08-25-2009 09:20 PM - edited 03-04-2019 05:50 AM
I need some help understanding why my two subnets are unable able to communicate when two particular route-maps are enabled. Yes, I do realize that this is a somewhat strange setup.
Here's the background:
I have an 1841 router, a 5505 switch, a Linux-based UTM, and several machines on different VLANs. All of these are plugged into the 5505, except for the Internet facing interfaces of the 1841.
I have machines on VLAN6 that need to have their traffic filtered by the UTM before they go to the Internet or anywhere else. The default gateway for these machines is 10.6.1.1, fe 0/0.6 of the 1841 router.
Here's the UTM interface and routing info:
Interfaces
WAN - eth0 192.168.2.2
Internal - eth1 192.168.1.2
Routes
Target Netmask Gateway
10.6.1.0 24 (255.255.255.0) 192.168.1.1
192.168.1.0 30 (255.255.255.252) eth1
192.168.2.4 30 (255.255.255.252) br.eth0
default 192.168.2.1
Here's some relevant router interface info:
Interface fastethernet 0/0.7
ip address 192.168.1.1 255.255.255.252
Interface fastethernet 0/0.8
ip address 192.168.2.1 255.255.255.252
Using the following configurations, I force all traffic from the VLAN6 machines to the internal interface of the UTM (192.168.1.2/30 - VLAN7).
ip sla 30
icmp-echo 192.168.1.2
ip sla schedule 30 life forever start-time now
track 30 ip sla 30 reachability
ip access-list extended VLAN6
permit ip 10.6.1.0 0.0.0.255 any
route-map VLAN6Filtering permit 10
match ip address VLAN6
set ip next-hop verify-availability 192.168.1.2 10 track 30
interface FastEthernet 0/0.6
ip address 10.6.1.1 255.255.255.0
ip policy route-map VLAN6Filtering
The UTM is only routing. Once traffic has gone through the UTM it arrives back at the router on a seperate sub-inteface (f0/0.8 - IP address of 192.168.2.1/30 - VLAN8). After that, the traffic goes just fine to the Internet via cable connection on f0/1.
I also have machines on VLAN9 (fastethernet 0/0.9 - IP address of 10.9.1.1). Because all outbound traffic from VLAN6 is routed through the UTM, I have to make sure that all traffic from other VLANs that needs to get to VLAN6 is routed to the external interface of the UTM (192.168.2.2/30). To do that, I do the following:
ip sla 40
icmp-echo 192.168.2.2
ip sla schedule 40 life forever start-time now
track 40 ip sla 40 reachability
ip access-list extended TrafficToVLAN6
permit ip any 10.6.1.0 0.0.0.255
route-map RouteToVLAN6
match ip address TrafficToVLAN6
set ip next-hop verify-availability 192.168.2.2 10 track 40
interface fastethernet 0/0.9
ip address 10.9.1.1 255.255.255.0
ip policy route-map RouteToVLAN6
With this setup, I can access the Internet from VLAN6 just fine via the UTM. However, with this setup, I cannot run pass traffic or run successful traceroute from a machine on VLAN9 to a machine on VLAN6. The packets stop at the Router's VLAN7 interface after initially passing through the router from VLAN6 to VLAN8, then through the UTM from VLAN 8 to 7, and then back to the router on VLAN7 (fastethernet 0/0.8 - 192.168.1.1), never reaching VLAN6 (fasthethernet 0/0.6). Here's an example:
traceroute to 10.6.1.15 (10.6.1.15), 30 hops max, 40 byte packets
1 router (10.9.1.1) 9.223 ms 20.994 ms 22.305 ms
2 192.168.2.2 (192.168.2.2) 5.731 ms 5.886 ms 6.027 ms
3 192.168.1.1 (192.168.1.1) 23.548 ms 25.738 ms 27.030 ms
4 192.168.1.1 (192.168.1.1) 29.667 ms 28.971 ms 28.304 ms
5 * * *
6 * * *
7 * * *
8 * * *
9 * * *
10 *
There are other VLANs as well and but there is no issue with connectivity from VLAN9 to those other VLANs (no route-maps involved). Please tell me how I can correct this error. Why isn't the router passing traffic out the other directly connected VLAN6 interface? What am I missing?
Thanks for any help you can give.
AB
08-25-2009 10:55 PM
Hello Alex,
I would suggest to move vlan6 ip subnet downstream the UTM linux box.
if also for talking with other vlan subnets you want traffic to go through the UTM box then the best choice is to move the ip subnet on the inside on the UTM.
Having a nested configuration of PBR is a problem for troubleshooting too.
then a simple static route can do the job on the router after the move.
Hope to help
Giuseppe
08-26-2009 06:00 PM
Thank you for the suggestion Guiseppe. I believe the client did think about that at one point but for certain reasons (I'm not sure of all of the details), they preferred the nested configuration.
I've resolved the issue by creating another route-map (applied to the VLAN6 interface) that routes all of the traffic from vlan6 to each specific VLAN through the proper interfaces and routes all other traffic, Internet traffic, through the Linux UTM.
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