BGP Frequently Asked Questions
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===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
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.
