Re: allowing DLSW through an access-list

From: Fred Ingham (fningham@xxxxxxxxxxxxxxxx)
Date: Mon Dec 18 2000 - 16:37:19 GMT-3


   
I've been wrong before but read the following excerpts:

Cisco Documentation:
DLSw Version 2 Standard

In the Version 1 standard, a network design requires fully meshed
connectivity so that all peers were connect to every
other peer. This design creates unnecessary broadcast traffic because an
explorer propagates to every peer for every
broadcast.

The Version 2 standard is documented in RFC 2166. It includes RFC 1795
and adds the following enhancements:

    IP Multicast

    UDP Unicast

    Enhanced Peer-on-Demand Routing Feature

    Expedited TCP Connection

Users implement DLSw Version 2 for scalability if they are using
multivendor DLSw devices with an IP multicast
network. DLSw Version 2 requires complex planning because it involves
configuration changes across an IP network.

RFC 2166

6.2.1.1 TCP Port Numbers

   DLSws implementing these enhancements will use a TCP destination port
   of 2067 (as opposed to RFC 1795 which uses 2065) for single session
   TCP connections. The source port will be a random port number using
   the established TCP norms which exclude the possibility of either
   2065 or 2067.

6.3 UDP Datagrams

   As mentioned above, UDP datagrams can be sent two different ways:
   unicast (e.g., sent to a single unique IP address) or multicast
   (i.e., sent to an IP multicast address). Throughout this document,
   the term UDP datagram will be used to refer to SSP messages sent over
   UDP, while unicast and multicast SSP messages will refer to the
   specific type/method of UDP packet transport. In either case,
   standard UDP services are used to transport these packets. In order
   to properly parse the inbound UDP packets and deliver them to the SSP
   state machines, all DLSw UDP packets will use the destination port of
   2067.

   In addition, the checksum function of UDP remains optional for DLSw
   SSP messages. It is believed that the inherent CRC capabilities of
   all data link transports will adequately protect SSP packets during
   transmission. And the incremental exposure to intermediate nodal
   data corruption is negligible. For further information on UDP packet
   formats see the Frame Formats section.

Cheers, Fred.

zheng jiang gu wrote:
>
> Sorry Fred
> But DLSW V2 use TCP 2065/2067,correct me if wrong!!
> ----- Original Message -----
> From: Fred Ingham <fningham@worldnet.att.net>
> To: Bill Young <byoung@cox.rr.com>; <ccielab@groupstudy.com>
> Sent: Monday, December 18, 2000 3:34 AM
> Subject: Re: allowing DLSW through an access-list
>
> > The replies so far state the correct ports:tcp 2065, and, if
> > prioritization is configured, 1981,1982, and 1983. DLSW v2 can also use
> > UDP 2065/2067.
> >
> > Best way to discover needed ports is to insert a "deny any any log"
> > statement at the end of your access-list and see the rejected packets.
> > Pick up the needed ports from the log messages.
> >
> > Cheers, Fred.
> >
> > Bill Young wrote:
> > >
> > > All,
> > >
> > > Anyone know what the required ACL port(s) for DLSW are? I have been =
> > > working on a lab all morning and couldn't figure out why my DLSW was =
> > > failing. As I was cutting and pasting the configs into an email for you
=
> > > all, I saw the ip access-group statement. As soon as I removed it, DLSW
=
> > > started working (DUH!)
> > >
> > > I can't seem to find the port numbers for DLSW though. Does anyone have
=
> > > this?
> > >
> > > Thanks,
> > > Bill
> > >



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