MPLS3 with GETVPN

Hello all…wanted to share my version of a MPLS lab with you....as if there's not enough MPLS material online! Well, here's one more! The base of the lab was configured with the guidance of Keith Barker, who put up an excellent you tube video on MPLS-check it out here!

https://www.youtube.com/watch?v=pia2WceaevQ&list=PLC3E6D83668FB81C7&index=2

I just kind of elaborated on it a bit-added a second customer, a third customer CE, and some GETVPN to get some traffic encryption going. Here’s the config for PE-R2…… at the end of all this, I’ll make my GNS3 lab available for those who want to download it.

version 15.2 service timestamps debug datetime msec service timestamps log datetime msec ! hostname PE-R2 ! boot-start-marker boot-end-marker ! ! vrf definition dtech  rd 120:120  !  address-family ipv4   route-target export 20:20   route-target import 30:30   route-target import 40:40   route-target import 137:137  exit-address-family ! vrf definition isp  rd 137:137  !  address-family ipv4   import map DTECH_SELECT   route-target export 137:137   route-target import 21:21   route-target import 31:31   route-target import 20:20   route-target import 30:30   route-target import 40:40  exit-address-family ! vrf definition pizza  rd 121:121  !  address-family ipv4   route-target export 21:21   route-target import 31:31   route-target import 137:137  exit-address-family ! no aaa new-model no ip domain lookup ip domain name lab.local ip cef no ipv6 cef ! ! multilink bundle-name authenticated ! interface Loopback0  ip address 2.2.2.2 255.255.255.255 ! interface FastEthernet0/0  ip address 10.0.23.2 255.255.255.0  speed auto  duplex auto  mpls ip ! interface FastEthernet0/1  ip address 10.0.24.2 255.255.255.0  speed auto  duplex auto  mpls ip ! interface FastEthernet1/0  vrf forwarding dtech  ip address 172.16.12.2 255.255.255.0  speed auto  duplex auto ! interface FastEthernet1/1  vrf forwarding pizza  ip address 172.16.29.2 255.255.255.0  speed auto  duplex auto ! router ospf 2 vrf pizza  router-id 0.0.29.29  redistribute bgp 27 subnets  network 172.16.29.0 0.0.0.255 area 0  default-information originate ! router ospf 1  network 2.2.2.2 0.0.0.0 area 0  network 10.0.0.0 0.0.255.255 area 0 ! router rip  !  address-family ipv4 vrf dtech   redistribute bgp 27 metric 2   network 172.16.0.0   no auto-summary   version 2  exit-address-family ! router bgp 27  bgp log-neighbor-changes  neighbor 7.7.7.7 remote-as 27  neighbor 7.7.7.7 update-source Loopback0  neighbor 11.11.11.11 remote-as 27  neighbor 11.11.11.11 update-source Loopback0  !  address-family vpnv4   neighbor 7.7.7.7 activate   neighbor 7.7.7.7 send-community extended   neighbor 11.11.11.11 activate   neighbor 11.11.11.11 send-community extended  exit-address-family  !  address-family ipv4 vrf dtech   redistribute rip  exit-address-family  !  address-family ipv4 vrf pizza   redistribute ospf 2  exit-address-family ! ip forward-protocol nd ! ! no ip http server no ip http secure-server ! ! ip prefix-list DTECH_LOOPS seq 5 permit 1.1.1.1/32 ip prefix-list DTECH_LOOPS seq 10 permit 8.8.8.8/32 ip prefix-list DTECH_LOOPS seq 15 permit 12.12.12.12/32 ! route-map DTECH_SELECT deny 10  match ip address prefix-list DTECH_LOOPS ! route-map DTECH_SELECT permit 20

Define your customer VRF and assign a unique Route Distinguisher value in order to keep possible overlapping customer routes unique when traversing MP-BGP. Define which routes in the customer’s VRF you want to share with other VRFs route-targets. Most times you can just assign the same value for import and export, since you would normally want to share all routes among the same customer vrf, but I just wanted to make them unique for each vrf instance. One for each PE. For the ISP vrf, I used a route map import so that only select routes were imported in, and others denied. Using the route-target values is all or nothing. Import and export maps will give you more control. In this case, the ISP vrf is importing all other vrf routes, with the exception of dtech, and are modified via the import map command. See at the bottom of the config… Enable mpls for the interfaces connecting your core routers This would be your customer facing interface- you’ll want to place this interface in the vrf for your customer. This interface will also exchange routes with the CE’s local routing protocol. This customer (pizza) uses OSPF as their IGP at the CE. This OSPF instance is placed in the customer vrf and MP-BGP is redistributed into it- which is carrying the injected routes through the MPLS core from the other customer VRFs\PE interface. Note the use of “default-information originate” here. This is necessary to distribute a default route to the CE via OSPF. The route is originated on PE-R7 in the isp vrf, and distributed via MP-BGP like the rest of the routes. OSPF 1 servers as the core IGP for the MPLS backbone This customer (dtech) uses RIPv2 as their IGP at the CE. This rip instance is placed in the customer vrf and MP-BGP is redistributed into it- which is carrying the injected routes through the MPLS core from the other customer VRFs\PE interfaces Here we are defining the BGP pairings for our PE routers that define the MPLS backbone. I did a full mesh between the 3. Also using the loopback0 as the update source instead of the physical interface for redundancy. It’s here, in the vpnv4 address family, where you are activating the PE BGP neighbors to send vpnv4 customer prefixes which are made globally unique by use of the Route Distinguisher defined earlier. Also, it is the enabling of the extended send-communities in MP-BGP that carry the RD and RT information needed for MPLS vpns to work. Next, we redistribute the CE’s local IGP into BGP within the respective customer vrfs Here’s the prefix used in the above import map. I didn't want the isp vrf to show the dtech loopback networks (lets pretend these were top secret networks). So the loopbacks are defined in the prefix list here, then denied in the DTECH_SELECT route map, effectively preventing them from importation on the to the isp network. Notice the unmatched permit statement at the end of the route map…basically saying “leave everything else as is”

