When the GRE tunnel interface comes up, it will start sending NHRP registration packets to the hub router. << /Dest (G1071956) Learn more about how Cisco is using Inclusive Language. All of the devices used in this document started with a cleared (default) configuration. The current method for solving this problem is to use generic routing encapsulation (GRE) tunnels in combination with IPsec encryption. If you have an earlier release you can use p-pGRE tunnels in this dual hub with dual DMVPN layout. Not only are these two similar, but all of the spoke router configurations will be similar. 15 0 obj For more information on document conventions, refer to Cisco Technical Tips Conventions. mask, ipv6 address address type to point-to-multipoint. >> show ip nhrpDisplays the IP Next Hop Resolution Protocol (NHRP) cache, optionally limited to dynamic or static cache entries for a specific interface. EIGRP. This feature is not supported on the C9500-12Q, C9500-16X, C9500-24Q, C9500-40X models of the Cisco Catalyst 9500 Series Switches. 17 0 obj /Parent 5 0 R Displays IPv6 content of the routing table. /accessLevel (Guest,Customer,Partner) /Count 20 Customers Also Viewed These Support Documents. Each spoke > builds a regular GRE tunnel, and will only connect to the hub. /MediaBox [0 0 612 792] /keywords () Use the following commands to verify the mGRE configuration: Displays IPv4 Next Hop Resolution Protocol (NHRP) mapping information. The dynamic routing protocol will not run over the dynamic IPsec+mGRE links between spokes. These hosts routes would cause packets destined to networks behind other spoke routers to be forwarded via the hub, rather then forwarded directly to the other spoke. The dynamic IP routing protocol running on the hub router can be configured to reflect the routes learned from one spoke back out the same interface to all of the other spokes, but the IP next-hop on these routes will usually be the hub router, not the spoke router from which the hub learned this route. This allows you some flexibility in deciding when you need to upgrade your spoke routers that are already deployed. GRE tunnels are used in combination with IPsec to solve this problem. /language (en) point-to-point GRE configuration at the spokes. /secondaryConcept () >> Multicast applications are also supported. /Names 2 0 R We have done the configuration on both the Cisco Routers . SOO. With a few additional configuration lines to the spoke routers you can set up dual (or multiple) hub routers, for redundancy. This is needed to enable dynamic routing protocols to work over the mGRE+IPsec tunnels between the hub and spokes. Configuring << Removed the crypto map vpnmap1 10 ipsec-isakmp command and replaced it with crypto ipsec profile vpnprof. On a Cisco router, each IPsec peer needs to be configured with the IP address of the other IPsec peer before the IPsec tunnel can be brought up. Currently, traffic in an mGRE interface is process-switched, resulting in poor performance. It then uses NHRP to notify the hub router of its current physical interface IP address. Note:When using the tunnel protection command on the tunnel interface, a crypto map command is not configured on the physical outgoing interface. can only be IPv4. Lastly, we define the Tunnel Destination IP address. Also, it is not necessary to configure any crypto ACLs, since these will be automatically derived from the GRE tunnel source and destination addresses. endobj The Hub router checks its NHRP mapping table for the destination 10.0.0.2 and finds that it maps to the address 172.16.1.24. /Subtype /Link << 12 0 obj The combination of these three commands make it unnecessary for the spokes external physical interface IP address to be configured. This is not a problem since the same routers are both the IPsec and GRE tunnel endpoints. << The spokes still send spoke-to-spoke traffic via the hub since they are using a point-to-point GRE tunnel interface. /Rect [162 194.3999938965 434.8200073242 205.6199951172] The above restrictions and some others are summarized in the following four points: IPsec uses an access control list (ACL) to define what data is to be encrypted. access-list 101 permit gre 172.16.2.0 0.0.0.255 host 172.17.0.1. It looks up this destination in the routing table and finds that it needs to forward this packet out the Tunnel0 interface to the IP nexthop, 10.0.0.3. /Pages 5 0 R endobj tunnel. