La documentazione per questo prodotto è stata redatta cercando di utilizzare un linguaggio senza pregiudizi. Ai fini di questa documentazione, per linguaggio senza di pregiudizi si intende un linguaggio che non implica discriminazioni basate su età, disabilità, genere, identità razziale, identità etnica, orientamento sessuale, status socioeconomico e intersezionalità. Le eventuali eccezioni possono dipendere dal linguaggio codificato nelle interfacce utente del software del prodotto, dal linguaggio utilizzato nella documentazione RFP o dal linguaggio utilizzato in prodotti di terze parti a cui si fa riferimento. Scopri di più sul modo in cui Cisco utilizza il linguaggio inclusivo.
Cisco ha tradotto questo documento utilizzando una combinazione di tecnologie automatiche e umane per offrire ai nostri utenti in tutto il mondo contenuti di supporto nella propria lingua. Si noti che anche la migliore traduzione automatica non sarà mai accurata come quella fornita da un traduttore professionista. Cisco Systems, Inc. non si assume alcuna responsabilità per l’accuratezza di queste traduzioni e consiglia di consultare sempre il documento originale in inglese (disponibile al link fornito).
Questo documento descrive il controllo del routing in BGP per VPN basate su route che usano Cisco SD-WAN su un firewall sicuro.
Cisco raccomanda la conoscenza dei seguenti argomenti:
Le informazioni fornite in questo documento si basano su:
Le informazioni discusse in questo documento fanno riferimento a dispositivi usati in uno specifico ambiente di emulazione. Su tutti i dispositivi menzionati nel documento la configurazione è stata ripristinata ai valori predefiniti. Se la rete è operativa, valutare attentamente eventuali conseguenze derivanti dall'uso dei comandi.
Con la nuova implementazione SD-WAN per la VPN da sito a sito basata su route con BGP abilitato per la sovrimpressione, Cisco concentra la propria attenzione sugli attributi BGP chiave per implementare il routing della sovrimpressione sicura e senza loop, garantendo che le reti di sovrimpressione e sovrapposizione rimangano segregate in tutta la topologia. Questa distribuzione garantisce inoltre che non sia necessario alcun intervento manuale per regolare gli attributi rilevanti.
Selezionare una topologia che includa sia le connessioni iBGP che eBGP tra HUB e spoke. Questo approccio offre la massima visibilità sui controlli di routing implementati come parte della soluzione SD-WAN sui firewall sicuri di Cisco.
Poiché l'obiettivo principale di questo documento è quello di fornire una chiara comprensione del controllo del routing implementato come parte della distribuzione SD-WAN su un firewall protetto, i passaggi fondamentali della configurazione richiesti per distribuire la topologia non vengono riesaminati. Per istruzioni dettagliate sulla configurazione iniziale, consultare il documento precedente Configure SD-WAN for Site-to-Site VPN over Secure Firewall (Configura SD-WAN per la VPN da sito a sito su firewall protetto).
Tutte le configurazioni nella sezione CLI vengono applicate mediante la procedura guidata di configurazione SD-WAN. Nessuna modifica o modifica viene apportata separatamente alla configurazione BGP o a qualsiasi configurazione delle route-map.
L'elenco comunitario è responsabile del filtraggio dei prefissi in entrata e in uscita. Per una spiegazione dettagliata, vedere la sezione Community List della documentazione di cisco nella Guida alla configurazione dei dispositivi di Cisco Secure Firewall Management Center.
firepower# show running-config community-list
community-list standard FMC_VPN_COMMUNITY_101010 permit 101010 <<<<<<<<<<
community-list standard FMC_VPN_COMMUNITY_202020 permit 202020 <<<<<<<<<<
Si noti che esiste un'unica coppia di route map in entrata e in uscita per topologia anche se le configurazioni sono identiche per entrambe le topologie, solo la convenzione di denominazione è univoca per topologia. Nel nostro scenario, FMC_VPN_RMAP_COMMUNITY_IN_8589939614 e FMC_VPN_RMAP_COMMUNITY_OUT_858939614 sono per la topologia 1 mentre FMC_VPN_RMAP_COMMUNITY_IN_8589942200 e FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 sono destinati alla topologia 2.
