Network Infrastructure Overview
The requirements of the network infrastructure needed to build an IPv6 Collaboration system in an enterprise environment are very similar to those for an IPv4 Collaboration system. Unified Communications places strict requirements on IP packet loss, packet delay, and delay variation (or jitter). Therefore, you must enable most of the Quality of Service (QoS) mechanisms available on Cisco switches and routers throughout the network. For the same reasons, redundant devices and network links that provide quick convergence after network failures or topology changes are also important to ensure a highly available infrastructure. The Cisco Catalyst 6000 Series and Catalyst 4000 Series Switches use the same QoS architecture (DSCP) for IPv6 as they used for IPv4. With the exception of the Cisco Catalyst 3560 Series and 3750 Series Switches (which support QoS trust features only for IPv6), the same QoS mechanisms (such as classification, policing, queuing, and so forth) used for IPv4 Unified Communications traffic in Cisco switches and routers can also be applied to IPv6 Unified Communications traffic. Likewise, the redundant design and availability mechanisms for IPv4 networks are generally available in Cisco switches and routers for IPv6.
This chapter discusses recommendations specific to IPv6 for Unified Communications network infrastructures. For other guidance on standard network infrastructure features required in IPv4 Unified Communications networks, refer to the Cisco Collaboration System Solution Reference Network Design (SRND), available at: Link.
The following list summarizes the key network infrastructure recommendations for IPv6 Unified Communications networks:
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For Layer 2 switched networks, enable Multicast Listener Discovery (MLD) snooping, if possible, so that multicast traffic can be forwarded selectively to the ports that you want to receive the data.
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Layer 3 routed networks require a mechanism to transport IPv6 traffic. Native Dual-stacks (IPv4 and IPv6) routing is supported, although various other IPv6 tunneling mechanisms may also be used.
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Use Hot Standby Router Protocol (HRSP) or Gateway Load Balancing Protocol (GLBP) if those protocols are supported by your Layer 3 campus devices. Otherwise, use IPv6 Neighbor Unreachability Detection.
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IPv6 traffic uses larger headers, which you must factor into the bandwidth requirements for IPv6 traffic, especially in the WAN where bandwidth can be limited.
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For intercluster IPv6 traffic over IPv6-only or IPv4-only SIP intercluster trunks, use call admission control that is based on topology-unaware locations. (RSVP is not supported for IPv6). Topology-unaware call admission control requires a hub-and-spoke topology for the WAN, or a spokeless hub in the case of a Multiprotocol Label Switching (MPLS) virtual private network (VPN).