newbie question, lost connection when ip routing enabled?

[sc.bill.lee]

hi there,

i am configuring a 3560, everthing is fine until i enable the "ip routing"

i lost connection to all vlan, any idea?

thanks in advance.

[JohnTylerPearce]

It looks like you want all traffic on the 3560 to go to the 3750 which is going to hit the default gateway on the 3750. Since this is most likely going to happen, it's going to hit the default route that is most likely going to the ASA in RoomA which is going to ISP1. You have one of two options.

1) Turn IP routing on the 3560

2) Create a route-map on the 3750 to have traffic sources from the 3560 back to the 3560 and out ISP2.

Choice one is the way you want to go, if you choose choice two, it's going to create ineffient routing.

You need to turn on IP routing on the 3560, and create a default route going out to the ISP2. Also, what VLAN is your management vlan?

[Richard Burts]

Bill

Am I correct in assuming that you are accessing the 3560 remotely (not on the console connection)? In that case the explanation by several of my colleagues may be correct that you lose connectivity because your source address is remote from the 3560. When you first access the 3560 the routing logic that connects the 3560 to your remote address is on the 3750 and it works. But when you enable routing on the 3560 then a problem develops  because it has no routing knowledge to access your remote subnet. I an think of a couple of options which could solve this:

- go to where the 3560 is located and connect to the console to make the config changes to enable routing. You certainly will not lose connectivity there when routing is enabled.

- access the 3750 (by telnet or SSH or whatever you use and from the 3750 access the 3560. Hopefully the 3560 will see this as a local connection and will not lose it when routing is enabled.

HTH

Rick

[sc.bill.lee]

Yes, I would like to take Option 1, but really dont have idea where to start with.

I have enabled ip routing, i can telnet to it now by inserting some static routes

and I tried to made some routes to achieve what I want, but it seems not working

"

Gateway of last resort is 10.161.9.14 to network 0.0.0.0

     10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks

S       10.0.0.0/8 [1/0] via 10.161.19.1

C       10.161.9.0/24 is directly connected, Vlan9

C       10.161.8.0/24 is directly connected, Vlan8

C       10.161.19.0/24 is directly connected, Vlan19

S*   0.0.0.0/0 [1/0] via 10.161.9.14"

I suppose all traffic starting with 10.x.x.x will go 10.161.19.1, all other traffic will go to the firewall 10.161.9.14 for the ISP_B

[Richard Burts]

Bill

Based on what I understand of this discussion it looks like you have most of what you need. You have configured a static default route and I assume that 10.161.9.14 is the next hop that gets to the ISP B. Can you confirm that?

You have a static route for some subnets in network 10.0.0.0 which I assume are the VLANs in room A. Can you confirm that? And I assume that there are no devices connected in room A that are not in network 10.0.0.0. Can you verify that?

From what I have understood in the config that you posted the main thing that you are missing is that you need to configure inteface vlan 160 and configure an IP address on it. Then you need to make sure that devices in vlan 160 use this address as their default gateway. (You also need to make sure that devices in vlan 8, 9, and 19 use the addresses on the 3560 as their default gateway - I would assume that their current default gateway is probably a vlan address on the 3750.)

If you do this it should achieve your goal of having traffic from devices connected to the 3560 will use ISP B and will have connectivity to devices in room A. It does not address the question of whether you want to be able to have failover so that if ISP B becomes not available you could send traffic through ISP A. This is possible but would require additional config changes and probably need implementation of a dynamic routing protocol.

HTH

Rick