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New Member

Cisco 3750--cisco Pix 515 E --- Cisco 877

Hello Experts,

If anyone can help me on this and provide some sample configuration will be great.

note: We have not yet purchased a 877 but planning too do so...

The pix has more than 5 ip add i.e.

*.*.*.1 Outside

*.*.*.2 webserver published

*.*.*.3 SMTP published

*.*.*.4 Bespoke app

*.*.*.5 spare

*.*.*.6 BT ADSL router ( default gateway for pix.

We will be replacing the BT router with a 877.

So we want to ensure the rotuer allows all traffic and only works as a ADSL side of things like the current BT rotuer does.

We do not have any seprate netwroks between the outside of PIX and BT rotuer

cisco 3750 -- pix inside 10*.*.*----outside *.*.*.1-----BT rotuer *.*.*.6

all clients Default gateway is the isnide of the pix 10.*.*.*

I hope I have explained this well.

Please provide any help.

cheers

7 REPLIES
Silver

Re: Cisco 3750--cisco Pix 515 E --- Cisco 877

Hi,

The BT ADSL router is the d/gateway for the PIX. The addressing on the inside of your network will probably not need to be changed. That means the the 877 will simply replace the BT router but use the same IP addressing between the pix outide interface and the current BT router IP address i.e. n.n.n.6

Looks like a straigt swap on face value.

hth,

Ajaz Nawaz

New Member

Re: Cisco 3750--cisco Pix 515 E --- Cisco 877

The problem is that I have not configured a 877 before and I am not a expert at pix either.

So to clarify furhter I wanted to configure the 877 in the similar fashion (like Bt rotuer) with no firewall capabilities so everything is allowed to the pix on any ip.

Secondly I also did not want to assign another ip on the internal int of the 877 rotuer which will create a problem as the pix config will need to be changed as well.

So any sample config you can point me too will be great....as BT refers to the existing box as a no NAT rotuer I think.

so all it does it routes and the ADSL line is terminated on it.

cheers

Silver

Re: Cisco 3750--cisco Pix 515 E --- Cisco 877

You have to configure the 877 router and there's no way out.

If BT are saying that their router is a 'No NAT' device, I am saying to you that your router will definately need to be configured for NAT.

If your outside interface on the PIX is configured with a public IP address then NAT will not be required on your router. Secondly, if the address on the PIX is public and was provided by BT then changes will inevitably be required on both PIX and replacement router (877).

It may take you a little while but it will save you ample time if you begin to read the basic and advanced configuration guides on the 877 device to start of with.

I'm afraid I don't have enough information in order to provide a sample config at this present momment in time.

hth,

Ajaz Nawaz

New Member

Re: Cisco 3750--cisco Pix 515 E --- Cisco 877

Ajaz,

I will try to explain this further..I am trying so please bear with me.

The reason I wanted to raise this question with all the experts was simply to ensure this router can do what we want it to do.

I have just come accross some terminology from Cisco called "ip unnumbered" by which you can use the same ip on two interfaces.

****************

So looking at the existing scenario I cannot login to the BT rotuer but the rotuer all i know has only one ip = *.*.*.6 < BT allocated pool live ip ) and our firewall pix points to this ip as the gateway. There is no other network which exist between the BT router and the PIX.

*****************

Note: Our PIX firewall also has many different public ips "outside interface" for different services as mentioned in my earlier post.

So what I wanted to know in some detail if at all with examples....

Can we possibly make a 877 rotuer work in the similar fashion...we dont want the firewall features on this rotuer to block any traffic we want the PIX to do that work....so allow all traffic period and simply rotue packets between the BT network to our PIX and LAN and so on.

any help will be greatly appreciated.

cheers

New Member

Re: Cisco 3750--cisco Pix 515 E --- Cisco 877

Anyone can advise on this on please.

cheers

New Member

Re: Cisco 3750--cisco Pix 515 E --- Cisco 877

Yes, you are replacing the BT router with the 877. On the 877 you will coinfigure a bridge group in order for it just to be a layer 2 device.

Connect an ethernet cable from one of the ports directly to the pix. Here is an example

!

bridge irb

!

!

interface Ethernet0

no ip address

bridge-group 1

bridge-group 1 spanning-disabled

hold-queue 100 out

!

!

interface ATM0

description ADSL interface

no ip address

no atm ilmi-keepalive

dsl operating-mode auto

bridge-group 1

bridge-group 1 spanning-disabled

pvc 0/35

!

New Member

Re: Cisco 3750--cisco Pix 515 E --- Cisco 877

Thank you for the help with the config...for a start this is great help.

I will rate this post and start a new thread for further queries on the same topic.

cheers

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