1. ONL NP Router xScale xScale TCAM SRAM Rx (2 ME) Mux (1 ME) Parse,
Assoc. Data
ZBT-SRAM
SRAM
64KW Rx
(2 ME)
Mux
(1 ME)
Parse,
Lookup,
Copy
(3 MEs) QM
(1 ME)
HdrFmt
(1 ME) Tx
(1 ME) NN
64KW
SRAM
64KW
Each
SRAM
Ring NN NN NN NN
Plugin0
Plugin1
Plugin2
Plugin3
Plugin4
Scratch
Ring
xScale
SRAM NN NN
Ring
Stats
(1 ME) QM
Copy
Plugins
SRAM
FreeList Mgr
(1 ME)
Tx, QM
Parse
Plugin
XScale

2. MUX -> PLC PLC Mux 1 2 3 7 Buffer Handle(24b) QID(16b) Flags:
Src: Source (2b):
00: Rx
01: XScale
10: Plugin
11: Undefined
PT(1b): PassThrough(1)/Classify(0)
Reserved (5b)
L3 (IP, ARP, …) Pkt
Length (16b)
Stats Index (16b)
QID(16b) In
Port
(3b)
Plugin
Tag
(5b)
Flags
(8b)
Rsv
(4b)
Out
Buffer Handle(24b)
PLC
Mux
Reserved (5b)
Src
(2b) PT
(1b) 1 2 3 7

3. PLC -> XScale PLC 1 2 3 7 4 5 XScale SRAM xScale Buffer Handle(24b)
Flags(8b):
Why pkt is being sent to XScale
TTL(1b): TTL expired
Options(1b): IP Options present
NoRoute(1b): No matching route or filter
NonIP(1b): Non IP Packet received
ARP_Needed(1b): NH_IP valid, but no MAC
NH_Invalid(1b): NH_IP AND NH_MAC both
invalid
Reserved(2b): currently unused
xScale
SRAM
L3 (IP, ARP, …)
Pkt Length (16b)
Buffer Handle(24b)
Stats Index (16b)
QID(16b) In
Port
(3b)
Flags
(8b)
Plugin
Tag
(5b)
NH MAC DA[47:16] (32b)
NH MAC DA[15:0]
(16b)
Unicast/MCast bits
Rsv
Reserved (16b)
EtherType (16b)
Same as ring_in
Based on Parse &
Lookup results
PLC 1 2 3 7
Reserved
(2b) NR
(1b)
TTL
Opt NI
ARP NH
INV 4 5

4. PLC -> Plugins PLC 1 2 3 7 4 5 Plugins 0-4 SRAM xScale
L3 (IP, ARP, …)
Pkt Length (16b)
Buffer Handle(24b)
Stats Index (16b)
QID(16b) In
Port
(3b)
Flags
(8b)
Plugin
Tag
(5b)
NH MAC DA[47:16] (32b)
NH MAC DA[15:0]
(16b)
Unicast/MCast bits
Rsv
Reserved (16b)
EtherType (16b)
Same as ring_in
Based on Parse &
Lookup results
PLC
Flags(8b):
Why pkt is being sent to XScale
TTL(1b): TTL expired
Options(1b): IP Options present
NoRoute(1b): No matching route or filter
NonIP(1b): Non IP Packet received
ARP_Needed(1b): NH_IP valid, but no MAC
NH_Invalid(1b): NH_IP AND NH_MAC both
invalid
Reserved(2b): currently unused 1 2 3 7
Reserved
(2b) NR
(1b)
TTL
Opt NI
ARP NH
INV 4 5
Plugins 0-4

5. PLC -> QM PLC QM Buffer Handle(24b) QID(16b) Reserved(16b)
Rsv
(4b)
Out
Port
L3 (IP, ARP, …)
Pkt Length (16b)
Reserved(16b)
(8b)
PLC QM
Same as ring_in
Based on Parse & Lookup results
Maybe the added hdr buffer handle

6. Types of Pkts Arriving at PLC
From Rx:
Only have a payload buf, ref_cnt == 1.
Subject to classification except mal-formed IP pkts detected by Parse.
From XScale/Plugins:
Passthrough (PT) pkt
May/May not have a hdr buf, ref_cnt >= 1.
Not processed by PLC.
Copy sends it to QM.
Non-PT pkt
Only have a payload buf at arrival, ref_cnt >= 1.
Is IP pkt.
Will be classified if it passes IP hdr validation done by Parse.