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. >> endobj When GRE tunnels are configured, the IP addresses for the endpoints of the tunnel (tunnel source , tunnel destination ) must be known by the other endpoint and must be routable over the Internet. The one main difference is that Hub2 is also a spoke (or client) of Hub1, making Hub1 the primary hub and Hub2 the secondary hub. It may take 1 to 10 seconds to complete the initiation of the IPsec tunnel and data traffic is dropped during this time. I tried to use EIGRP neighbor statements to see if the EIGRP peers would come up using unicast and it did but not when multicast was used. endobj nhs-address is the IPv6 address of the hub {ip | ipv6} nhrp registration With a slight modification, the configuration from the last section can be used to support spoke routers with dynamic IP addresses on their outside physical interfaces. Check the "Anonymous Mode" box. The IPsec proxy is derived from the Tunnel0 tunnel source

command and the NHRP mapping. /Rect [162 160.3800048828 444.299987793 171.6600036621] tunnel interfaces) are available on the same NHRP router. Click Next. This is because the resulting IPsec proxy on the hub would be equivalent to permit gre host 172.17.0.1 any. Each of the spoke routers is configured with two p-pGRE tunnel interface, one in each of the two DMVPNs. This has been tested and works, though there was a bug in earlier versions of Cisco IOS software where TED forced all IP traffic between the two IPsec peers to be encrypted, not just the GRE tunnel packets. At this point, take a look at the routing tables and the NHRP mapping tables on the Hub, Spoke1, and Spoke2 routers to see the initial conditions (just after the Spoke1 and Spoke2 routers come up) and the conditions after Spoke1 and Spoke2 have created a dynamic link between them. 20 0 obj With the DMVPN solution, you can configure a single multipoint GRE tunnel interface and a single IPsec profile on the hub router to handle all spoke routers. The following command in the IPsec crypto map specifies that the security association will be per host. This is large enough that it would be difficult to show the configuration and to find the section of the configuration that is relevant to a current problem that is being debugged. are a large number of spoke sites, the configuration of the hub router and the number of independent IP address ranges (one If you want to use both hubs by balancing the spokes across the hubs, with failover protection and no asymmetric routing, then the routing configuration is more complex, but you can do it when using EIGRP. The dynamic routing protocol, EIGRP, is run over both p-pGRE tunnel subnets and is used to select one p-pGRE interface (DMVPN) over the other. << The access-list would list the routes from behind all spokes and the access-list would list only the routes from behind spokes where another hub router is to be the primary hub. The configuration on each spoke router would increase by 6 lines. DMVPN uses GRE and, therefore, supports IP multicast and dynamic routing traffic across the VPN. /Type /Catalog IPsec is implemented on Cisco routers via a set of commands that define the encryption and then a crypto map command applied on the external interface of the router. I am having a hard time looking for the right document as everything is referring to DMVPN. If this preference is needed, then techniques internal to the configuration of the routing protocol must be used. per tunnel) can quickly get excessive. Dual DMVPN networks with each spoke having two GRE tunnel interfaces (either point-to-point or multipoint) and each GRE tunnel connected to a different hub router. GRE configuration at the spokes. show crypto isakmp saDisplays the state for the ISAKMP security association (SA). Instead, NHRP can be configured to automatically add each spoke to the multicast destination list on the hub with the ip nhrp map multicast dynamic command. << ip address address /First 47 0 R to work correctly the IP address of the NHS server must also be statically mapped on spoke routers. NHRP provides the capability for the spoke routers to dynamically learn the exterior physical interface address of the other spoke routers in the VPN network. 