Now, take a look at PE-R7…I’ll go over the differences from PE-R2- it’s all configured the same except for these exceptions.

When your CE’s are using EIGRP as there local routing IGP, you can just create a single EIGRP AS instance on the PE (AS 7 in this case)- then, under your address-family commands, reference the CE’s local EIGRP AS number…. (8, 10, 13 respectively)- then you’ll redistribute BGP into those AS’s so that your customers get the routes.

router eigrp 7

 !

 address-family ipv4 vrf dtech

  redistribute bgp 27 metric 1 1 1 1 1

  network 0.0.0.0

  autonomous-system 8

 exit-address-family

 !

 address-family ipv4 vrf pizza

  redistribute bgp 27 metric 1 1 1 1 1

  network 0.0.0.0

  autonomous-system 10

 exit-address-family

 !

 address-family ipv4 vrf isp

  redistribute bgp 27 metric 1 1 1 1 1

  network 0.0.0.0

  autonomous-system 13

 exit-address-family

Now, there’s a default static route on PE-R7 pointing to the ISP router. I have this route shared among all the vrfs, so that any traffic wo specific routes heads out towards the internet. I distributed this route via the MPLS network to the CEs.

ip route vrf isp 0.0.0.0 0.0.0.0 137.137.137.13

router bgp 27

address-family ipv4 vrf isp

  redistribute static

  default-information originate

 exit-address-family

You’ll want to redistribute static routes into BGP for the isp vrf as shown above- you’ll also need default-information originate so that’s it’s distributed via MP-BGP and shows up in the ipv4 tables for all the vrfs on all the Pes. I’m also peering with the ISP routers local EIGRP as show above on this PE-R7…..other than that, it’s the same as PE-2

The CE routers are just straight peering with their respective IGPs (no redistribution done at the CEs)- advertise the networks you want (I advertised all the CE loopbacks- ie R1 loopback is 1.1.1.1/32) and you should be good to go. You should see the routes for your respective customer offices on the CE (show ip route).

 To check the that you have the correct BGP routes on your PE routers, use show ip bgp all - you'll get a table for each vrf under the VPNv4 address family. (see below) Note the default route in each vrf

Now, you have a functioning MPLS network serving 2 customers! Pretty cool! But….dtech is worried about the security of their traffic between office locations. Pizza doesn’t care- they’re busy making pizzas! So, I’ll implement GETVPN over MPLS to encrypt the interoffice traffic for DTech in the next section. And I'll upload the lab files as well.......  until then....thanks for reading.

Update: 3-2015.............................................................................................................................

Actually....I went through the GETVPN config on another lab.....combining it with DMVPN....so if interested, you can head there and take a look.    http://techjuice.blogspot.com/2015/03/dmvpn-w-getvpn-for-encryption.html

Update: 1-2024...............................................................................................................................

Added new Cisco Modeling Labs version of the lab (Less the GET-VPN part)  Download Lab

Adjusting OSPF path selection

 

If you want to adjust the the path of an ospf router, beyond the route type (which is it's first and foremost criteria), there are a couple ways you can do it.

Link Cost:

Fist way is adjusting the cost of the link from the perspective of the ospf router. Lower cost is preferred, and if there are a couple links with equal cost, then they will be load balanced automatically.

First thing you may want to do is set your reference bandwidth across all ospf routers. A setting of 10,000 (expressed in Mbps - 10,000 Mbps is 10 Gbps) will be equivalent to 10 Gig, so  a 10 Gig interface will have a cost of 1, a 1 Gig interface a cost of 10, 100Mbps a cost of 100, and so on.

router ospf 1
auto-cost reference-bandwidth 10000

Consider the topology below...currently the route from R7 to the 4.4.4.4 network has the option of 2 paths -  both of equal cost - so they will be load balanced by ospf.

