Cisco 3600, configuring 3 T1's

[Semperfi2004]

I have a Cisco 3600 that I need to configure with 3 T1's. I'm not sure how pass all LAN traffic to the 3 T1's.
I have configured the 3 serial interfaces with the 3 serial IP's my ISP gave me. With the 2 Ethernet Interfaces I have, I've only configured One interface. My ISP gave me a /29 mask for my Ethernet Interfaces.

Example:
On the Cisco router, I have 2 Interfaces modules.

One Module has 1 Ethernet port with 2\T1 ports.
Ethernet 0/0 is configured with one IP in the /29 mask range. The 2\T1 ports are both configured
serial 0/0 & Serial 0/1

E0/0 - 1.1.1.1 255.255.255.240
S0/0 - 2.2.2.1 255.255.255.252
S0/0 - 2.2.2.5 255.255.255.252


Second Module has, 1 Ethernet port with 1\T1 port.
ethernet 0/1 is not configured
serial 1/0 is configured.

E0/0 - is not configued
S1/0 - 2.2.2.9 255.255.255.252


do I just create routes
ethernet 0/0
0.0.0.0 0.0.0.0 serial 0/0
0.0.0.0 0.0.0.0 serial 0/1

ethernet 1/0
0.0.0.0 0.0.0.0 Serial 1/0

will this combine all LAN traffic into one pipe ? Or am I not even in the right ball park in configuring this router ? Any suggestions would be greatly appreciated

Thank you.

 

[JOAMON]

first of all you need to contact your ISP and see if they support multilink. If they do then you will be assigned one /30 address to connect to them with and all three interfaces will become part of the multilink interface that you will build. You will the receive your /28 IP routeables that you will assigne the first useable to the ethernet port and the second to whatever firewall device you are connecting to.

Example:

interface Multilink1
description connected to ISP
ip address 64.110.22.22 255.255.255.252
ppp multilink
ppp multilink fragment disable
ppp multilink group 1
!
interface Serial0/0
description multilink 1 interface
no ip address
encapsulation ppp
tx-ring-limit 26
tx-queue-limit 26
no keepalive
no fair-queue
ppp multilink
ppp multilink group 1
!
interface Serial0/1
description multilink 1 interface
no ip address
encapsulation ppp
tx-ring-limit 26
tx-queue-limit 26
no keepalive
no fair-queue
ppp multilink
ppp multilink group 1
!
interface Serial1/0
description multilink 1 interface
no ip address
encapsulation ppp
tx-ring-limit 26
tx-queue-limit 26
no keepalive
no fair-queue
ppp multilink
ppp multilink group 1
!
ip route 0.0.0.0 0.0.0.0 64.110.22.21

 

[Semperfi2004]

Thank you, I found out through my ISP we are using CEF, ip load sharing per packets. Would you happen to have an example of this config ? or reference material ? thank you for your help.

 

[JOAMON]

Multilink would be the better choice as the three lines would be combined giving you 4.5 speed instead of 1.5. Load sharing will not increase the bandwidth as multilink will.
IP CEF is fairly easy to configure. See the following link:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/switch_c/xcprt2/xcdcefc.htm

Also make sure to log your processor performance before and after to make sure that during peak use the CPU does not get overwhelmed. Per packet is more CPU intensive than the default per destination. Form global configuration you just enbable ip cef by entering IP CEF. Then setup the three equal cost paths. If you want to parse out traffic over the different links then you will have to use policy based routing. I use the multilink with two T1's and it is great.

 

[Semperfi2004]

I would agree from what you say about multilink and from what I've read about multilink, it seems to be the better solution. But, higher folks in the company didn't want that. However, I think I am on the right track now. below is an example of my current config. I did apply "ip load-sharing per-packet" to each serial interface. I assume that is correct. I do appreicate your help. I am new to configuring cisco routers.

version 12.1
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname HOST
!
logging rate-limit console 10 except errors
!
ip subnet-zero
ip cef
ip cef accounting per-prefix non-recursive
ip cef load-sharing algorithm original
!
!
no ip finger
!
!
!
interface FastEthernet0/0
ip address 63.000.000.254 255.255.255.240
duplex auto
speed auto
!
interface Serial0/0
ip address 63.000.000.111 255.255.255.252
ip load-sharing per-packet
encapsulation ppp
!
interface Serial0/1
ip address 63.000.000.115 255.255.255.252
ip load-sharing per-packet
encapsulation ppp
!
interface FastEthernet1/0
no ip address
shutdown
duplex auto
speed auto
!
interface Serial1/0
--More--
ip address 63.000.000.119 255.255.255.252
ip load-sharing per-packet
encapsulation ppp
!
interface Serial1/1
no ip address
shutdown
!
router rip
network 10.0.0.0
!
ip classless
ip route 0.0.0.0 0.0.0.0 Serial0/0
ip route 0.0.0.0 0.0.0.0 Serial0/1
ip route 0.0.0.0 0.0.0.0 Serial1/0
no ip http server
!
line con 0
transport input none
line aux 0
line vty 0 4
login
!
end

 

[JOAMON]

Looks like it should be ok. Recommend that as you have static routes in place that you disable RIP....dont need it. I do not understand not wanting to bond them together for increased bandwidth. Did you also read on the Cisco site I listed about VOIP. If you are doing any VOIP it is not recommended to use per packet as the packets may take different paths to the destination which could put them there out of order and voice requires that they arive in order or the packets are just dropped giving your voice traffic that choppy effect.