7. PLC() PLC() { if (dlNextBlock != BID_FREELISTMGR) Lookup(); } Copy();
if (!ring_in.PT) {
Parse();
if (dlNextBlock != BID_FREELISTMGR)
Lookup(); }
Copy();
Inside Copy(), dl_sink() is called to enqueue pkts to downstream blocks.

8. dl_sink Special design of dl_sink(first, last, try_action)
“first” == TRUE, means current pkt is the first one of a sequence of pkts to be sunk.
“last” == TRUE, means current pkt is the last one of a sequence of pkts to be sunk.
“try_action” == 1, drop the pkt if ring is full; otherwise try till succeeds.
dl_sink() has a return value to indicate if enqueue is successful or not.
If DL_ORDERED is defined and “first” == TRUE, thread waits for signal from previous context before enqueuing the first pkt.
If DL_ORDERED is defined and “last” == TRUE, thread passes signal to next context after euqueuing the last pkt.

9. Parse Functions: Input: Output:
Do IP Router checks (wrong ver, Hlen, Plen, cksum), count error pkts.
Decrement TTL on pkts from Rx and recompute IP cksum
Detect exceptions (expired TTL, IP option, Non-IP)
Extract lookup key
Input:
ring_in data
Output:
lookup key, dlNextBlock, eth_type, DG QID.
IP DAddr (32b)
IP SAddr (32b) P
Tag
(5b) P
(3b)
Proto
(8b)
DPort (16b)
SPort (16b)
Exceptions
(16b)
TCP
Flags
(12b)
140 Bit Key: RL
PF and AF

10. Parse Operations: If pkt is from Rx: eth_type <= 0x0800.
Read eth_type in Ethernet hdr
If eth_type != 0x0800, set NIP in exception bits.
If eth_type == 0x0806, set ARP in exception bits.
Return.
eth_type <= 0x0800.
For pkt from Rx, offset <= 0x18E; for pkt from XScale/plugins, get offset from payload buf desc.
Read 20B IP hdr.
Check for ver, Hlen, Plen. If fails, count and dlNextBlock <= BID_FREELISTMGR. Return.
If Hlen > 5, set OPT in exception bits, read IP option.
Verify cksum. If fails, count and dlNextBlock <= BID_FREELISTMGR. Return.
If pkt is from Rx and TTL <= 1, or pkt is from plugins/XScale and TTL < 1, set TTL in exception bits.
If pkt is from Rx and TTL > 1, decrement TTL, recompute cksum and write them back to dram.
Form Datagram QID using DG QID = SA[9:8] SA[6:5] DA[6:5] (Used by Copy in case of a zero QID).
Extract key from IP hdr.
If IP protocol is TCP/UDP, read 14B, and extract key from TCP/UDP hdr.
Copy Plugin Tag and In Port to lookup key.

11. Lookup Key and Results Formats
IP DAddr (32b)
IP SAddr (32b) P
Tag
(5b) P
(3b)
Proto
(8b)
DPort (16b)
SPort (16b)
Exceptions
(16b)
TCP
Flags
(12b)
140 Bit Key: RL
PF and AF
32 Bit Result in TCAM
Assoc. Data SRAM:
96 Bit Result in
QDR SRAM Bank0: PF
Prio
(8b) D
(1b) H M
Address (21b) V
(4b)
UCast
MCast
(12b)
QID (16b)
Stats Index
(16b)
NH_MAC (48b)
NH_IP (32b)
Res (16b) AF
Res
(8b) D
(1b) H M
Address (21b) V
(4b) S B
(2b) R e s
(2b)
Uni
Cast
(8b)
QID (16b)
Stats Index
(16b)
NH_MAC (48b)
NH_IP (32b)
Res (16b) RL
Res
(8b) D
(1b) H M
Address (21b) V
(4b)
UCast
MCast
(12b)
QID (16b)
Stats Index
(16b)
NH_MAC (48b)
NH_IP (32b)
Res (16b)
TCAM Ctrl
Bits:
D:Done
H:HIT
MH:Multi-Hit
Entry
Valid
(1b) NH IP
MAC MC D
(1b)
PPS
UCast
Out Port
(3b)
Out Plugin
Reserved
(4b)
If IP MC Valid = 0
Multicast Copy Vector (11b)
PPS
(1b)
If IP MC Valid = 1