18 0 obj timeout seconds. Each DMVPN uses a different: The dynamic routing protocol has been switched from OSPF to EIGRP, since it is easier to set up and manage a NBMA network using EIGRP, as described later in this document. {ip | ipv6} nhrp authentication debug tunnel protectionDisplays information about dynamic GRE tunnels. DMVPN combines multiple GRE (mGRE) Tunnels, IPSec encryption and NHRP (Next Hop Resolution Protocol) to perform its job and save the administrator the need to define multiple static crypto maps and dynamic discovery of tunnel endpoints. I was able to ping all ends of the GRE cloud but I cannot make OSPF/EIGRP work even if I have mapped the multicast IP as well. ip nhrp nhs If the NHRP mappings are used within the last minute before expiring, then an NHRP resolution request and reply will be sent to refresh the entry before it is deleted. The IP routing table entries for the networks that were learned through the encrypted tunnel will have the other end of the tunnel (GRE tunnel interface IP address) as the IP next hop. Spokes will use NHRP and register with the hub router. endobj The traditional implementation of a GRE tunnel involves the configuration of a point-to-point tunnel going between two sites. ip ospf network The idea is to have a two separate DMVPN "clouds". Certain show commands are supported by the Output Interpreter Tool (registered customers only) , which allows you to view an analysis of show command output. For example, a set of retail stores that need to connect to the company headquarters for inventory and ordering may also need to connect to other stores within the company to check out product availabilty. We are trying to create a redundant VPN configuration.. - We have one Active/Active VPN Gateway in Azure with two public IPs and BGP enabled - We have two FortiGate Firewalls.. indusind net banking. /Last 11 0 R 14 0 obj /Outlines 3 0 R /Subtype /Link Since it is not already known which spokes will need to talk directly with each other, a full mesh is required, even though each spoke may not need to talk directly with every other spoke. Dynamic routing protocols rely on using IP multicast or broadcast packets, but IPsec does not support encrypting multicast or broadcast packets. All of the spoke routers can be configured identically, and only the local IP interface addresses need to be added. and dynamic NHRP is used on the hub router. Enables the spoke to send an NHRP registration request to the hub. HTn@+2FdvmRXuXEu)6Hs9Bh'g$7LZ,x:+!k1 puN8?=CqxaomE 9J#8u{4{y'9B0i1s~.0!3G! endobj Spoke-to-spoke traffic traversing the hub uses hub resources and can incur extra delays, especially when using IPsec encryption, since the hub will need to decrypt the incoming packets from the sending spokes and then re-encrypt the traffic to send it to the receiving spoke. /Title (Dynamic Layer 3 VPNs with Multipoint GRE Tunnels) 4 0 obj The following sequence of events takes place to build the direct spoke-to-spoke mGRE+IPsec tunnel. Note:The dynamic routing protocol only runs on the hub and spoke links, it does not run on the dynamic spoke-to-spoke links. No other changes are necessary. create a gre tunnel template to be applied !--- to all the dynamically created gre tunnels. Generic Routing Encapsulation (GRE) is one of the available tunneling mechanisms which uses IP as the transport protocol and can be used for carrying many different passenger protocols. If the underlying protocol is OSPF, execute this command to set the network The hub routers will only have a single multipoint GRE tunnel interface. debug nhrp packetDisplays information about NHRP packets. endobj Notice that the OSPF network type is set to broadcast and the priority is set to 2. Without the direct link between Hub1 and Hub2, Hub2 would not participate in the OSPF routing when Hub1 is also up. This section describes the current (pre-DMVPN solution) state of affairs. endobj GRE Tunnel Configuration on Cisco Packet Tracer Watch on GRE Tunnel Configuration In Router 0, we will create the Tunnel interface and then give this interface an IP Address. This information can then be used for each of the spokes to dynamically set up mGRE tunnels between each of the other spokes, Multipoint GRE (mGRE) is a protocol that can be used to enable one node to communicate with many nodes. << 8 0 obj Previously, NHRP required you to explicitly configure