Best practice wise - should I let the router or the ASA handle NAT
(Overloading)?
In the most general of design best practices NAT is performed between an inside and outside network. NAT overloading is generally performed at the edge when there is limited public IP address space. You can learn more about NAT overloading, also known as Port Address Translation or PAT, in RFC 2663 (PAT is referred to as Network Address Port Translation (NAPT) in section 4.1.2).
In this particular scenario you can argue that you have two inside and outside networks and will need to perform some form of NAT on both the ASA (whether that is the NAT overloading you're using now, NAT exemption, static NAT, etc) and the Cisco Router.
I can ping the 172.16.2.2
interface but not 172.16.2.1
from a pc
connected to one of the layer 2 switches (proves intervlan routing is
working -- i have a 172.20.100.8
address on the PC). Why can't I ping
172.16.2.1
from a PC but I can from the Layer 3 Switch?
The ASA 172.16.2.2
is receiving the ICMP echo-request but does not have a route back to 172.20.100.0/27
. The echo-reply is actually being forwarded to the Router 172.16.1.1
via the default route.
And most of all -- Why can't I get out to the Internet from the Layer 3 switch?
Currently your ASA and Cisco Router do not have routes to internal devices other than their connected routes.
Your ASA configuration:
route outside 0.0.0.0 0.0.0.0 172.16.1.1 1
This will provide a default route via the outside interface, but how will the ASA know how to reach subnets residing behind the Layer 3 Distribution Switch?
You'll need to add routes to the internal subnets via the inside interface using the Layer 3 Distribution Switch as the next-hop IP address.
ASA static routing example:
route inside 172.19.12.0 255.255.255.240 172.16.2.2
route inside 172.19.3.0 255.255.255.0 172.16.2.2
route inside 172.20.100.0 255.255.255.224 172.16.2.2
Further reading: ASA static routing
Your Cisco Router's configuration:
ip route 0.0.0.0 0.0.0.0 200.200.200.200
Additionally, how will your border router know how to reach subnets other than it's connected routes, and the catch all default route via the outside interface's next-hop address 200.200.200.200
?
Router static routing example:
ip route 172.19.12.0 255.255.255.240 172.16.1.10
ip route 172.19.3.0 255.255.255.0 172.16.1.10
ip route 172.19.100.0 255.255.255.224 172.16.1.10
ip route 172.16.2.0 255.255.255.224 172.16.1.10
Further reading: ISR static routing
I cannot get an ip address right now from the DHCP server (Windows).
Any insight into why?
Ensure you have end-to-end IP reachability between the client(s) sending DHCP discover messages and the DHCP server.
From what I can gather from your topology and configuration, the subnets 172.19.3.0/24
, 172.19.12.0/28
and 172.20.100.0/27
should have no issues connecting to each other (assuming they are configured to use their respective default gateways) from a networking perspective.
You can remove the ip helper-address
syntax from the SVI 100 given that the DHCP server is on the same segment and that command is used for a DHCP server(s) that is on a different segment.
interface Vlan100
ip address 172.20.100.1 255.255.255.224
ip helper-address 172.20.100.27
The Cisco 2960 switch is a L3 capable switch. Today switches are usually no longer confined to L2 and the router/switch delineation is blurred from the traditional definitions.
You are missing the ip routing
command from your config. If you add this command you will find that the VLAN SVIs can route directly between each other on the switch. More information on this feature can be found here:
Configure InterVLAN Routing on Layer 3 Switches
However I do not see any routing configuration or default gateway configured on your switch whatsoever, so I doubt that the switch itself could reach any remote network assistance. I suspect that proxy-arp is what is being used here and the major classes are what is 'choosing' the VLAN.
Proxy ARP
Best Answer
You can create svi in layer3 switch and connect firewall inside interfĂ ce(LAN) to layer3 switch (no-switchport interface ) Configure firewall inside interface with ip address 192.168.68.2 and switch interface leave as it is For example
Switch(config)# int f0/1 Switch(config)#no shutdown /*This interface ip will be vlan1 ip that is 192.168.68.1 this switch interface will connect to firewall LAN interface 192.168.68.2
Have a default route in layer3 switch
In layer3 switch
Ip route 0.0.0.0 0.0.0.0 192.168.68.2 (pointing towards firewall inside interface gateway
In firewall add route
ip route 192.168.68.0 255.255.255.0 192.168.68 .1
ip route 192.168.1.0. 255.255.255.0 192.168.68.1 Ip route 192.168.2.0 255.255.255.0 192.168.68.1 Ip route 192.168.6.0 255.255.255.248 192.168.68.1
Remaining configuration as usual in firewall configuration.....natting , default route in firewall pointing towards isp gateway for internet access and for reverse traffic for incoming traffic
In layer3 switch
Svi configurations , DHCP pool configuration if required , access-list configuration to restrict traffic among vlans , spanning -tree configuration..
. 2) In case if your are using C2960 layer2 switch
If your are using c2960 switch then this switch is layer2 switch you should create subinterface in firewall and connect switch 2960 and configure switch port as trunk connectiing firewall . ....