But if we want to only use say the link between R7 and and R1, we can do that by changing the link cost.

Current cost is 10 - and the route table for R7 is shown below- 2 equal cost routes to 4.4.4.4. Note that the loopback interface has a cost of 1, as it's a connected interface.....hence the 3 x 10 links + 1 gives you the 31.

Using the ip ospf cost # command under the respective interface will will change it the cost

R7(config)#interface gigabitEthernet 0/0
R7(config-if)#ip ospf cost 9

Now, we get this - a cost of 9

with a single "better" route (cost of 30 vs 31) to 4.4.4.4

This works fine...BUT...it will effect ALL routes advertised, and destined, across that link. May not be what we need. 

Administrative Distance (AD):

You can use the distance command to change the Administrative Distance of a specific route (AD)

First define the route you want to change the AD for in an access-list... in this case, it's 4.4.4.4/32 

R7(config)#access-list 1 permit host 4.4.4.4

Next determine the advertising router - the router that the route is learned from, in this case it's R3 - we need to use the routers ospf router id - which is 3.3.3.3 as shown below

Apply the distance command

distance <AD value> <advertising router id\wild card mask> <route defined in access list>

R7(config)#router ospf 1
R7(config-router)#distance 99 3.3.3.3 0.0.0.0 1 

This works, BUT, it does nothing to favor one link over another - you still have equal cost over the 2 links to the route

Due to OSPF's link-state nature, it's more preferable to use policy based routing (PBR), and direct the traffic type you want over a certain link.

PBR:

In the topology below, we will set the next hop to for ICMP traffic originating at R8, to use the link between the R1 and R7.

We will first create an access list to identify the route (destination in this case)

ip access-list extended ICMP

 permit icmp any host 4.4.4.4

Next we create a route-map to match the traffic type (icmp) and set the next hop

route-map PBR-ICMP permit 5

 match ip address ICMP

 set ip next-hop 10.1.17.1

Now tie it in and activate the PBR on the incoming incoming interface on R7 from R8

interface GigabitEthernet0/2

 ip policy route-map PBR-ICMP

Execute a ping on R8 to 4.4.4.4

You can observe the route-map matches incrementing here

Also, if you enable some debugging on R7 - then execute a ping on R8, you can validate the PBR is taking action on the traffic destine for 4.4.4.4

R7#debug ip policy

Hope this has been a useful reference on influencing OSPF routes

Here's a quick table of the OSPF route and LSA types:

Intra-Area (O)

Inter-Area (O IA)

External Type 1 (E1)

NSSA Type 1 (N1)

External Type 2 (E2)

NSSA Type 2 (N2)

LSA Type 1:            Router LSA

LSA Type 2:            Network LSA

LSA Type 3:            Summary LSA

LSA Type 4:            Summary ASBR LSA

LSA Type 5:            Autonomous system external LSA

LSA Type 6:            Multicast OSPF LSA

LSA Type 7:            Not-so-stubby area LSA

LSA Type 8:            External attribute LSA for BGP

 

Windows 10 Holds on to an IP address for dear life!

Came across an interesting, and horribly annoying, behavior with Windows 10..and probably any recent version of Windows. Windows will ALWAYS try to reuse the last successful dhcp lease it receives, even across reboots! So you may ask, why should I care about this? Well, if you are in say a school campus environment, with domain-ed clients, that are shared by students and faculty, which in turn are placed on different vlans...this behavior will indeed create havoc! The ip leased by say a student, will "stick" in the registry, and as long as the dhcp lease is still valid, it will be reused. Now a faculty member logs on, they end up associated to an AP and get assigned the faculty vlan at layer 2...but are stuck with an IP from the student vlan that's invalid for the that subnet.

The interface ip lease information is stored here (see example reg values below)



HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\{Interface GUID}

"DhcpIPAddress"="10.2.21.28"

"DhcpSubnetMask"="255.255.252.0"

"DhcpDomain"="mydomain.local"

"DhcpNameServer"="10.1.2.19 10.1.2.17"

"DhcpDefaultGateway"=hex(7):31,00,30,00,2e,00,32,00,2e,00,32,00,30,00,2e,00,31,\
00,00,00,00,00

"DhcpSubnetMaskOpt"=hex(7):32,00,35,00,35,00,2e,00,32,00,35,00,35,00,2e,00,32,\
00,35,00,32,00,2e,00,30,00,00,00,00,00

This key is changed to the broadcast address from 10.1.2.19

"DhcpServer"="255.255.255.255"

And like I mentioned...this is stored across reboots.

The various ways to "reset" or clear these reg key values are as follows:
 
ipconfig /release from an active connection under the current session then log off or shutdown- ready for the next user

Log in as an administrative user and restart\stop the DHCP service- then log off or shutdown.

