[HECnet] Maximum number of L2 routers?

[Hans Vlems]

Jordi, what made you ask the question in the first place, academic interest?

Verzonden  vanaf  mijn  BlackBerry  10-smartphone.
   Origineel bericht   
Van: Jordi Guillaumes i Pons
Verzonden: zaterdag 28 februari 2015 21:00
Aan: hecnet at Update.UU.SE
Beantwoorden: hecnet at Update.UU.SE
Onderwerp: Re: [HECnet] Maximum number of L2 routers?


El 28/02/2015, a les 20:55, Johnny Billquist <bqt at softjar.se> va escriure:

On 2015-02-28 20:51, Hans Vlems wrote:
64:-)?

You can definitely have more than one L2 router per area... :-)

I don't know for sure, as you probably    have guessed...
   There is an ncp executor parameter called maximum broadcast routers, default value 32 iirc.
Is there an architectural limit, depends on what you mean by ethernet segment. A 10base5 segment was limited to 200 nodes. 64 L2 routers might put a hefty broadcast load on it. On an extended ethernet LAN there is likely no technical limit.

Really? I have some vague memory of some limit of an ethernet segment, but I can't recall any details now. Why 200?


Got it. The (virtual) Big Orange Wall comes to the rescue:

3.7.3.1 Maximum Number of Routers and End Nodes Allowed

Certain NCP command parameter values limit the number of routers and end nodes that can be configured on broadcast circuits.

Use the SET CIRCUIT command with the MAXIMUM ROUTERS parameter to set the maximum number of routers permitted on a particular Ethernet or FDDI circuit. The largest number of routers allowed on a LAN is 33, which is the default value of the MAXIMUM ROUTERS parameter. Note that the recommended limit on the number of routers on a single broadcast circuit is 10, because of the control traffic overhead (routing messages and system identification messages) involved. For example, the following command specifies that no more than five routers can exist on Ethernet circuit SVA-0:

NCP>SET CIRCUIT SVA-0 MAXIMUM ROUTERS 5

Use the SET EXECUTOR command with the MAXIMUM BROADCAST ROUTERS parameter to specify the maximum number of routing nodes that will be permitted on all Ethernet and FDDI circuits to which the local node is attached.

So it is a global maximum, for both L1 and L2 routers.