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Cognitive radio technology solves the problem of spectrum underutilization by allowing the unlicensed users to opportunistically access available spectrum without affecting the activity of licensed user. Channel assignment and routing in cognitive radio networks is especially challenging in networks where nodes are equipped with only a single transceiver (as is the case in commodity wireless networks that run IEEE 802.11 DCF MAC). We propose a combined framework of routing and channel assignment that exploits channel diversity in cognitive radio networks to optimize routing performance and increase the network capacity. Specifically, we propose a joint cross-layer routing/ channel assignment protocol based on AODV that works without any central control channel and accounts for the state of the links. In this paper, we propose to keep a backup channel to cater for channel heterogeneity thereby avoiding end to end re-route procedures. We also propose cooperative channel switching in which various nodes exchange routing and control information in a coordinated way. Simulation results show that our proposed backup channel approach ensures higher connectivity as compared to the single channel approach as the number of channels interfered with increases.