Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

DS3 / HSRP Questions

Hello all,

I'm currently working at a site with a T1 connection between their main HQ, and remote sites. We are upgrading the existing T1, to a DS3 line, and I've run into a few questions.

I've never turned up a DS3 before, so I'm wondering what types of things i need to know, like for a T1, I'd need to know the type of framing used, and the linecoding as well.

What would I need to know from our carrier for the DS3 line?

Also, we're thinking just to be safe, to keep our existing T1 as a backup line until we make sure the circut is stable. Is there an easy way to configure HSRP on a 3845 to failover to our existing 2621XM T1 circuit?

Thanks, and i'm sure there will be more questions to follow.

Jonathan Kloza


Re: DS3 / HSRP Questions

Here's a working example of a interface (DS3).

interface Serial1/0

description DS-3

bandwidth 44210

ip address a.b.c.d

ip route-cache flow

dsu bandwidth 44210

framing c-bit

cablelength 250

serial restart-delay 0

The most important info to get from the carrier is the dsu bandwidth, it must match.

Hope that helps.

Hall of Fame Super Silver

Re: DS3 / HSRP Questions

Hello Jonathan,

the DS3 config info has been given in the previous post.

about HSRP: on C3845 you need to track the DS3 interface in the HSRP group so that if DS3 fails the HSRP master becomes the C2621XM with the T1 exit link.

standby 11 track interface serx/y

standby 11 pri 105

standby 11 preempt

you need to configure premption also on the C2621XM and the VIP address on both

Hope to help