Trunk sharing over multiple E1 trunks

cisco_nerd

Hi all,

I have a question for those with a bit more experience configuring a CME to interface with PABX systems.

My questions is can you effectivly "load share" over two E1 trunks for outgoing calls?

The topology is a CME Router that connects into a local Nortel PABX (we own it). The PABX is configured for 2 number ranges and has an E1 interface for each of the number ranges.

I am trying to see if I can configure the CME to have dual E1 connections into the PABX, 1 for each number range. Currently I have one connected and uses. The reason being that I can increase the capacity for outgoing PSTN traffic but double if I can share the outgoing traffic over the two trunks.

Currently my config has an outgoing dial-peer similar to this:

dial-peer 1 voice pots
destination-pattern 0T
port 0/0/0:15

I also have a default inbound dial-peer so that I can perform digit manipulation to strip back to a 5 digit extension for ease of internal dial-peers and to keep users happy. At the moment it just matches a (.) for incoming called-number.

So further to my question, is it possible to configure two dial-peers that match the same pattern, but have different outgoing ports? And then have an incoming-called number for each of the dial-peers that matches the number range that the E1 trunk can answer inbound calls from?

e.g.

dial-peer 1 voice pots
description TRUNK FOR 0212345... NUMBER RANGE
destination-pattern 0T
incoming called-number 212345...
port 0/0/0:15

dial-peer 2 voice pots
description TRUNK FOR 0212346... NUMBER RANGE
destination-pattern 0T
incoming called-number 212346...
port 0/0/1:15

*Our PABX strips the leading 0 for incoming calls.

I wasn't sure if I can do this or not, and don't have a real way to lab it out without doing it on a production network.

Any tips/suggestions/ideas?

Thanks greatly!!

cisco_nerd

Any ideas?

shodown

Send me your email in a PM.


You should be able to configure that. I'm not sure how the dial-peers would be setup I would really have to think about it. The thing about CME since its all IOS. You can try it during a change window and register a IP communicator phone to it, and make test calls in and out the system. If it doesn't work you can reboot the router and it will go back to normal. take a backup config before you start to be safe.

pitviper

Without setting a preference, I think the router will randomly pick a dial-peer match for outbound calls.

cisco_nerd

pitviper wrote: »

Without setting a preference, I think the router will randomly pick a dial-peer match for outbound calls.

If thats the case, it shouldn't matter too much if there are multiple dial-peers with the same destination pattern then? The router would in essence "load share" across the time slots for each E1 interface? The preference would just tell the router to use one E1 first until all time slots are saturated and then move to the next.

Which would be more efficient; bonding them together in a trunk group, assinging multiple dial-peers with a preference, or just let the router work it out itself?

pitviper

How many concurrent calls are we talking about? Since each call has its own 64k channel it doesn’t matter much from a performance perspective if 12 calls are on each port, or 24 of 1 (unless we’re taking SiP here with bad QoS config)

I stuck a 2951 in between an ancient NEC PBX. It had 2 T1 PRIs to the PSTN, and 2 T1s to the PBX. Also had to setup both FXO and FXS trunks between systems to transfer calls back and forth / direct dial. Sounds like a similar setup.

cisco_nerd

Potentially looking at around 30 concurrent calls, with surge to about 50%+.

Not talking SIP with this implementation, just MGCP and SCCP.

I am interfacing with a Nortel PBX system. I think I have it mostly nutted out now and pretty confident. Will be going down the path of a trunk group for the E1 controllers and using that as a target for the dial-peers.