WAN and LAN interfaces on Cisco 871

[Petar Milanov]

Hi all,

I have Cisco 871 router witch has 1 WAN interface and 4-port 10/100-Mbps managed switch.

My question is: Can I connect this router with 2 ISP's?  One of the ISP's I can connect with the WAN port, but can I connect the other ISP to one of the 4-port managed switch and to separate it in other VLAN.

My Idea is when one of the ISP's fails the LAN PC's to go over the other ISP.

What is in general the difference between WAN and LAN interface on Cisco 800 series.

Thanks in advance!

Tihomir Yosifov

[Leo Laohoo]

I am not sure if this can be achieved unless you have TWO c871.  The WAN interface is a routeable interface while the 4-port LAN ports is a cut-down Layer 2 switch (c2950).

[Petar Milanov]

Thanks for your reply leo.

OK it is a Layer-2 switch, but if i create a Vlan10 and attach a switchport to it, i can give an IP address to this vlan and to make it "nat ouside".  I think this will be routable ?!

Thanks

[spremkumar · Accepted solution]

Hi

You can connect the second isp link onto one of the switch ports and configure a VLAN(SVI) attached to it.

But the catch here is with the Base Image u have limitations in configuring the VLANs (SVI Interfaces).

You can overcome the same by upgrading the base image to Advanced IP services IOS image to have support for more numbers of VLANs(SVIs).

regds

[Petar Milanov]

Hi,

I already find that anwer and tryed it. It works!  I am with the "advanced ip services" IOS, so everything is OK.

I am really surprised what the Vlan(SVI) interface can do. I works like a real Layer 3 interface. It has all main features as routing, nat, PBR, ZBF  and that is all i need. I stiil cannot find a disadvantige of using SVI instead of a Layer 3 fa interface.

Thank you!