the broadcast/multicast mapping for the tunnel destination IP addresses to support GRE tunneling of Multicast and Broadcast IP packets. Enables the hub to use the next received hop while sending routing protocol The configuration changes are as follows. The two spokes then dynamically create an IPsec tunnel between them (via the single mGRE interface) and data can be directly transferred. To reduce this value, you could use dynamic crypto maps, which would reduce the above value by 1200 lines, leaving 2700 lines in a 300-spoke network. << This will only work if the data packets to be encrypted have routable IP addresses. This means that incoming multicast data packets may be associated with the wrong mGRE interface, breaking any dynamic routing protocol. Spoke1 and Spoke2 can now forward packets directly to each other. These NHRP registration packets will trigger IPsec to be initiated. >> application/pdf The Next Hop Resolution Protocol (NHRP) is like the Address Resolution Protocol (ARP) that dynamically maps a non-broadcast This is advantageous since, if this spoke-to-spoke data traffic was sent via the hub router, then it must be encrypted/decrypted, twice increasing the delay and the load on the hub router. service (QoS) are supported on the mGRE tunnel. In other words, it can be used for point-to-multipoint links using which one node can transmit data to many nodes. DMVPN allows better scaling in full mesh or in partial mesh IPsec VPNs. There are two different ways to configure mGRE on the hub and leave a normal GRE configuration on spokes: Static NHRP mapping statements on the hub router. For example, the routing table on a router, R2, that is connected directly to the 192.168.0.0/24 LAN would look like the following: The spoke routers have equal cost routes via both hub routers to the network behind the hub routers. No matter how the networks change at either end, the GRE IP tunnel packets will not change, so this ACL need not change. Before configuring multicast routing over multipoint Generic Routing Encapsulation (mGRE), you should be familiar with the EIGRP will, by default, set the IP next-hop to be the hub router for routes that it is advertising, even when advertising those routes back out the same interface where it learned them. /description () The configuration on the spoke routers above does not rely on features from the DMVPN solution, so the spoke routers can run Cisco IOS software versions prior to 12.2(13)T. The configuration on the hub router does rely on DMVPN features, so it must run Cisco IOS version 12.2(13)T or later. DMVPN reduces the size of the configuration needed on all the routers in the VPN. Perform this task to configure unicast mGRE at spokes: ip nhrp map ip-address Area 0 is used for the network behind the two hubs, and area 1 is used for the DMVPN network and networks behind the spoke routers. Since OSPF is a link-state routing protocol, there are not any split horizon issues. The Auvergne - Rhne-Alpes being a dynamic, thriving area, modern architects and museums also feature, for example in cities like Chambry, Grenoble and Lyon, the last with its opera house boldly restored by Jean Nouvel. The spoke-to-hub tunnels are up continuously, and spokes do not need configuration for direct tunnels to any of the other spokes. In the past, the only way to make the connection was to use a Layer-2 network such as ISDN or Frame Relay to interconnect everything. Tunnel This protocol provides an ARP-like solution which allow station data-link addresses to dynamically determine NHRP as a client id. /Type /Page show ip routeDisplays the routing table. By doing this, Hub2 will still forward packets directly to the spoke routers, but it will advertise a less desirable route than Hub1 to routers behind Hub1 and Hub2. Otherwise, the NHRP mapping will be deleted and that will trigger IPsec to clear the IPsec SAs. In contrast, the spoke routers will send packets for the networks behind the hub routers to both Hub1 and Hub2, since there is only a single mGRE tunnel interface on each spoke router and there will be two equal cost routes. The IPsec peer address and the match address clause for the IPsec proxy are automatically derived from the NHRP mappings for the GRE tunnel. This simplifies the configuration since the IPsec peer and the crypto ACLs are no longer needed. This