Fast path allows to forward packets without additional processing in the Linux kernel. It improves forwarding speeds significantly.
For fast path to work, interface support and specific configuration conditions are required.
List of devices with FastPath support
Interface FastPath support can be checked by doing "/interface print detail" and seeing fast-path property value.
|RB7xx series||all ethernets|
|RB9xx series||all ethernets|
|RB2011 series||all ethernets and sfp|
|CRS series routers||all ethernets and sfps|
|CCR series routers||all ethernets and sfps|
|All devices||wireless interfaces, if wireless-fp or wireless-cm2 package used|
|bridge interfaces (since 6.29)|
|vlan, vrrp interfaces (since 6.30)|
|bonding interfaces - rx only (since 6.30)|
|eoip, gre, ipip interfaces (since 6.33). Eoip, gre, ipip interfaces have per interface setting "allow-fast-path". Allowing fast path on eoip, gre, ipip interfaces have side effect of bypassing firewall, connection tracking, simple queues, queue tree with parent=global, ip accounting, ipsec, hotspot universal client, vrf assignment for encapsulated packets that go trough fastpath. Note that allowing fast path for tunnel does not guarantee that all packets will go fastpath, so for slowpath packets regular processing happens as before|
Currently RouterOS has following fast path handlers:
- ipv4 fasttrack
- traffic generator
IPv4 fast path is automatically used if following conditions are met:
- firewal rules are not configured;
Traffic flow is disabledrestriction removed in 6.33;
/ip traffic-flow enabled=no
- Simple and queue trees with parent=global are not configured;
- no mesh, metarouter interface configuration;
- sniffer, torch and traffic generator is not running;
- connection tracking is not active;
- ip accounting is disabled (/ip accounting enabled=no);
- VRFs are not set (/ip route vrf is empty);
- Hotspot is not used (/ip hostspot has no interfaces);
- IpSec policies are not configured (ROS v6.8);
no active mac-ping, mac-telnet or mac-winbox sessionsrestriction removed in 6.33;
- /tool mac-scan is not actively used;
- /tool ip-scan is not actively used;
/ip firewall connection tracking set enabled parameter has new auto value Which means that connection tracking is disabled by default until firewall rules are added.
IPv4 FastTrack handler
FastTrack is available on the devices with FastPath support. FastTrack is FastPath+Connection Tracking. Detailed information about the FastTrack.
Traffic Generator handler
Traffic Generator fast path is automatically used for interfaces that support this feature.
MPLS fast path is automatically used for interfaces that support this feature.
Currently MPLS fast-path applies only to MPLS switched traffic (frames that enter router as MPLS and must leave router as MPLS) - MPLS ingress and egress (including VPLS tunnel endpoints that do VPLS encap/decap) will operate as before.
Bridge fast path is automatically used if following conditions are met:
- no bridge firewall rules (
/interface bridge filter, /interface bridge nat) are configured,
/interface bridge settings use-ip-firwall=no,
- no mesh, metarouter interface configuration,
- sniffer, torch and traffic generator is not running,