Port 1989Cisco RSRB Priority 3

Cisco Remote Source-Route Bridging traffic using its priority-3 service.

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 6/10
lookups: 0

also known as tr-rsrb-p3, Remote Source-Route Bridging

1 other service is registered on port 1989. compare all 2 →

Technical Details

what runs on :1989

RSRB uses Cisco-specific encapsulation to carry source-route bridging traffic between router peers. IANA assigns TCP and UDP port 1989 to the Priority 3 RSRB service; the exact use of each transport depends on the Cisco implementation and configuration. Traffic is legacy bridging data rather than a general-purpose client protocol, and it is not encrypted by RSRB itself.

Security Information

exposure of :1989

risk score

6/ 10risk

treat as sensitive. widely scanned and regularly exploited when reachable — restrict it to known sources.

network services averages 2.7 across 1,385 ports — this one sits 3.3 above.

in transit

cleartext

credentials and payloads are readable by anyone on path

assignment

official

registered with iana for this service — scanners fingerprint it by number

reachable over

tcp · udp

udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite

security overview

RSRB should be restricted to explicitly trusted router peers and should not normally be exposed to the public internet. Because the protocol is legacy and lacks native confidentiality, integrity protection, and modern peer authentication, an exposed listener may permit traffic injection, unauthorized bridging behavior, or denial of service; filter the port to known peer addresses and use a protected network path.

Record

iana registry entry

port: :1989
service: Cisco RSRB Priority 3
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 6/10risk
category: Network Services
usage: This port is used by Cisco routers configured for Remote Source-Route Bridging (RSRB) to exchange bridged Token Ring or legacy SNA traffic across an IP network. It is normally encountered only in older enterprise networks connecting remote source-route bridge peers.
lookups: 0rank 993
added: 2026-09-07
updated: 2026-09-22
references: IANA service name registry — port 1989

Something wrong?

This record is maintained by the engineers who use port 1989. Every field on it is editable — change what's wrong, say how you know, and a reviewer publishes it, usually within a minute. Last touched 2026-09-22.

01edit any field on a page of its own
02a model checks it for accuracy and spam
03clean and confident goes live immediately

edit this record →back to the registry

Related Ports

all 1,385 in network services →

the 8 most looked-up other ports in network services — 1,385 ports carry that label.

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:3268	Microsoft Global Catalog (GC)	TCPUDP	Security	caution	54.6k
:135	Microsoft EPMAP	TCPUDP	Security	caution	51.9k
:3128	Tatsoft Default HTTP Proxy	TCP	Web Services	caution	46.8k

risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :1989Cisco RSRB Priority 3

Technical Details

Security Information

Related Ports

Port 1989Cisco RSRB Priority 3