As it is an 8 bit field, the maximum possible value is 255 (11111111 in binary).
Whilst this won’t prevent network issues caused by a routing loop or similar, it reduces their impact and may help avoid router failures. When the value eventually reaches one the packet is discarded by the device that receives it (as the value will be reduced to zero). Each time the packet arrives at a layer three network device (a hop) the value is reduced by one before it is routed onward. To ensure IP packets have a limited lifetime on the network all IP packets have an 8 bit Time to Live (IPv4) or Hop Limit (IPv6) header field and value which specifies the maximum number of layer three hops (typically routers) that can be traversed on the path to their destination.
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