12. Lookup Overview Initialization Runtime Updates
Control Plane initializes TCAM and Route and Filter DBs
Runtime Updates
Control Plane updates to Route and Filter DBs
Design – in upcoming slides
Processing – in upcoming slides
Lookup will be written in C
There are many things about writing IXP code in “C” that I need to learn. Here are some of them:
Performing multiple memory operations in parallel and waiting on a set of signals (If needed for performance reasons)
Performing timestamp waits
Calling IDT microcode macros

13. Lookup: Design -- Databases
Three Databases:
Route Lookup:
Unicast
Sorted by DAddr Prefix Length
Multicast
Exact match on DAddr and prefix of SAddr
Primary Filter
Filters should be sorted in the DB with higher priority filters first
Auxiliary Filter
Priority between Primary Filter and Route Lookup
A priority will be stored with each Primary Filter
A priority will be assigned to RLs (all routes have same priority)
PF priority and RL priority compared after result is retrieved.
One of them will be selected based on this priority comparison.
Auxiliary Filters:
If matched, cause a copy of packet to be sent out according to the Aux Filter’s result.

14. Lookup: Design -- Results
Use SRAM Bank 0 (2 MB per NPU) for Results
B0 Byte Address Range: 0x – 0x1FFFFF
21 bits
B0 Word Address Range: 0x – 0x1FFFFC
19 significant bits
2 trailing 0’s
Store result in two parts:
32-bit Associated Data SRAM result for Address of actual Result:
TCAM Control Bits (3b)
Done: 1b
Hit: 1b
MHit: 1b
Priority: 8b
Present for Primary Filters, for RL and Aux Filters should be 0
SRAM B0 Word Address: 21b
2 spare bitS if needed for anything else
3 Words (<= 96 bits) of Result in SRAM Bank0
Use Multi-Database Lookup (MDL) Indirect for searching all 3 DBs
Order of fields in Key is important.
Each thread will need one TCAM context

15. Lookup Processing write KEY to TCAM
use timestamp delay to wait appropriate time
make delay long enough that we are as sure as possible that we will
have to read the 1st word of the Results MB only once
while !DoneBit // DONE Bit BUG Fix requires reading just first word
read 1 word from Results Mailbox and check DoneBit
done
read words 2 and 3 from Results Mailbox
If (PrimaryFilter AND RouteLookup results HIT) {
PrimaryResult.Valid  TRUE
compare priorities
store higher priority result as Primary Result (read result from SRAM Bank0)
} else if (PrimaryFilter results HIT) {
PrimaryResults.*  PrimaryFilter.* (read result from SRAM Bank0)
} else if (RouterLookup results HIT) {
PrimaryResults.*  RouteLookup.* (read result from SRAM Bank0)
} else PrimaryResult.Valid  False
if (AuxiliaryFilter result HIT) {
AuxiliaryResult.Valid  TRUE
AuxiliaryResults.*  (read result from SRAM Bank0)
} else AuxiliaryResult.Valid  FALSE

