BGP Frequently Asked Questions

From ImageStream Router Documentation

(Difference between revisions)
Jump to: navigation, search
Line 1: Line 1:
===What is BGP?===
===What is BGP?===
 +
:The Border Gateway Protocol (BGP) is an exterior routing protocol. BGP version 4, described in RFC 1771, and further defined in version 5 of the BGP4 Internet Draft of January 1997, was designed for routing between Autonomous Systems. BGP Autonomous System Confederations information can be found in RFC 1965. BGP Route Reflection information can be found in RFC 1966. The BGP COMMUNITIES attribute is described in RFC1997. Although it can be used internally, BGP is primarily used to route between networks, rather within them (such as RIP, OSPF, IS-IS).
 +
===What is "multi-homing"?===
===What is "multi-homing"?===
 +
:"Multi-homing" means having multiple connections to the Internet. There are two basic types of multi-homed organizations:
 +
:* An organization which has connections to provider at more than one point of presence, and has internal links between these sites;
 +
:or
 +
:* An organization which has a connection to provider and at least one other Internet access provider.
 +
:If you have only a single connection to the Internet there is not a lot to be gained from using BGP. With only one gateway, your router already knows how to send all traffic not destined to one of your networks. Everyone should be conscious of keeping the Internet's routing table as small as possible. This can be best addressed by aggregating addresses using CIDR blocks. As a single-homed connection, your provider will likely choose to aggregate your networks with the networks of other single-homed customers and thus announce a single CIDR block under their ASN in order to reduce the routing table size.
 +
===What are the benefits of using BGP?===
===What are the benefits of using BGP?===
===Does using BGP make it easier to change providers?===
===Does using BGP make it easier to change providers?===

Revision as of 00:11, 18 May 2008

Contents

What is BGP?

The Border Gateway Protocol (BGP) is an exterior routing protocol. BGP version 4, described in RFC 1771, and further defined in version 5 of the BGP4 Internet Draft of January 1997, was designed for routing between Autonomous Systems. BGP Autonomous System Confederations information can be found in RFC 1965. BGP Route Reflection information can be found in RFC 1966. The BGP COMMUNITIES attribute is described in RFC1997. Although it can be used internally, BGP is primarily used to route between networks, rather within them (such as RIP, OSPF, IS-IS).

What is "multi-homing"?

"Multi-homing" means having multiple connections to the Internet. There are two basic types of multi-homed organizations:
  • An organization which has connections to provider at more than one point of presence, and has internal links between these sites;
or
  • An organization which has a connection to provider and at least one other Internet access provider.
If you have only a single connection to the Internet there is not a lot to be gained from using BGP. With only one gateway, your router already knows how to send all traffic not destined to one of your networks. Everyone should be conscious of keeping the Internet's routing table as small as possible. This can be best addressed by aggregating addresses using CIDR blocks. As a single-homed connection, your provider will likely choose to aggregate your networks with the networks of other single-homed customers and thus announce a single CIDR block under their ASN in order to reduce the routing table size.

What are the benefits of using BGP?

Does using BGP make it easier to change providers?

Do I have to use BGP with all of my upstream providers?

Where can I get an Autonomous System Number?

What is the Network Layer Reachability Information (NLRI)?

What is a BGP route?

What ImageStream routers support BGP4 and how much memory do they require?

How can I tell if BGP4 is enabled on my ImageStream router?

How can I enable BGP4 on the router?

What is the best source of information about ImageStream's BGP4?

Why must all BGP peers in an Autonomous System be peered with each other?

What is used as the BGP Router ID on ImageStream routers?

Do I need to define my static routes in my interface configuration file (wan.conf) and in the main gated configuration file (gated.conf)?

How long must a route exist before BGP will forward it?

Why do I have to inform my providers manually about the networks that I am announcing?

In the route precedence, where are Local (Directly Connected) routes in the precedence?

What third-party products are interoperable with BGP4 on an ImageStream router?

Personal tools
Router software releases