How do I find the IP address of the www next hop (backup) ISP router?

[jmaxwellUSAF]

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.

[MHM Cisco World]

you use egress not

next-hop

in your static route ?

[jmaxwellUSAF]

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.

[MHM Cisco World]

I dont get full your Q
but we can use 8.8.8.8 as destination of IP SLA 

[jmaxwellUSAF]

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 ?  

[MHM Cisco World · Accepted solution]

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 

[jmaxwellUSAF]

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.

[MHM Cisco World]

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  

[jmaxwellUSAF]

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.

[MHM Cisco World · Accepted solution]

OK 
then ping broadcast of the subnet, and check the reply, 
if the connection P2P only ISP router will reply to this ping 

[MHM Cisco World]

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 

[Joseph W. Doherty]

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.