R1#sho ip route 10.10.0.3% Subnet not in table We are running RIPv2 in the lab. While troubleshooting, we observed an ACL configured on R1’s F1/0 interface that blocks the RIP multicast packets/updates from R2. R1#show run int f1/0interface FastEthernet1/0 ip address 10.10.12.1 255.255.255.0  ip access-group 100 in R1#show ip access-lists 100Extended IP access list 100 10 […]

Route Redistribution Techniques: Redistribution is technique using which the boundary routers connecting different routing domains can exchange and advertise routing information. There are 2 methods of route redistribution. This method is also called one sided redistribution. In this method, we only use redistribute command only for one protocol. A default route is propagated into one […]

Route Redistribution in OSPF: Redistribution is a technique using which the boundary routers connecting different routing domains can exchange and advertise routing information. In this article, we will learn how to redistribute any routing protocol into OSPF. Below syntax is followed. The command has to be configured in router configuration mode for Route Redistribution in […]

Administrative Distance (AD) is an 8 bit value/number (Cisco) that defines trustworthiness of a route. AD has only local significance, and is not advertised in routing updates. Smaller the AD value of route/prefix, more preferred it is. Below is chart of AD values of protocols with respect to Cisco. If a router receives two updates […]

BGP Redistribute Internal: There is a slight difference in Route Redistribution from BGP to an IGP compared to route redistribution from an IGP to another IGP. By default, internal BGP or iBGP routes do not get redistributed into the IGPs OSPF or IS-IS. This blog explains what BGP Redistribute Internal concept is its related configuration. […]

EIGRP Packet Types: EIGRP has IP Protocol No. 88 and  runs on top of IP and hence is referred to as a Transport layer protocol. The Application layer protocols such as BGP, Telnet, FTP, etc, do not have any inbuilt reliability mechanism and therefore depend on TCP (Protocol No. 6) at the Transport layer to […]

BGP Best Path Selection Criteria is mechanism in BGP that helps finding the best path to a destination network. While you configure BGP (Border Gateway Protocol) between two peers, both the peers go through the various BGP Neighbor Adjaceny States and exchange a few BGP Messages to form the BGP Adjacency. As the BGP neighborship […]

Understanding of BGP States is important in order to understand How BGP Works. Just like the IGPs EIGRP, OSPF or ISIS, BGP also establishes a BGP Peering with other routers before exchanging any routing information. However, BGP does not use broadcast or multicast for the neighbor discovery. BGP is designed like that. Instead, the neighbors […]

BGP exchanges 4 different messages. These message are exchanged by BGP Peers to establish a connection, exchange network prefixes, maintain the status BGP connection and notify each other in case any error occurs. The 4 BGP Messages are listed below. Open Update Keepalive Notification  Important Note: Every BGP Message is divided into a header and […]

BGP BGP Messages BGP exchanges 4 different messages. These message are exchanged by BGP Peers to establish a connection, exchange network prefixes, maint… READ MORE » BGP BGP Best Path Selection Criteria BGP Best Path Selection Criteria is mechanism in BGP that helps finding the best path to a destination network. Whil… READ MORE » […]

Next-Hop Attribute shows some different behavior in shared media as well as in Non Broadcast Multi Access Networks. This Blog explains BGP Next-Hop in Shared Network. Below article will explain the both the behaviors in details with help of lab scenarios. When running BGP over a multiaccess network such as Ethernet, a BGP router uses […]

There are various compelling designs & architectures defined for SDN. This may include single vendor or multi vendor designs.  Majorly, whatever design a service provider may implement in its network, SDN technology centralizes the control of the network by separating the control plane and data plane for a particular networking device. To understand how SDN […]

A network enthusiast with vast experience in Enterprise and Service Provider domains. I have created this blog to share my knowledge and expertise to help the network aspirants. I can be contacted by writing to me at [email protected] for any of your queries. I also deliver coaching for CCIE (R&S and SP), CCNP, CCNA courses. […]

HomeISISISIS INTERVIEW QUESTIONS   What is attach-bit in ISIS?     Explain the format of an NSAP address.     What are CNSP packets? CSNP packets are similar to which packet type in OSPF?     What are PSNP packets? For what two purposes PSNP packets are forwarded?     Can L1 router form an adjacency with an L2 […]