Category Archives: Networking


Terminology: RIB – Routing Information Base FIB – Forwarding Information Base RIB This is a routing protocols database of routing prefixes that could potentially be installed in the routing table. Derived from the control plane, it is not used for forwarding. Every protocol such as OSPF, EIGRP, BGP has its own RIB and select their… Read More »

BGP RIB-Failure

When a Router receives a BGP UPDATE packet that contains Network Layer Reachability Information (NLRI) – this is, a route; the packet is processed in the next order: – Step 1. BGP checks for the NLRI (prefix received) against any BGP inbound filter configured on the Router. – Step 2. If the NLRI is not… Read More »

BGP Aggregate experiment

The BGP aggregate-address can be used to summarise a set of networks into a single prefix. For this post, I just wanted to show the difference between aggregate-address and aggregate-address with summary only. We have below topology. I’m going to summarise prefixes in R1. R1 config hostname R1 ! interface GigabitEthernet0/0 ip address… Read More »

Cisco DHCP Server: Excluding IP Addresses

Most of the time in a small network, we will be using the Layer 3 device as a default gateway and a DHCP server. And most of the time also, we will be excluding the gateway’s ip address from the dhcp pool. Just to save 1 more configuration line and for the sake of knowledge,… Read More »

How to obtain the Base DN or Bind DN Attributes from Active Directory

Basics of Active Directory With LDAP syntax the Bind DN, or the user authenticating to the LDAP Directory, is derived by using LDAP syntax and going up the tree starting at the user component. For example, the user user1 is contained in the Users container, under the domain. The corresponding Bind DN will look like the following: CN=user1,CN=Users,DC=example,DC=com, but this will be… Read More »