I have so simple network:
The cisco router connect to catalyst. On catalyst is definition two VLAN's. There are two hosts: host_1(10.0.0.1/32) and host_2, (10.0.0.2/32) is connected to catalyst. Hosts are in different VLAN and have network mask /32 ---- it couldn't change. Configuration on VLAN's couldn't change too.
Question: How I can change config on the router interface so host_1 can ping host_2? Is it possibility?
snipped-for-privacy@gmail.com wrote in comp.dcom.sys.cisco:
I don't think this would work at all. If your host has a subnet mask of
255.255.255.255 you are telling him that he is the only one in that subnet and since he doesn't have a default gateway he can't communicate with anyone else... You need to change the subnet mask.Note that I'm currently finishing semester 3 of CCNA classes so my understanding may not be correct and someone with more experience can correct me.
"/32" is not a valid network mask as it leaves no space to identify the network and broadcast address. What operating system has allowed you to apply that mask? The smallest network mask is "/30"
What are the network addresses of the vlans that router has configured? By that I mean the actual 'networks' .... not hosts. .
BernieM
Correction, there is an RFC that defines /31. It is used especially on point-to-point links.
A loopback interface on a router can have a /32 mask, but that or a something similar would be about it. To the original poster, is the host in question a router, PC, other??
It's PC.
It's PC.
and why can't the netmask be changed ?
On 19.08.2006 16:31 Walter Roberson wrote
That's theory ... reality tells me
gw001#sh inter loopback 0 Loopback0 is up, line protocol is up Hardware is Loopback Internet address is 80.81.196.177/32
On 19.08.2006 17:21 snipped-for-privacy@gmail.com wrote
And why don't you add host routes (unix slang), i.e.
host_1: ip route add 10.0.0.2/32 dev eth0 host_2: ip route add 10.0.0.1/32 dev eth0
I don't think that will work, because the hosts are in different VLANs. Routes like that cause the systems to ARP for each other. But since each VLAN is a separate broadcast domain, the ARPs will never reach each other.
The only way to communicate between VLANs is via a router. The OP didn't mention whether his router is connected to both VLANs -- in fact, he didn't say how the router is connected to the switch at all.
If the router is running proxy-arp the pc's hould be able to communicate.
BernieM
Only if the router is connected to both VLANs, and it has appropriate routing statements for the /32 addresses.
yes, and as long as there are no restrictions in place ie. acls' etc. The original poster doesn't indicate the extent to which they have access to this type of info.
BernieM
RFC number please? :-)
Usually in ptp links, ip-addresing scheme took /30 that leaves 4 ip addresses 1 for network, 2 for end-point ip, and 1 for broadcast.
Yes, this loopback addr can use /32 addressing. But it is only for redistributing/routing update only. It is a different case.
RFC 3021 "Using 31-Bit Prefixes on IPv4 Point-to-Point links"
Thank's everybody. It schema wasn't work, i.e. /32 is netmask without host. So for "live" interface in CORRECTLY work OS we couldn't config this mask. Because this mask contradict exist of interfaces. Another history with loopback, i.e. it is emulations networks without host.
All that I sad before --- folly. Question is unsolvable.
If the interface is more or less a loopback then you're right .. it's unsolvable. It's the same as configuring a "127.x.x.x" address. It doesn't matter what mask you use and how many hosts are in the same vlan configured this way .... they're never going to talk ... packet are never going to even hit the wire.
BernieM
Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.