01-10-2005 02:55 AM
I ran into an odd issue that I managed to understand and "fix", but I was curious as to how others feel about this confusing configuration option.
I enabled routing on the switch ("ip routing" command) to route between a several port based VLANs defined ON the switch. Each VLAN has an IP address defined on the switch. IP routing shows that these all work fine. i.e. I can ping between each VLAN and the VLAN interface OK.
I (thought) I had configured a "Default gateway" via the command line "ip default-gateway 10.1.1.1"
After testing routing I discovered that this option DID NOT forward packets from the VLAN ports of the switch with unknown destinations to "10.1.1.1" (also on a different VLAN port)!!!
I had to use the "ip route 0.0.0.0 0.0.0.0 10.1.1.1" command to accomplish this.
After much searching I found the following references to "IP Routing & Default Gateway"
Quoting from the Respective chapters in the Manuals:
7-5 - Advanced Traffic Management
The default gateway, which is configured as part of the IP address configuration described in chapter 7, "IP Addressing", is used only when routing is not enabled on the switch.
8-11 Management Guide: The switch uses the IP default gateway only while operating as a Layer 2 device. While routing is enabled on the switch, the IP default gateway is not used. Thus, to avoid loss of Telnet access to off-subnet management stations, you should use the ip route command to configure a static (default) route before enabling routing. Refer to chapter 16, "IP Routing Features", for more information.
How do others feel about having two different options, that technically should MEAN the SAME thing, do different things depending if the device acts on layer 2 or 3?
01-10-2005 07:15 AM
01-10-2005 07:32 AM
I do see why there is a difference... essentially the "Default gateway" option is used when the switch behaves like a single device on a network VS. "static routes" when routing is on..