nanog mailing list archives
Re: BFD for routes learned trough Route-servers in IXPs
From: Douglas Fischer <fischerdouglas () gmail com>
Date: Thu, 17 Sep 2020 14:51:16 -0300
About this comparison between CAM-Table Timeout, and ARP-Table Timeout. I tend to partially agree with you... Ethernet is a so widely used protocol to sever scenarios. We need to consider the different needs of the type of communications. For example: I'm not a big fan of Mikrotik/RouterOS. But I know they are there, and liking or not, I need to accept that I will need to deal with then(as a peer or even as an operator). One of most common uses of Mikrotik is for HotSpot/Captive Portal. And for that, an ARP Timeout of 30 seconds is very OK! Is a good way to check if the EndUser is still reachable on the network, and based on that do the billing. But 30 Seconds for an IXP? It does not make any sense! Those packets are stealing CPU cycles of the Control Plane of any router in the LAN. Another example: You suggested equalizing ARP-Timeout and MAC-Timeout For a campus LAN? With frequent topology changes, add/removes of hosts every time... That is perfect! But talking about an IXP LAN: In an ideal scenario, how often should happen topology changes on an IXP? How often new hosts get ins/outs of hosts in the and IXP LAN? Why should we spend CPU Cycles with 576K ARP Requests a day(2K participants, 5 min ARP-Timeout). Instead of 1.2K ARP Requests a day(2K participants, 4 hours ARP-Timeout)? I would prefer to use those CPU cycles to process other things like BGP messages, BFD, etc... Em qui., 17 de set. de 2020 às 02:54, Saku Ytti <saku () ytti fi> escreveu:
On Wed, 16 Sep 2020 at 23:15, Chriztoffer Hansen <chriztoffer.hansen () de-cix net> wrote:On 16/09/2020 04:01, Ryan Hamel wrote:CoPP is always important, and it's not just Mikrotik's with default low ARP timeouts. Linux - 1 minute Brocade - 10 minutes Cumulus - 18 minutes BSD distros - 20 minutes Extreme - 20 minutesJuniper - 20 minutesHP - 25 minutesIOS - 4 hours Why are these considered (by Ryan) low values? Does low have a negative connotation here? ARP timeout should be lower than MAC timeout, and MAC timeout usually is 300 seconds. Anything above 300seconds is probably poor BCP for default value, as defaults should interoperate in a somewhat sane manner. Of course operators are free to configure very high ARP timeout, as long as they also remember to equally configure higher MAC timeout. -- ++ytti
-- Douglas Fernando Fischer Engº de Controle e Automação
Current thread:
- Re: BFD for routes learned trough Route-servers in IXPs, (continued)
- Re: BFD for routes learned trough Route-servers in IXPs Randy Bush (Sep 15)
- Re: BFD for routes learned trough Route-servers in IXPs Christopher Morrow (Sep 16)
- Re: BFD for routes learned trough Route-servers in IXPs Randy Bush (Sep 16)
- Re: BFD for routes learned trough Route-servers in IXPs Christopher Morrow (Sep 16)
- Re: BFD for routes learned trough Route-servers in IXPs Douglas Fischer (Sep 17)
- Re: BFD for routes learned trough Route-servers in IXPs Randy Bush (Sep 17)
- Re: BFD for routes learned trough Route-servers in IXPs Christopher Morrow (Sep 16)
- Re: BFD for routes learned trough Route-servers in IXPs Randy Bush (Sep 15)
- Re: BFD for routes learned trough Route-servers in IXPs Nick Hilliard (Sep 16)
- BFD for routes learned trough Route-servers in IXPs Chriztoffer Hansen (Sep 16)
- Re: BFD for routes learned trough Route-servers in IXPs Saku Ytti (Sep 16)
- Re: BFD for routes learned trough Route-servers in IXPs Douglas Fischer (Sep 17)
- Re: BFD for routes learned trough Route-servers in IXPs Saku Ytti (Sep 17)
- Re: BFD for routes learned trough Route-servers in IXPs Douglas Fischer (Sep 17)
- Re: BFD for routes learned trough Route-servers in IXPs Paul Timmins (Sep 17)
- Re: BFD for routes learned trough Route-servers in IXPs Robert Raszuk (Sep 17)
- Re: BFD for routes learned trough Route-servers in IXPs Jared Mauch (Sep 22)