04-24-2023
09:11 AM
- last edited on
04-27-2023
10:08 PM
by
Translator
Hello.
How do I find the IP address of the www next hop (backup) ISP router? (
#sh cdp nei
reveals nothing.) (
#sh arp
only lists my own IP address.) (The
default gateway
is not this interface.) (
#sh ip route 1.1.1.0
outputs only that this subnet is directly connected.)
4431#sh arp
Internet (!! only the local ip address 1.1.1.1 is shown here !!)
ab.cd.ef ARPA GigabitEthernet0/0/2
Thank you.
Solved! Go to Solution.
04-24-2023
09:48 AM
- last edited on
04-27-2023
10:44 PM
by
Translator
so this not relate to IP SLA,
now you can deactivate the first
default route
(that with track) and then do
ping to 8.8.8.8
the ARP table must show you if the
next-hop is 10.0.13.2
or not.
before you deactivate the first
default route
the router never ask
Next-hop
MAC address and hence it disappear from the table
04-25-2023 06:31 AM
OK
then ping broadcast of the subnet, and check the reply,
if the connection P2P only ISP router will reply to this ping
04-24-2023
09:16 AM
- last edited on
04-27-2023
10:41 PM
by
Translator
you use egress not
next-hop
in your static route ?
04-24-2023 09:19 AM
Static route is used with main ISP DG.
My task is to config SLA failover to 2nd ISP. I cannot find the IP-address of the next hop router of this 2nd ISP link.
04-24-2023 09:23 AM
I dont get full your Q
but we can use 8.8.8.8 as destination of IP SLA
04-24-2023 09:32 AM
ISP Failover with Default Routes Using IP SLA Tracking - Cisco
Track, IP SLA, and Default Route Configurations:
track 8 ip sla 1 reachability ip sla 1 icmp-echo 10.0.12.2 source-ip 10.0.12.1 ip sla schedule 1 life forever start-time now ip route 0.0.0.0 0.0.0.0 10.0.12.2 track 8 ip route 0.0.0.0 0.0.0.0 10.0.13.2 10
============
QUESTION: How do i find what is my next-hop address that corresponds to 10.0.13.2 ?
04-24-2023
09:48 AM
- last edited on
04-27-2023
10:44 PM
by
Translator
so this not relate to IP SLA,
now you can deactivate the first
default route
(that with track) and then do
ping to 8.8.8.8
the ARP table must show you if the
next-hop is 10.0.13.2
or not.
before you deactivate the first
default route
the router never ask
Next-hop
MAC address and hence it disappear from the table
04-25-2023 05:37 AM
Your reply is helpful, but I don't have an SLA config yet. I am now configuring it, so I need to know this IP address.
I'm concluding that there is no way to know this address except to ask the administrator who controls the box.
Thanks.
04-25-2023
05:42 AM
- last edited on
04-27-2023
10:47 PM
by
Translator
if you deactive the first
default route
and use the second with
next-hop
that you not sure about it, then if the ARP success you can know that the
next-hop
is correct if not then the
next-hop
is wrong
also one more point after I review the issue,
why you need IP SLA for backup static route? if it failed what will happened? you dont need it at all
04-25-2023
05:48 AM
- last edited on
04-27-2023
10:11 PM
by
Translator
MHM, there is no SLA at all, there never was.
Let me rephrase the question-- I have a router that is connected to an ISP controlled box. There is no config inside my router. How do I know the IP address of the ISP box?
I have tried ... (
#sh cdp nei
reveals nothing.) (
#sh arp
only lists my own IP address.) (The
default gateway
is not this interface.) (
#sh ip route 1.1.1.0
outputs only that this subnet is directly connected.)
I am concluding there is no way. My next step is to verify layer 1 connectivity.
Thank you.
04-25-2023 06:31 AM
OK
then ping broadcast of the subnet, and check the reply,
if the connection P2P only ISP router will reply to this ping
04-25-2023
05:46 AM
- last edited on
04-27-2023
10:12 PM
by
Translator
I config R1 and R2
R1 dont know the IP of R2
so I
ping 100.0.0.255
broadcast
the 100.0.0.2 reply to this request as shown below
04-25-2023 10:02 AM
Why is the backup ISP unable to provide this information?
If you can determine the next hop's IP, does that tell you the network mask too? (Another reason to talk with ISP.)
Depending on the link topology being used, do you know what your up and down bandwidths actually are? If not full link bandwidth, if not full interface bandwidth, any burst capacity or over CIR additional charges? (Another reason to talk with ISP.)
I'm assuming on your side of the link, interface show "up", but how do you know ISP is actually configured to work on their side? (Another reason to talk with ISP.)
If you're paying for an ISP service, generally they will discuss what you're paying for with you.
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