unable to ping default gateway (urgent)

[richard268]

hi, guys,

We are setting up a backbone network right now. we are using two 4506 super IV as the central switch (each with one 24 port 10/100/1000 module), and using nine gigastack 2950 switches.

The port connection is like this:

ws-g5484(4506 - I ) -- ws-g5484 (2950- 1)- ws-x3500-xl (2950-1) -ws-x3500-xl (2950-2)- ws-x3500-xl (2950-3) - ws-g5484 (2950-3) - ws -g5484 (2950-4) - ws-x3500xl (2950-4) - ws -x3500-xl (2950-5) - ws-x3500-xl (2950-6) - ws-g5484 (2950-6) - ws-g5484 (2950 - 7) - ws -x3500-xl (2950-7) -ws-x3500-xl (2950-8) - ws-x3500-xl (2950-9) - ws-g5484(2950-9) -ws-g5484 (4506 - II)

The two 4506 are all connected by one GB port (10/100/1000).

we are connecting like this because 4506-I , 4506-II and switch 2950-4 , 2950-5, and 2950-6 is place in one computer room, 2950-1, 2950-2, 2950-3 is in another room, and 2950-7, 2950-8, 2950-9 is in third room.

we have 6 vlans, for vlan 10. 20 . 30 , I plan to use 4506-I as its default router

for vlan 30 40 50, I plan to use 4506-II as its default router.

My question is:

after all coniguration, if I connect my computer in either of 2950 switches, I can not ping my default gateway. but I can ping it if I connect to 4506.

I check the arp table in 2950, it has no mac address for the default-gateway.

2) if I unplug the port connection between two 4506, the hsrp interface seems down. why? one of them should take over, accroding to hsrp. but now it seems 'no active router',

any suggestion would be greatly appreciated.

regards

Richard

[richard268]

the ws5484gigabit int can not be used as a trunk, that is why hsrp is down (or vlan interface is down when I unplug the 1000 port)

I conigure the 5484 port as:

int gigab 0/1

switchport trunk encap dot1q

switchport mode dynamic desirable

why it is still only used by vlan 1?

[richard268]

now the spanning tree in 4506-I and 4506 II seems fine. both 4506-I and 4506-II has learned all the vlan info and the vlan interface can see two forwarding ports, but the 2950 in the middle (such as 2950-2) canot learn any vlan information from its neighbors.

it seems that the ws-3500-xl module is not working in trunk mode.

For ws-3500-xl module, I write:

int giga 0/1

switch port mode trunk

Any suggestion?

Richard

[richard268]

I fixed the problem. the solution is that I unplug the cascaded gigastack cables and then the first gigastack port is working in trunk mode, and I plug it in again, then all the gigastack ports are working in trunk mode as hoped, seems funny, huh? not sure if there is any buy in IOS 12.1(12c)EW. Anyway, it works.

Richard