Connectivity question/help

Question

Hi...
I need some help troubleshooting the following connectivity issue
Our setup consists of a core 6509 IOS with sup720 at our site. We have a
remote site that we need to connect temporarily via leased line. We have a 2821
router at the remote site and a 1721 at our site.
I connected the 1721 FE port to a gig ethernet port in the core which is assigned as a
switchport under vlan 10.30.11.0 255.255.255.0 (VLAN 11), 10.30.11.1 being the vlan ip address. The 1721 FE port is assigned 10.30.11.2/24
I can ping to the 1721 fe port from the core switch, but cannot ping or telnet
from a pc on a vlan on the same core. There is a default route on the core switch that points a firewall connecting the core to another wan site.
Since the 1721 router is directly connected to the core router, do i need to have a
static route to allow vlans on the core to connect to it? Or the Gig ethernet port on the
core should be a layer 3 port? I removed all access lists on interface vlan 11
Any help is appreciated

Answer 1

I believe that the issue is not anything to do with how you configured the port on the 6509. I believe the issue is that the 1721 does not have a route for the subnets that exist on the 6509 (other than it knows vlan 11 as a connected subnet). You can ping to the 1721 from the 6509 because the ping packet has the VLAN address (10.30.11.1) as the source address and the 1721 knows how to send the response. When you attempt to ping or telnet from devices in other subnets the 1721 does not know how to get to them because they are not in its routing table.
It is easy to check whether my theory is correct. Do a standard ping to the 1721 from the 6509 to verify that it still does work. Then do an extended ping from the 6509 and in the extended ping specify (in extended commands) that the source address is some other interface. If my theory is correct the standard ping will work and the extended ping will fail.
Of course you can also check my theory by doing a show ip route on the 1721 and see if the 6509 other subnets are in the routing table.
If I am right you can fix the problem by configuring static routes on the 1721 or by running a dynamic routing protocol.
You will have a similar problem about how to access the remote 2821. Both the 6509 and the 1721 will need routes to the 2821 and the 2821 will need routes to the 1721 and the 6509.
HTH
Rick