firepower# show running-config route-map
Topology 1
Inbound
route-map FMC_VPN_RMAP_COMMUNITY_IN_8589939614 permit 10
match community FMC_VPN_COMMUNITY_101010 exact-match
set community 202020
route-map FMC_VPN_RMAP_COMMUNITY_IN_8589939614 permit 20
match community FMC_VPN_COMMUNITY_202020 exact-match
Outbound
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 permit 10
match community FMC_VPN_COMMUNITY_101010 exact-match
set metric 1
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 permit 20
match community FMC_VPN_COMMUNITY_202020 exact-match
set metric 100
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 deny 100
Topology 2
Inbound
route-map FMC_VPN_RMAP_COMMUNITY_IN_8589942200 permit 10
match community FMC_VPN_COMMUNITY_101010 exact-match
set community 202020
route-map FMC_VPN_RMAP_COMMUNITY_IN_8589942200 permit 20
match community FMC_VPN_COMMUNITY_202020 exact-match
Outbound
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 permit 10
match community FMC_VPN_COMMUNITY_101010 exact-match
set metric 1
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 permit 20
match community FMC_VPN_COMMUNITY_202020 exact-match
set metric 100
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 deny 100
Common Across All The Hubs & Spokes Wherever Redistribution Of Inside Network Is Present
route-map FMC_VPN_CONNECTED_DIST_RMAP_101010 permit 10
match interface inside
set community 101010
Viene mostrata la configurazione BGP tra i dispositivi nella topologia:
firepower# show running-config router bgp
router bgp 65500
bgp log-neighbor-changes
address-family ipv4 unicast
neighbor 198.51.100.1 remote-as 65500 <<<<< tunnel from spokes to HUB 1 via ISP1
neighbor 198.51.100.1 activate
neighbor 198.51.100.1 send-community
neighbor 198.51.100.1 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589939614 in
neighbor 198.51.100.1 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 out
neighbor 198.51.100.2 remote-as 65510 <<<<< tunnel from spokes to HUB 2 via ISP1
neighbor 198.51.100.2 ebgp-multihop 2
neighbor 198.51.100.2 activate
neighbor 198.51.100.2 send-community
neighbor 198.51.100.2 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589939614 in
neighbor 198.51.100.2 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 out
neighbor 198.51.100.3 remote-as 65500 <<<<< tunnel from spokes to HUB 1 via ISP2
neighbor 198.51.100.3 activate
neighbor 198.51.100.3 send-community
neighbor 198.51.100.3 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589942200 in
neighbor 198.51.100.3 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 out
neighbor 198.51.100.4 remote-as 65510 <<<<< tunnel from spokes to HUB 2 via ISP2
neighbor 198.51.100.4 ebgp-multihop 2
neighbor 198.51.100.4 activate
neighbor 198.51.100.4 send-community
neighbor 198.51.100.4 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589942200 in
neighbor 198.51.100.4 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 out
redistribute connected route-map FMC_VPN_CONNECTED_DIST_RMAP_101010 <<<<<<< route-map to redistribute inside network into BGP
maximum-paths 8
maximum-paths ibgp 8
no auto-summary
no synchronization
exit-address-family
firepower# show running-config router bgp
router bgp 65500
bgp log-neighbor-changes
address-family ipv4 unicast
neighbor 198.51.100.10 remote-as 65500 <<<<< tunnel from HUB 1 to Spoke 1 via ISP 1
neighbor 198.51.100.10 activate
neighbor 198.51.100.10 send-community
neighbor 198.51.100.10 route-reflector-client
neighbor 198.51.100.10 next-hop-self
neighbor 198.51.100.10 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589939614 in
neighbor 198.51.100.10 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 out
neighbor 198.51.100.11 remote-as 65500 <<<<< tunnel from HUB 1 to Spoke 2 via ISP 1
neighbor 198.51.100.11 activate
neighbor 198.51.100.11 send-community
neighbor 198.51.100.11 route-reflector-client
neighbor 198.51.100.11 next-hop-self
neighbor 198.51.100.11 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589939614 in
neighbor 198.51.100.11 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 out
