I have seen on some ISPs an IP address and a subnet mask of
255.255.255.255 (/32)I'm a little confused of this as one needs a default gateway. The default gateway of this network would be???
This to me is a network address and broadcast address, so I'm not sure how to understand this.
Does anyone have a proper explanation of this?
Regards
James
James wrote in news:g29knc$cnu$1$ snipped-for-privacy@news.demon.co.uk:
Hi James
This type of IP address is often known as a loopback address, normally issued to a loopback interface on your router for management purpose. The router announces the particular IP address via its routing protocol to other routers. Actually some routing protocols demand such an IP address on a loopback for proper functionallity.
A loopback interface is actually a virtual interface on the router, that never goes down unless you explicit do a shutdown on the interface.
Regards, Lars Christensen CCIE #20292
The default route would be the interface itself.
ip route 0.0.0.0 0.0.0.0 Dialer0
or
ip route 0.0.0.0 0.0.0.0 BVI1
I use /32 loopbacks but have never thought about it in depth as to how and why.
So this would count for an > James wrote:
A subnet mask of 255.255.255.255 or /32 represents a single address. This can commonly be found in routing tables as an entry for a route to a single IP address.
EXAMPLE: A router within the internal routing protocol (IGP) domain, such as EIGRP or OSPF, might have two FastEthernet interfaces. One FastEthernet interface could lead to an Internet connection and have an IP address of
192.168.42.254 and a subnet mask of 255.255.255.0 (/24). The other FastEthernet interface could lead to another Internet connection have an IP address of 192.168.59.254 and a subnet mask of 255.255.255.0 (/24). In this situation, the routing table of a neighbor router to this Internet border router would receive a route for 192.168.42.0/255.255.255.0 and 192.168.59.0/255.255.255.0. Now the Internet border router configures a static default route through the first Internet connection and a static route for traffic to a single destination IP address through the second Internet connection. The static route for the default route would be for 0.0.0.0/0.0.0.0 and the static route for the individual IP address could be something like 172.16.15.14/255.255.255.255. After this static route configuration and redistribution into the IGP, the neigbor router now sees a route for 172.16.15.14/32 in its routing table. The effect is that all traffic not matching a route table entry will match the default route and go to the Internet border router to use the first Internet interface. Traffic specifically to 172.16.15.14 will go to the Internet border router and use the second Internet interface.----- Scott Perry Indianapolis, IN
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