h a big machine has to be modular as much as pos- sible, and this aspect is accurately considered. All the important parts of the router can grow in pace with the traffic capacity that the router has to manage. Moreover, a large amount of effort is devoted in providing reliability while avoiding a useless proliferation of redundant units. From this point of view, 1:N redundancy is used when possible, leveraging on the modu- lar architecture of the router elements. From a software point of view, both traditional IP over MPLS or pure IP and GMPLS working are foreseen. If the GMPLS network architecture is chosen by the carrier, the user network interface (UNI) is implemented to realize interworking with the trans- port layer. SNMP is used to manage the network element as in almost all present technology rout- ers, but the machine is ready to be updated to more complex network management as far as ASON will be completely implemented. A similar overview of the features of a core gigabit router is reported in Table 7.7. Under several points of view, being a core machine devoted to the same application of the terabit router, where such a huge capacity is not needed, the gigabit router is similar from the architecture point of view, but with reduced capacity. From a platform point of view the design of the gigabit router is based on particularly wide cards (quite out of normal standards). This has allowed compacting the machine in a single rack, SO avoiding the complexity of inter-rack communication. Looking at the available interfaces, the lower capacity of the gigabit router implies the presence of lower capacity, high density interfaces that allows lower capacity client to be connected to the router. Moving from the core to the edge, the features of a practical BRAS/edge router are sum- marized in Table 7.8. From a hardware point of view, this is a simpler machine with respect to core routers. The distributed architecture is constituted by a single redundant forwarding processor working in team with the line cards pro