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IP Address Dialing Expressway-C

Ben Morgan
Level 3
Level 3

Have a requirement to route IP Address dialing from CUCM registered Endpoints to both Internal H.323 endpoints and external H.323 endpoints.

Have Expressway-C and E configured and configured 'IP Address' SIP route pattern toward the Expressway-C.

Question.

If I configure 'Calls to unknown IP Addresses' to Direct on the Expressway-C, I understand that the Expressway-C can then reach out and signal the standalone H.323 endpoint directly. However, how does one also have the ability to route to External unknown IP Addresses via the Expressway-E.

So, if I set the expressway-c to Direct mode, does it fallback to Indirect mode if it doesn't receive a response from an endpoint?

Thanks

Ben

1 Accepted Solution

Accepted Solutions

The idea is not bad and it can actually be made to work, especially if you can distinguish internal / foreign IPs. (superficially tested in lab, it worked)

Since search rules don't seem to apply pattern matching to IP addresses, and CUCM not supporting IP dialing anyway, I would leave the transform of the IP-like "alias" used for CUCM IP dialing workaround to a real IP to the Exp-E/Exp-C(2) and then route to either depending on whether alias pattern matches an internal or external IP.

For example, let's say you use <ip>@ip.net as SIP URI pattern for IP dialing from CUCM and your internal IP's are all in 10.0.0.0/8

On Exp-C(1) create two search rules, 10\.[0-9\.]*@ip.net, pointing to Exp-C(2) neighbor zone, then a second rule [0-9\.]*@ip.net pointing to the Exp-E traversal zone.

On both Exp-C(2) and Exp-E have a regex transform for \([0-9\.]*\)@ip.net to replace with \1

Also, both will need the H323-SIP interworking gateway license.

Cheers,
  Zoltán

View solution in original post

10 Replies 10

Manish Gogna
Cisco Employee
Cisco Employee

Hi Ben,

Is the IP address dialing working already? If not you may review the following config guide

http://www.cisco.com/c/en/us/support/docs/unified-communications/telepresence-video-communication-server-vcs/118884-config-vcs-00.html#anc10

Manish

Thanks Manish, while the document provided allows for the standard communication stream going through the Expressway-E.. I need to allow for both the Expressway-C to directly communicate with Internal H.323 endpoints as well as indirectly by sending through the Expressway-E via the Traversal zone.

Hence, If a CUCM registered SIP endpoint was to dial an IP Address of an Internal Corporate H.323 device, I need the Expressway-C to handle the interworking between SIP and H.323 and directly call the h.323 device as it would be internally routable. However, If I was to call an external h.323 endpoint not routable from the internal network, the Expressway-C will have to pass the signalling onto the Expressway-E for it to do the interworking between SIP and H.323 and communicate directly with the external h.323 endpoint.

Do you know if this is possible with the Expressway-C/E environment?

Hi Ben,

It may be doable depending on your internal H.323 architecture.

Expressways cannot act as gatekeepers (H.323 devices cannot register to them) so the Expressway-C would need to know some way to reach the h.323 endpoints. If you have a VCS or a GK in your network for example, you can set up a neighbor zone towards it and set up search rules on Expressway-C to route calls that way as well.

The challenge is that you cannot have two "default behaviors" at once - unknown destinations can either be called directly (this is what Expressway-E does usually) or indirectly this is what Expressway-C does, sending all unknowns towards Expressway-E.

So your goal is making sure the local H.323 endpoints are not "unknown destinations".

On the other hand, you could just leave it up to Expressway-E to deal with it, as long as you ensure that it can reach those internal destinations correctly.

Cheers,
  Zoltán

So thinking at a high level.. If I was to implement a second Expressway-C, then create a neigbour zone between the two Expressway-Cs. Add in the search rule covering the 'Internal Endpoint IP Addresses' and point to this neighbour zone. Theoretically, this may work.

Have the 'Calls to unknown IP Addresses' configured to 'Direct' on the second Expressway-C

so traffic flow would be...

SIP Endpoint -> CUCM -> Expressway-C(1) -> Expressway-C(2) -> H.323 endpoint.

The idea is not bad and it can actually be made to work, especially if you can distinguish internal / foreign IPs. (superficially tested in lab, it worked)

Since search rules don't seem to apply pattern matching to IP addresses, and CUCM not supporting IP dialing anyway, I would leave the transform of the IP-like "alias" used for CUCM IP dialing workaround to a real IP to the Exp-E/Exp-C(2) and then route to either depending on whether alias pattern matches an internal or external IP.

For example, let's say you use <ip>@ip.net as SIP URI pattern for IP dialing from CUCM and your internal IP's are all in 10.0.0.0/8

On Exp-C(1) create two search rules, 10\.[0-9\.]*@ip.net, pointing to Exp-C(2) neighbor zone, then a second rule [0-9\.]*@ip.net pointing to the Exp-E traversal zone.

On both Exp-C(2) and Exp-E have a regex transform for \([0-9\.]*\)@ip.net to replace with \1

Also, both will need the H323-SIP interworking gateway license.

Cheers,
  Zoltán

I'm thinking also would the expressway-C(2) need any RMS Licenses to support the above architecture..

Yes. If it's doing interworking it's using a traversal/RMS license.

Lalit pamnani
Level 1
Level 1

Hi Ben,

The typical configuration is to have the VCS-C provisioned to use the Indirect method and provision a search rule on the VCS with a match criteria of AnyIPAddress and a target zone that points to a traversal zone. Then the VCS Expressway (cluster or node) is provisioned to use the Direct method. While that is what I usually see, it is worth noting that the target zone can be any neighbor zone, it doesn't have to be a traversal zone.


It is important to note that you can have the VCS Control provisioned to use the Indirect routing method for IP dialing to unknown IP addresses while also supporting IP dialing to known IP addresses at the same time. The configuration requirement is that you have at least two search rules with the match criteria of AnyIPAddress. One rule would cover the "intra-net" IP address ranges and a separate rule would "punt" to neighbor zones to find the destination. I typically recommend that these rules are configured with equal priority and, if that is not possible, that the LocalZone search rule is provisioned with a higher priority than neighbor zone search rules.

Few points:

Direct mode - we are instructing the VCS to route calls using IP dialing directly, it means that the VCS is going to start the TCP handshake with the IP address specified in the call setup message

The VCS consider an IP address to be known if one of the following is true:
A.The IP address is associated with a locally registered endpoint.
B. The IP address falls within the range of an active sub-zone membership rule.


Hope it helps.

Thank you.

Thanks Lalit, I think you are referring to the VCS-C and not the Expressway-C.. The Expressway-C doesn't have a local zone, hence there are no locally registered endpoints and no active sub-zone membership rules available.

My bad, i overlooked :(

Thank you.

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