OSPFv2 BR/BDR, Unnumbered Interface(Network Area, IP OSPF Area) Simple Concept.

1. Simple OSPF Parameters to Use

Before configuring the OSPF, I will handle some concept necessary to configure. For interface configuration, there is some term of network type. In this blog, those are compared simply.

In the above, DR/BDR terms are shown. If you did not study about the OSPF, it is not easy. DR has the role to share the OSPF information between the routers and switches. In this blog, it show simple diagram to explain about these.

DR make simple to share routing table information. Because of this, it is useful in Broadcast network. Howerver, I confuse about the Point to Multipoint concept. It looks like Broadcast. I refers this blog. It is different I need to annount the neighbor IP address with "Neighbor" or "Frame-relay" options.

 

2. Unnumbered Interfaces | net.ipv4.conf.<interface name>.rp_filter value=0

In fact, I did not realize this concept. I met the error message "Please remove network command first" during configure OSPF with FRR. In this post, there are some explain about this.

Unnumberd Interface improve the performance. I need to edit "net.ipv4.conf.<interface name>.rp_filter value=0" in the "/etc/sysctl.conf"

Because of this "unnumbered interface existance", FRRouting give some limitation. After network definition in router ospf part, I can not activate the interface for OSPF.

 

 

Reference

[ 1 ] https://docs.cumulusnetworks.com/cumulus-linux-37/Layer-3/Open-Shortest-Path-First-OSPF/

[ 2 ] https://www.freeccnaworkbook.com/workbooks/ccna/configuring-ospf-network-types

[ 3 ] https://www.fir3net.com/Networking/Protocols/ospf-the-dr-and-bdr-roles.html

[ 4 ] https://packetlife.net/blog/2008/jun/19/ospf-network-types/

[ 5 ] http://www.getnetworking.net/tutorials/ospf-point-to-multipoint-over-frame-relay

[ 11 ] https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_ospf/configuration/xe-16/iro-xe-16-book/iro-cfg.html