BGP Route Refresh Capability

Service Providers or Large enterprises commonly change routing policies from time to time, specially when adding new links or peering relationships with other entities. When you change the inbound policy of your BGP speaker you need to reprocess the updates you received from that peer. BGP4 has no mechanism of requesting a re-advertisements from one of its peers. One solution to this problem is to store the received information local on the router and reprocess them without the need to refer to the peer who sent these updates. This option consumes a lot of resources on the router when you …

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IS-IS MTU Mismatch

IS-IS is a link-state routing protocol, it uses the concept of distributed map/database and local computation , each router originates an LSP to describes himself , this LSP carries links and topological information, reach router on the domain generates its own LSP and relays other routers LSPs untouched (With respect to the Level that the LSP originated in) this information is used to build up the distributed map, a local computation is then performed on the database to extract IP reachability information to formalize the forwarding plane. What is the problem? IS-IS is an extended protocol by nature, Initially it …

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BGP 4-Byte ASN

The internet growth is awesome, day by day people recognizes how  internet is important in their daily personal  and business life and even for their culture, so the internet has a good bit of newbie everyday which depleted some internet resources such as IPv4 address space and the BGP AS numbers (IPv4 exhaustion dilemma is more severe than the BGP ASN dilemma). The BGP AS number space is a finite amount of address space. It is defined as a 16 bit integer and hence limited to 65535 unique AS numbers. Not all can be used!! Out of the AS number …

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BGP Security

BGP is a critical component of the internet, bring BGP down and you bring the internet down or at least large portions of the internet. The problem is that BGP is highly vulnerable to many types of attacks for its implementation. BGP runs over TCP on port 179 and inherits all types of TCP common attacks like replay, man-in-the-middle or DOS attacks. Also BGP is an application has its unique set of attacks against its implementation and messages. If you want to know how sever an attack against BGP can be check out the six worst internet routing attacks. A …

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Choosing PE-CE Routing protocol

When it comes to choosing your PE-CE routing protocol, Which one do you think is best? Choosing the PE-CE routing protocol for MPLS VPN  is an ongoing debate between back end network teams and those who have customer interface roles. They are always trying to satisfy the customer and we are always trying to keep the network simple, clean and stable. To approach this issue we have to look from different perceptual views, as customers and service providers, as customer interface engineers and back end engineers. We need to see the big picture and work on a WIN-WIN solution. The …

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BGP Routing Information Base (RIB)

BGP is an intimate friend for all service provider engineers. Without BGP there is no internet, there is no MPLS VPN and there are no many other things now and in the days to come. I believe its healthy to visit your friends from time to time and know how you live 🙂 Any BGP speaker receives routing updates from other peers, processes the information for local use and then advertise selected routes to different peers based on predefined policies. In order for BGP to be able to perform its functions it stores this information is a special type of …

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