From MikroTik Wiki
< SwOS
Revision as of 09:27, 22 January 2019 by Becs (talk | contribs) (Summary: CRS317 features)
Jump to: navigation, search


SwOS is an operating system designed specifically for administration of MikroTik switch products.

SwOS is configurable from your web browser. It gives you all the basic functionality for a managed switch, plus more: allows to manage port-to-port forwarding, broadcast storm control, apply MAC filter, configure VLANs, mirror traffic, apply bandwidth limitation and even adjust some MAC and IP header fields.


Warning: Each RouterBOARD switch series device has its own firmware which cannot be installed on other series models! CRS317-1G-16S+ supports SwOS v2.3 and newer.

CRS317 series features

  • Full non-blocking wirespeed switching
  • Up to 16k MAC entries in Host table
  • Forwarding Database works based on SVL or IVL
  • Port Isolation
  • Jumbo frame support - 10218 bytes
Spanning Tree Protocol
  • RSTP support
Link Aggregation
  • Supports 802.3ad LACP groups
  • Supports static link aggregation groups
  • Up to 16 link aggregation groups
  • Up to 8 member ports per a group
  • Hardware automatic failover and load balancing
Multicast Forwarding
  • IGMP Snooping support
  • Unknown Multicast Filtering
  • Port based mirroring
  • Fully compatible with IEEE802.1Q
  • Port based VLAN
  • Up to 250 VLAN entries (limited by SwOS)
  • VLAN filtering
  • Port Lock
  • Broadcast Storm Control
  • DHCP & PPPoE Snooping
Quality of Service (QoS)
  • Ingress traffic limiting
Access Control List
  • Ingress ACL tables
  • Up to 32 ACL rules (limited by SwOS)
  • Classification based on ports, L2, L3, L4 protocol header fields
  • ACL actions include filtering, forwarding and modifying of the protocol header fields

Connecting to the Switch

Open your web browser and enter IP address of your Switch ( by default) and login screen will appear.

Alt text
CRS317-1G-16S+ with loaded SwOS (CSS317-1G-16S+)

SwOS default IP address:, user name: admin and there is no password.


Note: MikroTik Neighbor Discovery protocol tools can be used to discover IP address of Mikrotik switch. Manual:IP/Neighbor_discovery. Currently LLDP is not supported.

Interface Overview

CRS317-1G-16S+ SwOS interface menu consists of multiple tabs: Link, SFP, SFP Status, Port Isolation, LAG, Forwarding, Stats, Errors, Histogram, VLAN, VLANs, Static Hosts, Hosts, SNMP, ACL, System and Upgrade.

Description of buttons in SwOS configuration tool:

  • Append - add new item to the end of the list
  • Apply All - applies current configuration changes
  • Cut - removes item from the list
  • Clear - resets properties of the item
  • Discard Changes - removes unsaved configuration
  • Insert - add new item to the list (places it before current item)
  • Sort - sort VLAN table by VLAN-IDs; sort host table by MAC addresses

  • Change Password - changes password of the switch
  • Logout - logout from current Switch
  • Reboot - reboot the switch
  • Reset Configuration - reset configuration back to factory defaults
  • Choose File - browse for upgrade or backup file
  • Upgrade - upgrade firmware of the Switch
  • Restore Backup - restore Switch using selected backup file
  • Save Backup - generate and download backup file from the Switch


System Tab performs the following functions:

  • General information about Switch
  • Switch management
  • Configuration reset
  • Backup and restore configuration


Note: SwOS uses a simple algorithm to ensure TCP/IP communication - it just replies to the same IP and MAC address packet came from. This way there is no need for Default Gateway on the device itself.

Alt text
CRS317-1G-16S+ General Settings

Property Description
IP AddressIP address of the switch
IdentityName of the switch (for Mikrotik Neighbor Discovery protocol)
Allow FromIP address from which the switch is accessible. Default value is '' - any address
Allow From PortsList of switch ports from which it is accessible
Allow From VLANVLAN ID from which the switch is accessible (VLAN Mode on ingress port must be other than disabled in order to connect)
WatchdogEnable or disable system Watchdog. It will reset CPU of the switch in case of fault condition
Independent VLAN LookupEnable or disable independent VLAN lookup in the Host table for packet forwarding
Mikrotik Discovery ProtocolEnable or disable Mikrotik Neighbor Discovery protocol
MAC AddressMAC address of the switch (Read-only)
Serial NumberSerial number of the switch (Read-only)
Board NameMikroTik model name of the switch (Read-only)
UptimeCurrent switch uptime (Read-only)

Health and Global RSTP

Alt text
CRS317-1G-16S+ Health and Global RSTP Settings

Property Description
TemperatureShows PCB temperature in celsius temperature scale (Read-only)
Property Description
Bridge Priority (hex)RSTP bridge priority for Root Bridge selection
Port Cost ModeThere are two methods for automatically detecting RSTP port cost depending on link speed.
  • short: 10G - 2; 1G - 4; 100M - 10; 10M - 100
  • long: 10G - 2000; 1G - 20000; 100M - 200000; 10M - 2000000
Root BridgeThe priority and MAC address of the selected Root Bridge in the network (Read-only)

Password and Backup

Alt text
CRS317-1G-16S+ System Management Settings


Link Tab allows you to:

  • Configure Ethernet and SFP+ ports
  • Monitor link status of Ethernet and SFP+ ports


Note: CRS317-1G-16S+ supports up to 10232 byte Jumbo frames when running SwOS.

