In IOS XR when you are configuring something you need to commit it, so it is in runing config. The configuration is saved to candidate config before committing. You show the candidate config via command „show config“. When you commit the config thats gonna be merged with the running config. When you execute „show config  Full Article…

BEWARE! that configuration in IOS XR is hierarchical. What does it mean? Check the picture of basic configuring for OSPF. You specify the same thing on different levels. For example the network point-to-multipoint is above the area. That means that all interfaces in all areas that does not have anything configured will have this type.  Full Article…

Router to Router communication link-state IGP similar to OSPF Used in core of SP networks because its very scalable for flat network designs it has very simple design and implementation supports both ipv4 and ipv6 routing there is not as much functionality as in OSPF, because OSPF is designed to enterprise routing and IS-IS to  Full Article…

Aggregation applies to routes that exist in the BGP routing table. This is in contrast to the network command, discussed earlier in this chapter, which applies to routes that exist in the IP routing table. Aggregation can be performed if at least one more-specific route of the aggregate exists in the BGP routing table. Before we go to  Full Article…

Before we go into the CCIE SP INE BGP details, we must have good BGP foundation knowledge. The CCIE INE starts from the Basic BGP WorkFlow article BGP is currently in version 4 and it replaced the EGP in the 1990. When you see the EGP tag in your BGP table this is not „Exterior  Full Article…

BGP calculates its metric through a series of attributes. There are two braod categories of attributes and also we can say that 4 subcategories : Well known – These attributes must be supported  by every BGP router that is compatible for the BGP routing protocol Mandatory – must be included in every single BGP routing  Full Article…

BGP Header Marker – 16 byte field used for BGP authentication. If authentication is not used, Marker field contains all 1s Length – Length of BGP message Type – OPEN, UPDATE, NOTIFICATION, KEEPALIVE, ROUTE REFRESH (if peer support this capability) OPEN Message Format Open message is used for BGP session establishment. First we check what  Full Article…

Information can be injected into BGP dynamically or statically. Dynamically injected routes come and go from the BGP routing table, depending on the status of the networks they identify. Statically injected routes are constantly maintained by the BGP routing tables, regardless of the status of the networks they identify. Each method has its pros and cons. Dynamic route injection  Full Article…

BGP is a fairly simple protocol, which is why it’s so flexible. When the BGP session is established, routes are exchanged between BGP peers via UPDATE messages. BGP routers receive the UPDATE messages, run some policies or filters over the updates, and then pass the routes to other BGP peers. An implementation is required to keep all BGP  Full Article…

The ORIGIN Attribute The ORIGIN attribute is a well-known mandatory attribute (Type Code 1) that indicates the origin of the routing update with respect to the autonomous system that originated it. BGP considers three types of origins: IGP – via command network EGP – old EGP protocol Incomplete – redistributed into BGP The AS-PATH The AS_PATH attribute  Full Article…