Multiple T1s on a 2811

Answered Question
Jul 10th, 2009

Just a check to verify that a 2811 can only handle a maximum of two T1s. Is that correct? Thakns in advance! All replies rated.

Correct Answer by John Blakley about 7 years 7 months ago

That looks to be correct:

Table 1. Cisco 2800 Series Performance


Recommended Performance with Services Enabled (IMIX traffic)

Cisco 2801

Up to 1 T1/E1/xDSL

Cisco 2811

Up to 2 T1/E1s/xDSL

Cisco 2821

Up to 4 T1/E1s/xDSL

Cisco 2851

Up to 6 T1/E1s/xDSL



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Overall Rating: 4 (3 ratings)
Joseph W. Doherty Fri, 07/10/2009 - 16:11

Only two? That's a Cisco recommendation, but a 2811 may do more. Cisco's recommendation is very conservative and safe.

I've worked with 2811s running 3 T1s or 3 E1s w/o any performance issues. May have also seen 2811 support 4 T1s, but I'm not positive. Have worked with 2811 connected to full T3, although it could only handle about 50% DS3 utilization (duplex); which would also run the CPU to 100%. (NB: Often enough traffic to drive WAN links to 100%, sometimes for hours [especially when server or user backups were active, the latter during normal business hours].)

Above 2811s were running OSPF (site internal - very small, only several subnets) and BGP routing (MPLS VPN, couple hundred prefixes), QoS, providing NetFlow records, monitiored by multiple SNMP management stations, often running (BGP) OER, running IP SLA tests (for VoIP quality), and perhaps also performing LAN routing while running GLBP. Mutiple serial links, bonded, either with MLPPP or ATM IMA.


Ouch! A "1" - not helpful vote? Sorry, to whoever voted such. Really thought highlighting actual production experience with this platform would be helpful in answering OP's "Just a check to verify that a 2811 can only handle a maximum of two T1s. Is that correct?"


Oh, if the person who voted the "1" could explain why the above information was "not helpful", I would appreciate learning why they think so. (Not looking for an argument, just trying to improve myself.)

riedmueller Sat, 07/11/2009 - 04:15

I have seen a 2811 with two VWIC-2MFT-T1

running 4 full T1s. The T1s were bonded using MLPPP.

The router was not running any routing protocols - default route to the provider was the only routing configuration.


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