Alt text
CRS317-1G-16S+ Link Settings

Property Description
EnabledEnable or disable port
NameEditable port name
Link StatusCurrent link status (Read-only)
Auto NegotiationEnable or disable auto negotiation
SpeedSpecify speed setting of the port (requires auto negotiation to be disabled)
Full DuplexSpecify duplex mode of the port (requires auto negotiation to be disabled)
Flow control Enable or disable 802.3x Flow control

SFP and SFP Status

SFP and SFP Status Tabs allow you to monitor status of SFP modules.

Alt text

Alt text
SFP Status Tab

Port Isolation

Port Isolation table allows or restricts traffic forwarding between specific ports.

Alt text
CRS317-1G-16S+ Port Isolation Tab

Note: It is possible to check/uncheck multiple checkboxes by checking one of them and then dragging horizontally (Click & Drag)


CRS317-1G-16S+ supports 802.3ad (LACP) compatible link aggregation as well as static link aggregation to ensure failover and load balancing based on Layer2 and Layer3 hashing.

Up to 16 link aggregation groups with up to 8 ports per a group are supported.

Alt text
CRS317-1G-16S+ LAG Tab

Each individual port can be configured as an passive, active or static LACP using the control protocol.

Property Description
Mode (default: passive) Specify LACP packet exchange mode between ports:
  • Passive: Place port in listening state, use LACP only when it's countrary port uses active LACP mode
  • Active: Prefer to start LACP regardless countrary port mode
  • Static: Place port in LACP mode=on
Property Description
GroupCreate static LACP group
Trunk (read only)Represents group number port belongs to.
Partner (read only)Represents partner mac-address.


Forwarding Tab provides advanced forwarding options among switch ports, port locking, port mirroring, bandwidth limit and broadcast storm control features.

Alt text
CRS317-1G-16S+ Forwarding Settings

Property Description
Port Lock
  • Port Lock - Enable or disable MAC address learning on this port
  • Lock On First - Enable or disable MAC address learning on this port (MAC address from the first received packet will still be learnt)
Port Mirroring
  • Mirror Ingress - Whether traffic entering this port must be copied and forwarded to mirroring target port
  • Mirror Egress - Whether traffic leaving this port must be copied and forwarded to mirroring target port
  • Mirror To - Mirroring target port
Broadcast Storm Control
  • Storm Rate (%) - Limit the number of broadcast packets transmitted by an interface. The rate is measured in percents of the link speed.
  • Include Unknown Unicast - Include unicast packets without an entry in host table in Storm Rate limitation
Bandwidth Limit
  • Ingress Rate - Limit traffic entering this port (bps)


Per port RSTP configuration and monitoring is available in the RSTP menu.

Alt text
CRS317-1G-16S+ RSTP Settings

Stats, Errors and Histogram

These menus provide detailed information about received and transmitted packets.

Alt text
CRS317-1G-16S+ Port Statistics
Alt text
CRS317-1G-16S+ Port Statistics
Alt text
CRS317-1G-16S+ Port Statistics

Note: Statistics for SFP+ interface are cleared whenever an active SFP+ link is established.


Port VLAN settings

Property Description
VLAN Mode (disabled | optional | enabled | strict; Default: optional) VLAN filtering mode, these options are relevant to egress ports (except for strict mode).
  • disabled - VLAN table is not used. Switch discards packets with a VLAN tag on egress ports. If the packet has a VLAN tag and the VLAN ID matches Default VLAN ID on egress ports, then with VLAN Receive=any the switch will remove the VLAN tag and forward the packet.
  • optional - Disabled VLAN filtering. Handle packets with VLAN tag ID that is not present in VLAN table just like packets without VLAN tag.
  • enabled - Enabled VLAN filtering. Drop packets with VLAN tag ID that is not present in VLAN table. Default VLAN ID must be specified for access ports since it will be used to tag ingress traffic and untag egress traffic for the certain port.
  • strict - Enabled VLAN filtering with additional ingress filtering, which checks if the ingress port is a member of the received VLAN ID in the VLAN table. Received packets on the ingress port with a VLAN ID that does not match with VLAN table will be dropped. Default VLAN ID must be specified for access ports since it will be used to tag ingress traffic and untag egress traffic for the certain port.
VLAN Receive (any | only tagged | only untagged; Default: any) Ingress traffic filtering based on VLAN tag presence.
  • any - Allows tagged and untagged packets on a certain port
  • only tagged - Allows only packets with a VLAN tag
  • only untagged - Allows only packets without a VLAN tag
Default VLAN ID (integer: 1..4095; Default: 1) VLAN ID which will be assigned on ingress traffic. Only has effect on untagged traffic, it will be ignored for tagged traffic. This parameter is usually used to allocate access ports with specific VLAN. It is also used to untag egress traffic if packet's VLAN ID matches Default VLAN ID.
Force VLAN ID (integer: yes | no; Default: no) Assigns the Default VLAN ID value to all ingress traffic (tagged and untagged). Has effect in all VLAN Modes. If port receives tagged traffic and Default VLAN ID is set to 1, then with this parameter the egress traffic will be untagged.

