When do calls on a VCS use a traversal call license?

Introduction

This article relates to Cisco TelePresence Video Communication Server Expressway.

Q. When do calls on a VCS use a traversal call license?

A. Any call where the VCS takes the media as well as the signaling is a traversal call and will use a traversal call license on that VCS. The following calls require the VCS to take the media, and are therefore traversal calls:

• for a VCS Control, calls to or from a traversal server (i.e. firewall traversal calls)

• for a VCS Expressway, calls to or from a traversal client (i.e. firewall traversal calls); traversal clients include other VCSs, gatekeepers, Border Controllers, or traversal-enabled endpoints

• calls that are gatewayed (interworked) between H.323 and SIP on the local VCS

• calls that are gatewayed (interworked) between IPv4 and IPv6 on the local VCS

• for VCSs with Dual Network Interfaces enabled, calls that are inbound from one LAN port and outbound on the other

• a SIP to SIP call when one of the participants is behind a NAT (unless both endpoints are using ICE for NAT traversal)

Also, a non-traversal call on a VCS Expressway will consume a traversal license if there are no non-traversal call licenses available (if using VCS version X5 or later).

Note that a call may be a traversal call on one VCS but a local (non-traversal) call on another VCS in the call route, depending on whether each VCS in the route is required to take the media.

Related Information

• Technical Support & Documentation - Cisco Systems