neighbor 198.51.100.70 remote-as 65500 <<<<< tunnel from HUB 1 to Spoke 1 via ISP 2
neighbor 198.51.100.70 activate
neighbor 198.51.100.70 send-community
neighbor 198.51.100.70 route-reflector-client
neighbor 198.51.100.70 next-hop-self
neighbor 198.51.100.70 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589942200 in
neighbor 198.51.100.70 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 out
neighbor 198.51.100.71 remote-as 65500 <<<<< tunnel from HUB 1 to Spoke 2 via ISP 2
neighbor 198.51.100.71 activate
neighbor 198.51.100.71 send-community
neighbor 198.51.100.71 route-reflector-client
neighbor 198.51.100.71 next-hop-self
neighbor 198.51.100.71 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589942200 in
neighbor 198.51.100.71 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 out
no auto-summary
no synchronization
exit-address-family
firepower# show running-config router bgp
router bgp 65510
bgp log-neighbor-changes
address-family ipv4 unicast
neighbor 198.51.100.40 remote-as 65500 <<<<< tunnel from HUB 2 to Spoke 1 via ISP 1
neighbor 198.51.100.40 ebgp-multihop 2
neighbor 198.51.100.40 activate
neighbor 198.51.100.40 send-community
neighbor 198.51.100.40 next-hop-self
neighbor 198.51.100.40 as-override
neighbor 198.51.100.40 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589939614 in
neighbor 198.51.100.40 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 out
neighbor 198.51.100.41 remote-as 65500 <<<<< tunnel from HUB 2 to Spoke 2 via ISP 1
neighbor 198.51.100.41 ebgp-multihop 2
neighbor 198.51.100.41 activate
neighbor 198.51.100.41 send-community
neighbor 198.51.100.41 next-hop-self
neighbor 198.51.100.41 as-override
neighbor 198.51.100.41 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589939614 in
neighbor 198.51.100.41 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 out
neighbor 198.51.100.100 remote-as 65500 <<<<< tunnel from HUB 2 to Spoke 1 via ISP 2
neighbor 198.51.100.100 ebgp-multihop 2
neighbor 198.51.100.100 activate
neighbor 198.51.100.100 send-community
neighbor 198.51.100.100 next-hop-self
neighbor 198.51.100.100 as-override
neighbor 198.51.100.100 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589942200 in
neighbor 198.51.100.100 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 out
neighbor 198.51.100.101 remote-as 65500 <<<<< tunnel from HUB 2 to Spoke 2 via ISP 2
neighbor 198.51.100.101 ebgp-multihop 2
neighbor 198.51.100.101 activate
neighbor 198.51.100.101 send-community
neighbor 198.51.100.101 next-hop-self
neighbor 198.51.100.101 as-override
neighbor 198.51.100.101 route-map FMC_VPN_RMAP_COMMUNITY_IN_8589942200 in
neighbor 198.51.100.101 route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 out
no auto-summary
no synchronization
exit-address-family
Lo spoke annuncia la propria rete interna, 192.0.2.8/29, in BGP con un tag della community specifico di 101010, come configurato nella route-map FMC_VPN_CONNECTED_DIST_RMAP_101010.
Spoke1# show bgp community 101010 exact-match <<<< to verify the exact network redistributed into BGP BGP table version is 4, local router ID is 203.0.113.35 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> 192.0.2.8/29 0.0.0.0 0 32768 ? <<<<<<<<<<< local inside network
Spoke modifica il valore metrico della propria rete interna, 192.0.2.8/29, e lo annuncia agli hub, come configurato nelle route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 e FMC_VPN_RMAP_COMMUNITY_OUT_8589942200.
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 permit 10
match community FMC_VPN_COMMUNITY_101010 exact-match
set metric 1
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 permit 20
match community FMC_VPN_COMMUNITY_202020 exact-match
set metric 100
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 deny 100
L'HUB1 apprende la rete Spoke 1 192.0.2.8/29 con il tag della community 101010 e cambia il tag della community in 202020, mantenendo la metrica prima di inoltrarla ad altri spoke, come definito nelle route-map configurate.
