How will our Network Diagram look like with Two T1s and two Routers? 1

[texnut]

Hello all,

We will be signing a contract with a new VoIP provider shortly and I'm a bit confused as to what our network diagram will look like once the install is complete - here is a description of what they are offering us:

One T1 line that will be Voice & Data (with voice having priority) going to a Cisco 2431 Router.

One T1 line that will be Data only going to a Cisco 1721 Router.

We will be providing a Cisco PIX-506E firewall and a Catalyst Switch.

My question is this: They claim they will load balance the two T's. How will our Network Diagram look like when all is said and done?

Normally, our Network Diagram would like this (assuming one T1 and one router, or even Two T1s, one router using MLPPP):

(ISP) <-> Cisco 1721 <-> Cisco PIX <-> Switch/Internal Network. But throwing in a second router and the load balancing is throwing me off.

Any help and direction is much appreciated.

thanks all!

 

[swabs]

We have a similar process in place.

If you use a switch with VLANS you can plug the both of the router's LAN interfaces and the PIX interface into a seperate VLAN that is not accessible by other VLANS. This allows you to use 2 connections into one firewall.


We use this process for our internet connections. We have the LAN side of 2 different ISP provider routers in the same VLAN as our ASA failover pair.

 

[texnut]

Interesting...so are you saying the network would look something like this? :

Router 1 e0/0 -> VLAN_OUTSIDE_INTERFACE
Router 2 e0/0 -> VLAN_OUTSIDE_INTERFACE
PIX 506 e0/0 -> VLAN_OUTSIDE_INTERFACE

Then, the PIX 506 e0/1 interface would connected to the default VLAN right?

Would you mind posting the configs of your routers and ASA? (excluding sensitive IP info of course) - I would really appreciate that.

Thanks!

 

[swabs]

Texnut,

I can't post the configs but here is more details:
I am using a 2950 switch for vlans.


Router1 - e0/1 plugged into ISP A's media converter
e0/0 plugged into 2950 switchport VLAN 2

Router2 - e0/1 plugged into ISP B's media converter
e0/0 plugged into 2950 switchport VLAN 2

CiscoASA1 - e0/0 plugged into 2950 switchport VLAN 2
e0/1 plugged into 2950 switchport VLAN 1

CiscoASA2 - e0/0 plugged into 2950 switchport VLAN 2
e0/1 plugged into 2950 switchport VLAN 1

LAN traffic on VLAN 1.

This is oversimplified because I actually have many VLANs within the LAN traffic, but the idea is the same. You just need VLAN1 to have connectivty to the other LAN Vlans.

We also complicate things a bit using HSRP on the ISP routers for automatic failover.

 

[texnut]

Ok, no problem.

So this is getting interesting - in your scenario, are your routers implementing the load balancing or are the ASAs?

Since we only have one PIX we would like to implement the load balancing in the routers - this should be possible right?

You wouldn't happen to know of any locations where I could find sample configs of two routers like such?

Thanks!

 

[swabs]

Texnut,
In your post you stated that "They claim they will load balance the two T's" so they must have a method for that. If then can set up HSRP that would be ideal.

But for another network I manage we use 1 router to load-balance 2 T1's using ip load-sharing per packet.


Example below>

Router#
ip cef


interface FastEthernet0/0
ip address 172.168.1.1 255.255.0.0
ip policy route-map hipri
duplex auto
speed auto
no mop enabled
!
interface Serial0/0
description T1 #1
bandwidth 1544
ip address 192.168.2.1 255.255.255.252
ip load-sharing per-packet
service-module t1 timeslots 1-24
!

!
interface Serial0/1
description T1 #2
bandwidth 1544
ip address 192.168.2.5 255.255.255.252
ip load-sharing per-packet
service-module t1 timeslots 1-24

 

[texnut]

I suspect that they will use HSRP to perform it, but not sure.

Thanks for the tips, I'll post back when I hear more from them!

 

[burtsbees]

Why would you want to load balance two separate T1's? They are already going to "load balance" just by virtue of being two totally different lines! Right? Or am I nuts? Are you thinking of not being able to BUNDLE the T1's in separate routers? For this to happen, you would need a third router to terminate the two incoming lines...is this what you mean?

Burt

 

[chipk]

Just a quick interjection here: HSRP does not do load balancing. In an HSRP config, no L3 traffic is passed through the standby unless the active router fails.

 

[texnut]

Chipk - yes, I believe you're right after doing some more reading.

Burts - to be honest, I'm not really sure. I get what you're saying but I thought that you could balance the traffic between the two so that no one individual for example could saturate the entire T1. Or for example to take advantage of the "left over" bandwidth when the phones are not being used.

But maybe I have my wires crossed?