Manual:MPLS
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General
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Summary
MikroTik RouterOS supports MPLS. All MikroTik RouterBOARD hardware products support MPLS.
General Porperties
| Property | Description |
|---|---|
| dynamic-label-range (range of integer[16..1048575]; Default: 16-1048575) | Range of Label numbers used for dynamic allocation. First 16 labels are reserved for special purposes (as defined in RFC). If you intend to configure labels statically then adjust dynamic default range not to include numbers that will be used in static configuration. |
| propagate-ttl (yes | no; Default: yes) | Whether to copy TTL values from IP header to MPLS header. If this option is set to no then hops inside MPLS cloud will be invisible from traceroutes. |
Forwarding Table
Sub-menu: /mpls forwarding-table
Entries in this sub-menu shows label bindings for specific routes that will be used in MPLS label switching. Properties in this menu are read-only
| Property | Description |
|---|---|
| bytes (integer) | Total number of packet bytes matched by this entry |
| destination (IP/Mask) | Destination prefix for which labels are assigned |
| in-label (integer) | Label number for incoming packet |
| interface (string) | |
| ldp (yes | no) | Whether labels are LDP signaled |
| nexthop (IP) | IP address of the nexthop |
| out-label (integer) | Label number which is added or switched to for outgoing packet. |
| packets (integer) | Number of packets matched by this entry |
| traffic-eng (yes | no) | Shows whether entry is signaled by RSVP-TE (Traffic Engineering) |
| vpls (yes | no) | Shows whether entry is used for VPLS tunnels. |
For example we have forwarding table as shown below.
[admin@RB493G] /mpls forwarding-table> print Flags: L - ldp, V - vpls, T - traffic-eng # IN-LABEL OUT-LABELS DESTINATION IN NEXTHOP 0 expl-null 1 L 105 10.255.255.36/32 lo 10.5.101.36 2 L 120 112 3.3.3.1/32 lo 10.5.101.3 3 L 121 113 3.3.3.2/32 lo 10.5.101.3 [admin@RB493G] /mpls forwarding-table>
You can see that all labels are LDP signaled. Note that for entry #1 there is no out-label, it means that MPLS label switching will not occur, packet will be sent out as regular IP packet. In the other hand entry #2 has in-label and out-label, which means that during packet forwarding label will be switched from 120 to 112.
Interface
Sub-menu: /mpls interface
This menu allows to configure MTUs including MPLS headers that interface can forward without fragmentation.
Note: If Ethernet card does not support Jumbo frames, then MPLS MTU for all interfaces on all devices participating in LSP should be set to 1500
Properties
| Property | Description |
|---|---|
| comment (string; Default: ) | Short description of the interface |
| disabled (yes | no; Default: no) | If set to yes then this configuration is ignored. |
| interface (string | all; Default: all) | Interface name to which apply settings. If set to all then the same config will be used for every interface if there is no specific configuration for the interface. |
| mpls-mtu (integer [512..65535]; Default: 1508) | Option represents how big packets can be carried over the interface with added MPLS labels. Read More >> |
In RouterOS by default have entry which sets MS MTU to 1508 for all interfaces.
[admin@RB493G] /mpls interface> print Flags: X - disabled # INTERFACE MPLS-MTU 0 all 1508
Local Bindings
Sub-menu: /mpls local-bindings
This sub-menu shows labels bound to the routes locally in the router
Properties
| Property | Description |
|---|---|
| comments (string; Default: ) | Short description of the entry |
| disabled (yes | no; Default: no) | |
| dst-address (IP/Mask; Default: ) | Destination prefix for which label is assigned |
| label (integer[0..1048576] | alert | expl-null | expl-null6 | impl-null | none; Default: ) | Label number assigned to destination. |
Read-only Properties
Remote Bindings
Sub-menu: /mpls remote-bindings
Sub-menu shows label bindings for routes received from other routers. This table is used to build Forwarding Table
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| Property | Description |
|---|---|
| adv-path () | |
| advertised (yes | no) | Whether binding was advertised to the neigbors |
| dynamic (yes | no) | Whether entry was dynamically added |
| egress (yes | no) | |
| gateway-route (yes | no) | Whether destination is reachable through the gateway. |
| local-route (yes | no) | Whether destination is locally reachable on the router |
| peers (IP:label_space) | IP address and label space of the peer to which this entry was advertised. |