Date: Wed, 17 May 2006 16:08:45 -0700 From: sfp <mosfet@planet.eon.net> To: Unix-Solutions - Steven <steven@unix-solutions.be> Cc: freebsd-net@freebsd.org Subject: Re: /31 on 2 interfaces Message-ID: <1147907325.446bacfd29d21@webmail.telus.net> In-Reply-To: <009d01c679a5$a8444910$aa00000a@cloe> References: <001301c67946$604b7f70$aa00000a@cloe><20060517005546.GJ65555@funkthat.com><20060517010927.GA656@gremlin.foo.is><DF6D4C18-F116-4ABD-AE7A-A1AC5266D660@tinker.com> <009701c67964$fe20f0e0$42764eca@ilo.skyinet.net> <009d01c679a5$a8444910$aa00000a@cloe>
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No love with a /31 mask & default bcast addr. Perhaps ARP reqs are failing to
the subnet bcast address, didn't check. To fix, specify an all ones broadcast.
Tested this against 6.0-Release & a Juniper box that was handy.
As always, YMMV. Oliver has a point though, why not just use a /30 & save
yourself the grief?
ifconfig vlan20 10.10.20.2 netmask 255.255.255.254 broadcast 255.255.255.255
[root@itestbox itest1]# ifconfig vlan20
vlan20: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet6 fe80::210:4bff:fe14:bc03%vlan20 prefixlen 64 scopeid 0x11
inet 10.10.20.2 netmask 0xfffffffe broadcast 255.255.255.255
ether 00:02:b3:ab:66:3c
media: Ethernet 100baseTX <full-duplex>
status: active
vlan: 20 parent interface: em1
set interfaces fxp1 unit 0 family inet address 10.10.20.3/31 broadcast
255.255.255.255
jtest1@jtestbox> show interfaces fxp1.0 extensive
Logical interface fxp1.0 (Index 66) (SNMP ifIndex 14) (Generation 3)
Flags: SNMP-Traps Encapsulation: ENET2
Protocol inet, MTU: 1500, Generation: 9, Route table: 0
Flags: None
Addresses, Flags: Is-Preferred Is-Primary
Destination: 10.10.20.2/31, Local: 10.10.20.3, Broadcast: Unspecified,
Generation: 23
[root@itestbox itest1]# ping -qnc2 10.10.20.3
PING 10.10.20.3 (10.10.20.3): 56 data bytes
--- 10.10.20.3 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.369/0.439/0.508/0.070 ms
jtest1@jtestbox> ping 10.10.20.2 count 2
PING 10.10.20.2 (10.10.20.2): 56 data bytes
64 bytes from 10.10.20.2: icmp_seq=0 ttl=64 time=0.407 ms
64 bytes from 10.10.20.2: icmp_seq=1 ttl=64 time=0.412 ms
--- 10.10.20.2 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.407/0.409/0.412/0.002 ms
jtest1@jtestbox> monitor traffic interface fxp1 extensive
Listening on fxp1, capture size 96 bytes
19:31:39.559772 In 0:2:b3:ab:66:3c > 0:2:b3:9:57:dd, ethertype IPv4 (0x0800),
length 98: (tos 0x0, ttl 64, id 6478, offset 0, flags [none], proto: ICMP (1),
length: 84) 10.10.20.2 > 10.10.20.3: ICMP echo request seq 0, length 64
19:31:39.559865 Out 0:2:b3:9:57:dd > 0:2:b3:ab:66:3c, ethertype IPv4 (0x0800),
length 98: (tos 0x0, ttl 64, id 39612, offset 0, flags [none], proto: ICMP
(1), length: 84) 10.10.20.3 > 10.10.20.2: ICMP echo reply seq 0, length 64
19:31:40.561499 In 0:2:b3:ab:66:3c > 0:2:b3:9:57:dd, ethertype IPv4 (0x0800),
length 98: (tos 0x0, ttl 64, id 6482, offset 0, flags [none], proto: ICMP (1),
length: 84) 10.10.20.2 > 10.10.20.3: ICMP echo request seq 1, length 64
19:31:40.561579 Out 0:2:b3:9:57:dd > 0:2:b3:ab:66:3c, ethertype IPv4 (0x0800),
length 98: (tos 0x0, ttl 64, id 39615, offset 0, flags [none], proto: ICMP
(1), length: 84) 10.10.20.3 > 10.10.20.2: ICMP echo reply seq 1, length 64
^C
4 packets received by filter
0 packets dropped by kernel
Quoting Unix-Solutions - Steven <steven@unix-solutions.be>:
> I'm need a point-to-point link between 2 servers
> with just a crossover cable between the servers.
>
> ----- Original Message -----
> From: "fooler" <fooler@skyinet.net>
> To: "Kim Shrier" <kim@tinker.com>; "Unix-Solutions - Steven"
> <steven@unix-solutions.be>
> Cc: <freebsd-net@freebsd.org>
> Sent: Wednesday, May 17, 2006 5:49 AM
> Subject: Re: /31 on 2 interfaces
>
>
> > ----- Original Message -----
> > From: "Kim Shrier" <kim@tinker.com>
> > To: "Unix-Solutions - Steven" <steven@unix-solutions.be>
> > Cc: <freebsd-net@freebsd.org>
> > Sent: Wednesday, May 17, 2006 9:20 AM
> > Subject: Re: /31 on 2 interfaces
> >
> >
> >>A /31 is not a point-to-point link.
> >
> > see RFC 3021
> >
> >> A /31 is a network with nothing but a loopback and broadcast address.
> >
> > not a loopback address but a network address (all zeros bit) and a
> > broadcast address (all ones bit)
> >
> > fooler.
> >
> > _______________________________________________
> > freebsd-net@freebsd.org mailing list
> > http://lists.freebsd.org/mailman/listinfo/freebsd-net
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> >
>
>
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