Neither option is particularly easy to trigger and schedule via a scheduled task....so what I ended up doing was multi-layered approach. I needed the above reg values to be cleared whether the machine was connected to the network or not...so this meant dropping the scripts locally. I used group policy preferences in a GPO to do that. 2 files, one the PS script to clear the reg...which is also searches for the correct interface GUID based on the name of the network connection...in our case "WiFi"

cd\cls$ErrorActionPreference='silentlycontinue'$NIC=Get-WmiObject -class Win32_NetworkAdapter -Filter "NetConnectionID='Wi-Fi'" | select -Property GUID -ExpandProperty GUID #needed to just get string wo headerRemove-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\$NIC -Name DhcpIPAddressRemove-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\$NIC -Name DhcpSubnetMaskRemove-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\$NIC -Name DhcpDomainRemove-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\$NIC -Name DhcpNameServerRemove-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\$NIC -Name DhcpDefaultGatewayRemove-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\$NIC -Name DhcpSubnetMaskOptSet-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\$NIC" -Name DhcpServer -Value 255.255.255.255exit

The other, a one liner cmd script to trigger the ps script:


C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -noprofile -executionpolicy bypass -file C:\users\IPReleaseV3.ps1


The latter script, I used the same computer based GPO configured with a shutdown script referencing the local cmd script....so once the domained machine has the GPO associated and applied, the script will trigger on shutdown or restart whether on the network or not.....which is what we want.

C:\users\IPRelease.cmd

I seemingly had it licked now...but found out that thanks to Windows Hiberboot or Fast Startup they call it, a shutdown script will NOT be processed on shutdown ! It will just be skipped. On restart it does seem to execute though.

Anyway...I went ahead and pushed the following reg setting to disable Hiberboot..again, using GP preferences:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Power\

HiberbootEnabled=0

So there you have it...a bit of a clunky solution but an absolute life saver in our situation. 

Hope somebody finds this helpful ! 

Unable to advertise static routes via MP BGP to PE routers

Wanted to quickly post this MP BGP MPLS config I had trouble with here. Below is the Cisco support thread that covers it.

I wanted to do a straight bgp only L3 service across my ISP PEs....using different AS for each customer site. No other core IGP is used- just BGP and static routes to form the neighborships between PE-R8 and PE-R9. In order to get full end to end connectivity for the site networks, I had to advertise the transit networks between the PE routers and the P router. (the .140 and .144) The key to get them advertised out to the CEs was first get define the static routes on the PE in the global routing table. Then redistribute those into the ipv4 BGP table. THEN...import those routes into the customer vrf using the import command that references a route-map, that references an ip prefix-list to scope the routes. After all that- they finally appeared in the vpnv4 address family on the PE routers, and in BGP on the vrf attached CEs
This was the only way I could get them to work - maybe there's an easier way !


Unable to advertise static routes via MP BGP to PE routers


PE-R8#show ip bgp
  Network          Next Hop            Metric LocPrf Weight Path
 r>i 8.8.8.8/32       152.177.58.146           0    100      0 ?
 *>  9.9.9.9/32       152.177.58.141           0         32768 ?
 r>i 152.177.58.140/30
                             152.177.58.146           0    100      0 ?
 *>  152.177.58.144/30
                             152.177.58.141           0         32768 ?
show ip bgp all
For address family: VPNv4 Unicast
Route Distinguisher: 120:120 (default for vrf TGI)
Import Map: IMPORT_STATIC_MAP, Address-Family: IPv4 Unicast, Pfx Count/Limit: 1/1000
 *>  10.7.1.0/24          152.177.58.138    0             0 65002 i
 *>i 10.24.20.0/22      9.9.9.9                  0    100      0 65001 i
 *>i 51.64.56.252/30  9.9.9.9                  0    100      0 65001 i
 *>i 130.148.200.126/32
                                  9.9.9.9                  0    100      0 65001 i
 *>i 152.177.58.132/30
                                 9.9.9.9                  0    100      0 65001 i
 r>  152.177.58.136/30
                                152.177.58.138           0             0 65002 i
 *>  152.177.58.144/30
                       152.177.58.141           0         32768 ?


So..to sum up...here's the config that worked: (for PE-R8....R9 config'd similarly)

ip vrf TGI
rd 120:120
import ipv4 unicast map IMPORT_STATIC_MAP
route-target export 20:20
route-target import 20:20

router bgp 65000
bgp router-id 8.8.8.8
bgp log-neighbor-changes
neighbor 9.9.9.9 remote-as 65000
neighbor 9.9.9.9 update-source Loopback8
!
address-family ipv4
redistribute static
neighbor 9.9.9.9 activate
exit-address-family
!
address-family vpnv4
neighbor 9.9.9.9 activate
neighbor 9.9.9.9 send-community both
exit-address-family
!
address-family ipv4 vrf TGI
neighbor 152.177.58.138 remote-as 65002
neighbor 152.177.58.138 activate
exit-address-family

ip route 9.9.9.9 255.255.255.255 152.177.58.141
ip route 152.177.58.144 255.255.255.252 152.177.58.141
!
!
ip prefix-list IMPORT_STATIC seq 5 permit 152.177.58.144/30
!
route-map IMPORT_STATIC_MAP permit 10
match ip address prefix-list IMPORT_STATIC

Windows VLAN Stripping - Intel(R) PRO/1000 PT Quad Port NIC w GNS3

It's been widely know that Windows OS's by default, will strip VLAN tags as they enter the stack. It's driver dependent really....and some nic driver are designed to cope with it, and some not. Luckily, my Intel(R) PRO/1000 PT Quad Port LP Server Adapter (aka "HP NC364T PCI EXPRESS QUAD-PORT GIGABIT SERVER ADAPTER") is able to deal with this annoyance with a couple of simple settings.

