From: Aidan Marks (amarks@cisco.com)
Date: Sat Dec 28 2002 - 03:31:43 GMT-3
DLSw Port Number Usage - TCP & UDP
Introduction: This document lists the source & destination udp & tcp port
numbers used by DLSw
Versions: 11.3 onwards
By default DLSw uses both TCP & UDP to communicate between peers from IOS
version 11.3 onwards.
In version before this only TCP was used.
For UDP, each DLSw router will source packets from port 0 going to port
2067 on its peer routers. You can turn off udp via the global config command:
dlsw udp-disable
By default for TCP, the router will source packets from ports anywhere
between 11000-65025 going to port 2065 on its peer router. With DLSw
priority enabled for TCP packets will be sourced from ports 11000-65025
going to ports 1981-1983 & 2065.
These TCP ports must be open bidirectionally between the devices as DLSw
initially builds a TCP session in both direction, before one session is
dropped in Cisco's implementation.
The range of source TCP ports used will change every time the router is
rebooted as a random seed number is generated. However the port will
always be inside the 11000-65025 range as the lower port are reserved for
well-known ports; and reverse-telnet ports.
At 04:37 PM 28/12/2002, Jay Greenberg wrote:
>Any idea how to explicitly allow a DSLw+ TCP session through an ACL? On
>a recent practice lab, I used:
>
>permit tcp any any eq 2065
>permit tcp any any ge 11000
>
>which worked, however I wonder if there is a more practical / direct way
>of doing this.
>.
.
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