I take it that this is connecting to another router or firewall device.

Quote from Cisco on VOIP:
Path utilization with per-packet load balancing is good, but packets for a given source-destination host pair might take different paths. Per-packet load balancing could introduce reordering of packets. This type of load balancing would be inappropriate for certain types of data traffic (such as voice traffic over IP) that depend on packets arriving at the destination in sequence.

 

[JOAMON]

Question:
I see a /28 .240 subnet one your fast ethernet. Usually when you receive a T1 connection your will be assigned a /30 .252 address to connect to your ISP with and your public IP addresses associated with it in this case the /28 .240. You have 3 /30 .252 subnets do you also have 3 ranges of public IP addresses?

 

[Semperfi2004]

Funny you bring that up, we tried to implement VOIP serveral years ago, and had the chopped results when communicating on the phone. I'll have inform them of this. Because, we plan to try and implement VOIP soon again. Thanks.
Yea, my ISP issued me a /28 .240 for my ethernet. So, I configured the First usable IP in that range on E 0/0. My ISP also issued an additional Class C range /24. We requested an additional Class C range, because, well, its related to VPN's issue with our clients. For my serial Interfaces, they issued me three serial IP's /30 .252.

 

[JOAMON]

I must be tired because I am not following you. Typically a T1 internet will be setup as follows. ISP side /30 through NIU to CPE router T1 card with other side of /30. CPE router ethernet configured with first IP routeable and a gateway of the ISP side. Are you saying that your ISP has given you a /28 .240 pool and is routing that traffic over the three connections? Are you certain there are not 3 groups of public IP address (1 for each t1)?

 

[Semperfi2004]

Sorry my bad, not a /28 .240 but a /29 .248
My ISP issued this (Example):
Network: 63.0.0.96/29
Broadcast: 63.0.0.103
HostMin: 63.0.0.97
HostMax: 63.0.0.102

I used 63.0.0.97 on FastEthernet0/0
because my ISP told me my
router LAN I/F: would be 63.0.0.97
I'm not sure what I/F stands for.

They also issued me a Class C example64.0.1.0/24) This will be used for VPN issues we have with remotes.

Both 63.0.0.97/29 and 64.0.1.0/24 are point to our domain.

Then my ISP issued me 3 IP's for my serial interfaces, each one being a /30 .252

Does this sound correct ?

Thanks for your help.

 

[JOAMON]

Whay I am trying to find out is how your ISP is setup on there side. Here is how it typically will work.

1 T1 internet connection:
ISP /30------NIU-----Router Serial /30--Router Ethernet /29
ISP 63.0.1.17 255.255.255.252
Router Serial 63.0.1.18 255.255.255.252
Router Ethernet 64.0.1.49 255.255.255.248
Default Gateway for Edge Router 0.0.0.0 0.0.0.0 63.0.1.17

The /29 .248 subnet will only get to you via the specific /30 .252 path assigned to that T1 connection.

If you setup load balancing and only have one subent configured you will find all of your traffic using only one T1 span. Without knowing the ISP setup for these connections I would suggest you talk to one of their techs as to helping with the proper configuration for your edge router. Remember about the per-packet load balancing and the problems it may bring with VOIP. Hope I was of some help. I still beleive bonding them together to be the better choice though.

 

[Semperfi2004]

You've been a great help, thank you. this is an example of what My ISP sent me. I looks like we are planned to turn the curcuit on Tuesday.

IP Address: 63.100.200.100 to 63.100.200.108 255.255.255.248
63.99.100.0 to 63.99.100.255 255.255.255.0
to Domain

Router LAN I/F: 63.100.200.101

Encapsulation: PPP
Serial IP Address: 1. 63.98.100.100 2. 63.98.100.104 3. 63.98.100.108 4. 63.98.100.112

ISP Access Router IP: 1. 63.98.100.99 2. 63.98.100.103 3. 63.98.100.107 4. 63.98.100.111

Cisco Router Configuration
Encapsulation: PPP
IP Classless: In global configuration
Default Route: 0.0.0.0.0.0.0.0 serial 1 or whatever interface is connected to CSU/DSU or MUX

CSU/DSU or multiplexer configuration
Net Signal: ESF
Line Coding: B8ZS
Timing: Net (from Network)
Port Base Rate: 64K
Port Speed: 3xT1

 

[JOAMON]

What are you going to use between the 3600 and your LAN?

 

[Semperfi2004]

I'll be using a Netscreen 208. I've been using it for long time now and pretty efficient with it.

 

[JOAMON]

The info your ISP gave you list 4 serial address...thought you were only getting 3????

 

[Semperfi2004]

We are, the fourth T will be configured on a later date.

 

[Semperfi2004]

Hey JOAMON, thank you for all your help. We decided to turn the circuits on today, and everything connected without any problems. Thank you again.

 

[JOAMON]

No problem...glad it worked. Something to consider when truning on the fourth. Bond the T1 lines together in groups of 2 then you can still use load balancing but it will be over 2 3 meg circuits instead of 4 1.5 meg circuits.

 

[Semperfi2004]

ahhh ok. I will do that. thanks