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humtum82
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OSPF Overwrites End User Public IP

Sat Aug 12, 2017 12:30 pm

Hi Support,

We are burning bridges and planning to deploy OSPF routed network. We have a public IP allocation of X.X.0.0/22 and we split that into /30, /29 /28 depending on customers requirements. We also have radius manager and PPPOE for residence users.

The first router we are deploying at our furthest tower, we put public IP as follows:

CORE: X.X.0.201/30
Tower: X.X.0.202/30

The OSPF works well, we are able to test the PPPOE with the radius manager, we are also able to set up customers with Public IP as follows:

We create customer gateway on the Tower Router e.g X.X.1.1/30 and then customer end we setup X.X.1.2/30.. Customer end works well, we can traceroute from customer, shows perfectly going through tower then CORE.

The problem is that if the customer tries wants to check his public IP through sites like speedtest or https://www.whatismyip.com etc, it shows the Tower Router IP X.X.0.202 instead of X.X.1.2

We have other customers connected directly from our CORE, same procedure and when they do the above tests, it shows their public IP fine.

For the PPPOE user, it shows Tower Router IP which is fine, but for customers with public IP allocation is the problem.

Will really appreciate any assistance or guidance.

Thanks in advance.
 
JimmyNyholm
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Re: OSPF Overwrites End User Public IP

Sat Aug 12, 2017 1:00 pm

Hi this is just my gues:

1. You begin your post saying we went from bridge to routed ospf fine: (That is L2 -> L3)
2. Ospf changes traffic source ip's? No tis is not possible for ospf to do it is a routing protocol talking to other routers modifying the local routers routing table.

My Conclusion then is how did you do this in the first place with only l2? Probably you have forgot about a nat or masquerade rule in the core router because it would have been there at first out of necessity but now when you have public ip's this should be gone or if you are in migration phase modify to only inflect old bridged traffic.
 
humtum82
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Re: OSPF Overwrites End User Public IP

Sat Aug 12, 2017 1:12 pm

The NAT is there on the Tower Router for PPPOE Clients, The CORE distributes the default route. Therefore PPPOE clients have no issues.

Customers with Public IP also are connected fine, issue is not about NAT or Masquerade. Issue is the customer with public IP when he opens the site whatismyip.com he doesn't see the Public IP configured on his router, he see's the Public IP of the Tower Router which /30 which is for OSPF to the CORE.
 
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pukkita
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Re: OSPF Overwrites End User Public IP

Sat Aug 12, 2017 1:20 pm

With all due respect, my advice is hiring a consultant for this migration. Additionaly, you're wasting precious and scarce public ip addressing space.

OSPF won't ever change an IP, as JimmyNyHolm pointed, your edge router is masquerading connections from that customer.
 
humtum82
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Re: OSPF Overwrites End User Public IP

Mon Aug 14, 2017 2:26 pm

Thank you Pukita, during the initial tests I had enabled masquerading on the tower router and so its working fine now after removing my public IP prefix.

Since this is a test deployment on a new tower, I can take the hard route by doing it myself so I understand the setup better.

I have another challenge and will appreciate if you can shed some light.

On the core router where we are currently doing bandwidth shapping using simple queues and radius queues. We have ThunderCache which delivers cached content at e.g 5Mbps to each user.. and also BGP session to local IX connection with AKAMAI cache, which we also offer as a free service at e.g 5Mbps to each user.. These queues are on top and even if a user has 1Mbps subscribed plan.. The cache, IX and AKAMAI will be delivered at 5Mbps.

Now for clients connected to the tower router they are unable to get this, they get only what their subscribed plan is, how can we offer the same cache services?
 
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pukkita
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Re: OSPF Overwrites End User Public IP

Mon Aug 14, 2017 3:38 pm

Now for clients connected to the tower router they are unable to get this, they get only what their subscribed plan is, how can we offer the same cache services?
Difficult to say anything specific without knowing your network with more detail, guess you'll need to deploy same mangle / top queues strategy as in core router:
We have ThunderCache which delivers cached content at e.g 5Mbps to each user.. and also BGP session to local IX connection with AKAMAI cache, which we also offer as a free service at e.g 5Mbps to each user.. These queues are on top and even if a user has 1Mbps subscribed plan.. The cache, IX and AKAMAI will be delivered at 5Mbps
 
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ZeroByte
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Re: OSPF Overwrites End User Public IP

Mon Aug 14, 2017 5:00 pm

While you're in the learning stage, I suggest that you try for a different installation methodology than giving users /30, /29, /28 directly on their PPPoE sessions.
This means that each and every customer is going to burn 4 IP addresses at the minimum.

The best method for PPPoE is to use /32 assignments from a single pool of some size (e.g. a /27 or /26 to get started with if the POP is small).
Route the pool's master prefix - e.g. 192.0.2.64/26 - to the PPPoE server and then don't bother announcing the individual /32's from that pool into OSPF.

This keeps things lean and mean on several levels:
IP density is maximized
Routing table size is minimized
Less routing updates go out due to the individual users' links going up and down for various reasons.
 
humtum82
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Re: OSPF Overwrites End User Public IP

Mon Aug 14, 2017 8:05 pm

Hi ZeroByte! I just envy the way you explain!! Thanks a lot.

For my PPPOE users I am creating a single pool /24. I only give out static IP to corporates and NGO's /30.

I managed to setup the cache priorities on the tower routers, my last point to sort is how do I setup a separate QUEUE at the tower router for local IX traffic? (To other service providers)

I have a BGP session and receiving about 700 local IX routes, I need my customers to access these resources and local sites directly without consuming their allocated bandwidth plans.

awaiting for any assistance. Thanks
 
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ZeroByte
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Re: OSPF Overwrites End User Public IP

Mon Aug 14, 2017 8:30 pm

For my PPPOE users I am creating a single pool /24. I only give out static IP to corporates and NGO's /30.
You can give out static /32 addresses as well. If you're using RADIUS, then include the attribute framed-address=x.x.x.x framed-netmask=255.255.255.255
done.

If you're using local profiles in the PPPoE server, just set the remote address on the business user's profile.
I managed to setup the cache priorities on the tower routers, my last point to sort is how do I setup a separate QUEUE at the tower router for local IX traffic? (To other service providers)

I have a BGP session and receiving about 700 local IX routes, I need my customers to access these resources and local sites directly without consuming their allocated bandwidth plans.

awaiting for any assistance. Thanks
I'll have to let someone else field this one. Good luck!

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