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Inter-area route summarization can be configured from OSPF area range menu.
Let's consider that we have two areas backbone and area1, area1 has several /24 routes from the 10.0.0.0/16 range and there is no need to flood the backbone area with each /24 subnet if it can be summarised. On the router connecting area1 with the backbone we can set up area range:
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| Property | Description |
|---|---|
| domain-id (Hex | Address) | MPLS-related parameter. Identifies the OSPF domain of the instance. This value is attached to OSPF routes redistributed in BGP as VPNv4 routes as BGP extended community attribute and used when BGP VPNv4 routes are redistributed back to OSPF to determine whether to generate inter-area or AS-external LSA for that route. By default Null domain-id is used, as described in RFC 4577. |
| domain-tag (integer [0..4294967295]) | if set, then used in route redistribution (as route-tag in all external LSAs generated by this router), and in route calculation (all external LSAs having this route tag are ignored). Needed for interoperability with older Cisco systems. By default not set. |
| in-filter (string) | name of the routing filter chain used for incoming prefixes |
| mpls-te-address (string) | the area used for MPLS traffic engineering. TE Opaque LSAs are generated in this area. No more than one OSPF instance can have mpls-te-area configured. |
| mpls-te-area (string) | the area used for MPLS traffic engineering. TE Opaque LSAs are generated in this area. No more than one OSPF instance can have mpls-te-area configured. |
| originate-default (always | if-installed | never; Default: never) | Specifies default route (0.0.0.0/0) distribution method. |
| out-filter-chain (name) | name of the routing filter chain used for outgoing prefixes filtering |
| out-filter-select (name) | name of the routing filter select chain, used for output selection |
| redistribute (bgp,connected,copy,dhcp,fantasy,modem,ospf,rip,static,vpn; ) | Enable redistribution of specific route types. |
| router-id (IP | name; Default: main) | OSPF Router ID. Can be set explicitly as an IP address, or as the name of the router-id instance. |
| version (2 | 3; Default: 2) | OSPF version this instance will be running (v2 for IPv4, v3 for IPv6). |
| vrf (name of a routing table; Default: main) | the VRF table this OSPF instance operates on |
| use-dn (yes | no) | Forces to use or ignore DN bit. Useful in some CE PE scenarios to inject intra-area routes into VRF. If a parameter is unset then the DN bit is used according to RFC. Available since v6rc12. |
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| Property | Description |
|---|---|
| address (IP) | An IP address of the OSPF neighbor router |
| adjacency (time) | Elapsed time since adjacency was formed |
| area (string) | |
| bdr (string) | An IP address of the Backup Designated Router |
| comment (string) | |
| db-summaries (integer) | |
| dr (IP) | An IP address of the Designated Router |
| dynamic (yes | no) | |
| inactive (yes | no) | |
| instance (string) | |
| ls-requests (integer) | |
| ls-retransmits (integer) | |
| priority (integer) | Priority configured on the neighbor |
| router-id (IP) | neighbor router's RouterID |
| state (down | attempt | init | 2-way | ExStart | Exchange | Loading | full) |
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| state-changes (integer) | Total count of OSPF state changes since neighbor identification |
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| Property | Description |
|---|---|
| address (IP%iface; mandatory ) | The unicast IP address and an interface that can be used to reach the IP of the neighbor. For example, address=1.2.3.4%ether1 indicates that a neighbor with IP 1.2.3.4 is reachable on the ether1 interface. |
| area (name; mandatory ) | Name of the area the neighbor belongs to. |
| comment (string) | |
| disabled (yes | no) | |
| instance-id (integer [0..255]; Default: 0) | |
| poll-interval (time; Default: 2m) | How often to send hello messages to the neighbors which are in a "down" state (i.e. there is no traffic from them) |
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Sub-menu: /routing ospf sham-link
Description
A sham-link is required between any two VPN sites that belong to the same OSPF area and share an OSPF backdoor link. If there is no intra-area link between the CE routers, you do not need to configure an OSPF sham link.
Sham link configuration example
Sham link must be configured on both sides.
For a sham link to be active, two conditions must be met:
- src-address is a valid local address with /32 netmask in the OSPF instance's routing table.
- there is a valid route to dst-address in the OSPF instance's routing table.
When the sham link is active, hello packets are sent on it only until the neighbor reaches the full state. After that, the hello packet sent on the sham link is suppressed.
RouterOS does not support periodic LSA refresh suppression on sham-links yet.