Dell Networking OS10 - Introduzione alla configurazione GRE
Summary: GRE (Generic Routing Encapsulation) è un protocollo di incapsulamento IP utilizzato per stabilire una connessione point-to-point virtuale tra due router su una rete. Viene comunemente utilizzato per eseguire il tunneling di protocolli di routing come RIP e OSPF tra siti diversi. GRE è descritto in Request for Comments (RFC 2784. ...
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Instructions
Principali argomenti trattati
Configurazione dei tunnel GRE:
- I tunnel GRE sono configurati tra due router per inviare e ricevere direttamente pacchetti GRE.
- La configurazione prevede la configurazione delle interfacce del tunnel, specificando la modalità del tunnel, l'origine e la destinazione.
Restrizioni e limitazioni:
- Un massimo di 100 tunnel supportati
- IPv6 non è supportato sui percorsi underlay e overlay.
- Alcune interfacce e indirizzi IP presentano restrizioni quando vengono utilizzati con tunnel GRE.
Impostazioni di Tunnel Keepalive:
- Configurazione delle impostazioni keepalive per monitorare la raggiungibilità degli endpoint del tunnel utilizzando i pacchetti eco e di risposta ICMP (Internet Control Message Protocol).
Overlay e underlay ECMP (Equal-Cost MultiPath):
- Condivisione del carico ECMP per la distribuzione del traffico tra le route disponibili
- Combinazioni supportate per le route ECMP di overlay e underlay.
Comandi ed esempi:
- Sintassi dettagliata dei comandi ed esempi per la configurazione di tunnel GRE, impostazioni keepalive e route ECMP
Possibili problemi di configurazione errata
Tunnel Flapping:
- Impostazioni errate di keepalive possono causare frequenti interruzioni del tunnel, con conseguente instabilità.
MTU non corrispondente:
- I tunnel GRE su percorsi con impostazioni MTU diverse possono causare la frammentazione o la perdita di pacchetti.
Cicli di routing:
- Un routing configurato in modo errato può causare loop, causando traffico eccessivo e potenziali interruzioni della rete.
Best practice
Impostazioni MTU coerenti:
- Assicurarsi che le impostazioni MTU siano coerenti in tutto il tunnel GRE per evitare la frammentazione.
Configurazione corretta di Keepalive:
- Configurare le impostazioni keepalive per monitorare lo stato del tunnel ed evitare inutili involucri.
Documentazione chiara:
- Mantenere una documentazione chiara delle configurazioni del tunnel e dei percorsi associati per evitare configurazioni errate.
Casi d'uso per tunnel GRE.
Connessione di siti remoti:
- I tunnel GRE possono connettere siti remoti tramite Internet, consentendo una comunicazione sicura ed efficiente.
Tunneling del traffico non IP:
- GRE è in grado di incapsulare il traffico non IP, il che lo rende versatile per vari protocolli di rete.
Bilanciamento del carico:
- L'utilizzo di ECMP con tunnel GRE può distribuire il carico del traffico su più percorsi, migliorando le prestazioni di rete.
Esempio di topologia di rete
Immagina una rete con due siti remoti, il sito A e il sito B, connessi tramite Internet. Ogni sito dispone di un router con un tunnel GRE configurato tra di loro.