VLAN table settings

Property Description
VLAN ID (integer: 1..4095; Default: 0) VLAN ID to which assign ports.
Port Isolation (yes | no; Default: yes) Use settings from Port Isolation menu to isolate the defined VLAN to only certain ports. When disabled, the switch will ignore port isolation configuration and forward traffic with the defined VLAN ID only to ports that are checked as members.
Learning (yes | no; Default: yes) Enables or disables MAC address learning on the defined VLAN. If disabled, then all learned MAC addresses will appear as they have had been learned from VLAN 1.
Mirror (yes | no; Default: no) Enables or disables VLAN based mirroring. When enabled and Mirror To is set in the Forwarding menu, then all traffic from the defined VLAN will be mirrored to the selected port.
IGMP Snooping (yes | no; Default: no) Enables or disables IGMP Snooping on the defined VLAN. When enabled, the switch will listen to IGMP Join and Leave requests from the defined VLAN and only forward traffic to ports, which have sent IGMP membership requests from the defined VLAN. When disabled, the switch will flood all VLAN member ports with Multicast traffic.
Members (ports; Default: none) Group of ports, which are allowed to forward traffic on the defined VLAN.

VLAN configuration for switch ports.

Alt text
CRS317-1G-16S+ Port VLAN Settings

VLAN membership configuration for switch ports.

Alt text
CRS317-1G-16S+ VLAN Membership Settings

Static Hosts

Static host table entries. Static entries will take over dynamic if dynamic entry with same mac-address already exists. Also by adding a static entry you get access to some more functionality.

Alt text
CRS317-1G-16S+ Static Host Table


This table represents dynamically learnt MAC address to port mapping entries. When Switch receives a packet from certain port, it adds the packets source MAC address and port it received the packet from to host table, so when a packet comes in with certain destination MAC address it knows to which port it should forward the packet. If the destination MAC address is not present in host table then it forwards the packet to all ports in the group. Dynamic entries take about 5 minutes to time out. CRS317-1G-16S+ supports 16383 host table entries.

Alt text
CRS317-1G-16S+ Host table

IGMP Snooping

IGMP Snooping which controls multicast streams and prevents multicast flooding is implemented in SwOS starting from version 2.5. The feature allows a switch to listen in the IGMP conversation between hosts and routers.

Enable option under System tab.

Alt text
IGMP Snooping under System tab

Available IGMP snooping data:

  • Group Adress
  • VLAN
  • Member Ports
Alt text
CRS/CSS3XX series IGMP Snooping

Possibility to enable IGMP Snooping for specific VLAN ID.

Alt text
CRS/CSS3XX series IGMP Snooping


SwOS supports SNMP v1 and uses IF-MIB, SNMPv2-MIB and BRIDGE-MIB for SNMP reporting.

Available SNMP data:

  • System information
  • System uptime
  • Port status
  • Interface statistics
  • Host table information
Alt text
SNMP settings
Property Description
EnabledEnable or disable SNMP service
CommunitySNMP community name
Contact InfoContact information for the NMS
LocationLocation information for the NMS


An access control list (ACL) rule table is very powerful tool allowing wire speed packet filtering, forwarding and VLAN tagging based on L2,L3 protocol header field conditions.

CRS317-1G-16S+ ACL table

Each rule contains a conditions part and an action part.

Conditions part parameters

Property Description
FromPort that packet came in from
MAC SrcSource MAC address and mask
MAC DstDestination MAC address and mask
EthertypeProtocol encapsulated in the payload of an Ethernet Frame

VLAN header presence:

  • any
  • present
  • not present
PriorityPriority in VLAN tag
IP Src (IP/netmask:port)Source IPv4 address, netmask and L4 port number
IP Dst (IP/netmask:port)Destination IPv4 address, netmask and L4 port number
ProtocolIP protocol

Action part parameters

Property Description
Redirect ToForce new packets destination port
MirrorClones packet and sends it to mirror-target port
RateLimits bandwidth (bps)
DropDrop packet
Set VLAN IDChanges the VLAN tag ID, if VLAN tag is present
PriorityChanges the VLAN tag priority bits, if VLAN tag is present

Dual Boot

“Dual Boot” feature allows you to choose which operating system you prefer to use, RouterOS or SwOS. Boot RouterOS option is under System tab:

Alt text
Boot RouterOS option

Alternative Dual Boot possibilities: Dual Boot manual

Reset and Reinstall

CRS317-1G-16S+ has built-in backup SwOS firmware which can be loaded in case standard firmware breaks or upgrade fails:

  • Holding Reset button for few seconds while CRS317-1G-16S+ is booting resets configuration and loads backup firmware SwOS 2.3p.
  • After loading backup firmware SwOS 2.3p it is possible to connect to using web browser and install new SwOS firmware.