interfaces geneve gnv0 remote <address>
Configure GENEVE tunnel far end/remote tunnel endpoint.
set interfaces geneve gnv0 vni <vni>
VNI is an identifier for a unique element of a virtual network. In many situations this may represent an L2 segment, however, the control plane defines the forwarding semantics of decapsulated packets. The VNI MAY be used as part of ECMP forwarding decisions or MAY be used as a mechanism to distinguish between overlapping address spaces contained in the encapsulated packet when load balancing across CPUs.