command is now needed because the spokes GRE tunnel has changed to multipoint and there is more then one possible destination. /Dest (G1056884) The subnet is now /24 instead of /30, so all of the nodes are in the same subnet, instead of different subnets. %PDF-1.4 As IPsec hub-and-spoke networks were deployed and grew in size, it became more desirable to have them route IP packets as dynamically as possible. The functionality that is used in the new spoke configuration is as follows. These parameters are automatically determined from the NHRP mappings for the mGRE tunnel interface. show crypto engine connections active Displays the total encrypts/decrypts per SA. For Cisco, you can configure a mulipoint GRE interface like so . /Resources 31 0 R /Type /Metadata But, this is not a problem because with DMVPN the mGRE+IPsec tunnel is automatically initiated when the spoke router starts up, and it always stays up. The hub maintains 5 0 obj endobj Use these resources to familiarize yourself with the community: There is currently an issue with Webex login, we are working to resolve. Thus, if the networks change on either side of the tunnel, then the other side will dynamically learn of the change and connectivity will continue without any configuration changes on the routers. The main difference is that each is the hub of a different DMVPN. as point-to-point GRE tunnels. number. >> interface FastEthernet0/0ip address 21.1.77.1 255.255.255.0, interface Tunnel10ip address 1.0.0.1 255.255.255.0no ip redirectsip mtu 1400ip pim dense-modeip nhrp authentication cisco10ip nhrp map 1.0.0.3 21.97.10.1ip nhrp map multicast 1.0.0.3ip nhrp map 1.0.0.2 203.177.7.1ip nhrp map multicast 1.0.0.2ip nhrp network-id 10ip tcp adjust-mss 1300tunnel source FastEthernet0/0tunnel mode gre multipointtunnel key 10, interface FastEthernet0/0ip address 203.177.7.1 255.255.255.0, interface Tunnel10ip address 1.0.0.2 255.255.255.0no ip redirectsip mtu 1400ip pim dense-modeip nhrp authentication cisco10ip nhrp map 1.0.0.1 21.1.77.1ip nhrp map multicast 1.0.0.1ip nhrp map 1.0.0.3 21.97.10.1ip nhrp map multicast 1.0.0.3ip nhrp network-id 10ip tcp adjust-mss 1300tunnel source FastEthernet0/0tunnel mode gre multipointtunnel key 10, interface FastEthernet0/0ip address 21.97.10.1 255.255.255.0, interface Tunnel10ip address 1.0.0.3 255.255.255.0no ip redirectsip pim dense-modeip nhrp authentication cisco10ip nhrp map 1.0.0.1 21.1.77.1ip nhrp map multicast 1.0.0.1ip nhrp map 1.0.0.2 203.177.7.1ip nhrp map multicast 1.0.0.2ip nhrp network-id 10tunnel source FastEthernet0/0tunnel mode gre multipointtunnel key 10. If the "any" from the ACL were used as the source in the IPsec proxy, it would preclude any other spoke router from also setting up an IPsec+GRE tunnel with this hub. At this point, let us take a look at the routing tables, the NHRP mapping tables, and IPsec connections on the Hub1, Hub2, Spoke1 and Spoke2 routers to see the initial conditions (just after the Spoke1 and Spoke2 routers come up). Internet Access. Phase 1 was the original implementation of DMVPN . The NHRP mappings will expire after five minutes ( the current value of NHRP holdtime = 300 seconds). To get around this problem, configure the OSPF network type to be broadcast using the command. However, we need to initiate the traffic towards the remote networks to make the tunnel up and run. 10:49 PM. Sample mGRE Configuration at Hub and Spokes DMVPN can require the hub-to-spoke link to constantly be up. Note:Before issuing debug commands, please see Important Information on Debug Commands. The most feasible method to scale a large point-to-point network is to organize it into a hub-and-spoke or full (partial) mesh network. I'm trying to figure out if it is possible to do mGRE without doing DMVPN. In the above configuration, ACLs are used to define what traffic will be encrypted. With large hub-and-spoke networks, the size of the configuration on the Hub router can become very large, to the extent that it is unusable. Also this size configuration may be too large to fit in NVRAM and would need to be stored on Flash memory. Setting the OSPF network type to broadcast will cause OSPF to install routes for networks behind the spokes routers with an IP next-hop address as the GRE tunnel address for that spoke router.
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