16. Lookup Key and Results Formats
IP DAddr (32b)
IP SAddr (32b) P
Tag
(5b) P
(3b)
Proto
(8b)
DPort (16b)
SPort (16b)
Exceptions
(16b)
TCP
Flags
(12b)
140 Bit Key: RL
PF and AF
32 Bit Result in TCAM
Assoc. Data SRAM:
96 Bit Result in
QDR SRAM Bank0: PF
Prio
(8b) D
(1b) H M
Address (21b) V
(4b)
UCast
MCast
(12b)
QID (16b)
Stats Index
(16b)
NH_MAC (48b)
NH_IP (32b)
Res (16b) AF
Res
(8b) D
(1b) H M
Address (21b) V
(4b) S B
(2b) R e s
(2b)
Uni
Cast
(8b)
QID (16b)
Stats Index
(16b)
NH_MAC (48b)
NH_IP (32b)
Res (16b) RL
Res
(8b) D
(1b) H M
Address (21b) V
(4b)
UCast
MCast
(12b)
QID (16b)
Stats Index
(16b)
NH_MAC (48b)
NH_IP (32b)
Res (16b)
TCAM Ctrl
Bits:
D:Done
H:HIT
MH:Multi-Hit
Entry
Valid
(1b) NH IP
MAC MC D
(1b)
PPS
UCast
Out Port
(3b)
Out Plugin
Reserved
(4b)
If IP MC Valid = 0
Multicast Copy Vector (11b)
PPS
(1b)
If IP MC Valid = 1

17. Exception Bits in Lookup Key
IP DAddr (32b)
IP SAddr (32b) P
Tag
(5b) P
(3b)
Proto
(8b)
DPort (16b)
SPort (16b)
Exceptions
(16b)
TCP
Flags
(12b)
140 Bit Key: RL
PF and AF
Reserved (12b)
Non-IP
(1b)
ARP
(1b)
IP Opt
(1b)
TTL
(1b)
Exception Bits:
TTL: TTL has expired. It was 0 or 1 on arriving packet
IP Opt: IP Packet contained Options
ARP: Ethertype field in ethernet header was ARP
Non-IP: Ethertype field in ethernet header was NOT IP
NOTE: An ARP packet will have ARP bit and Non-IP bit set

18. Lookup Block Diagram mem access Latency Write Lookup Key to TCAM
Setup Lookup Key
Write Lookup Key to TCAM
SRAM Write: 5W
TimeStamp Delay
315 cycles
ctx_swap
Read 1W Result from AD
SRAM Read: 1W cycles
ctx_swap
Check Done Bit
Read 2W Result from AD
SRAM Read: 2W cycles
ctx_swap
SRAM Read: 3W cycles
Read 2 Full Results from QDR
ctx_swap
SRAM Read: 3W cycles
Setup Results for Copy
TOTAL (No optimization) cycles

19. Lookup File locations Code Include Paths
src/applications/ONL_Router/src/plc/ONL/lookup.c
Include Paths
src/applications/ONL_Router/src/dispatch_loop/ONL/
dl_source.h and dl_source.c
dl_source() and dl_sink() functions
src/IDT_NSE/data_place_IXP2XXX/include
IDT IIPC defines and macros
others?

20. Copy Functions: Input: Output: Drop error pkts detected by Parse.
Count and send PT pkts to QM.
Process lookup results:
When “control error” (NH_IP and NH_MAC both invalid or both valid), or “ARP request needed” (Uncast pkt with valid NH_IP but invalid NH_MAC), or “no route” (invalid PR and AR) is detected, pkt should be sent to XScale, or one of five plugins, or dropped based on user preference (dynamically configurable).
Compute MAC DAddr for IP multicast pkts.
Update total ref_cnt in paylod buf desc for each classified pkt.
If total ref_cnt == 1 and pkt goes to QM, fill in payload buf desc with NH_MAC, Stats index and EtherType.
If total ref_cnt > 1, add hdr buf to each pkt going to QM, and fill in hdr buf desc with buffer_next, packet_size, ref_cnt (=1), NH_MAC, Stats index, EtherType.
For each copy, form ring_out data and enqueue it to the outgoing ring.
Input:
ring_in data, exception bits, dlNextBlock, eth_type, DG QID, lookup results
Output:
Ring_out data

21. Copy Operations: Error pkt detected by Parse (to freelist_mgr):
Construct ring_out data to Freelist_mgr
Call dl_sink(TRUE, TRUE, 0). Return.
PT pkt (to QM):
dlNextBlock <= BID_QM
Construct ring_out data to QM from ring_in data
Classified pkt:
Pre-check:
Copy exception bits to flags.
If PR and AR are both invalid, this pkt has no route.
Set NR bit in flags.
Set dlNextBlock to user preference.
Construct ring_out data.
Call dl_sink(TRUE, TRUE, 1). Return.
Pre-process lookup results, because:
Both PR and AR can generate pkt copies to QM and XScale/plugins.
Need to know total num of copies to
Decide whether hdr buffer decs should be added to copy going to QM.
Set “last” bit in dl_sink().
Update total ref_cnt in payload buf desc using one atomic addition.
Post-process lookup results, copy and send pkts to proper rings.

