Port 1996Cisco Remote Source-Route Bridging (RSRB)

Cisco RSRB carries Token Ring source-routed frames between routers over IP.

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 2/10
lookups: 0

also known as tr-rsrb-port, RSRB, Cisco RSRB, Remote SRB

Technical Details

what runs on :1996

RSRB encapsulates Token Ring source-routed bridge frames for transport between configured Cisco routers, commonly using TCP port 1996; UDP is also registered for the service. It is a peer-to-peer tunneling function rather than a general-purpose application protocol, has no normal internet-facing default, and carries the original bridged traffic rather than providing application-layer encryption.

Security Information

exposure of :1996

risk score

2/ 10safe

routine exposure. this port is rarely the way in on its own — keep it patched and logged and move on.

network services averages 3.4 across 769 ports — this one sits 1.4 below.

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 traffic is not encrypted by default and can expose bridged Layer 2 traffic to anyone able to observe the tunnel. The service should be restricted to trusted router peers and protected with network filtering; it should not be exposed directly to the public internet.

Record

iana registry entry

port: :1996
service: Cisco Remote Source-Route Bridging (RSRB)
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 2/10safe
category: Network Services
usage: Cisco routers use Remote Source-Route Bridging to connect Token Ring segments across an IP network. It is a legacy, explicitly configured inter-router service and is rarely encountered on the public internet.
lookups: 0rank 994
added: 2026-08-26
updated: 2026-08-26
references: IANA service name registry — port 1996

Something wrong?

This record is maintained by the engineers who use port 1996. 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 2026-08-26.

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risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :1996Cisco Remote Source-Route Bridging (RSRB)

Technical Details

Security Information

Related Ports

Port 1996Cisco Remote Source-Route Bridging (RSRB)