TWAMP Features – Reflect OCTETS draft draft-ietf-ippm-reflect-octets-03 Al Morton and Len Ciavattone November, 2009

2 2009, The year of New TWAMP Features  RFC 5357 core spec done  First new Feature – Mixed Security Mode, RFC 5618  “Individual Session Control” to WGLC in August (?)  “Reflect Octets” refined and clarified as two features.

3 Refresh: TWAMP Entities controller responder | Control-Client | | Server | | | | | | Session-Sender | | Session-Reflector |

4 Reflect Octets in BOTH Control and Test Packets Reflect Octets in BOTH Control and Test Packets  TWAMP-Control: –Contol-Client Inserts 2 octets in Request-TW-Session –Server moves 2 octets from Request- TW-Session message to the Accept (reply) message, and –Can Insert 2 Octets of its own, and –Learns the length (N) of padding in Test packets that it will need to reflect. –Length N < Overall Padding Length

5 Reflect Octets in BOTH Control and Test Packets (2) Reflect Octets in BOTH Control and Test Packets (2)  TWAMP-Test: –Session-Reflector moves N octets of the Padding to the reflected Test packet  Control-Client and Session-Sender know what was put in, the format used, etc.  Adds some possibilities for senders  No Test packet format changes involved in Reflect Octets aspect

6 Symmetrical Size Feature Symmetrical Size Feature  TWAMP Test packets (Unauth) are: –14 octets from Sender to Reflector –41 octets from Reflector to Sender  Most want symmetrical sizes, so…  TWAMP core spec RECOMMENDS –Reflector truncate pad. to compensate –Sender SHOULD add sufficient padding  This feature defines a larger size Sender format, no truncation needed  Interaction w/ Reflect Octets Option

7 Reflect Octets and Symmetric Size: Modes Field Value Description Reference/Explanation Unauth. TEST protocol, new bit position (3) 8 Unauth. TEST protocol, new bit position (3) Encrypted CONTROL Encrypted CONTROL xxx Reflect Octets new bit position (X) xxx Reflect Octets new bit position (X) Capability Capability yyy Symmetric Sender new bit position (Y) yyy Symmetric Sender new bit position (Y) Test Packet Format Test Packet Format

8 Symmetric Size: TWAMP Test SENDER packet | Sequence Number | | Timestamp | | | | Error Estimate | MBZ | | MBZ | | | | MBZ | | MBZ | | | | MBZ | MBZ | | MBZ | Packet Padding (to be Reflected) | (IF used in combo with Relect Octets) | Packet Padding (to be Reflected ) | | | |. Additional Packet Padding

9 Reflect Octets: TWAMP Test Reflector packet (same for Symmetrical Size) | Sequence Number | | Timestamp | | | | Error Estimate | MBZ | | Receive Timestamp | | | | Sender Sequence Number | | Sender Timestamp | | | | Sender Error Estimate | MBZ | | Sender TTL | Packet Padding (from Session-Sender) | | Packet Padding (from Session-Sender) | | | |. Additional Packet Padding

10 TWAMP Control: Request-TW-Session Command | 5 | MBZ | IPVN | Conf-Sender | Conf-Receiver | | Number of Schedule Slots | Many fields not shown | Padding Length | Two fields not shown... | | Type-P Descriptor | | Octets to be reflected | Length of padding to reflect | was MBZ | MBZ (4 octets) | | | HMAC (16 octets) | |

11 TWAMP Control: Accept-Session Command | Accept | MBZ | Port | | | SID (16 octets) | | | Reflected octets | Server Octets | | MBZ (8 octets) | | | | HMAC (16 octets) | |

12 Reflect Octets: TWAMP Test Sender packet | Sequence Number | | Timestamp | | | Error Estimate | | | | Packet Padding (to be reflected) | | (length in octets specified in command) | Additional Packet Padding (Additional padding includes enough to truncate and keep sizes symmetrical if the TRUNCATE PADDING option is turned-on)

13 Next Steps  We will just specify what we think is reasonable if no other opinions!  We think it’s ALWAYS Reasonable as an OPTION (at least) to be certain of symmetric packet sizes in Both Directions  Comments on all aspects appreciated, Authors are fully satisfied with the TWAMP-Control modifications…  Authors will gladly discuss changes