DEMO: CRC4EVER: Cyclic Redundancy Check o
Enhanced Ve i ica ion and E icien Rou ing
E e son Bo ges
UFES
Fab icio Rod iguez
Tele onica Resea ch
Ra ael Sil a Guima ães
IFES
Magnos Ma inello
UFES
C is ina K. Dominicini
IFES
Moises R. N. Ribei o
UFES
Edua d Ma in
Tele onica Resea ch
Ch is ian Ro henbe g
Unicamp
ABSTRACT
This demons a ion in oduces Cyclic Redundancy Check o En-
hanced Ve i ica ion and E icien Rou ing (CRC4EVER). We p opose
how he Residue Numbe Sys em (RNS) — a numbe sys em ha
employs a sha ed sec e scheme dis ibu ed ac oss ne wo k nodes
(nodeIDs)— can enable ligh weigh o wa ding and p oo -o - ansi
(PoT) in pa h-awa e ne wo ks, elying solely on CRC ope a ions.
Ou app oach le e ages an RNS-based sou ce ou ing, whe e a
ou eID encodes he en i e packe pa h. A each hop, he ou eID
is decoded ia simple modulo ope a ions, execu ed a line a e, by
epu posing exis ing CRC ha dwa e in p og ammable swi ches.
Fu he mo e, he unique mapping be ween he ou eID and i s co -
esponding se o nodeIDs p o ides in insic pa h e i iabili y ia
CRC-based hash ope a ions. A p oo -o -concep was implemen ed
on p og ammable To ino swi ches, demons a ing he easibili y o
execu ing bo h ou ing and pa h e i ica ion a line a e, h ough
able- ee CRC ope a ions.
CCS CONCEPTS
•Ne wo ks
→
P og ammable ne wo ks;P o ocol es ing and
e i ica ion;Ne wo k p o ocol design;
ACM Re e ence Fo ma :
E e son Bo ges, Fab icio Rod iguez, Ra ael Sil a Guima ães, Magnos Ma -
inello, C is ina K. Dominicini, Moises R. N. Ribei o, Edua d Ma in, and Ch is-
ian Ro henbe g. 2025. DEMO: CRC4EVER: Cyclic Redundancy Check o
Enhanced Ve i ica ion and E icien Rou ing . In ACM SIGCOMM 2025 Con-
e ence (SIGCOMM Pos e s and Demos ’25), Sep embe 8–11, 2025, Coimb a,
Po ugal. ACM, New Yo k, NY, USA, 3 pages. h ps://doi.o g/10.1145/3744969.
3748446
1 INTRODUCTION
Pa h-Awa e Ne wo king (PAN) eme ges as a pa adigm ha shi s
he ne wo k con ol o end hos s. By empowe ing end hos s wi h
he abili y o selec op imal pa hs based on applica ion equi emen s
Pe mission o make digi al o ha d copies o all o pa o his wo k o pe sonal o
class oom use is g an ed wi hou ee p o ided ha copies a e no made o dis ibu ed
o p o i o comme cial ad an age and ha copies bea his no ice and he ull ci a ion
on he i s page. Copy igh s o componen s o his wo k owned by o he s han he
au ho (s) mus be hono ed. Abs ac ing wi h c edi is pe mi ed. To copy o he wise, o
epublish, o pos on se e s o o edis ibu e o lis s, equi es p io speci ic pe mission
and/o a ee. Reques pe missions om [email p o ec ed].
SIGCOMM Pos e s and Demos ’25, Sep embe 8–11, 2025, Coimb a, Po ugal
©2025 Copy igh held by he owne /au ho (s). Publica ion igh s licensed o he
Associa ion o Compu ing Machine y.
ACM ISBN 979-8-4007-2026-0/2025/09...$15.00
h ps://doi.o g/10.1145/3744969.3748446
Red Pa h: Rou ing Example
po ID = ou eID mod nodeID
Heade
Payload
Heade
Payload
Inse PoT
me ada a &
ou eID
Heade
Payload
ou eID
PoT
SRC DST
EDGE
Heade
Payload
ou eID
PoT
EDGE
Heade
Payload
ou eID
PoT
Heade
Payload
ou eID
PoT
Ve i y &
Remo e
me ada a
Fwd: 1 CRC
PoT: 1 CRC
01011
01101
11001
11111
001
010
011
010
110
011
Fwd: 1 CRC
PoT: 1 CRC
Fwd: 1 CRC
PoT: 1 CRC
Pa h-1
ou eID = 100101111
nodeID - 01011, 01101, 11111
po ID - 001, 011, 110
Pa h-3
ou eID = 10111010011001
nodeID - 01011, 01101, 11001, 11111
po ID - 001, 010, 011, 110
Pa h-2
ou eID = 110001010
nodeID - 01011, 11001, 11111
po ID - 010, 011, 110
Figu e 1: Concep ual Design o CRC4EVER
and cu en ne wo k condi ions, PAN c ea es aluable oppo uni ies
in applica ion-d i en a ic enginee ing. I enhances bo h eliabili y
and e icien ne wo k esou ce u iliza ion a he hos le el [4].
