  We consider the network reliability problem in wireless sensor networks
secured by the heterogeneous random key predistribution scheme. This scheme
generalizes Eschenauer-Gligor scheme by considering the cases when the network
comprises sensor nodes with varying level of resources; e.g., regular nodes vs.
cluster heads. The scheme induces the inhomogeneous random key graph, denoted
$\mathbb{G}(n;\pmb{\mu},\pmb{K},P)$. We analyze the reliability of
$\mathbb{G}(n;\pmb{\mu},\pmb{K},P)$ against random link failures. Namely, we
consider $\mathbb{G}(n;\pmb{\mu},\pmb{K}, P,\alpha)$ formed by deleting each
edge of $\mathbb{G}(n;\pmb{\mu},\pmb{K},P)$ independently with probability
$1-\alpha$, and study the probability that the resulting graph i) has no
isolated node; and ii) is connected. We present scaling conditions on
$\pmb{K}$, $P$, and $\alpha$ such that both events take place with probability
zero or one, respectively, as the number of nodes gets large. We present
numerical results to support these in the finite-node regime.
