external L2 ethernet connections

Does anyone have a best practice list of things to disable/filter/turn off on ethernet ports l2 connected to other AS's

switchport negotiate
if trunking, limit vlans, no vlan1

So on so forth.

Switches do so many darn things all by themselves, as any packet capture shows.




has some great info specific to IX connections..



I take credit card payments ....and we can agree on a daily rate ...as after all you are into "IT Consultancy".
Just use the available search engine optimizers to build your knowledge based by performing the "black had v white hat" searches :slight_smile:

I am here still ....what is your budget?

If you're using a Cisco device on your side, you'll likely want to disable MOP as well:


Adam Davenport / adam@choopa.com
www.choopa.com / 1.866.2.CHOOPA

Joe Maimon wrote:

I like your community spirit.

Are you a member of the NANOG community because:

a) You want to educate yourself
b) You want to educate others
c) You want to participate in flame wars
d) You want to read flame wars
e) You want to denigrate those seeking to educate themselves or others

You cant have your cake and eat it too.

Thanks but no thanks, I am going to avoid the pissing contest.


isabel dias wrote:

I ma not too sure if that is a comment that needs another expert answer .....but i can think of a few possible answers YES.

"although I'm a little afraid, however I'd like to try it" ....."IT Consultancy"?

A more sensible approach is to not run Enterprise code if you only
need to route IP.

Paul Wall

All of the protocols below should be turned off; my understanding is
that with dot1q trunking vlan1 cannot be removed from the trunk,
although Cisco's isl trunking allows the removal of all vlans. If Cisco
equipment is used, the "bpdu filter" command is useful as it instructs
the switch to neither send bpdus nor accept them. These are good
practices not just for connectivity to other AS's, but also in cases
where Ethernet switches comprise a geographically dispersed WAN
backbone. The key is to turn off all layer 2 state machines in the
connected Ethernet switches, enabling only layer 3 state machines.

We have found with some vendors' equipment that the layer 2/layer 3
state machines are not tightly integrated so, for instance, a cam
timeout in layer 2 will remove the underlying port/mac table entry for a
destination layer 3 network, resulting in unknown unicast flooding with
noticeable effects on user response time.