Despi e he PAN boos ing capabili ies, i s p ac ical deploymen
s ill aces signi ican obs acles. Mos exis ing me hods o pa h e -
i ica ion such as ICING [
6
] and EPIC [
5
], a e no compa ible wi h
p og ammable swi ches and ypically impose high compu a ional
o e head on sou ce o co e nodes. These app oaches o en ely on
chained MAC [
3
], o nes ed s uc u es o pa h e i ica ion, bu
hey deal wi h ou ing and e i ica ion as sepa a e p ocesses. In con-
as , CRC4EVER has been designed o igh ly in eg a ing ou ing
wi h pa h e i ica ion, keeping compa ibili y wi h p og ammable
swi ches, esul ing in a uni ied and e icien a chi ec u al design
o mode n ne wo ks.
This demo showcases CRC4EVER, a new way o design ne wo k-
ing unc ions by using he ma hema ical p ope ies o he Residue
Numbe Sys em (RNS) implemen ed by exis ing CRC mechanisms
[
2
]. RNS ope a es as a sec e -sha ing scheme ha can be dis ibu ed
ac oss ne wo k nodes (nodeIDs). We implemen a sou ce ou ing
mechanism in which a ou eID encodes he en i e packe pa h. A
each hop, his ou eID is decoded using modulo ope a ions, exe-
cu ed a line a e. The unique mapping be ween a ou eID and i s
co esponding se o (nodeIDs) enables in insic pa h e i iabili y
h ough RNS. By chaining CRC-based hash ope a ions, we can c e-
a e a pa h signa u e ha suppo s p oo -o - ansi (PoT), con i ming
he packe ollowed he in ended pa h1.
While MPLS-s yle label s acks o e simila o wa ding beha io
wi hou he complexi y o modulo-based decoding, hei la labels
lack inhe en pa h seman ics. In con as , CRC4EVER employs a
1h ps://gi hub.com/ne ds-u es/CRC4EVER
178
SIGCOMM Pos e s and Demos ’25, Sep embe 8–11, 2025, Coimb a, Po ugal Bo ges e al.
ou e iden i ie ha ep esen s a unique pa h, meaning ha all
swi ches and hei in e aces along he pa h a e explici ly known,
enabling addi ional ea u es such as pa h e i ica ion.
To demons a e he CRC4EVER app oach, we deployed i on a
single To ino swi ch con igu ed wi h mul iple logical swi ches, and
emula ed i using he P7 es bed [
7
] enhanced wi h PINT-BoX [
1
].
P7 wi h PINT-BoX enables dynamic pa h con ol, un ime econ ig-
u a ion, and eal- ime obse a ion o la ency, loss, and h oughpu .
CRC4EVER dis inguishes i sel by in oducing a no el o wa ding
and pa h e i ica ion mechanism ha elies exclusi ely on CRC
ope a ions, enabling ligh weigh , able- ee pa h e i ica ion a line
a e. This se up allows use s o ace packe s hop-by-hop ac oss
logical pa hs, e i y he selec ed ou e, and gain in ui i e insigh
in o he pa h-awa e beha io o CRC4EVER.
2 ARCHITECTURE & DEMO
The CRC4EVER a chi ec u e is speci ically designed o pa h e i-
ica ion and ou ing using a unique encoding scheme. I ope a es
wi hin p og ammable swi ches, le e aging CRC-based ope a ions
a i s co e. Figu e 1 p esen s he concep ual design, illus a ing he
s ep-by-s ep packe low h ough a sequence o ne wo k nodes in a
pa h-awa e ne wo k.
A he sou ce node, a Type o Se ice(ToS) ield is used o map
he low o i s co esponding ou eID and PoT me ada a inse ed
in o he packe heade a he edge. A each hop, CRC ope a ions
a e employed bo h o packe o wa ding and o upda ing he
PoT. Packe o wa ding ollows he PolKA echnique [
2
], which
enables commodi y swi ches o compu e polynomial modulo op-
e a ions using wo SHIFT, one CRC, and wo XOR ope a ions. Fo
example, he blue pa h a he i s node, he ou eID=100101111 mod
nodeID=01011 gi es po ID=001, ollowing he compu a ion s eps
below:
(1) 𝐺=nodeID =01011, so 𝑟=deg(𝐺)=3
(2) 𝐷= ou eID ÷2𝑟=100101111 ≫3=100101 (SHIFT RIGHT)
(3) di = ou eID −𝐷·2𝑟=100101111 ⊕ (100101 ≪3)
=100101111 ⊕100101000 =111 (SHIFT LEFT, XOR)
(4) 𝑅=⟨𝐷·2𝑟⟩𝐺=⟨100101000⟩01011 =110 (CRC)
(5) po ID =di ⊕𝑅=111 ⊕110 =001 (XOR)
Fo he PoT, a unique mapping be ween he ou eID and he
sequence o node iden i ie s (nodeIDs) gene a es a pa h signa u e,
as shown in Equa ion 1. This mechanism enables in insic pa h
e i ica ion by suppo ing end- o-end PoT h ough chained CRC
compu a ions. A he eg ess edge, he pa h e i ica ion p ocess
alida es he PoT me ada a.
