●●●● ●●●● ●●●● ●●●● DHTS: Problems ●●●● ●●●● Problem 1(dynamicity): adding or removing nodes With hash mod N, virtually every key will change its location! hk)modm≠h(kmod(m+1)≠h(Kmod(m-1) Solution: use consistent hashing Define a fixed hash space All hash values fall within that space and do not depend on the number of peers(hash bucket) Each key goes to peer closest to its ID in hash space (according to some proximity metric Peer-to-Peer Networks -P. FelberPeer-to-Peer Networks — P. Felber 7 DHTs: Problems ⚫ Problem 1 (dynamicity): adding or removing nodes ⚫ With hash mod N, virtually every key will change its location! h(k) mod m ≠ h(k) mod (m+1) ≠ h(k) mod (m-1) ⚫ Solution: use consistent hashing ⚫ Define a fixed hash space ⚫ All hash values fall within that space and do not depend on the number of peers (hash bucket) ⚫ Each key goes to peer closest to its ID in hash space (according to some proximity metric)