First time IPIPGW design questions

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Dec 15th, 2007
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Hi. I'm implementing our first, of many, IP-to-IP Gateways across our WAN. I've been made aware that this needs to be a hub and spoke setup with our main site (Site A) being the hub. For now we are just creating a single interconnect with one other remote site as a test. Both sites have CM 4.1.3, are using SCCP, and I have two 2811s reserved at each end for implementation. My problem (after scouring over countless Cisco documents, and having a fair amount of success) is still an issue of overall design. I'm under the impression that I should be able to combine the IPIPGW and via zone gatekeeper into one router on each side. So in my mind the diagram would go something like:


The closest diagram I've come across spreads everything over many devices, like so:


Also, in the same document I've read conflicting answers as to which type of trunk I would want to use in this scenario. One page says H.225(w/ GK) the next page ICT(w/ GK), so if anyone could direct me there, that would be awesome. I've read some pros and cons to both, made progress with ICT, but would like to see if I could get a more definitive answer on best usage. Thanks.

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Avner Izhar Sun, 12/16/2007 - 10:57
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With regards to the first part, not sure why you want a gatekeeper at each site, that would make things very hard, but then again the design considerations are not given so it would be hard to comment.

As for the ict vs gw, in call manager 4.1 as far as my readings told me, it makes no difference since the H.323 features are negotiated per call. If you are to connect with an actual cluster then use ict due to the multi ip address you can configure there.

HTH, Avner.

n.drellos Sun, 12/16/2007 - 12:07
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Thanks for the advice on the trunks.

As far as the design, each site is an independent CM cluster behind it's own firewall. So, it's possible for me to just use the single GK at the head site, and just use and IP2IP gateway at the remote that is registered to that gatekeeper?

I've looked through a ton of documents at this point. Here is one that shows what I was thinking topology wise. It's a CAC document, but a diagram of interest is about 1/3 of the way down the page. Figures 9-13 and 9-14.

Avner Izhar Sun, 12/16/2007 - 17:04
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Hi again,

Seems like the single gatekeeper in the main site will be a good solution, might want to cluster it with another one for redundancy.

The ip-to-ip gw will register with him so that you will have just one ip address going out from every site.

How many sites do you have, a single gateway can have up to 100 zones, and you will need zone per cluster in order to cac between them.

Regagrds, Avner.

n.drellos Sun, 12/16/2007 - 17:39
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Hey, thanks for the response.

At first just the two sites, and by the end maybe 10 - 20. Each a completely

separate network, behind there own ASA, with there own CCM cluster, or CME.

So, I need one GK at the main site, and trunks from each call manager cluster that points to that GK, or do I need an H.323 GW or second IPIPGW at the remote site to point back to the GK?

I guess I figured that I would need something extra at the remote site. The original thought being that extra GK/IPIPGW. I actually was able to make some calls with the two GKs and an ICT at each end, so I just want to make sure that it doesn't have some purpose inside my topology (Like having a single exit point from each site through the ASA).

n.drellos Sun, 12/16/2007 - 18:44
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Wait, sorry to reply twice to the same post, but are you suggesting to have a GK at the main site, and an IPIPGW at each remote site?

Avner Izhar Sun, 12/16/2007 - 20:06
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Yes, thats is what I am suggesting. One GK and then multi ip2ip, one per site, where the ip2ip is registered to the GK and the ccm is using the ip2ip as a gateway. No ccm registration to the gatekeeper is required.

Makes sense?

n.drellos Mon, 12/17/2007 - 03:58
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Yes, I think I finally understand. Thanks for your patience! I'm going to be re-implementing today and tomorrow, so I'll let you know how it goes. Thanks!

n.drellos Mon, 12/17/2007 - 08:22
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Ok, I'm back. Here is my current configuration:

CM at Site A has an ICT(nonGK) to an IPIPGW that runs on the same 2811 as the GK. The CM at Site B has a ICT(nonGK) that connects to an IPIPGW there (no GK on that router). Both IPIPGWs are registered to the GK. The GK as local zones configured for each GW to register to with invia and outvia to that same local zone.

zone local SiteA invia SiteA outvia SiteA enable-intrazone

zone local SiteB invia SiteB outvia SiteB enable-intrazone

zone prefix SiteB 71*

gw-type-prefix 1#* default-technology

On the SiteB IPIPGW I have a dial peer with a session target ipv4: to the CM ip.

dial-peer voice 71 voip

destination-pattern 71...

session target ipv4:

SiteA has the same dialpeer but it points to ras.

I can do debugs on both ends, call from siteA to siteB but see it finally fail on the siteB IPIPGW with:

//-1/xxxxxxxxxxxx/H323/validate_crv: No CCB for crv: 0x805Ch225ParseData: RELEASE COMPLETE message with non-matching crv[32860] received. Will take no action.

If I do a show H323 gateway I see the "unassigned number" tally rising from Other Peers and H323 Peers.

If I set the dial peer on the SiteB router to point to loopback:rtp that works, and I can hear myself talk.

I would try leaving the ICT trunks out and just try to register them as H.323 gateways, but they never seem to register with the CM, so I'm not sure what I'm doing wrong there. I don't have much experience with H.323 gateways in general. Just MGCP.

Avner Izhar Mon, 12/17/2007 - 12:51
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Why are you using a via-zone config? imho there is no need for that in your scenario.

It usually complicate things and therefore my advise is to not use it.

Regards, Avner.

n.drellos Mon, 12/17/2007 - 13:24
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I thought that is what told the gatekeeper to start setting up the call leg with an IPIPGW. Should I just leave off the invia and outvia?

Avner Izhar Tue, 12/18/2007 - 14:14
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yes, take out the invia and outvia and then it should work.

That is without looking at your gateway config and gatekeeper active registration status, if they are ok then it should work.

BTW, we are going to run a gatekeeper related session after xmas, you are invited to register at:

HTH, Avner.


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