Chain two FWSM contexts

markus.segervall · ‎06-13-2007

Hi!

Is it possible to chain two contexts in one 6500 FWSM so that for example vlan60 is outside (x.y.36.98/29) for FW-one and vlan61 inside for FW-one (IP x.y.37.1/24) and vlan61 is also outside for FW-two(IP x.y.37.254/24). Vlan62 is inside(IP x.y.38.1/24) for FW-two. Outside = sec0, Inside = sec100.

I use no NAT. I have a PC in vlan61 with IP x.y.37.10 and it all works well when I only have FW-one configured. As soon as I go into context FW-two and starts to configure interface vlan61 FW-one stops working. The only way to get FW-one up-and-running again is to delete context FW-two.

I use FWSM-version 3.2(1)

This is what I'm trying to do:

Internet-vlan60-FWone-vlan61-FWtwo-vlan62

Any ideas?

Can anyone try this in a lab?

Thanks!

Markus

Jon Marshall · ‎06-13-2007

Hi Markus

I believe you can cascade contexts in version 3.x (you couldn't in v 2.x). What do you mean by stops working - does it stop passing traffic ?

if you do cascade contexts then you need a static translation for all the destinations on the outside of FW-one as otherwise the classifier does not know which context to send the packet to.

HTH

Jon

markus.segervall · ‎06-13-2007

Yes it stop passing traffic.

I tried to configure the static translation for the FW-two inside net and the configuration of FW-one now looks like this:

interface Vlan60

nameif outside

security-level 0

ip address x.y.36.98 255.255.255.248

!

interface Vlan61

nameif inside

security-level 100

ip address x.y.37.1 255.255.255.0

!

access-list inside-in extended permit ip any any

access-list outside-in extended permit icmp any any

pager lines 24

mtu outside 1500

mtu inside 1500

icmp permit any echo-reply outside

icmp permit any echo outside

icmp permit any echo inside

icmp permit any echo-reply inside

no asdm history enable

arp timeout 14400

nat (inside) 0 x.y.37.0 255.255.255.0

static (inside,outside) x.y.38.0 x.y.38.0 netmask 255.255.255.0

access-group outside-in in interface outside

access-group inside-in in interface inside

route outside 0.0.0.0 0.0.0.0 x.y.36.97 1

route inside x.y.38.0 255.255.255.0 x.y.37.254 1

With only FW-one configured I surf the Net but when I try to configure FW-two then traffic thru FW-one stops immediately.

Markus.

markus.segervall · ‎06-13-2007

I could describe what I do when FW-one stops:

I write(in FWSM system):

int vlan 62

context FW-two

allocate-interface Vlan61

allocate-interface Vlan62

config-url disk:/FW-two.cfg

cha con FW-two

conf t

int vlan 61

nameif outside

-> Then FW-one stops passing traffic. I don't even have to put any IP-address information to FW-two before FW-one stops.

Is this a bug or am I doing something strange?

(And by the way, anyone knows where to find ASDM 5.2 for FWSM?)

Markus.

Jon Marshall · ‎06-13-2007

Markus

For every address you want to surf on the internet you have to have a static on fw-one for it. This is obviously not the most practical setup because in effect if you want to be able to surf to any internet site out there you would have to have static translations for every site on the internet.

This is why cascading contexts to the internet is not a good thing to do.

Have i misunderstood what you are trying to do ?

Jon

Christian Chautems · ‎06-13-2007

Hey,

If you need the cascading contexts one way to make it working is to insert a router (it can be a VRF on the MSFC) between the two context. You will then use two separate VLANs between the contexts instead of this problematic shared VLAN.

This has already been addresses in ASA software "Automatically Assigning MAC Addresses to Context Interfaces" but it still missing for the FWSM.

Has anybody infos about this last feature on FWSM ?

Chris

markus.segervall · ‎06-14-2007

Hi!

Thanks alot! So this is not yet possible in FWSM...

At first I was going to put a vrf in between but I thought this way of sharing a vlan could be possible. Obviously not...

Regards,

Markus