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Chapter 10A sample bgpd.conf file looks like the following command lines:# BGP ConfigurationAS 65001router-id 10.3.0.1# Address of networks we advertise to peersnetwork 10.3.0.0/23network 172.17.8.0/21# Peering with ISP A with TCP MD5 signatures enabledneighbor 10.0.0.2 {remote-as 65002descr "ISP A"tcp md5sig password changethis}# Peering with ISP B that is not directly connectedneighbor 192.168.0.21 {remote-as 65003descr "ISP B"multihop 5}We have assumed our AS number to be 65001 (That is a valid AS number for privateuse, as AS numbers 64512 to 65535 are reserved by IANA for this reason), and set therouter-id to 10.3.0.1.If nothing is specified, router-id is automatically set to the highest IP address thatis assigned to your host interfaces. While setting the router-id manually, make surethat the IP address is already assigned to an interface on your host.In the above example there are also two lines that specify the networks that we wantto advertise to our peers. There are two networks in this example: 10.3.0.0/23 and172.17.8.0/21These networks have literally originated from AS65001, and are advertised to ourpeers. They may in turn advertise the routes they learned from our router to theirpeers (depending on their policy).There are two neighbors in this example, each with its unique AS number andpolicies—ISP A and ISP B. ISP A, with IP 10.0.0.2 on its BGP speaking router,requires TCP MD5 security for peering. Whereas ISP B is not directly connected toour router and is a few hops away.[ 167 ]