Users Guide

Table Of Contents
Disable announcements of ASN values
Modify the AS_PATH attribute of the received routes.
Disable prepending the local AS number in CONFIG-ROUTER-NEIGHBOR mode.
local-as as-number no-prepend
Disable prepending the globally-configured AS number in CONFIG-ROUTER-NEIGHBOR mode.
local-as as-number no-prepend replace-as
Configure Dual Stack
OS10 supports dual stack for BGPv4 and BGPv6. Dual stack BGP allows simultaneous exchange of the same IPv4 or IPv6 prefixes
through different IPv4 and IPv6 peers. You can enable dual stack using the activate command in the corresponding address-family
mode. By default, activate command is enabled for the IPv4 address family for all the neighbors.
If a BGP-v4 neighbor wants to carry ipv6 prefix information, it activates the IPv6 address-family. For a BGP-v6 neighbor to carry ipv4
prefix, it activates the IPv4 address-family.
1. Enable support for the IPv6 unicast family in CONFIG-ROUTER-BGP mode.
address family ipv6 unicast
2. Enable IPv6 unicast support on a BGP neighbor/template in CONFIG-ROUTER-BGP-AF mode.
activate
Configure administrative distance
Routers use administrative distance to determine the best path between two or more routes to reach the same destination. Administrative
distance indicates the reliability of the route; the lower the administrative distance, the more reliable the route. If the routing table manager
(RTM) receives route updates from one or more routing protocols for a single destination, it chooses the best route based on the
administrative distance.
You can assign an administrative distance for the following BGP routes using the distance bgp command:
External BGP (eBGP) routes
Internal BGP (iBGP) routes
Local routes
If you do not configure the administrative distance for BGP routes, the following default values are used:
eBGP—20
iBGP—200
local routes—200
To change the administrative distance for BGP, use the following command:
distance bgp external-distance internal-distance local-distance
Configure administrative distance
1. Enable BGP and assign the AS number in CONFIGURATION mode, from 0.1 to 65535.65535 or 1 to 4294967295.
OS10# configure terminal
OS10(config)# router bgp 100
2. Use one of the following commands to enter the respective ADDRESS-FAMILY mode from ROUTER-BGP mode:
IPv4:
address-family ipv4 unicast
522
Layer 3