First, you want to set you Priority and VLAN settings to enabled for both..

Second is a registry key and setting. In the case of the Intel Quad, there'll be 4 of these...one for each physical interface:

[HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4d36e972-e325-11ce-bfc1-08002be10318}\0006]

"MonitorModeEnabled"=dword:00000001


You want to create the DWORD value "MonitorModeEnabled" under the above key and set it to 1. Note that the numbered end of the key name "00nn" will be different on your system- one of mine is 0006.

That's it.... give your machine a reboot and you'll be passing VLAN tags through your Windows systems to your virtual machines or for example, GNS3 labs. This is huge to able able to attach your virtual GNS3 routers to say, your real physical switch stack and trunk VLAN tags as normal for labbing etc.....


As an example, I labbed a little MPLS network recently, and took a capture to make sure my physical laptop, plugged in to a real switch port in VLAN 40, was not having the tags stripped after the above changes.

I sent a ping from the laptop, through the switch port, out the trunk connected to my Quad 2 nic, into my GNS3 network....to the CE-5 loopback at 5.5.5.5...... proof that VLAN tags are now in tact!

Here's a capture of the ping below. And incidentally, you'll want to set your destination Cisco SPAN port with dot1q encapsulation, like this....or it will get stripped there as well. Hope this helps somebody....

monitor session 1 source interface Fa0/48

monitor session 1 destination interface Fa0/47 encapsulation dot1q

Basic Campus Network with Cisco Packet Tracer

 

    As if there's not enough network diagrams and designs out there...here's one more! I wanted to just share out a basic campus network design using good old CPT. For all it's limitations and flakiness, it's still damm cool to have an entire functioning network, albeit somewhat dated, stuffed into a single pkt file! A good review and reference of some basic design principles using HSRP, splitting Vlan traffic among the distribution switches, gateway redundancy, split DHCP scopes... things like that. Even has a telephony router and some ip phones...not too shabby! I'll make the pkt file available too for anybody who wants to download the topology.

Download PKT File

DMVPN w GETVPN for encryption

I thought it would be cool to lab out a combination of DMVPN (Dynamic Multipoint VPN, utilizing multipoint GRE dynamic tunnels) with the integration of GETVPN. Group Encrypted Transport VPN, which utilizes a key server that distributes group keys to it's registered members and controls the group security associations between the peers. GETVPN does not use static ipsec tunnels or create the VPN frame work....you would need to have a vpn in place...DMVPN in this example, although GETVPN is best suited over MPLS.  BTW...a great guide for setting up and understanding DMVPN can be found here at firewall.cx:

CONFIGURING CISCO DYNAMIC MULTIPOINT VPN (DMVPN)


Below is my GNS 3 lab diagram. I started by using a single router to represent the internet. I also Port Address Translated the 2 spoke and hub routers public interfaces to allow the private hosts to communicate with the rest of the "Internet" to add some realism. The DMVPN config is below

------------------------------------------------------------------------------------------------------------------------

interface Tunnel0  description mGRE DMVPN Tunnel  ip address 192.168.1.1 255.255.255.0  no ip redirects  no ip split-horizon eigrp 1 no ip next-hop-self eigrp 1 ip nhrp authentication DMVPN ip nhrp map multicast dynamic  ip nhrp network-id 1  tunnel source 11.11.11.1  tunnel mode gre multipoint router eigrp 1  network 10.1.1.0 0.0.0.255  network 192.168.1.0

These are the pertinent  parts of the DMVPN config. Nothing special with the physical interfaces- just assign them IPs and activate them. All the config is done on the tunnel interface- which is the fist thing you'll create. This the hub config. You'll want to use a private address network for your tunnel interfaces. You will definitely need to disable split-horizon for the EIGRP process running on the tunnel interface. If you don't, your spokes will never get eachothers routes, only the updates from the hubs routes will be present on the spokes. Also if you want direct communication\routes between spoke routers, and not send all traffic via the hub, then disable next-hop-self as well for your EIGRP, Set your authentication string to allow queries and updates to the NHRP database Map multicast traffic to the spokes dynamically- this is used and necessary for routing protocols that use multicast packets (ie EIGRP in this case) in their routing updates. Set the network ID- which will be the same for all participating routers in the VPN cloud. Your tunnel source is the public facing interface IP. This command enables the tunnel interface as a multipoint GRE tunnel. This is your basic advertising of your routers networks- you'll need to add the tunnel network as well in order for EIGRP adjacencies to form.