La topologia potrebbe essere simile alla seguente:
Sito A (10.10.10.0/24) ---- OS10-1 ---- Internet ---- OS10-2 ---- Sito B (10.20.10.0/24)
OS10(config)# interface tunnel 10 OS10(conf-if-tunnel-10)# <165>1 2022-11-11T17:55:16.614662+00:00 OS10 dn_alm 731 - - Node.1-Unit.1:PRI [event], Dell (OS10) %IFM_ASTATE_UP: Interface admin state up :tunnel10 OS10(conf-if-tunnel-10)# ip vrf forwarding red % Error: Interface tunnel10, Tunnel mode is mandatory config and must exist for other tunnel configs. OS10(conf-if-tunnel-10)# mode gre-ipv4 OS10(conf-if-tunnel-10)# ip vrf forwarding red OS10(conf-if-tunnel-10)# ip address 120.1.1.1/24 OS10(conf-if-tunnel-10)# <165>1 2022-11-11T17:55:31.454972+00:00 OS10 dn_alm 731 - - Node.1-Unit.1:PRI [event], Dell (OS10) %IP_ADDRESS_ADD: IP Address add is successful. IP 120.1.1.1/24 in VRF:red added successfully OS10(conf-if-tunnel-10)# tunnel destination 16.16.16.16 OS10(conf-if-tunnel-10)# tunnel source loopback10 OS10(conf-if-tunnel-10)# <165>1 2022-11-11T17:56:17.197783+00:00 OS10 dn_alm 731 - - Node.1-Unit.1:PRI [event], Dell (OS10) %IFM_OSTATE_UP: Interface operational state is up :tunnel10
OS10(conf-if-tunnel-10)# show configuration ! interface tunnel10 mode gre-ipv4 no shutdown ip vrf forwarding red ip address 120.1.1.1/24 tunnel destination 10.10.10.10 tunnel source loopback10 keepalive down-timer 10 keepalive enable keepalive probe-interval 6 keepalive up-timer 12
| Route ECMP underlay | Sovrapposizione route ECMP | Supportato |
|---|---|---|
| Statico | Statico | Sì |
| Statico | OSPF | Sì |
| Statico | BGP | Sì |
| OSPF | Statico | Sì |
| OSPF | OSPF | No |
| OSPF | BGP | Sì |
| BGP | Statico | Sì |
| BGP | OSPF | Sì |
| BGP | BGP | No |
OS10(config)# hardware overlay-ecmp-profile mode balanced-overlay-ecmp OS10(config)# <165>1 2022-10-11T10:25:26.474891+00:00 AG1-9978 dn_alm 717 - - Node.1- Unit.1:PRI [event], Dell (OS10) %VXLAN_OVERLAY_ECMP_PROFILE_MODIFIED: VxLAN Overlay ECMP: Configuration is modified, Save and Reload the device for the profile to be effect
OS10# show running-configuration interface tunnel 21 ! interface tunnel21 mode gre-ipv4 no shutdown ip address 10.10.10.2/24 tunnel destination 5.5.5.5 tunnel source loopback3 OS10# show running-configuration interface tunnel 22 ! interface tunnel22 mode gre-ipv4 no shutdown ip address 10.10.10.3/24 tunnel destination 6.6.6.6 tunnel source loopback4 OS10# show running-configuration interface tunnel 23 ! interface tunnel23 mode gre-ipv4 no shutdown ip address 10.10.10.4/24 tunnel destination 7.7.7.7 tunnel source loopback5 OS10# show running-configuration interface tunnel 24 ! interface tunnel24 mode gre-ipv4 no shutdown ip address 10.10.10.5/24 tunnel destination 8.8.8.8 tunnel source loopback6 OS10# show running-configuration route ! ip route 77.1.1.0/24 100.1.1.2 ip route 77.1.1.0/24 10.10.10.2 ip route 77.1.1.0/24 10.10.10.3 ip route 77.1.1.0/24 10.10.10.4 ip route 77.1.1.0/24 10.10.10.5 OS10# show ip route 10.1.1.0/24 Routing entry for 77.1.1.0/24 Known via static Distance 1, Metric 0 Last update 08:57:53 Routing descriptors Blocks: via 100.1.1.2 tunnel10 via 10.10.10.2 tunnel21 via 10.10.10.3 tunnel22 via 10.10.10.4 tunnel23 via 10.10.10.5 tunnel24
OS10# show ip route 67.67.67.0/24 Routing entry for 67.67.67.0/24 Known via ospf, type Distance 110, Metric 21 Last update 09:35:46 Routing descriptors Blocks: via 10.1.1.2 ethernet1/1/25:1 via 12.1.1.2 ethernet1/1/25:2 via 23.2.2.2 vlan2 via 23.2.3.2 vlan3 via 23.2.4.2 vlan4 via 23.2.5.2 vlan5 via 23.2.6.2 vlan6 via 23.2.7.2 vlan7 via 23.2.8.2 vlan8 via 23.2.9.2 vlan9 OS10# show ip route 68.68.68.0/24 Routing entry for 68.68.68.0/24 Known via ospf, type Distance 110, Metric 21 Last update 09:36:35 Routing descriptors Blocks: via 10.1.1.2 ethernet1/1/25:1 via 12.1.1.2 ethernet1/1/25:2 via 23.2.2.2 vlan2 via 23.2.3.2 vlan3 via 23.2.4.2 