Date: Wed, 9 Oct 2002 15:41:21 -0600 (MDT) From: Nick Rogness <nick@rogness.net> To: TheGlenMann <cumquott@suscom.net> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Ping to broadcast ok from subnet, not ok otherwise Message-ID: <20021009153149.A645-100000@skywalker.rogness.net> In-Reply-To: <3686.12.151.4.177.1034180332.squirrel@webmail.suscom.net>
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On Wed, 9 Oct 2002, TheGlenMann wrote: > >From the deft fingers of Nick Rogness... > > On Wed, 9 Oct 2002, TheGlenMann wrote: > > > >> Hi all- > >> > >> (Is this list working right? - I'm getting lots of wierd stuff in the > >> digests...but anyway...) > >> > >> Other attempts to find the answer to this have failed, hopefully this > >> isn't too off-topic. > >> > >> We have several subnets connected via Frame Relay. Call them 10.10.1, > >> 10.10.2, 10.10.3, etc. On each, the gateway is the 254 address, e.g., > >> 10.10.1.254. > >> > >> Sitting at a 10.10.1.n machine, I can ping the gateway 10.10.x.254 on > >> every subnet. However, a ping to the broadcast address as > >> ping -c1 10.10.x.255 > >> fails on some of the subnets (from outside that subnet). From within > >> the subnet, the ping to the broadcast succeeds everywhere. Pings to > >> known hosts (and 10.10.x.254) succeed always from everywhere. > >> > >> So, my question is, why would I be able to successfully ping to the > >> broadcast address from within a subnet but not from outside the > >> subnet, but only in certain cases? We have a mix of windows, FreeBSD, > >> router, and other machines on each subnet. (I'm led to ask all this > >> since where the broadcast doesn't work from outside the subnet, > >> neither does DHCP, which is proving to be a real problem!) > > > > Do you have Cisco routers connecting your frame's together? > > > > We have a Cisco router for the T1 to the internet, but the frame routers > are Motorola/Vanguard 320 with a Vanguard 6520 at our main location. > I've looked at the settings on the 320's, but with no luck (I cannot > access the 6520 at all - I'm locked out). The reason I asked is because cisco's 'no ip directed-broadcast' would be dropping these packets. My guess is that the Vanguard is doing the same. This was mentioned in a another email. > > I've was told by our vendor that "Well, DHCP is known to 'just stop > working' on the 320's...you need an expensive software upgrade." Not > acceptable, since nothing changed. Vanguard (who bought the Motorola > Vanguard equipment line) would not even think about the question for > less than $600. If you are not getting DHCP requests through then you need to be running some sort of DHCP relay or rely on the router to forward these broadcast requests to your DHCP servers (which actually turn the broadcast into a unicast and forward it). Also, some OS's do not respond to directed broadcasts. Nick Rogness <nick@rogness.net> - WARNING TO ALL PERSONNEL: Firings will continue until morale improves. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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