Member Avatar for dimaraja

hi all
how can i connect dsl to cisco router 2525
connector avail on router : db60, isdn nt1.
need help
thanks...

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  • Latest Post Latest Post by w1r3sp33d

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Short answer: the DB60 serial on your Cisco can’t be turned into a DSL Ethernet/ATM link by using passive adapters. already tried DB60→DB25→RJ45, and and were correct to point out the mismatch — the physical connector is only part of the story; the link-layer and framing are completely different.

Why it fails (brief): DSL is terminated by a modem (or an ADSL-capable interface) that speaks ATM/Ethernet and usually runs PPPoE/PPPoA or provides NAT/DHCP. A Cisco serial port expects a synchronous serial link (HDLC/PPP, clocking, DTE/DCE), so a passive pin adaptor cannot translate frames or clocking between those worlds.

Practical options and a working example

  • Easiest: use the ISP DSL modem and put it into bridge mode (if supported). Let the Cisco act as the PPPoE client. Typical IOS pattern (adjust interface names and creds):
interface FastEthernet0/0
 no ip address
 pppoe enable
 pppoe-client dial-pool-number 1

interface Dialer1
 ip address negotiated
 encapsulation ppp
 dialer pool 1
 ppp chap hostname YOUR_ISP_USER
 ppp chap password 0 YOUR_ISP_PASS
 ip nat outside

interface FastEthernet0/1
 ip address 192.168.1.1 255.255.255.0
 ip nat inside

ip nat inside source list 1 interface Dialer1 overload
access-list 1 permit 192.168.1.0 0.0.0.255
  • Alternate: keep the modem in router/NAT mode and connect the Cisco WAN (Ethernet) to the modem’s LAN; configure the Cisco WAN as DHCP client or static IP per ISP.

Troubleshooting checklist

  • Confirm the modem reports bridge mode when using PPPoE.
  • Check link lights and run show ip interface brief, show interface Dialer1, show running-config.
  • Verify ISP username/password and authentication method (PAP/CHAP).
  • Use debug ppp negotiation only when safe to see PPP progress.

If you want a single-box solution, you’ll need a router with a native ADSL/ADSL2+ interface — a passive adapter won’t do the job.

Recommended Answers

All 7 Replies

Member Avatar for w1r3sp33d

For DSL use a Cisco 827, it is designed specifically for it, or use the dsl modem provided with a PIX 501 just for firewall/VPN function.

2525 can do:

-DB60: t1, fractional t1, or frame relay (beware there are some caveats to using only low speed serial lines 56/64k on some of those interfaces)

-isdn bri, that is all that will work on it

-the "LAN" interface is actually token ring on a 2525

Really the only thing it is good for anymore is a lab router to practice dial backup or as a frame switch if you have four serial ports.

Member Avatar for dimaraja

thanks for your reply man.
i have a serial cable which i connected to db60 of router 2525 and the other end is a db25 connected to a converter to rj45 which i connected to the dsl.
what can i configure on the router to make it work.
thanks again.

Member Avatar for w1r3sp33d

You may be able to convert the connector types but you will not be able to get dsl working on a 2525, let it go.

It's "lan" connection is token ring and I am the only guy I know that has functional mau's running today (nobody panic, I have lot's of ethernet too) and getting pci cards and drivers for token is quite the trick anymore.

What you have is a neat little lab router than can run old code and teach you more about networking than most people will ever know, expecially if you can find another Cisco router to hook it up too.

If I had a 2525 and needed to hook up a dsl line I would ebay the cisco, take the money and buy a netgear or linksys soho grade router. two cents.

Member Avatar for alc6379

thanks for your reply man.
i have a serial cable which i connected to db60 of router 2525 and the other end is a db25 connected to a converter to rj45 which i connected to the dsl.
what can i configure on the router to make it work.
thanks again.

That's absolutely not going to work. What you'd be able to do on that is basically run a serial protocol down a CAT5 line. That's not going to help you at all with Ethernet. w1r3sp33d is right; forget using the 2525 for a DSL connection.

Member Avatar for dimaraja

hi
i know that it will work with netgear, linksys routers....that's what i have now.
i also know about mau and token ring, i have also 3 routers 2500 series and 2900, 1900 cisco switches, i practiced frame relay, routing, access list...vlans, vtp,....etc.
what i want to do is instead of (ISDN or T1) i wanted to try dsl on routers.
somebody told it will work since the dsl is a WAN and a serial db60 is designed for WANs.
what you think?

Member Avatar for dimaraja

hi
how come when i connect the 3 routers by their serial db60 i can configure them as frame relay or ISDN Wich is a WAN
WHY NOT WITH DSL?
IS IT BECAUSE IS FASTER AND ROUTER 2500 SERIES DOES NOT SUPPORT DSL?

Member Avatar for w1r3sp33d

Can I see your config for using a 2500's serial as ISDN?

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