1. Jiang XingFeng (Johnson) Jiang.x.f@huawei.com P2PSIP WG, IETF #68
Requirements for Peer protocol draft-jiang-p2psip-peer-protocol-requirement-00.txt
Jiang XingFeng (Johnson)
P2PSIP WG, IETF #68

2. Background
Lots of protocol proposals, some use cases, no agreed requirements
We need good requirements, so David Bryan suggested that we work on them
Previous draft-draft-baset-sipping-p2preq-00 (expired May 2006)
Authors: S. Baset, H. Schulzrinne, E. Shim, K. Dhara
This draft is mostly independent - some text reuse, with permission (thank you)
Will compare more carefully now that we met 00 deadline!

3. Basic requirements - 1
Peer protocol should rely on a transport mechanism which would guarantee reliable message delivery
The ratio of payload to message size should be kept as high as possible
Peer protocol must provide a few primitive functions which are essential for most DHT algorithms
Join, Leave, Get, Put, Remove
Peer protocol should provide routing function in the overlay

4. Basic requirements - 2
Peer protocol should provide redundant storage function in the overlay
Peer protocol should accommodate a few existing DHT algorithms and at the same time, be extensible enough to support new DHT algorithms in the future
Peer protocol should allow Peers to communicate with each other by traversing NAT device

5. UDP or TCP UDP or TCP for Transport?
Hard to fit enough info in one MTU
But UDP good for NAT traversal, reduces load with more connections
Open issues
Compress headers, leave out some information
Binary or ASCII protocol?
Self-fragment/reassemble?
Is the TCP overhead worth it?
(DHTs maintain a lot of connections and frequently use short-lived connections)

6. Additional Requirements
Security requirements
Need certificates to authenticate all messages
Distributed mechanism to distribute/acquire certs
Resource registrations need to be authenticated by registering entity, not responsible peer

7. Advanced requirements
Availability
Neighbor detection
Some remedial actions could be taken after peer’s failure is detected
Replication
Peer protocol should place several replicas into the overlay and make the corresponding information available all the time
Routing efficiency
Cache mechanism
Hops which requests traversed are shorten and the lookup operations become more efficient

8. Thanks!