BGP Attributes: Local Preference Attribute

December 18th, 2010 Wael Osama Posted in BGP 2 Comments »

The local preference attribute is a well-know discretionary attribute. This means local preference must be recognized by all BGP implementations, but will not exist in all BGP update messages; specifically it will not exist in E-BGP update messages. BGP local preference attribute is one of the most used attributes in BGP real world to influence [...]

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BGP Attributes: Atomic Aggregate Atribute

December 14th, 2010 Wael Osama Posted in BGP 3 Comments »

Atomic aggregate is a Well-known Discretionary attribute; it must be recognized by all BGP implementations and does not have to exist in all BGP updates. The purpose of the attribute is to alert BGP speakers along the path that some information have been lost due to the route aggregation process and that the aggregate path [...]

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BGP Attribute Types and Flags

December 8th, 2010 Wael Osama Posted in BGP 5 Comments »

BGP attributes is an interesting subject of study.  BGP is a very flexible and extensible protocol and I like that, let’s see how flexible is that protocol when it comes to attributes handling. We all know that BGP has four types of attributes as listed: Well-known mandatory. Well-known discretionary. Optional transitive. Optional non-transitive. I am [...]

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The Role of BGP in MPLS networks

April 5th, 2010 Wael Osama Posted in BGP, MPLS 3 Comments »

In almost every book you will read about MPLS, the author will state that one of the MPLS benefits is having a BGP free core network; sometimes they explain it sometimes not. However, to really understand this statement I encourage you to imagine removing MPLS from your core network and see what adjustments you need [...]

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BGP Route Refresh Capability

March 28th, 2010 Wael Osama Posted in BGP No Comments »

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 [...]

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BGP 4-Byte ASN

March 23rd, 2010 Mounir Mohamed Posted in BGP 2 Comments »

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 [...]

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