I announce /21 but now want to use one of /24 in another ISP

RouterOS Forwarding Protocols
1

I know the answer is easy but I am a noob so please help me ..
Let’s say my ASN is 22344 and my assigned ip block is 1.2.16.0/21 from ripe.

I am announcing 1.2.16.0/21 to my single ISP using bpg.
Ripe DB have this:
% Information related to ‘1.2.16.0/21AS22344’

route: 1.2.16.0/21
descr: MYOWN-AS ROUTE OBJECT
origin: AS22344
mnt-by: MNT-MYOWN-AS
source: RIPE # Filtered

No problem here so far. I can use 1.2.16.1- 1.2.23.255 in my network behind my mikrotik router.
everything works.

BUT, Now I want to use 1.2.23.0/24 in another location in another ISP.
So I added ro my Ripe DB
% Information related to ‘1.2.23.0/24ASOFOTHEISP’

route: 1.2.23.0/24
descr: MY OUTSIDE SERVERS
origin: ASNOFOTHERISP
mnt-by: OTHERISP-mnt
source: RIPE # Filtered

And the Other Isp started announcing 1.2.23.0/24 and because /24 is specific than /21 whole internet knows that my 1.2.23.0/24 is on the other ISP

No Problem here works as expected.

The PROBLEM IS After this configuration.
My servers behind my mikrotik router can not access the 1.2.23.0/24 network.
$ping 1.2.23.1
PING 1.2.23.1 (1.2.23.1) 56(84) bytes of data.
From 1.2.16.1: icmp_seq=1 Redirect Host(New nexthop: 82.25.68.43) (my ISP gateway)

and stuck here.

What must I do to tell my Mikrotik router that 1.2.23.0/24 is in some other place without having to change my 1.2.16.0/21 announcement?

Do I have have to add a static route or something? Or some other solution?

2

Provided that your ISP behind which you run the /21 knows the proper route to the /24 all you need is a route (static or dynamic - if you do not know, use a static one) pointing the /24 to your ISP at the /21 location.

3

Hello thanks for your post.
After your post I checked my own router:

[admin@R-GW] > ip route print detail where dst-address=1.1.23.0/24
Flags: X - disabled, A - active, D - dynamic, C - connect, S - static, r - rip, b - bgp, o - ospf, m - mme, B - blackhole, U - unreachable, P - prohibit
7 ADb dst-address=1.1.23.0/24 gateway=95.39.0.250 gateway-status=95.39.0.250 recursive via 82.25.68.43 outside distance=20 scope=40 target-scope=30 bgp-as-path=“xxx84,xxx13,xx39,3xxxx” bgp-origin=igp received-from=MYISP
[admin@R-GW] >

So my router knows how to reach 1.1.23.0/24
But my isp router does not! Because it is looping the requests I sent to it and turning them back to me:
as in my first post:

$ping 1.2.23.1
PING 1.2.23.1 (1.2.23.1) 56(84) bytes of data.
From 1.2.16.1: icmp_seq=1 Redirect Host(New nexthop: 82.25.68.43) (my ISP gateway)

I mailed my isp about that providing my results.
Hope level2 tech will fix this when they come back on monday morning…

Any more advices?

4

If the problem is with that ISP there is nothing you can do. They have to fix their router.