|
-----Original Message-----
From: Roberto Nibali [mailto:ratz@xxxxxx]
Sent: Friday, February 16, 2001 12:11 AM
To: lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re: LVS with mark tracking
Hi,
> DR is not an realistic option for us, there can be any kind of real
servers involved,
This is absolutely not a problem ... (unless you try it with Plan9 or
Amoeba)
> with other administrators.
...this however can be a problem.
BTW, stupid question: If your incoming requests come through different
interfaces,
do they all leave through the same one and go to the realservers? Sketch:
The problem for multihoming
Many companies require for high availability by using links to more than one
ISP. The ISP market is not as mature as other countries and we find that
each ISP is either unwilling or unable to provide proper BGP support. This
places and overhead on the content provider or hosting site to use multiple
address spaces, one registered address space per ISP.
The solution
One solution to this problem would be to create a dummy VIP for each ISP
connection. To the dummy VIP address a member is added that would be
unavailable should the link or ISP be unavailable. The availability of the
member could be checked using a simple ping. Should the member be
unavailable then the VIP will also be unavailable since it has only one
member. To ensure that the director sends ping checks to the correct ISP
connection a static host route should be added to the director routing table
to force the check through the correct ISP connection and thus the correct
interface address.
Now that we have a mechanism to determining the availability, from the
Internet, of each registered address space we can tie the dummy VIP port and
real VIP port together using DNS. DNS is configured to use a VIP only if the
real port and the dummy VIP port are both available.It means that DNS should
be intelligent health check the vip. Should either VIP port be unavailable
then the real VIP address will not be returned to the client.
____________ ____________ ____________
| | | | | |
| ISP1 | | ISP2 | | ISP3 |
|____________| |____________| |____________|
| | |
| | |
(router) (router) (router)
| | |
+-----------+ | +---------+
___|_____|_____|____
| |
| director (VIP) |
|____________________|
|
|
|
------------------------------------
| | |
| | |
____________ ____________ ____________
| | | | | |
|real-server1| |real-server2| |real-server3|
|____________| |____________| |____________|
If the setup looks like this, you can still do some kind of VS-DR approach
without having to deal with the arp-problem. I used this setup together with
HP/UX 10.20 and 11 boxes.
Regards,
Roberto Nibali, ratz
--
mailto: `echo NrOatSz@xxxxxxxxx | sed 's/[NOSPAM]//g'`
_______________________________________________
LinuxVirtualServer.org mailing list - lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Send requests to lvs-users-request@xxxxxxxxxxxxxxxxxxxxxx
or go to http://www.in-addr.de/mailman/listinfo/lvs-users
|