--------------------------------------------------------------------------------------------------------------------------

Next is the spoke config for the VPN........

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interface Tunnel0  description mGRE DMVPN Tunnel  ip address 192.168.1.3 255.255.255.0  no ip redirects  ip nhrp authentication DMVPN  ip nhrp map multicast dynamic  ip nhrp map 192.168.1.1 11.11.11.1  ip nhrp map multicast 11.11.11.1  ip nhrp network-id 1  ip nhrp nhs 192.168.1.1  tunnel source FastEthernet0/0  tunnel mode gre multipoint router eigrp 1  network 10.3.3.0 0.0.0.255  network 192.168.1.0 ip route 0.0.0.0 0.0.0.0 33.33.33.254 ip access-list extended NATISP  deny   ip 192.168.0.0 0.0.255.255 any  deny   ip 10.3.3.0 0.0.0.255 10.0.0.0 0.255.255.255  permit ip 10.3.3.0 0.0.0.255 any

Almost the same thing for the spokes...but here are the differences: Maps the hubs NHS tunnel IP to it's public IP Send multicast traffic to the hub, so that the hub processes it- this is essential for EIGRP to form adjacencies! They will not form otherwise, unless maybe you specify static EIGRP neighbors from hub to spoke, which use unicast instead. This command tells the spoke who the hub NHRP router is-- in this case GM-R1 The tunnel source is specified as the public interface itself and not the IP- this can be used in case the IP changes dynamically. I also have a static default route pointing to my ISP router so that clients behind my spoke router can get out to the internet. What I did here is, deny the private networks in including the tunnel network, from being being natted. I had PAT overloaded the public interface on the spoke routers so that clients can NAT out to the internet, but we obviously don't want the VPN traffic to NAT.

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The other spoke is the same exact thing as the first one....

At this point you should see the peers that have GRE tunnels- as expected, there are 2 tunnels connected to the hub router:

GM-R1#show dmvpn

Interface: Tunnel0, IPv4 NHRP Details

Type:Hub, NHRP Peers:2,

 # Ent  Peer NBMA Addr Peer Tunnel Add State  UpDn Tm Attrb

 ----- --------------- --------------- ----- -------- -----

     1 33.33.33.3          192.168.1.3    UP 03:07:36     D

     1 44.44.44.44         192.168.1.4    UP 02:59:23     D

You should have EIGRP neighborships between the hub and each spoke:

GM-R1#show ip eigrp neighbors

EIGRP-IPv4 Neighbors for AS(1)

H   Address                 Interface              Hold Uptime   SRTT   RTO  Q  Seq

                                                   (sec)         (ms)       Cnt Num

1   192.168.1.4             Tu0                      10 02:10:58  166  1470  0  31

0   192.168.1.3             Tu0                      10 02:14:55  179  1470  0  28

And, if all is well each router should have routes to the other routers networks- and you should be able to ping and pass traffic at this point.

GM-R4#show ip route

Gateway of last resort is 44.44.44.254 to network 0.0.0.0

S*    0.0.0.0/0 [1/0] via 44.44.44.254
      10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
D        10.1.1.0/24 [90/26882560] via 192.168.1.1, 02:12:47, Tunnel0
D        10.3.3.0/24 [90/28162560] via 192.168.1.1, 02:00:59, Tunnel0
C        10.4.4.0/24 is directly connected, FastEthernet0/1
L        10.4.4.4/32 is directly connected, FastEthernet0/1
      44.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        44.44.44.0/24 is directly connected, FastEthernet0/0
L        44.44.44.44/32 is directly connected, FastEthernet0/0
      192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks
C        192.168.1.0/24 is directly connected, Tunnel0
L        192.168.1.4/32 is directly connected, Tunnel0

Ok......so here's the GETVPN part...utilizing the GDOI protocol running on UDP port 848. The IKE SAs are setup between the group members and the Key Server...communicating over the public internet. Since my key server sits behind R1 on the private network, I had to port forward UDP 848 and IKE 500 and 4500 (when behind NAT, which is my case) on R1- I used a static NAT mapping IP 11.11.11.5 to the private IP of the KS server......