22. Copy Pre-processing data structure: struct copy_qm_prep{
unsigned int pkt_cnt;
bool pr_ucast;
bool pr_mcast;
bool ar_ucast;
} qm;
PR:
QID (16b)
Stats Index
(16b)
UCast
MCast
(12b) V
(4b)
NH_MAC (48b)
NH_IP (32b)
Res (16b)
struct copy_plugins_prep{
unsigned int pkt_cnt;
bool pr_arp;
bool pr_nh_inv;
bool pr_ucast;
bool pr_mcast;
bool ar_arp;
bool ar_nh_inv;
bool ar_ucast;
} plugins;
AR:
QID (16b)
Stats Index
(16b)
Uni
Cast
(8b) V
(4b) S B
(2b)
NH_MAC (48b)
NH_IP (32b)
Res (16b) R e s
Pre-process fields
Post-process fields
Only one can be TRUE

23. Multicast Copy Vector (11b)
Copy (pre-process PR) V
(4b)
UCast
MCast
(12b)
QID (16b)
Stats Index
(16b)
NH_MAC (48b)
NH_IP (32b)
Res (16b)
Entry
Valid
(1b) NH IP
MAC MC D
(1b)
PPS
UCast
Out Port
(3b)
Out Plugin
Reserved
(4b)
If IP MC Valid = 0
Multicast Copy Vector (11b)
PPS
(1b)
If IP MC Valid = 1
If PR is valid,
If NH_IP is valid and NH_MAC is invalid and IP_MC is invalid, this pkt needs ARP.
Set APR bit in flags.
If pkt should be sent to XSclae/plugins,
plugins.pkt_cnt ++; plugins.pr_arp <= TRUE.
Else if NH_IP and NH_MAC are both invalid or both valid, lookup entry is mis-configured.
Set NH_INV bit in flags.
plugins.pkt_cnt ++; plugins.pr_nh_inv <= TRUE.

24. Multicast Copy Vector (11b)
Copy (pre-process PR)
Else,
If MC_valid == 0 (unicast),
If Drop == 0,
If PPS == 0, qm.pkt_cnt ++, qm.pr_ucast <= TRUE.
Else (PPS == 1), plugins.pkt_cnt ++, plugins.pr_ucast <= TRUE.
Else (MC_valid == 1 (Multicast)),
If PPS == 0,
qm.pkt_cnt <= total 1’s in high 5 bits in MCast_copyVector;
plugins.pkt_cnt <= total 1’s in low 6 bits in MCAST_copyVector.
If qm.pkt_cnt > 0, qm.pr_mcast <= TRUE.
If plugins.pkt_cnt > 0, plugins.pr_mcast <= TRUE.
Else (PPS == 1),
plugins.pkt_cnt <= total 1’s in low 6 bits in Mcast_copyVector;
If plugins.pkt_cnt > 0, plugins.pr_mcast <= TURE. D
(1b)
PPS
UCast
Out Port
(3b)
Out Plugin
Reserved
(4b)
Multicast Copy Vector (11b)
PPS
(1b)

25. Copy (pre-process AR) If AR is valid,
QID (16b)
Stats Index
(16b)
Uni
Cast
(8b) V
(4b) S B
(2b)
NH_MAC (48b)
NH_IP (32b)
Res (16b) R e s
Entry
Valid
(1b) NH IP
MAC MC D
(1b)
PPS
UCast
Out Port
(3b)
Out Plugin
If AR is valid,
If NH_IP is valid and NH_MAC is invalid, this pkt needs ARP.
Set APR bit in flags.
If pkt should be sent to XSclae/plugins,
plugins.pkt_cnt ++; plugins.pr_arp <= TRUE.
Else if NH_IP and NH_MAC are both invalid or both valid, lookup entry is mis-configured.
Set NH_INV bit in flags.
plugins.pkt_cnt ++; plugins.pr_nh_inv <= TRUE.

