RTP Flow via VCS-Expressway

[k.mahesh]

Hi,

If 2 of my home users (EX90) are registered on to the VCS-Expressway from internet, when they make calls,

1. will the RTP necessarily flow via the VCS expressway and consume traversal licenses; assume that there are no inter-working required for H.323 to SIP or IPV4 to IPv6.

2. Will it make a difference if the EX90 end points have a public IP address and not Natted in the SOHO router?

3. What if the home uers are using Jabber or Movi?

warm regards

Mahesh K

[Tomonori Taniguchi]

> 1. will the RTP necessarily flow via the VCS expressway and consume traversal licenses;
> assume that there are no inter-working required for H.323 to SIP or IPV4 to IPv6.
If EX90s are registered on VCS-E as H.323 Endpoint, then RTP go through VCS-E as VCS-E will treat as traversal call.

If EX90s are registered on VCS-E as SIP UA, then depend on IP addressing on those E90, RTP flow may change.

If call between EX90 and one or both of EX90's sip contact address differs from source IP address, then call will treat as traversal call therefore RTP will go through VCS-E.

If call between EX90 and both EX90'ss have same sip contact address and source IP address, then call will treat as non-traversal call therefore RTP will flow directly between two EX90s.

> 2. Will it make a difference if the EX90 end points have a public IP address and not Natted in the SOHO router?

Yes, as above, if EX90 has public IP address on itself (not NAT), then call may establish as non-traversal call where RTP will flow directly between other SIP UA.

> 3. What if the home uers are using Jabber or Movi?

Same for EX90 with SIP deployment except call with ICE.

Jabber video support ICE, therefore if Jabber Video and Jabber Video made a point-to-point call and ICE negotiation success during call setup, then RTP directly flow between two Jabber Video client.

EX90 does not support ICE as of current release software version.

[Tomonori Taniguchi]

License consumption overview (for SIP client) on VCS Expressway.

RTP will go through VCS-E when call treat as traversal call.

RTP will directly flow between two SIP UAs when call treat as non-traversal call.

[k.mahesh]

Hi,

I did not understand the scenario where both EX90 could have same SIP contact address and Source IP. How is this possible?

If the EX90 has a natted IP sitting behing a NAT router, will the RTP need to flow via VCS-E?

warm regards

Mahesh K

[Tomonori Taniguchi · Accepted solution]

If you connect public network directly to EX90 with public IP address assignment, then that EX90 will have same contact IP address (local IP address on EX90) and source IP address.

Also PC with 3G mobile connection (3G+, LTE service, etc.), ISP may assign public IP address which Jabber Video will have same contract IP address and source IP address.

If EX90 is behind home router and NAT to communicate VCS-E, call will treat as traversal call unless call establish ICE/TURN call.

ICE (Interactive Connectivity Establishment), two SIP UA try to establish RTP/RTCP link directly during call setup and if successfully establish the link, then media flow directly otherwise fall back to TURN Relay (traversal call via VCS-E).

[Tomonori Taniguchi]

BTW for H323, VCS-E treat call like follow;

• If H.323 Endpoint support either of ASSENT or H.460.18 traversal protocol, call will treat as traversal call regardless H.323 Endpoint has public IP address or NAT and behind firewall.
• If H.323 Endpoint does not support both ASSENT and H.460.18 traversal protocol & have accessibility (either have public IP address on Endpoint or 1:1 NAT on router front of Endpoint), then call will treat as non-traversal call.

Please note, Cisco MXP-series Endpoint and C-series Endpoint automatically negotiate traversal registration (either using ASSENT or H.460.18 depend on VCS-E preference configuration) and can’t disable traversal protocol itself.