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Difference between WAN & LAN ports on 800 routers

Hi there,

 

i was checking the cisco 800 routers data sheet, found it says it has 4 LAN 09port and 1 WAN port, all ethernet interfaces. 

 

My question is, is there a difference between these ports? As i remember port 0 is the WAN port and port 1 till 4 are the LAN ports, why can’t I use port 1 for the WAN connection? Are there a certain configuration or commands supported on the WAN ports that are not supported on the LAN ports?

 

thanks in advance. 

1 ACCEPTED SOLUTION

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VIP Mentor

Hello
On a device like this usually you would have switchports (in your case -4 LAN) and routed ports (WAN port)

Switchports are layer 2 specific meaning that can belong to a vlan in an access mode or to many vlans in a trunk mode But because of there L2 capability they cannot support any form of routing (l3 - ip addressing , belonging to a routing protocol).

Switchports support various L2 protocols such like PPP, Frame relay, LLDP CDP, VTP,STP etc..as such they usually cannot become routed ports however In higher end switches switchports can become routed ports by turning of switching mode (no switchport)

Routed ports like your WAN port support l3 protocols (ip addressing, rip/opsf eigp bgp, pim etc..).and as such do not support the protocols that a switchport can at L2.

 

So you would use your wan port to connect to the ISP or another L3 routing device and the LAN ports to your end hosts or another switch via a trunk or access port to extend your l2 capability



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future

View solution in original post

2 REPLIES 2
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VIP Advocate

Hi,

You didn't share complete model number but I am taking a "Cisco 892FSP" router for the reference. As this router is having "1-port GE or 1‑port SFP, 1-port GE" (2 ports) as WAN and 8 Ports for LAN (Managed Switch). As 8 ports are layer 2 ports and it is working as Switchport. So those ports we can't use as WAN because we will face issue NATing, FIrewall configuration as. 

https://www.cisco.com/c/en/us/products/collateral/routers/800-series-routers/data_sheet_c78-519930.html

Regards,
Deepak Kumar,
Don't forget to vote and accept the solution if this comment will help you!
Highlighted
VIP Mentor

Hello
On a device like this usually you would have switchports (in your case -4 LAN) and routed ports (WAN port)

Switchports are layer 2 specific meaning that can belong to a vlan in an access mode or to many vlans in a trunk mode But because of there L2 capability they cannot support any form of routing (l3 - ip addressing , belonging to a routing protocol).

Switchports support various L2 protocols such like PPP, Frame relay, LLDP CDP, VTP,STP etc..as such they usually cannot become routed ports however In higher end switches switchports can become routed ports by turning of switching mode (no switchport)

Routed ports like your WAN port support l3 protocols (ip addressing, rip/opsf eigp bgp, pim etc..).and as such do not support the protocols that a switchport can at L2.

 

So you would use your wan port to connect to the ISP or another L3 routing device and the LAN ports to your end hosts or another switch via a trunk or access port to extend your l2 capability



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future

View solution in original post