Route-Map for ISP1 DVTI
Inbound
route-map FMC_VPN_RMAP_COMMUNITY_IN_8589939614 permit 10
match community FMC_VPN_COMMUNITY_101010 exact-match
set community 202020
route-map FMC_VPN_RMAP_COMMUNITY_IN_8589939614 permit 20
match community FMC_VPN_COMMUNITY_202020 exact-match
Outbound
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 permit 10
match community FMC_VPN_COMMUNITY_101010 exact-match
set metric 1
set ip next-hop 198.51.100.1 <<<<<<<<<< only next-hop is changed in ISP2 tunnel route-map with ISP2 DVTI IP
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 permit 20
match community FMC_VPN_COMMUNITY_202020 exact-match
set metric 100
set ip next-hop 198.51.100.1 <<<<<<<<<< only next-hop is changed in ISP2 tunnel route-map with ISP2 DVTI IP
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 deny 100
Route-Map for ISP2 DVTI
Inbound
route-map FMC_VPN_RMAP_COMMUNITY_IN_8589942200 permit 10
match community FMC_VPN_COMMUNITY_101010 exact-match
set community 202020
route-map FMC_VPN_RMAP_COMMUNITY_IN_8589942200 permit 20
match community FMC_VPN_COMMUNITY_202020 exact-match
Outbound
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 permit 10
match community FMC_VPN_COMMUNITY_101010 exact-match
set metric 1
set ip next-hop 198.51.100.3 <<<<<<<<<< only next-hop is changed in ISP2 tunnel route-map with ISP2 DVTI IP
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 permit 20
match community FMC_VPN_COMMUNITY_202020 exact-match
set metric 100
set ip next-hop 198.51.100.3 <<<<<<<<<< only next-hop is changed in ISP2 tunnel route-map with ISP2 DVTI IP
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589942200 deny 100
HUB1# show bgp community 202020 exact-match <<<< this will confirm if received prefixes have community tags flipped
BGP table version is 5, local router ID is 198.51.100.3 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path * i192.0.2.8/29 198.51.100.70 1 100 0 ? *>i 198.51.100.10 1 100 0 ? * i192.0.2.16/29 198.51.100.71 1 100 0 ? *>i 198.51.100.11 1 100 0 ?
HUB1# show bgp 192.0.2.8 <<<< this will display available paths in BGP for the network
BGP routing table entry for 192.0.2.8/29, version 4 Paths: (2 available, best #2, table default) Advertised to update-groups: 1 2 Local, (Received from a RR-client) 198.51.100.70 from 198.51.100.70 (203.0.113.35) <<<<< spoke 1 ISP 2 tunnel to HUB 1 Origin incomplete, metric 1, localpref 100, valid, internal Community: 202020 Local, (Received from a RR-client) 198.51.100.10 from 198.51.100.10 (203.0.113.35) <<<<< spoke 1 ISP 1 tunnel to HUB 1 Origin incomplete, metric 1, localpref 100, valid, internal, best Community: 202020 <<<<< community updated as per the route-map configured on spoke side
HUB1# show route 192.0.2.8 Routing entry for 192.0.2.8 255.255.255.248 Known via "bgp 65500", distance 200, metric 1, type internal Last update from 198.51.100.10 0:09:18 ago Routing Descriptor Blocks: * 198.51.100.10, from 198.51.100.10, 0:09:18 ago Route metric is 1, traffic share count is 1 AS Hops 0 MPLS label: no label string provided
HUB1# show bgp ipv4 unicast neighbors 198.51.100.10 routes <<<<<< to check specific prefixes learnt via ISP1 spoke1 tunnel BGP table version is 5, local router ID is 198.51.100.3 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *>i192.0.2.8/29 198.51.100.10 1 100 0 ? <<< preferred route Total number of prefixes 1
HUB1# show bgp ipv4 unicast neighbors 198.51.100.70 routes <<<<<< to check specific prefixes learnt via ISP2 spoke1 tunnel BGP table version is 5, local router ID is 198.51.100.3 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path * i192.0.2.8/29 198.51.100.70 1 100 0 ? Total number of prefixes 1
L'HUB2 apprende anche la rete Spoke 1 192.0.2.8/29 con il tag della community 101010 e cambia il tag della community in 202020 e aggiorna la metrica a 100 prima di inoltrarla ad altri spoke, come specificato nelle route-map configurate. La modifica della metrica ha effetto a causa del peering eBGP. Ciò è dovuto al fatto che MED (Multi-Exit Discriminator) è un attributo BGP facoltativo e non transitivo utilizzato per influenzare il traffico in entrata suggerendo un punto di ingresso preferito in un AS. MED in genere non viene propagato tra peer iBGP all'interno dello stesso AS e viene invece pubblicizzato nei peer BGP (eBGP) esterni in sistemi autonomi diversi.
