Hi everyone, I’m studying to take my exam MTCNA and MTCRE. I see two points and I want to know if it refers to RFC3031. that is, use an address with a mask 32?
example RouterA RouterB
address: 192.168.1.8/32 address 192.168.7.6/32
netmask: 192.168.7.6 netmask 192.168.1.8
This end ping to each other
The image didnt come through, nor is the question all that intelligible.
The image is not visible, you can use “attachment” when posting on forum for attach directly the image without problems.
@anav at same time 
ok, link fixed…
And to think I spotted you 5 hours and i still beat you by a whole minute.
Current time Halifax 1200 Current Time Rome 1700
Not that I am competitive but…
https://www.youtube.com/watch?v=snnA1CX1gzs&t=6s
What is you exact question? In MikroTik routers you can use 2 /32 addresses not adjacent to each other for point to point addressing. This way you can save IPs in multirouter setups
this is the image about MTCNA and MTCRE topic poin to point addresing
you can study the same topic but with different context and at a different depth in different courses
maybe we can hope a trainer can share with us some details about the differences
Hola quisiera saber si este punto se trata de la explicación de como usar /32 en mikrotik o se refiere a otra cosa, ya que en los cursos tanto MTCNA como MTCRE el instructor no toco ni comento estos puntos y tengo la incógnita de a que se refiere el temario en si sobre este punto del curso.
Oscar … English please as … 不是每個人都能理解你寫的東西。
Hello, I would like to know if this point is about the explanation of how to use /32 in mikrotik or it refers to something else, since in both the MTCNA and MTCRE courses, the instructor did not touch or comment on these points and I have the question of what they are refers to the agenda itself on this point of the course.
Consider there’s a point-to-point connection between two routers. Can be either a tunnel (e.g. wireguard or IPIP or anything else) or direct ethernet connection. To make that connection usable for passing packets between devices, one has to assign IP address to the interface and then configure routing.
Classical use on ethernet interfaces would be to create a routing subnet (/30 or larger) in this way:
/ip address
add address=192.168.254.25/30 interface=etherX network=192.168.254.24
/ip route
add dst-address=<remote network> gateway=192.168.254.26
(this assumes the other end of that ethernet link is set with IP address 192.168.254.26/30).
The /32 way of doing it is slightly different. Let’s say local router can use 192.168.15.233 as PtP interface IP address and the remote router uses 10.20.30.45 as interface of its end of same PtP tunnel. So the configuration of local end would be like this:
/ip address
add address=192.168.15.233/32 network=10.20.30.45 interface=PtPinterface
/ip route
add dst-address=<remote network> gateway=10.20.30.45
One can then further obfuscate the /32 addressing by reusing one of existing IP address that router might already have. For example, local router has several LANs attached, one of addresses is 172.19.13.1/24. It is possible to reuse the address, but with /32 network mask:
/ip address
add address=172.19.13.1/24 interface=<LAN interface> network=172.19.13.0 # existing LAN address
add address=172.19.13.1/32 interface=PtPinterface network=10.20.30.45
/ip route
add dst-address=<remote network> gateway=10.20.30.45
The difference between the two /32 examples is in what traceroute shows: when a device from remote network (beyond remote router) starts traceroute, the IP address shown with hop hitting local router will be different as IP address shown is the one of ingress interface. So the difference is only cosmetics (and avoiding to use separate set of addresses for link only).
Next possibility (out of scope of the question) is that it is possible to use PtP links completely address-less, like this
/ip address
add address=172.19.13.1/24 interface=<LAN interface> network=172.19.13.0 # existing LAN address
/ip route
add dst-address=<remote network> gateway=Ptpinterface pref-src=172.19.13.1
(the pref-src setting is to fix the IP address shown in ICMP replies, such as the one shown by traceroute. If this property is not set explicitly, router will select one of existing own IP addresses (I’m not sure how exactly selection is done).
When thinking about it, it seems to me that from addressing point of view it should be possible to configure mutiple logical PtP links using /32 addressing over same physical ethernet interface, but I don’t know how would that actually work. One would have to wireshark such ethernet link to see what kind of MAC addresses are used in such case. The fact that IP address used is /32 implies that sender doesn’t look for MAC address of receiver’s NIC and thus uses broadcast MAC address when sending packets out. If this is indeed the case, then multiple logical PtP links could co-exist, but all traffic would hit all involved NICs (any ethernet switch in between wouldn’t have anything to work with when selecting egress port for individual frames).
So, in short, don’t do it
For /32 point to point, there’s ARP as usual:
xx:xx:xx:xx:xx:xx → ff:ff:ff:ff:ff:ff ARP Who has 192.168.0.1? Tell 10.0.0.1
yy:yy:yy:yy:yy:yy → xx:xx:xx:xx:xx:xx ARP 192.168.0.1 is at yy:yy:yy:yy:yy:yy
It’s not supported everywhere (sometimes it could be just UI limitation), but Linux can do it, even Windows.