𝑃𝑜𝑇𝑖=𝐶𝑅𝐶(𝑛𝑜𝑑𝑒𝑖𝑑(𝑖) || 𝑝𝑜𝑟𝑡𝑖𝑑(𝑖) || 𝑃𝑜𝑇𝑖−1)(1)
Figu e 2 illus a es a PoC deploymen o CRC4EVER on a sin-
gle co e swi ch, demons a ing how mul iple logical swi ches can
coexis h ough pipeline isola ion. The design spli s p ocessing
in o wo sepa a e pipelines: one o packe o wa ding and ano he
o PoT compu a ion. The packe heade is inse ed a he ing ess
edge (s ep 1). Packe s en e h ough he ing ess pipeline, whe e he
ou eID and PoT heade a e p ocessed. A CRC8 ope a ion is used o
decode he ou eID by compu ing i s modulo wi h he nodeID (s ep
2), de e mining he po ID o he nex logical swi ch. The packe is
hen eci cula ed and e-en e s h ough he ing ess pipeline, (s ep
3). In he e i ica ion pipeline, a CRC32 ope a ion upda es he PoT
INGRESS
EGRESS
INGRESS
EGRESS
INGRESS
PIPE
INGRESS
PIPE EGRESS
PIPE
EGRESS
PIPE
PIPELINE 0 - FORWARD
PIPELINE 1 - VERIFICATION
CORE NODE
CRC32 (Upda e POT Heade ):
NodeID + Po _ID + p e ious
POT Heade
Change pipeline
CRC8 (Ge Rou eID)
Resul : Rou eID mod NodeID
Ge esul o he
mod ope a ion and change pipeline
Fo wa d o he nex
swi ch
1
2
4
5
POT
Rou eID
3Reci cula e and sen
back o ing ess
POT
Rou eID
POT
Rou eID
T a ic
Manage
Figu e 2: CRC4EVER deploymen wi h mul iple logical
swi ches in a single To ino box
me ada a heade using he Equa ion 1 nodeID,po ID, and he p e i-
ous PoT alue (s ep 4). Finally, he packe is o wa ded o he nex
logical swi ch (s ep 5). This a chi ec u e enables accu a e o wa d-
ing and pa h e i ica ion en i ely wi hin a single To ino 1 de ice,
using he modula i y o CRC ope a ions.
Du ing he demo: To alida e he implemen a ion and c ea e a
ealis ic es en i onmen , we will use P7 wi h PINT-BoX, which em-
ula es a ne wo k wi h link-me ic ins umen a ion and P4 suppo .
P7 le s use s de ine cus om opologies and—e en be e —modi y
he en i onmen a un ime. Fo he demons a ion, a endees will
s a om a p ede ined opology and selec one o h ee a ailable
pa hs. Demo a endees will be able o wa ch CRC-based o wa ding
in ac ion and inspec he swi ch-by-swi ch PoT. Real- ime packe -
le el isualiza ion a each swi ch will le pa icipan s con i m he
e ec i eness o CRC4EVER on he ly. Finally, we will showcase
P7’s un- ime abili y o econ igu e node IDs and link me ics while
he expe imen is unning.
3 CONCLUSIONS AND FUTURE WORK
The CRC4EVER demo showcases an RNS-based ou ing and PoT
mechanism using CRC ope a ions, enabling able- ee, line- a e
pa h p ocessing and e i ica ion. The PoC on To ino swi ches con-
i ms i s easibili y design and e iciency o pa h-awa e ne wo king.
Fu u e wo k. We en ision designing ne wo k p o ec ion mech-
anisms agains link ailu es by enabling packe de lec ions using
addi ional nodes encoded in he ou eID. We also in end o ca y
ou a comp ehensi e secu i y analysis o iden i y and unde s and
po en ial a ack ec o s.
ACKNOWLEDGEMENTS
Po i -5G Resea ch P ojec (G an 20/05182-3), and Fapes (941/2022,
732/2024). Also, his wo k was suppo ed by E icsson Telecomuni-
cações L da and by he Sao Paulo Resea ch Founda ion (FAPESP),
g an
2021/00199-8
, CPE SMARTNESS. This s udy was pa ially
unded by CAPES, B azil - Finance Code
001
and CNPq ellow (G an
312058/2023-3). This wo k has been pa ially suppo ed by he Eu-
opean Union’s Ho izon Eu ope p ojec unde g an ag eemen No.
101070473 (FLUIDOS).
179
DEMO: CRC4EVER: Cyclic Redundancy Check o
Enhanced Ve i ica ion and E icien Rou ing SIGCOMM Pos e s and Demos ’25, Sep embe 8–11, 2025, Coimb a, Po ugal
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