I'll start with the Key Server setup here:

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KS-R5(config)#crypto key generate rsa label VPNKEY1 modulus 1024 exportable crypto isakmp policy 1  encr aes  authentication pre-share  group 2  lifetime 14400 crypto isakmp key getvpn address 0.0.0.0       crypto ipsec transform-set TRANS1 esp-aes esp-sha-hmac  mode tunnel ! crypto ipsec profile IPSEC1  set transform-set TRANS1 crypto gdoi group GDOI1  identity number 1  server local   rekey algorithm aes 128   rekey lifetime seconds 14400   rekey retransmit 15 number 2   rekey authentication mypubkey rsa VPNKEY1   rekey transport unicast   sa ipsec 10    profile IPSEC1    match address ipv4 GETVPN-ACL    replay counter window-size 64   address ipv4 10.1.1.5 crypto map CRYPTO1 10 gdoi  set group GDOI1 no ip routing ip default-gateway 10.1.1.1 ip access-list extended GETVPN-ACL  deny   udp any eq 848 any eq 848  permit gre any any

You'll want to create an RSA keypair here, to use for signing the packets. ISAKMP policy is defined here. I lazily used the 0.0.0.0 (any ip) as the "allowed" addresses for the key usage among the GDOI members. You would want to restrict these to the public facing IP addresses of your member routers- use one line per address. Your ipsec transform set and encryption types are set here. Ipsec profile specifying your transform set The gdoi group settings here. Note the reference to the rsa key generated earlier. You will also match the traffic that is to be encrypted via an ACL....and reference the ipsec profile you just created (IPSEC1) You actually don't need to enable the crypto map on the interface of the key server since it sits on the private network-but I left it here for reference. Here, I disabled routing and set the KS's default gateway as if it was just a host unit.  I denied the gdoi control traffic on udp port  848 here....and permitted GRE tunnel packets, which includes everything running through the DMVPN. This ACL will be downloaded by the member routers too.

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Here's is one of the Group Member routers- R1-you'll do the same for R3 and 4, with the exception of addressing the KS by it's statically natted public IP.

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ip nat inside source list NATISP interface FastEthernet0/0 overload ip nat inside source static udp 10.1.1.5 500 11.11.11.5 500 extendable ip nat inside source static udp 10.1.1.5 848 11.11.11.5 848 extendable ip nat inside source static udp 10.1.1.5 4500 11.11.11.5 4500 extendable crypto isakmp policy 1  encr aes  authentication pre-share  group 2  lifetime 14400 crypto isakmp key getvpn address 10.1.1.5 crypto gdoi group GDOI1  identity number 1  server address ipv4 10.1.1.5 ! ! crypto map CRYPTO1 10 gdoi  set group GDOI1 interface FastEthernet0/0  ip address 11.11.11.1 255.255.255.0  ip nat outside  speed auto  duplex auto  crypto map CRYPTO1

With this router- I Natted an additional public IP (11.11.11.5) to the necessary ports on the KS server sitting on the private network. Isakmp policy here, and, with this router, I referenced the KS server by it's real private IP address- on R3 and 4, you'll use the public natted IP defined above to reach the KS. GDOI group- basically specifying the KS server- same thing here- use the public natted IP address of the KS on the remote routers- use the real IP here. Tie it in w the crypto map- CRYPTO1 "Turn on" the Crypto map for the outside public facing interface.

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As soon as you enable the crypto map on the outside interface- the member router should register with the KS, and display the console output similar to below:

GM-R1(config-if)#crypto map CRYPTO1
GM-R1(config-if)#
*Mar 9 22:05:44.991: %CRYPTO-5-GM_REGSTER: Start registration to KS 10.1.1.5 for group GDOI1 using address 10.1.1.1
GM-R1(config-if)#
*Mar 9 22:05:45.007: %CRYPTO-6-GDOI_ON_OFF: GDOI is ON
GM-R1(config-if)#
*Mar 9 22:06:06.455: %GDOI-5-GM_REKEY_TRANS_2_UNI: Group GDOI1 transitioned to Unicast Rekey.
*Mar 9 22:06:06.459: %GDOI-5-SA_KEK_UPDATED: SA KEK was updated
*Mar 9 22:06:06.475: %GDOI-5-SA_TEK_UPDATED: SA TEK was updated
*Mar 9 22:06:06.583: %GDOI-5-GM_REGS_COMPL: Registration to KS 10.1.1.5 complete for group GDOI1 using address 10.1.1.1
*Mar 9 22:06:06.643: %GDOI-5-GM_INSTALL_POLICIES_SUCCESS: SUCCESS: Installation of Reg/Rekey policies from KS 10.1.1.5 for group GDOI1 & gm identity 10.1.1.1

On the KS server, after configuring the other member routers, you should see Security Associations with each of the 3 member routers, as shown here:

KS-R5#show crypto isakmp sa

IPv4 Crypto ISAKMP SA

dst             src             state          conn-id status

10.1.1.5        11.11.11.1      GDOI_IDLE         1007 ACTIVE

10.1.1.5        44.44.44.44     GDOI_IDLE         1008 ACTIVE

10.1.1.5        33.33.33.3      GDOI_IDLE         1005 ACTIVE

This will show you group info, number of members, key lifetimes, group ACL etc

KS-R5#show crypto gdoi

GROUP INFORMATION

    Group Name               : GDOI1 (Unicast)

