In questo documento viene fornita una configurazione di esempio con IPv6 che consente di configurare il filtro route in uscita basato sul prefisso BGP. Questa funzionalità utilizza le funzionalità di invio e ricezione ORF (Outbound Route Filter) BGP che riducono al minimo il numero di aggiornamenti BGP inviati tra router peer. La configurazione di questa funzione può aiutare a filtrare gli aggiornamenti indesiderati del routing all'origine.
Prima di provare la configurazione, verificare che siano soddisfatti i seguenti requisiti:
Conoscenza del protocollo di routing BGP e del relativo funzionamento
Conoscere lo schema di indirizzamento IPv6
Il documento può essere consultato per tutte le versioni software o hardware.
Le configurazioni di questo documento si basano sul router Cisco serie 7200 con software Cisco IOS® versione 15.0(1).
Per ulteriori informazioni sulle convenzioni usate, consultare il documento Cisco sulle convenzioni nei suggerimenti tecnici.
Nell'esempio, il router R1 è configurato in modo da annunciare le funzionalità di invio ORF basate sul prefisso al router R2. Sull'altra estremità, il router R2 è configurato in modo da annunciare le funzionalità di ricezione ORF basate sul prefisso al router R1. Prima di abilitare la funzionalità BGP Prefix-Based Outbound Route Filtering per inviare o ricevere annunci ORF basati sul prefisso, le sessioni di peering BGP devono essere attive e in esecuzione e le funzionalità BGP ORF devono essere abilitate su ciascun router partecipante prima di un router.
In questo documento viene usato il comando neighbors o prefix-filter per abilitare la funzionalità ORF prefix list sul router. Questo comando è stato introdotto nel software Cisco IOS versione 12.0(11)ST.
Nota: per ulteriori informazioni sui comandi menzionati in questo documento, usare lo strumento di ricerca dei comandi (solo utenti registrati).
Nel documento viene usata questa impostazione di rete:
Nel documento vengono usate queste configurazioni:
Router R1 |
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! hostname R1 ! ipv6 unicast-routing ipv6 cef ! ! interface Loopback1 no ip address ipv6 address 1111::1/128 ! ! interface Loopback2 no ip address ipv6 address 2222::1/128 ! ! interface Serial1/0 no ip address ipv6 address 2011:11:11:11::1/64 serial restart-delay 0 ! ! router bgp 6501 no synchronization no bgp default ipv4-unicast bgp router-id 1.1.1.1 bgp log-neighbor-changes neighbor 2011:11:11:11::2 remote-as 6502 neighbor 2011:11:11:11::2 ebgp-multihop 255 no auto-summary ! address-family ipv6 neighbor 2011:11:11:11::2 activate neighbor 2011:11:11:11::2 capability orf prefix-list send neighbor 2011:11:11:11::2 prefix-list FILTER_IPv6 in exit-address-family ! ! ipv6 prefix-list FILTER_IPv6 seq 10 permit 1111::1/128 ipv6 prefix-list FILTER_IPv6 seq 20 permit 2222::1/128 ! ! end |
Router R2 |
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! hostname R2 ! ! no ip domain lookup ipv6 unicast-routing ipv6 cef ! interface Loopback1 no ip address ipv6 address 1010::1/128 ! ! interface Loopback2 no ip address ipv6 address 2020::1/128 ! interface Serial1/0 no ip address ipv6 address 2011:11:11:11::2/64 serial restart-delay 0 ! ! router bgp 6502 no synchronization bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 2011:11:11:11::1 remote-as 6501 neighbor 2011:11:11:11::1 ebgp-multihop 255 no auto-summary ! address-family ipv6 network 1010::1/128 network 2020::1/128 neighbor 2011:11:11:11::1 activate neighbor 2011:11:11:11::1 capability orf prefix-list receive neighbor 2011:11:11:11::1 prefix-list R2_list in exit-address-family ! ipv6 prefix-list R2_list seq 10 permit 1010::1/128 ipv6 prefix-list R2_list seq 20 permit 2020::1/128 ! end |
In questo scenario, un indirizzo di loopback 1000::1/45 viene configurato in R1 nell'interfaccia loopback 0. Viene creato un elenco di prefissi per consentire tutte le route che superano la lunghezza del prefisso ::/64.