26. Copy (pre-process AR) Else,D
(1b)
PPS
UCast
Out Port
(3b)
Out Plugin
Rsv
(2b) SB
Else,
Each SB value is associated with a sampling rate rt(SB) that is dynamically configurable by users.
Generate a random number rd.
If rd <= rt(SB),
If PPS == 0,
qm.ar_ucast <= TRUE, qm.pkt_cnt ++.
Else (PPS == 1),
plugins.ar_ucast <= TRUE, plugins.pkt_cnt ++.

27. Copy (post-process) PR: AR:
struct copy_qm_prep{
unsigned int pkt_cnt;
bool pr_ucast;
bool pr_mcast;
bool ar_ucast;
} qm;
struct copy_plugins_prep{
unsigned int pkt_cnt;
bool pr_arp;
bool pr_nh_inv;
bool pr_ucast;
bool pr_mcast;
bool ar_arp;
bool ar_nh_inv;
bool ar_ucast;
} plugins;
QID (16b)
Stats Index
(16b)
UCast
MCast
(12b) V
(4b)
NH_MAC (48b)
NH_IP (32b)
Res (16b)
AR:
QID (16b)
Stats Index
(16b)
Uni
Cast
(8b) V
(4b) S B
(2b)
NH_MAC (48b)
NH_IP (32b)
Res (16b) R e s
If qm.pkt_cnt + plugins.pkt_cnt == 0, dlNextBlock <= BID_FREELISTMGR, dl_sink(TRUE, TRUE, 0). Return.
Read ref_cnt from payload buf desc.
If qm.pkt_cnt + plugins.pkt_cnt + (ref_cnt – 1) == 1,
If qm.pkt_cnt == 1, DO NOT add hdr buf desc.
Based on qm.pr_ucast, qm.pr_mcast, qm.ar_ucast,
Fill in NH_MAC, stats index, and eth_type in payload buf desc.
Construct QM ring_out data.
dlNextBlock <= BID_QM.
dl_sink(TRUE, TRUE, 0). Return.
Else (plugins.pkt_cnt == 1),
Based on plugins.*,
construct plugins/XScale ring_out data.
Set dlNextBlock to XScale or one of the five plugins.
dl_sink(TRUE, TRUE, 1). Return.

28. Copy (post-process)
Else (qm.pkt_cnt + plugins.pkt_cnt + (ref_cnt – 1) > 1),
Add (qm.pkt_cnt + plugins.pkt_cnt – 1) to ref_cnt in payload buf desc.
If qm.pkt_cnt >0,
for each copy to QM, add hdr buf desc.
Based on qm.pr_ucast, qm.pr_mcast, qm.ar_ucast,
Fill in buffer_next, packet_size, ref_cnt (=1), NH, stats index, and eth_type in hdr buf desc.
Construct QM ring_out data.
dlNextBlock <= BID_QM.
Call dl_sink() qm.pkt_cnt times.
If plugins.pkt_cnt == 0, Set “last” bit in dl_sink() for the last copy and return.
If plugins.pkt_cnt > 0,
Based on plugins.*,
Construct plugins/XScale ring_out data.
Set dlNextBlock to XScale or one of the five plugins.
Call dl_sink() plugins.pkt_cnt times.
Set “last” bit in dl_sink() for the last copy and return.

29. PLC Typical Case
Valid IP Pkt from Rx, no option, go to one port as a result of PR. AR entry is invalid.
Operation
Memory Access
Cycle Count
dl_source
Dequeue pkt from MUX
3LW Scratch Ring read 60
Read eth_type, IP, TCP/UDP hdr
Aligned 10LW DRAM read
300
Parse
Write TTL, IP cksum
Aligned 4LW DRAM write
300
Lookup
Lookup
915
Write NH MAC, stats index, eth_type
Copy
Aligned 3LW SRAM write
150
dl_sink
Enqueue pkt to QM
3LW Scratch Ring write 60
Total:
1785