HUB2# show bgp community 202020 exact-match <<<< this will confirm if receieved prefixes have community tags flipped
BGP table version is 5, local router ID is 198.51.100.4 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path * 192.0.2.8/29 198.51.100.1 100 0 65500 ? <<<<<< advertised back by spoke 2 ISP1 to HUB2 previously learnt via HUB1 iBGP * 198.51.100.1 100 0 65500 ? <<<<<< advertised back by spoke 2 ISP2 to HUB2 previously learnt via HUB1 iBGP * 198.51.100.100 1 0 65500 ? <<<<<< advertised by spoke 2 ISP tunnel *> 198.51.100.40 1 0 65500 ? <<<<<< advertised and preferred by spoke 1 ISP 1 tunnel * 192.0.2.16/29 198.51.100.1 100 0 65500 ? * 198.51.100.1 100 0 65500 ? * 198.51.100.101 1 0 65500 ? *> 198.51.100.41 1 0 65500 ?
HUB2# show bgp 192.0.2.8 <<<< this will display available paths in BGP for the network
BGP routing table entry for 192.0.2.8/29, version 4 Paths: (4 available, best #4, table default) Advertised to update-groups: 1 2 65500 198.51.100.1 (inaccessible) from 198.51.100.41 (203.0.113.36) <<<<<< advertised back by spoke 2 ISP1 to HUB2 previously learnt via HUB1 iBGP Origin incomplete, metric 100, localpref 100, valid, external Community: 202020 65500 198.51.100.1 (inaccessible) from 198.51.100.101 (203.0.113.36) <<<<<< advertised back by spoke 2 ISP2 to HUB2 previously learnt via HUB1 iBGP Origin incomplete, metric 100, localpref 100, valid, external Community: 202020 65500 198.51.100.100 from 198.51.100.100 (203.0.113.35) <<<<<< advertised by spoke 1 ISP 2 tunnel Origin incomplete, metric 1, localpref 100, valid, external Community: 202020 65500 198.51.100.40 from 198.51.100.40 (203.0.113.35) <<<<<< advertised and preferred by spoke 1 ISP 1 tunnel Origin incomplete, metric 1, localpref 100, valid, external, best Community: 202020
HUB2# show bgp ipv4 unicast neighbors 198.51.100.40 routes <<<<<< to check specific prefixes learnt via ISP1 spoke1 tunnel
BGP table version is 5, local router ID is 198.51.100.4 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> 192.0.2.8/29 198.51.100.40 1 0 65500 ? <<<< preferred * 192.0.2.16/29 198.51.100.1 100 0 65500 ? Total number of prefixes 2
HUB2# show bgp ipv4 unicast neighbors 198.51.100.41 routes <<<<<< to check specific prefixes learnt via ISP1 spoke2 tunnel
BGP table version is 5, local router ID is 198.51.100.4 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path * 192.0.2.8/29 198.51.100.1 100 0 65500 ? <<<<<< *> 192.0.2.16/29 198.51.100.41 1 0 65500 ? Total number of prefixes 2
HUB2# show bgp ipv4 unicast neighbors 198.51.100.100 routes <<<<<< to check specific prefixes learnt via ISP2 spoke1 tunnel
BGP table version is 5, local router ID is 198.51.100.4 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path * 192.0.2.8/29 198.51.100.100 1 0 65500 ? <<<<<< * 192.0.2.16/29 198.51.100.1 100 0 65500 ? Total number of prefixes 2
HUB2# show bgp ipv4 unicast neighbors 198.51.100.101 routes <<<<<< to check specific prefixes learnt via ISP2 spoke2 tunnel BGP table version is 5, local router ID is 198.51.100.4 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path * 192.0.2.8/29 198.51.100.1 100 0 65500 ? <<<<<< * 192.0.2.16/29 198.51.100.101 1 0 65500 ? Total number of prefixes 2
Lo spoke 2 riceve la rete Spoke 1 192.0.2.8/29 da entrambi i tunnel HUB1 ISP1 e HUB1 ISP2 con metrica 1, mentre riceve la stessa rete dai tunnel HUB2 ISP1 e HUB2 ISP2 con hop successivo aggiornato di HUB1.