vlan4 via 23.2.5.2 vlan5 via 23.2.6.2 vlan6 OS10# show running-configuration interface vlan 2 ! interface vlan2 no shutdown ip address 23.2.2.1/24 ip ospf 1 area 0.0.0.0 OS10# show running-configuration interface vlan 3 ! interface vlan3 no shutdown ip address 23.2.3.1/24 ip ospf 1 area 0.0.0.0 OS10# show running-configuration interface vlan 4 ! interface vlan4 no shutdown ip address 23.2.4.1/24 ip ospf 1 area 0.0.0.0 OS10# show running-configuration interface tunnel 21 ! interface tunnel21 mode gre-ipv4 no shutdown ip address 131.131.131.1/24 tunnel destination 67.67.67.67 tunnel source loopback3 OS10# show running-configuration interface tunnel 22 ! interface tunnel22 mode gre-ipv4 no shutdown ip address 132.132.132.1/24 tunnel destination 68.68.68.68 tunnel source loopback4
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OS10# clear counters interface tunnel 10
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OS10(config)# interface tunnel 10
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OS10(conf-if-tunnel-40)# ip address 10.1.1.1/24
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OS10(conf)# ip route 1.1.1.0/24 interface tunnel 10 OS10(conf)# ip route 2.2.2.0/24 3.3.3.3 interface tunnel 10
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OS10(conf-if-tunnel-4)# ip vrf forwarding Vrf_red
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OS10(conf-if-tunnel-1)# keepalive down-timer 10
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OS10(conf-if-tunnel-1)# keepalive enable
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OS10(conf-if-tunnel-1)# keepalive probe-interval 10
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OS10(conf-if-tunnel-1)# keepalive up-timer 10
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OS10(conf-if-tunnel-1)# mode gre-ipv4
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OS10(conf-if-tunnel-40)# tunnel destination 10.10.10.10
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OS10(conf-if-tunnel-4)# tunnel source vlan 10
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OS10(conf-if-tunnel-1)# tunnel ttl 220
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OS10# show interface tunnel 10 Tunnel 10 is up, line protocol is up Hardware is Tunnel Tunnel mode GREv4 Tunnel source IP 2.2.2.2, Tunnel source Intf loopback1 Tunnel destination 7.7.7.7 Tunnel TTL 255 Tunnel keepalive enabled Keepalive probe interval 10, Up timer 5, Down timer 5 Interface index is 45 Internet address is 10.1.1.1/24 Mode of IPv4 Address Assignment: MANUAL Interface IPv6 oper status: Enabled ARP type: ARPA, ARP Timeout: 60 Last clearing of "show interface" counters: 00:11:22 Queuing strategy: fifo Input statistics: 0 packets, octets Output statistics: 0 packets, octets Time since last interface status change: 00:27:11
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OS10# show running-configuration interface tunnel ! interface tunnel10 no shutdown mode gre-ipv4 ip address 100.1.1.1/24 tunnel destination 3.3.3.3 tunnel source 1.1.1.1 ! interface tunnel20 no shutdown mode gre-ipv4 ip address 101.1.1.1/24 tunnel destination 5.5.5.5 tunnel source 6.6.6.6 OS10# show running-configuration interface tunnel 10 ! interface tunnel10 no shutdown mode gre-ipv4 ip address 100.1.1.1/24 tunnel destination 3.3.3.3 tunnel source 1.1.1.1
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OS10# show tunnel Name Mode Source-IP Destination-IP SrcIntf TTL VRF Status Protocol ================================================================================================= Tunnel 1 GREv4 1.1.1.1 6.6.6.6 Loopback 2 255 default up up Tunnel 2 GREv4 2.2.2.2 7.7.7.7 Loopback 123 255 default up up Tunnel 3 GREv4 3.3.3.3 8.8.8.8 Loopback 100 255 default up up OS10# show tunnel 10 Name Mode Source-IP Destination-IP SrcIntf TTL VRF Status Protocol ================================================================================================= Tunnel 10 GREv4 1.1.1.1 7.6.6.6 Loopback 2 255 default up up
