CM duplex: Active CM and Standby CM can be in different IP subnet ? 1

[nortavaya]

Hi all,

We try to deploy new CM duplex for our customer, and we want to know if it is possible to put the Active CM in seperate IP subnet than the Standby CM (eth0) in VM ? if so, which IP address we should assign to the virtual IP ? from subnet 1 or subnet 2 ?

The duplication link it will be on the same IP subnet (eth1)

Thank you in advance.

 

[janni78]

Maybe I'm missing something here but what would be the point of that?

When it changes to the standby it takes the virtual IP so they should be in the same subnet.

"Trying is the first step to failure..." - Homer

 

[nortavaya]

Hi janni78,

Thanks for your reply, the customer want to put each duplicate machine (VM) of Avaya in seperate VLAN/IP Subnet (internal company rules), so why I asked this question

I seach on the Avaya doc, but didn't figure out something talking about LAN recomandations of CM duplex (same subnet, ....etc)

Thank you

 

[Wanebo]

Again, what would be the point of doing that? It would be possible to put them on separate IP-subnets located on different VLANs but the required routing work would negate any perceived benefit of doing so. Doing that is just making unnecessary work for and network engineer and overly complicating the setup for no benefit. It would be better to put them in the same subnet and just make that subnet very narrow to only include each of the servers IP address and the virtual IP used as the active connection.

 

[nortavaya]

Thank you Wanebo, so you mean that it is technically supported but it is not recommanded by Avaya due to network delay (level 3) will impact communication between the both servers

Thank you again

 

[janni78]

There are so many questions regarding why the customer even wants this.
What is the gain of having 2 different subnets beside it's their "Internal Company Rules"?

You need to ask the customer why this is a request, and tell them how it could be implemented or why it shouldn't be done that way.
Just because a customer wants to do it one way doesn't mean it's a good idea.

"Trying is the first step to failure..." - Homer

 

[Wanebo]

I mean that it is technically feasible. I would not make statements on Avaya's support or recommendations on this configuration, since I do not work for or represent them.

I agree with janni that I would want to know more from the customer why they would require this configuration.

 

[nortavaya]

@ janni78, the customer has two VMware datacenter (two sites) and in each datacenter use different IP subnet

So we want to deploy CM version 8 duplex, and he prefer to put each CM in seperate datacenter

What is recommanded again VMware datacenter ?

Thank you

 

[phoneguy55]

the customer has two VMware datacenter (two sites) and in each datacenter use different IP subnet
So we want to deploy CM version 8 duplex, and he prefer to put each CM in seperate datacenter
What is recommanded again VMware datacenter ?

If thsts the case then 2 servers on the same subnet in one DC and 2 survivable core servers in the 2nd data center. This would be the right way to do things.

 

[dialtonebone]

phoneguy555 said it right


You need layer 2 connectivity with certain requirements (see install guide, mainly latency and packet loss maximums) for a duplex core. That's it - nothing else to discuss as far as that changing.
If you can get L2 between the two datacenters AND it meets the requirements then great, it should work (barring any split brain scenarios if the two sites become islands). If you can not, just through an ESS/Survivable Core over at the second DC.

 

[janni78]

the customer has two VMware datacenter (two sites) and in each datacenter use different IP subnet

This would have been vital information to have from the start and would gotten us to the answer faster


"Trying is the first step to failure..." - Homer

 

[nortavaya]

Thank you janni78, so what is the answer for that ?

Thank you.

 

[janni78]

What phoneguy55 and randycaroll said.

"Trying is the first step to failure..." - Homer

 

[bignose21]

Communication Manager server separation
From the Administration Release 8.0:

In earlier releases, Communication Manager duplex configurations required a cable for connecting
two Communication Manager instances with dedicated Communication Manager server hardware.
With Communication Manager 7.1, you can physically separate the Communication Manager
duplex instances.

For server separation support, the duplex servers must be in the same availability zone (AZ) to
ensure that both the servers are in the same subnet.

Following are the minimum requirements for software duplex connectivity that must be met
between the two Communication Manager instances:

• Total capacity must be 1 Gbps or more.
• Round-trip packet loss must be 0.1% or less.
• Round trip delay must be 60 ms when Application Enablement Services is not configured and
30 ms when Application Enablement Services is configured.
• The duplication ports of both servers must be on the same LAN/IP subnet.
• Duplication link encryption must be disabled for the busy-hour call rates that results in greater
than 40% CPU occupancy.
• CPU occupancy on the active server must be less than 65% to allow memory refresh from
the active to standby server.

 

[nortavaya]

Thank you bignose21, this is for duplication port, it is already on the same IP Subnet

I'm asking about the LAN interface PE

Thank you.

 

[kyle555]

The LAN PE interface is a single IP. Say you call it 10.10.10.10. CM-A might be installed with 10.10.10.11 and CM-B with 10.10.10.12 but both have the job of assuming 10.10.10.10 if they are live.

So let's say you had a plain old H323/H248 system and your duplex was up and happy and refreshed and you wanted to interchange from server A to B to do some maintenance on server A.

When you interchange, server A, from 10.10.10.10 sends FIN and RST packets to all the phones and gateways, then A tells B to go live, then A drops the subinterface eth0.1 10.10.10.10 and tells B to go live. B then fires up 10.10.10.10 as a subinterface and sends SYN packets to everything and gets stuff set back up.

If you do ifconfig on a happy duplex, you'll see both servers have eth0 - 10.10.10.11 or 12 in this case - and the live server has a subinterface of 10.10.10.10.

They cannot be in different subnets.