Ipv6 Unicast Routing On Cisco Asr 9000'S A9K-Sip-700; Ipv6 Urpf Support On Cisco Asr 9000'S A9K-Sip-700; Remove And Replace Private As Numbers From As Path In Bgp - Cisco ASR 9000 Series Configuration Manual
Aggregation services router
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Also See for ASR 9000 Series:
- Command reference manual (1138 pages) ,
- Routing configuration manual (702 pages) ,
- Reference manual (696 pages)
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Implementing BGP
For more information on BGP policy accounting and how to configure BGP policy accounting, refer the
Implementing Cisco Express Forwarding module in Cisco ASR 9000 Series Aggregation Services Router IP
Addresses and Services Configuration Guide.
IPv6 Unicast Routing on Cisco ASR 9000's A9K-SIP-700
Cisco ASR 9000's A9K-SIP-700 provides complete Internet Protocol Version 6 (IPv6) unicast capability.
An IPv6 unicast address is an identifier for a single interface, on a single node. A packet that is sent to a unicast
address is delivered to the interface identified by that address. Cisco IOS XR software supports the following
IPv6 unicast address types:
• Global aggregatable address
• Site-local address
• Link-local address
• IPv4-compatible IPv6 address
For more information on IPv6 unicase addressing, refer the Implementing Network Stack IPv4 and IPv6
module in Cisco ASR 9000 Series Aggregation Services Router IP Addresses and Services Configuration
Guide.
IPv6 uRPF Support on Cisco ASR 9000's A9K-SIP-700
Unicast IPv6 Reverse Path Forwarding (uRPF) mitigates problems caused by the introduction of malformed
or spoofed IP source addresses into a network by discarding IP packets that lack a verifiable IP source address.
Unicast RPF does this by doing a reverse lookup in the Cisco Express Forwarding (CEF) table. Therefore,
uRPF is possible only if CEF is enabled on the router.
Use the ipv6 verify unicast source reachable-via {any | rx} [allow-default] [allow-self-ping] command in
interface configuration mode to enable IPV6 uRPF.
For more information on IPv6 uRPF, refer Implementing Cisco Express Forwarding module in Cisco ASR 9000
Series Aggregation Services Router IP Addresses and Services Command Reference
Remove and Replace Private AS Numbers from AS Path in BGP
Private autonomous system numbers (ASNs) are used by Internet Service Providers (ISPs) and customer
networks to conserve globally unique AS numbers. Private AS numbers cannot be used to access the global
Internet because they are not unique. AS numbers appear in eBGP AS paths in routing updates. Removing
private ASNs from the AS path is necessary if you have been using private ASNs and you want to access the
global Internet.
Public AS numbers are assigned by InterNIC and are globally unique. They range from 1 to 64511. Private
AS numbers are used to conserve globally unique AS numbers, and they range from 64512 to 65535. Private
AS numbers cannot be leaked to a global BGP routing table because they are not unique, and BGP best path
calculations require unique AS numbers. Therefore, it might be necessary to remove private AS numbers from
an AS path before the routes are propagated to a BGP peer.
External BGP (eBGP) requires that globally unique AS numbers be used when routing to the global Internet.
Using private AS numbers (which are not unique) would prevent access to the global Internet. The remove
OL-30423-03
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.1.x
IPv6 Unicast Routing on Cisco ASR 9000's A9K-SIP-700
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