Bgp path selection juniper

1. How a Juniper router selects the best path BGP?
2. What is the BGP path selection?
3. How do I find my BGP Best Path?
4. How does router know which path to choose?
5. What is path selection?
6. What is the function of path selection?
7. How to manipulate traffic in BGP?
8. What is the default route preference for BGP?
9. How does BGP choose router ID?
10. How does BGP add path work?
11. How many routes can BGP handle?
12. What is the default preference of BGP routes on Juniper routers?
13. What protocol will the routers use to determine the most optimal path?
14. How does BGP use the AS path attribute?
15. Does BGP advertise only best routes?
16. Why use BGP local preference?
17. What is the difference between local preference and as path in BGP?
18. What are the 3 types of routing performed by BGP?
19. What factors are used to determine path routing?
20. Which is better OSPF or BGP?
21. What port does BGP use?
22. How many path attributes are there in BGP?
23. How do you manipulate BGP routes?
24. What is weight in BGP path selection?

How a Juniper router selects the best path BGP?

If multiple BGP routes to the same destination exist, BGP selects the best path based on the route attributes of the paths. One of the route attributes that affects the best-path decision is the length of the AS paths of each route. Routes with shorter AS paths are preferred over those with longer AS paths.

What is the BGP path selection?

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.

How do I find my BGP Best Path?

This BGP router has 5 paths for network 1.0. 0.0/24. Look at the > symbol at the bottom left. The > symbol means that BGP has selected this path as the best path.

How does router know which path to choose?

A primary function of a router is to determine the best path to use to send packets. To determine the best path, the router searches its routing table for a network address that matches the destination IP address of the packet.

What is path selection?

The Path Selection tool lets you quickly select paths, giving you the versatility to move or edit objects. Select the Path Selection tool (A) . Use the Options bar to customize tool settings, like Path Operations, Path Alignment, and Arrangement, to get the effect you want. Select one or more paths.

What is the function of path selection?

Path selection ensures the right traffic travels the right path, by choosing a predefined WAN gateway for certain traffic flows in real time, based on availability. You define a path, called an uplink, by specifying a WAN egress point and providing a direction for the egressing packets to take.

How to manipulate traffic in BGP?

To influence the inbound traffic path, customers can use certain attributes (such as MED, AS-PATH, BGP communities) in the updates sent to their providers. Another method is based on the longest prefix-matching behavior and can be accomplished by the BGP conditional route injection.

What is the default route preference for BGP?

By default, the routing software assigns a preference of 170 to routes that originated from BGP. Of all the routing protocols, BGP has the highest default preference value, which means that routes learned by BGP are the least likely to become the active route.

How does BGP choose router ID?

BGP normally uses the highest IP address assigned to an interface as the router ID. If loopback interfaces are used, the BGP router ID is the highest address assigned to a loopback interface, regardless of the IP addresses assigned to any physical interface.

How does BGP add path work?

The BGP Additional Paths feature allows the advertisement of multiple paths through the same peering session for the same prefix without the new paths implicitly replacing any previous paths. This behavior promotes path diversity and reduces multi-exit discriminator (MED) oscillations.

How many routes can BGP handle?

There is not a single plot in this figure where each BGP speak sees essentially the same network. There is a variance across the various peers of these route collectors that is around 50,000 routes.

What is the default preference of BGP routes on Juniper routers?

The default value depends on the source of the route. The preference value is a value from 0 through 4,294,967,295 (2 ³² – 1), with a lower value indicating a more preferred route.

What protocol will the routers use to determine the most optimal path?

OSPF: The Open Shortest Path First (OSPF) protocol is commonly used by network routers to dynamically identify the fastest and shortest available routes for sending packets to their destination.

How does BGP use the AS path attribute?

A path attribute is a list of AS numbers that a route has traversed to reach a destination. BGP uses path attributes to provide more information about each route and to help prevent routing loops in an arbitrary topology. You can also use path attributes to determine administrative preferences.

Does BGP advertise only best routes?

BGP routers only advertise the best path to their neighbors. When a better path is found, it replaces the current path. Advertising a path and replacing it with a new path is called an implicit withdraw. Since we only advertise the best path, a lot of other possible paths are unknown to some of the routers.

Why use BGP local preference?

You can use local preference to configure your autonomous system to select a certain exit point. Instead of configuring weight on each router, you can use local preference because it is exchanged on all internal BGP routers. By increasing the local preference to 800, we can make AS 1 send all traffic toward AS 2.

What is the difference between local preference and as path in BGP?

local-preference influences route we receive from our neighbor and therefore influences how we will send traffic out. path prepend influences what we advertise to our neighbors and therefore influences how the Internet sends to us.

What are the 3 types of routing performed by BGP?

Enhanced Interior Gateway Routing Protocol (EIGRP) Border Gateway Protocol (BGP) Intermediate System-to-Intermediate System (IS-IS)

What factors are used to determine path routing?

The three attributes for Route Preference are the Route Specificity, the Administrative Distance, and the Metric. If multiple routes exist and all three of these attributes are identical, the Router will load balance across the available paths.

Which is better OSPF or BGP?

OSPF has faster convergence times than BGP. Network convergence is the speed at which a router can adjust the path used to a destination network if a network outage occurs.

What port does BGP use?

Among routing protocols, BGP is unique in using TCP as its transport protocol. BGP peers are established by manual configuration between routing devices to create a TCP session on port 179.

How many path attributes are there in BGP?

There are four categories of BGP attributes: Well-known mandatory:Recognized by all BGP peers, passed to all peers, and present in all Update messages.

How do you manipulate BGP routes?

Incoming Traffic Manipulation Using AS_PATH Prepending. The AS path is a well-known mandatory attribute of BGP. It is presented for all prefixes exchanged between any BGP neighbors. When a BGP router sends out an update to an eBGP neighbor, it adds its own AS number to the front (left side) of the AS path.

What is weight in BGP path selection?

The BGP Weight Attribute

Weight is a value that is assigned to our prefixes as a locally significant value. Weight is a simple number in the range of 0 through 65535, and the higher the weight value, the higher the preference for that path. When the prefix is locally generated, it will get a weight of 32768.