Nota: la configurazione del router R2 rimane la stessa di quella indicata in precedenza e la configurazione di R1 viene modificata come mostrato di seguito. Gli indirizzi IP su questi router rimangono invariati.
Router R1 |
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!--- Output omitted. ! interface Loopback0 no ip address ipv6 address 1000::1/45 ! !--- Output omitted. router bgp 6501 no synchronization bgp router-id 1.1.1.1 bgp log-neighbor-changes neighbor 2011:11:11:11::2 remote-as 6502 neighbor 2011:11:11:11::2 ebgp-multihop 255 no auto-summary ! address-family ipv6 network 1000::1/45 network 1111::1/128 network 2222::1/128 neighbor 2011:11:11:11::2 activate neighbor 2011:11:11:11::2 prefix-list IPV6-LONG in !--- Applies the prefix-list and filters !--- the incoming updates from the neighbor 2011:11:11:11::2. exit-address-family ! ipv6 prefix-list IPV6-LONG description Match any prefix longer than /64 ipv6 prefix-list IPV6-LONG seq 1 permit ::/0 ge 64 !--- seq 1 permit ::/0 ge 64 permits anything !--- that is ge /64 subnet mask. ! end |
Per verificare che la configurazione funzioni correttamente, consultare questa sezione.
Lo strumento Output Interpreter (solo utenti registrati) (OIT) supporta alcuni comandi show. Usare l'OIT per visualizzare un'analisi dell'output del comando show.
I seguenti comandi show vengono utilizzati per verificare la configurazione:
show running-config | beg bgp
mostra router adiacenti unicast ipv6 bgp
Nel router R1:
show running-config | beg bgp |
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router bgp 6501 no synchronization bgp router-id 1.1.1.1 bgp log-neighbor-changes neighbor 2011:11:11:11::2 remote-as 6502 neighbor 2011:11:11:11::2 ebgp-multihop 255 no auto-summary ! address-family ipv6 neighbor 2011:11:11:11::2 activate neighbor 2011:11:11:11::2 capability orf prefix-list send !--- Indicates that the neighbor 2011:11:11:11::2 !--- is configured with the prefix-based !--- ORF feature in send mode. |
mostra router adiacenti unicast ipv6 bgp |
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R1#show bgp ipv6 unicast neighbors 2011:11:11:11::2 BGP neighbor is 2011:11:11:11::2, remote AS 6502, external link BGP version 4, remote router ID 2.2.2.2 Session state = Established, up for 01:30:36 Last read 00:00:44, last write 00:00:42, hold time is 180, keepalive interval is 60 seconds BGP multisession with 2 sessions (2 established), first up for 01:31:26 Neighbor sessions: 2 active, is multisession capable Neighbor capabilities: Route refresh: advertised and received(new) on session 1, 2 Four-octets ASN Capability: advertised and received on session 1, 2 Address family IPv4 Unicast: advertised and received Address family IPv6 Unicast: advertised and received !--- Output omitted. For address family: IPv6 Unicast Session: 2011:11:11:11::2 session 2 BGP table version 1, neighbor version 1/0 Output queue size : 0 Index 2 session 2 member 2 update-group member AF-dependant capabilities: Outbound Route Filter (ORF) type (128) Prefix-list: !--- Shows that the neighbor 2011:11:11:11::2 !--- is configured with the prefix-based !--- ORF feature in send mode. Send-mode: advertised Receive-mode: received Outbound Route Filter (ORF): sent; Incoming update prefix filter list is FILTER_IPv6 Sent Rcvd Prefix activity: ---- ---- Prefixes Current: 2 4 Prefixes Total: 0 0 Implicit Withdraw: 1 0 Explicit Withdraw: 1 0 Used as bestpath: n/a 0 Used as multipath: n/a 0 Outbound Inbound Local Policy Denied Prefixes: -------- ------- !--- Output omitted. |
Nel router R2:
show running-config | beg bgp |
