netwk management and ports

[dmalamba]

I have a cisco 2611 router which i want to use both of its ethernet ports to be conected to same LAN i.e switch. The moment i configure the ports to be in the same network i.e having similar ip addresses e.g 192.168.100.207 and 192.168.100.208 i am receiving an error that there is an overlap. What do i do to resolve this. What if i connect another router to the same switch would their be a conflict as well. I want to do that inorder that i reduce load on one ethernet port which is my gate way to about 16 remote sites and the internet

[spremkumar]

hi

can u clarify how ur remote sites are getting connected to ur end router ? is all of the links getting connected to the same router ?r u using point to point links or via any SP ? r u using IPSEC or GRE ??again whts the B/W specifications of the links ?

though u put both ur routers on the same switch and try to do balancing accordingly as per ur post the incoming traffic will be taken for task which is not mostly recommended and dont think will work out for u to achieve ur req.

myself again running 2611 with 15 remote sites all of them GREing into tht.but thts with enough H/W resources.its working fine w/o any issues ..

i would suggest to chek up ur CPU,mem utilisation on the current router.if u see any abnormality in those things all the time then u can segregate some of the links to the other router and the router can hv the ip as u mentioned.

but in ur servers u need to add the entries for the sites connected to the routers accordingly using route add otherwise all ur packets will hit ur defaul g/w of ur server ..

regds

[Kevin Dorrell]

You could split the hosts into two /25 subnets, and put one router interface in each half. The two halves could still be on the same VLAN. It wouldn't give you any fallback though.

There should be no problem adding a second router to the subnet at the switch.

Kevin Dorrell

Luxembourg

[konigl]

If you're using a serial WAN link on your router to reach your 16 remote sites and the Internet, then that's probably your bottleneck, not the Ethernet LAN interface.

Are you running the router's Ethernet interface at full duplex? That will at least maximize its performance on the LAN side. If you set it manually, make sure you do the same to the switch port that it plugs into.

Are you looking to increase performance, or add redundancy? Or something else? There are several ways you can get two LAN interfaces from the same router plugged into the same switch, but how you configure them depends on what you're trying to accomplish.

[Craig Norborg]

You cannot resolve that problem while you're in routing mode, and you don't want to switch to bridging mode in a case like this. A router can only have one interface in a subnet at any given time.

Do you know that your Ethernet port is taxed? You can see this by "show int" and looking at the 5 minute averages or by graphing it with something like MRTG. Solarwinds also has tools in its toolset for doing this (free trial). I'll also bet its your WAN links being overloaded.

If your getting alot of collisions on your Ethernet port, you might be able to help with this if you have it running into a good switch like a Cisco. All you need to do is put both sides into 10/full mode instead of 10/half, but not all switches support this.

Other approaches to take would be to utilize L3 switching in your network (say expensive compared to upgrading your router) and use a couple of /252 networks to connect both ethernets from your router to your L3 switch.

One approach I've never tried but might work would be to take off the IP addresses off of your Ethernet interfaces. Put them both in the same bridge-group, then create a BVI interface (Bridged Virtual Interface) with the IP address your router takes on the LAN.

That's about all I can think of. Let us know which approach you used and how it worked...