Cisco

Hello guys,

Here it is a tips / reminder how to implement an site-ot-site IKEv2 tunnel :

crypto ikev2 proposal aes-cbc-256-proposal 
 encryption aes-cbc-256
 integrity sha1
 group 2
crypto ikev2 policy policy1 
 match address local x.x.x.x
 proposal aes-cbc-256-proposal
crypto ikev2 keyring v2-kr1
 peer abc
  address y.y.y.y
  pre-shared-key somesecretpass
 !
crypto ikev2 profile profile1
 description IKEv2 profile
 match address local x.x.x.x
 match identity remote address y.y.y.y 255.255.255.255 
 authentication local pre-share
 authentication remote pre-share
 keyring v2-kr1

crypto ipsec transform-set myset esp-des esp-md5-hmac 

crypto map mymap 20 ipsec-isakmp 
 set peer y.y.y.y
 set security-association lifetime seconds 27000
 set transform-set ESP-AES-SHA 
 set ikev2-profile profile1
 match address 120

With ACL 120 is your flows / SA and your implement your crypto map on your WAN interface.

We will dive into IPv6 prefix delegation prefix.

First of all, we will make a real simple topology :

R1 acts as a DHCP server and use the prefix delegation feature. But how it works ? How it is configured ?

R1 :

ipv6 unicast-routing
ipv6 cef
ipv6 dhcp pool POOLv6
 prefix-delegation pool p lifetime 180 120
 domain-name lucas.fr.eu.org

ipv6 local pool p 2001:DB8::/40 48

interface FastEthernet0/0
 ip address 10.0.0.1 255.255.255.0
 duplex half
 ipv6 address 2A02::1/48
 ipv6 enable
 ipv6 dhcp server POOLv6

R1#   show ipv6 dhcp interface 
FastEthernet0/0 is in server mode
  Using pool: POOLv6
  Preference value: 0
  Hint from client: ignored
  Rapid-Commit: disabled
R1#

R2 :

IP SLA is a great tool to automation some treatment. You could do great things with it. We will work on IP SLA Reaction here.

What is it ? You could launch some action on some state of an IP SLA. Such as (Even if it is not a good example) : some nested ping.

 

 

 

 

 

 

 

The job here, is to check R4 - R3 and R4 - R2 if IP SLA beetween R1 - R4 is awful.

I think everyone now what is a RIB-Failure in BGP context. It sounds obviously as an exact same route with a lowest AD as {e|i}BGP. We have VRF-Lite on R1 here :

We have :

1#show ip bg vpnv4 vrf CUST
BGP table version is 11, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
              x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 65001:1 (default for vrf CUST)
 *>  10.1.1.1/32      12.0.0.2                 0             0 65002 ?
 *>  10.2.2.1/32      12.0.0.2                 0             0 65002 ?
 r>  10.3.3.1/32      12.0.0.2                 0             0 65002 ?
 r>  10.4.4.1/32      12.0.0.2                 0             0 65002 ?
 r>  10.5.5.1/32      12.0.0.2                 0             0 65002 ?
 r>  10.5.5.5/32      12.0.0.2                 0             0 65002 ?
 r>  10.6.6.6/32      12.0.0.2                 0             0 65002 ?
 r>  12.0.0.0/24      12.0.0.2                 0             0 65002 ?
R1#
R1#show ip route vrf CUST

Routing Table: CUST

Gateway of last resort is not set

      10.0.0.0/32 is subnetted, 2 subnets
B        10.1.1.1 [20/0] via 12.0.0.2, 00:37:49
B        10.2.2.1 [20/0] via 12.0.0.2, 00:37:49
      12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        12.0.0.0/24 is directly connected, Ethernet0/0
L        12.0.0.1/32 is directly connected, Ethernet0/0
R1#

So the only route we can have a RIB-Failure due to lowest AD is : 12.0.0.0/24. What is the problem with others ? We can know this by using :

Today a little review :

edge12.bor03>show ip bg 37.8.8.8
BGP routing table entry for 37.8.0.0/20, version 47221703
Paths: (3 available, best #2, table Default-IP-Routing-Table)
  Advertised to update-groups:
     1
  15975, (received-only)
    17.69.240.117 from 17.69.240.117 (17.69.255.1)
      Origin IGP, metric 16, localpref 500, valid, internal
  12671 15975 15975 15975 15975, (received & used)
    46.218.1.1 from 46.218.1.1 (172.17.1.6)
      Origin IGP, localpref 100, valid, external, best
  12671 15975 15975 15975 15975, (received & used)
    46.218.1.1 from 46.218.1.1 (172.17.1.2)
      Origin IGP, localpref 100, valid, external
edge12.bor03>

Why the path through 17.69.240.117 is not used, although it is the a better path to 37.8.0.0/20 ? Why is it marked as “received-only”

	Here it comes. We will use the same topology as the last two blog posts. This time we will play with GETVPN. GETVPN is a Cisco technology. One of the advantage of GETVPN is that we are able to build somespoke-to-spoke IPSEC tunnel without Tunnel interface and it is highly scalable.

We could say to me : ok, man ! but you could do this by means of static tunnels. Yes you can, BUT with GETVPN you can maintain easily full mesh networks by means of Key Server and the GETVPN technology.

IPSEC VTI stands for IPSEC Virtual Tunnel Interface.

Besides traditionnal IPSEC configuration with cyrpto map, VTI allows to use an interface. It is useful to apply some policies as we can do as other : service-policy, …

For this example, I will use the previous topology with four routers (R1, R2, R3, R4) : see the blog post below for a diagram.

I will implement a IPSEC VTI tunnel between R2 and R4.

How can DMVPN can make some QOS per spoke ?

It is what we will configure today :

Here is the network :

 

 

 

 

I will not explain how NHRP works in detail here.

R1, R2, R3, R4 use IS-IS (for fun) as IGP.

router isis
net 49.MAC_ADD.00

interface etc x/y
ip router isis

Now, here it comes DMVPN configurations :

R4#show run int tun 0
Building configuration...

Current configuration : 351 bytes
!
interface Tunnel0
 bandwidth 1000
 ip address 77.0.0.4 255.255.255.0
 no ip redirects
 ip nhrp authentication 1111
 ip nhrp map multicast dynamic
 ip nhrp map group toto service-policy output pm
 ip nhrp network-id 1111
 ip nhrp redirect
 load-interval 30
 qos pre-classify
 tunnel source Loopback0
 tunnel mode gre multipoint
 tunnel key 1111
end

R4#

And for R3 :

If you read/see videos about OSPF, it will be said that you can only filter on INBOUND or 1/0 on OUTBOUND (via ip ospf database-filter all out / neighbor x.x.x.x database-filter all out). You will say to me, no problem I can filter by means of “area range xxxxx not-advertise” (LSA Type 3) or “summary-address xxxx no-advertise” (LSA Type 5). Ok, now let’s say, I want with distribute-list and ACL, you filter out some routes ?

I have found again this networking game. The first time I play with it was in 2009. It was fun to take some hours to play with it.
It is not hosted by Cisco, so if you want to retrieve the archive you can download it here for those of you that were not in this industry or not know this cisco networking game.