The question I have is are the two links going to two separate ISPs? If
so then you have to overcome the issue of how to get the packets routed
back to you. If you are not using BGP, there is no way I know of to have
a single IP address routed to two different ISPs.
For example, if I have two different ISPs and they assign me
192.168.100.101 and 192.168.200.101 respectively, as follows:
USER
172.16.1.201
|
PROXY
|
192.168.100.101 ---+---- 63.100.1.101
/ \
/ \
/ \
ISP1 ---------- ISP2
\ /
\ /
\ /
ISP3
|
|
|
WEB SERVER
Then you have to hide behind 192.168.100.101 or 192.168.200.101, but not
both. Depending on which IP address you hide behind, all of the traffic
will come in through ISP1 or ISP2. If both links are to the same ISP, you
can negotiate RIP or OSPF or other internal routing protocol, but if the
two ISPs are independant, BGP is your only option. A load balancer or
OSPF provide almost nothing for most sites because there is much more
traffic coming in than out, and all you can load balance is outbound
traffic.
BGP does not have inherent load balancing, but if you are connect to two
separate providers with a lot of clients, then some load balancing will
occur because all traffic to/from a site that is connected to each ISP
will get transfered through the link to the ISP if set up right. Not
really load balancing, but I have seen customers in the US using a
combination of AT&T, Sprint, and UUNET getting pretty good load balancing
because both providers have a big enough range of influence. But not
really load balancing.
Otherwise, you would have to set up a proxy that could send request out on
different addresses. IE, request one gets a source address of
192.168.100.101 and request two get a source address of 192.168.200.101. I
do not know of such a proxy, but please let me know if anyone know of one.
Cheers,
Eric
"Pradeep Kumar" <[EMAIL PROTECTED]>
12/08/2001 06:47 PM
Please respond to pradeep.pillai
To: "Eric Schroeder" <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]>
cc: <[EMAIL PROTECTED]>
Subject: RE: Source-sensitive Routing ...
If I were you Rakesh, I would use a WAN link load balancing in this
scenario.
Can you spend $800 more for a load balancer.
I tried brain storming this with a few collegues and someone suggested to
do
ospf on both and load balance.
Do you have statics to the isp 1, 2 or are u routing ?
Eric- can you do lb using BGP ?
-Pradeep Kumar
-----Original Message-----
From: Eric Schroeder [mailto:[EMAIL PROTECTED]]
Sent: Thursday, December 06, 2001 10:18 AM
To: [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
Subject: Re: Source-sensitive Routing ...
One way to do this is to use BGP. This load balances ok if you have two
Teir 1 providers, but will not load balance otherwise. The advantage is
this is the only way to provide uptime if one of the ISPs goes down unless
you do NAT on the Cisco 2514. You may have problems running BGP on a
2514, but I think this will work as long as you only get routes to connect
hosts from each ISP, and then set the default route to the least used
link.
Hope this helps.
Eric Schroeder
[EMAIL PROTECTED]
12/05/2001 09:44 PM
To: [EMAIL PROTECTED]
cc:
Subject: Source-sensitive Routing ...
Dear memebers,
I have the following network
configuration:
--------------------------------------------------------
| |
| 10.x.x.x |
| |
--------------------------------------------------------
|
|
----------------------
| Dual Homed Gateway |
----------------------
|
|
--------+-------------
| Cisco 2514 Dual LAN |
| Router |
| |
| wan1 wan2 |
---+------------+-----
| |
| |
| |
ISP1 | |
ISP2
========================================
+ +
+ INTERNET
+
+ +
========================================
All our clients in the private network address (10.x.x.x). Using the
Proxy Server at Dual homed gateway, these clients get connected to
Internet using ISP1 link. Recently we have received another link for
Internet connection from ISP2. Hence we are planning to route some of the
clients of private network address(10.x.x.x) through ISP1 link and the
remaining ones through ISP2 link, using Cisco 2514 Dual LAN Router
running IOS software 11.0. After reading the Cisco documents, I came to
know that this is possible through SOURCE-SENSITIVE routing at the
Router.
I want to know the followings:
1. Is there any alternative way(s) to achieve this goal using the same
router having two WAN interfaces?
2. What are the security issues related to SOURCE-SENSITIVE routing ?
Waiting for your suggestions ....
Rakesh Kumar
============
-------------------------------------------------