Spoke2# show bgp community 202020 exact-match <<<< this will confirm if receieved prefixes have community tags flipped
BGP table version is 8, local router ID is 203.0.113.36 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *mi192.0.2.8/29 198.51.100.3 1 100 0 ? *>i 198.51.100.1 1 100 0 ? <<<< HUB1 ISP1 route preferred * 198.51.100.2 100 0 65510 65510 ? * 198.51.100.4 100 0 65510 65510 ? * 192.0.2.16/29 198.51.100.4 100 0 65510 65510 ? * 198.51.100.2 100 0 65510 65510 ?
route-map FMC_VPN_RMAP_COMMUNITY_IN_8589939614 permit 10
match community FMC_VPN_COMMUNITY_101010 exact-match
set community 202020
route-map FMC_VPN_RMAP_COMMUNITY_IN_8589956263 permit 20
match community FMC_VPN_COMMUNITY_202020 exact-match
Spoke 2 annuncia anche le reti apprese dall'HUB1 all'HUB2, come definito dalla route-map in uscita configurata, con la metrica aggiornata.
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 permit 10
match community FMC_VPN_COMMUNITY_101010 exact-match
set metric 1
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 permit 20
match community FMC_VPN_COMMUNITY_202020 exact-match
set metric 100 <<<<<
route-map FMC_VPN_RMAP_COMMUNITY_OUT_8589939614 deny 100
Spoke2# show bgp ipv4 unicast neighbors 198.51.100.2 advertised-routes <<<<< to check specific prefixes advertised via ISP1 HUB2 tunnel back to HUB2 BGP table version is 8, local router ID is 203.0.113.36 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *>i192.0.2.8/29 198.51.100.1 1 100 0 ? <<<<<<< *> 192.0.2.16/29 0.0.0.0 0 32768 ? Total number of prefixes 2
Spoke2# show bgp ipv4 unicast neighbors 198.51.100.4 advertised-routes <<<<< to check specific prefixes advertised via ISP2 HUB2 tunnel back to HUB2 BGP table version is 8, local router ID is 203.0.113.36 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *>i192.0.2.8/29 198.51.100.1 1 100 0 ? <<<<<<< *> 192.0.2.16/29 0.0.0.0 0 32768 ? Total number of prefixes 2
Lo scopo di questo documento è quello di fornire una procedura dettagliata per l'implementazione del routing back-end, con particolare attenzione ai controlli di routing implementati all'interno di BGP per garantire sia la contingenza che la ridondanza.
In sintesi, il spoke 2 e gli altri spoke nella topologia utilizzano lo stesso approccio quando pubblicizzano le loro reti nel dominio BGP. Il controllo più importante del routing in questo scenario è il filtro dell'elenco delle comunità, che assicura che solo le reti all'interno di questa topologia vengano pubblicizzate agli altri peer, evitando la propagazione involontaria della rete.
Inoltre, l'attributo MED Multi-exit Discriminator viene utilizzato per influenzare la selezione delle route per i peer eBGP, garantendo che le route apprese tramite il peer iBGP configurato come HUB primario siano preferite rispetto ai prefissi appresi dall'HUB secondario tramite eBGP.
Effettuando regolazioni della topologia, ad esempio configurando iBGP per l'HUB secondario, è possibile eliminare la necessità di manipolazione MED e route-map in ingresso che capovolgono i tag della community prima di pubblicizzare la stessa rete ad altri spoke.
Revisione | Data di pubblicazione | Commenti |
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1.0 |
01-Oct-2025
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Versione iniziale |