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router bgp 6502 no synchronization bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 2011:11:11:11::1 remote-as 6501 neighbor 2011:11:11:11::1 ebgp-multihop 255 no auto-summary ! address-family ipv6 network 1010::1/128 network 2020::1/128 neighbor 2011:11:11:11::1 activate neighbor 2011:11:11:11::1 capability orf prefix-list receive !--- Indicates that the neighbor 2011:11:11:11::1 !--- is configured with the prefix-based !--- ORF feature in receive mode. |
mostra router adiacenti unicast ipv6 bgp |
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R2#show bgp ipv6 unicast nei 2011:11:11:11::1 BGP neighbor is 2011:11:11:11::1, remote AS 6501, external link BGP version 4, remote router ID 1.1.1.1 Session state = Established, up for 01:47:11 Last read 00:00:44, last write 00:00:32, hold time is 180, keepalive interval is 60 seconds multisession with 2 sessions (2 established), first up for 01:48:02 Neighbor sessions: 2 active, is multisession capable Neighbor capabilities: Route refresh: advertised and received(new) on session 1, 2 Four-octets ASN Capability: advertised and received on session 1, 2 Address family IPv4 Unicast: advertised and received Address family IPv6 Unicast: advertised and received Multisession Capability: advertised and received !--- Output omitted. For address family: IPv6 Unicast Session: 2011:11:11:11::1 session 2 BGP table version 3, neighbor version 3/0 Output queue size : 0 Index 3 session 2 member 3 update-group member AF-dependant capabilities: Outbound Route Filter (ORF) type (128) Prefix-list: !--- Shows that the neighbor 2011:11:11:11::1 !--- is configured with the prefix-based !--- ORF feature in receive mode. Send-mode: received Receive-mode: advertised Outbound Route Filter (ORF): received (2 entries) Incoming update prefix filter list is R2_list Sent Rcvd Prefix activity: ---- ---- Prefixes Current: 2 5 Prefixes Total: 0 0 Implicit Withdraw: 0 0 Explicit Withdraw: 2 0 !--- Output omitted. |
Eseguire il comando show ipv6 route bgp nel router R1 per visualizzare il contenuto corrente della tabella di routing BGP IPv6.
show ipv6 route bgp |
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Nel router R1: R1#show ipv6 route bgp IPv6 Routing Table - default - 9 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary D - EIGRP, EX - EIGRP external, ND - Neighbor Discovery O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 B 1010::1/128 [20/0] via 2011:11:11:11::2 B 2020::1/128 [20/0] via 2011:11:11:11::2 !--- In this ouput, 1000::1/45 is not !--- displayed because the network is lesser !--- than ::/64 prefix and its filtered. |
Utilizzare il comando show ipv6 prefix-list per visualizzare informazioni su un elenco di prefissi IPv6 o sulle voci dell'elenco di prefissi IPv6.
show ipv6 prefix-list |
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Nel router R1: R1#show ipv6 prefix-list detail Prefix-list with the last deletion/insertion: IPV6-LONG ipv6 prefix-list IPV6-LONG: Description: Match any prefix longer than /64 count: 1, range entries: 1, sequences: 1 - 1, refcount: 3 seq 1 permit ::/0 ge 64 (hit count: 14, refcount: 1) R1#show ipv6 prefix-list summary Prefix-list with the last deletion/insertion: IPV6-LONG ipv6 prefix-list IPV6-LONG: Description: Match any prefix longer than /64 count: 1, range entries: 1, sequences: 1 - 1, refcount: 3 R1#show ipv6 prefix-list IPV6-LONG ipv6 prefix-list IPV6-LONG: 1 entries seq 1 permit ::/0 ge 64 |
Revisione | Data di pubblicazione | Commenti |
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1.0 |
14-Jun-2012 |
Versione iniziale |