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OS10# show ip int gig 1/3 GigabitEthernet 1/3 is up, line protocol is down Internet address is 10.11.0.1/24 Broadcast address is 10.11.0.255 Address determined by user input IP MTU is 1500 bytes Helper address is 192.168.0.1 192.168.0.2 Directed broadcast forwarding is disabled
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OS10# show ip route Codes: C - connected S - static B - BGP, IN - internal BGP, EX - external BGP, EV - EVPN BGP O - OSPF, IA - OSPF inter area, N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2, E1 - OSPF external type 1, E2 - OSPF external type 2, * - candidate default, + - summary route, > - non-active route Gateway of last resort is not set Destination Gateway Dist/Metric Last Change -------------------------------------------------------------------- C 1.1.1.0/24 via 1.1.1.1 ethernet1/1/1:1 0/0 01:32:53 C 10.1.1.0/24 via 100.1.1.1 loopback1 0/0 00:00:06 C 2.2.2.0/24 via 2.1.1.1.1 Tunnel 1 0/0 00:00:15 OS10# show ip route static Codes: C - connected S - static B - BGP, IN - internal BGP, EX - external BGP, EV - EVPN BGP O - OSPF, IA - OSPF inter area, N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2, E1 - OSPF external type 1, E2 - OSPF external type 2, * - candidate default, + - summary route, > - non-active route Gateway of last resort is not set Destination Gateway Dist/Metric Last Change ---------------------------------------------------------------------- C 1.1.1.0/24 via 1.1.1.1 ethernet1/1/1:1 0/0 01:32:53 C 10.1.1.0/24 via 100.1.1.1 loopback1 0/0 00:00:06 S 80.1.10.0/24 via 100.1.1.1 tunnel10 1/0 00:02:33
OS10# show ip ospf interface tunnel 10 tunnel10 is up, line protocol is up Internet Address 100.1.1.1/24, Area 0.0.0.0 Process ID 1, Router ID 1.1.1.1, Network Type broadcast, Cost: 1 Transmit Delay is 1 sec, State DR, Priority 1 Designated Router (ID) 1.1.1.1 (local), Interface address 100.1.1.1 Backup Designated router (ID) , Interface address 0.0.0.0 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Neighbor Count is 0, Adjacent neighbor count is 0 OS10# show ip ospf 1 interface tunnel 10 tunnel10 is up, line protocol is up Internet Address 100.1.1.1/24, Area 0.0.0.0 Process ID 1, Router ID 1.1.1.1, Network Type broadcast, Cost: 1 Transmit Delay is 1 sec, State DR, Priority 1 Designated Router (ID) 1.1.1.1 (local), Interface address 100.1.1.1 Backup Designated router (ID) , Interface address 0.0.0.0 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Neighbor Count is 0, Adjacent neighbor count is 0
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OS10# show ip ospf 1 statistics interface tunnel 10 Interface tunnel10 Receive Statistics rx-invalid 0 rx-invalid-bytes 0 rx-hello 0 rx-hello-bytes 0 rx-db-des 0 rx-db-des-bytes 0 rx-ls-req 0 rx-ls-req-bytes 0 rx-ls-upd 0 rx-ls-upd-bytes 0 rx-ls-ack 0 rx-ls-ack-bytes 0 Transmit Statistics tx-failed 0 tx-failed-bytes 0 tx-hello 52 tx-hello-bytes 3328 tx-db-des 0 tx-db-des-bytes 0 tx-ls-req 0 tx-ls-req-bytes 0 tx-ls-upd 0 tx-ls-upd-bytes 0 tx-ls-ack 0 tx-ls-ack-bytes 0 Error packets (Receive statistics) bad-src 0 dupe-id 0 hello-err 0 mtu-mismatch 0 nbr-ignored 0 wrong-proto 0 resource-err 0 bad-lsa-len 0 lsa-bad-type 0 lsa-bad-len 0 lsa-bad-cksum 0 auth-fail 0 netmask-mismatch 0 hello-tmr-mismatch 0 dead-ivlmismatch 0 options-mismatch 0 nbr-admin-down 0 own-hellodrop 0 self-orig 0 wrong-length 0 checksumerror 0 version-mismatch 0 area-mismatch 0
Additional Information
Affected Products
SmartFabric OS10 SoftwareArticle Properties
Article Number: 000228691
Article Type: How To
Last Modified: 03 Oct 2025
Version: 2
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