    Group Identity           : 1

    Crypto Path              : ipv4

    Key Management Path      : ipv4

    Group Members            : 3

    IPSec SA Direction       : Both

    Group Rekey Lifetime     : 14400 secs

    Group Rekey

        Remaining Lifetime   : 9195 secs

    Rekey Retransmit Period  : 15 secs

    Rekey Retransmit Attempts: 2

    Group Retransmit

        Remaining Lifetime   : 0 secs

      IPSec SA Number        : 10

      IPSec SA Rekey Lifetime: 3600 secs

      Profile Name           : IPSEC1

      Replay method          : Count Based

      Replay Window Size     : 64

      SA Rekey

         Remaining Lifetime  : 2213 secs

      ACL Configured         : access-list GETVPN-ACL

     Group Server list       : Local

This is the SA from a member router perspective

GM-R3#show crypto isakmp sa

IPv4 Crypto ISAKMP SA

dst             src             state          conn-id status

33.33.33.3      10.1.1.5        GDOI_REKEY        1004 ACTIVE

11.11.11.5      33.33.33.3      GDOI_IDLE         1003 ACTIVE

And again, GDOI info from a group member router- reference the KS via it's public IP

GM-R3#show cry gdoi

GROUP INFORMATION

    Group Name               : GDOI1

    Group Identity           : 1

    Crypto Path              : ipv4

    Key Management Path      : ipv4

    Rekeys received          : 1

    IPSec SA Direction       : Both

     Group Server list       : 11.11.11.5

    Group member             : 33.33.33.3       vrf: None

       Version               : 1.0.4

       Registration status   : Registered

       Registered with       : 11.11.11.5

       Re-registers in       : 1426 sec

       Succeeded registration: 2

       Attempted registration: 6

       Last rekey from       : 10.1.1.5

       Last rekey seq num    : 6

       Unicast rekey received: 1

       Rekey ACKs sent       : 1

       Rekey Rcvd(hh:mm:ss)  : 01:27:29

       allowable rekey cipher: any

       allowable rekey hash  : any

       allowable transformtag: any ESP

    Rekeys cumulative

       Total received        : 1

       After latest register : 0

       Rekey Acks sents      : 1

 ACL Downloaded From KS 11.11.11.5:

   access-list   deny udp any port = 848 any port = 848

   access-list   permit gre any any

KEK POLICY:

    Rekey Transport Type     : Unicast

    Lifetime (secs)          : 8521

    Encrypt Algorithm        : AES

    Key Size                 : 128

    Sig Hash Algorithm       : HMAC_AUTH_SHA

    Sig Key Length (bits)    : 1024

TEK POLICY for the current KS-Policy ACEs Downloaded:

  FastEthernet0/0:

    IPsec SA:

        spi: 0x4F0F578E(1326405518)

        transform: esp-aes esp-sha-hmac

        sa timing:remaining key lifetime (sec): (1540)

        Anti-Replay : Disabled

At this point, you'll want to send some pings over the network via the tunnel-  the encaps and decaps should increment, confirming that the traffic is indeed being encrypted via GETVPN. 

GM-R3#show crypto ipsec sa

interface: FastEthernet0/0

    Crypto map tag: CRYPTO1, local addr 33.33.33.3

   protected vrf: (none)

   local  ident (addr/mask/prot/port): (0.0.0.0/0.0.0.0/47/0)

   remote ident (addr/mask/prot/port): (0.0.0.0/0.0.0.0/47/0)

   current_peer 0.0.0.0 port 848

     PERMIT, flags={}

    #pkts encaps: 964, #pkts encrypt: 964, #pkts digest: 964

    #pkts decaps: 438, #pkts decrypt: 438, #pkts verify: 438

    #pkts compressed: 0, #pkts decompressed: 0

    #pkts not compressed: 0, #pkts compr. failed: 0

    #pkts not decompressed: 0, #pkts decompress failed: 0

    #send errors 0, #recv errors 64

     local crypto endpt.: 33.33.33.3, remote crypto endpt.: 0.0.0.0

     path mtu 1500, ip mtu 1500, ip mtu idb FastEthernet0/0

     current outbound spi: 0x501F7AB8(1344240312)

     PFS (Y/N): N, DH group: none

     inbound esp sas:

      spi: 0x501F7AB8(1344240312)
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So there you have it- 2 cool vpn technologies combined - hope this is helpful and thanks for reading. Also, here's a few excellent references on DMVPN , GETVPN, and IPSEC\IKE\ISAKMP in general.

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/901-cisco-router-dmvpn-configuration.html

http://www.cisco.com/c/en/us/products/collateral/ios-nx-os-software/getvpn-solution-managed-services/prod_white_paper0900aecd804c363f.html

http://searchcio.techtarget.com.au/news/2240102148/How-to-implement-VPNs-using-Cisco-products-and-EzVPN-IPsec

http://searchcio.techtarget.com.au/news/2240102144/What-is-the-ISAKMP-policy-and-how-does-it-impact-IPsec-VPN-router-configuration

Also, here are the GNS3 Lab files- downloadable here:

Download Lab