Performance error

Unanswered Question
Mar 3rd, 2009
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I have the following extructure.

Router A (3825) connected to a fiber 200 MB (Gigabit Ethernet 0 / 0) with the ISP, a router B (3825) which connects (Gigabit Ethernet 0 / 0) to the router via radio.

The router B has a gigabit Ethernet (0 / 1)with 12 subinterfaces and is connected to a stackswitch 3750 with four switch , performance problems are caused and are continuing the interface 0 / 1 of Router B, and affect all subinterfaces I have lost connectivity and latency to soar.

Researchers found the following, but I can not find how to solve

Someone can help me

Thanks


GigabitEthernet0/0 is up, line protocol is up

MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

reliability 255/255, txload 1/255, rxload 3/255

Full-duplex, 1000Mb/s, media type is RJ45

Input queue: 0/75/162/10998 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo Output queue: 0/40 (size/max)

5 minute input rate 14430000 bits/sec, 2320 packets/sec

5 minute output rate 5958000 bits/sec, 1897 packets/sec

248123696 packets input, 4292553566 bytes, 359 no buffer

Received 18207 broadcasts, 0 runts, 0 giants, 338 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog, 16648 multicast, 0 pause input

0 input packets with dribble condition detected

200688794 packets output, 1369045837 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 unknown protocol drops

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 pause output

0 output buffer failures, 0 output buffers swapped out

GigabitEthernet0/1 is up, line protocol is up

Encapsulation 802.1Q Virtual LAN, Vlan ID 1., loopback not set

Last clearing of "show interface" counters 20:03:49

Input queue: 0/4096/27526/292903413 (size/max/drops/flushes); Total output dro

ps: 0 Queueing strategy: fifo Output queue: 0/40 (size/max)

5 minute input rate 6204000 bits/sec, 2032 packets/sec

5 minute output rate 15102000 bits/sec, 2385 packets/sec

212134649 packets input, 140779593 bytes, 11019737 no buffer

Received 308249547 broadcasts, 0 runts, 0 giants, 3643 throttles

1209413 input errors, 0 CRC, 0 frame, 1209413 overrun, 0 ignored

0 watchdog, 1052084 multicast, 0 pause input

0 input packets with dribble condition detected

255647753 packets output, 2056922115 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

18808 unknown protocol drops

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 pause output

0 output buffer failures, 0 output buffers swapped out



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Giuseppe Larosa Tue, 03/03/2009 - 03:20
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Hello Alejandro,

a C3825 cannot handle a GE at wire speed.


so the huge errors of type overruns are caused by this.


overrun definition is the following:


Number of times the receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to handle the data.


see


http://www.cisco.com/en/US/docs/ios/interface/command/reference/ir_s4.html#wp1020803



So to improve inter-vlan routing performances you need to promote the stack to L3.


see


http://www.cisco.com/web/partners/tools/quickreference/index.html


http://www.cisco.com/web/partners/downloads/765/tools/quickreference/isr.pdf


Hope to help

Giuseppe


agrindley Tue, 03/03/2009 - 07:28
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Thank you for you explanations. apologize if I understood well your answers

What I do is say that

1. I buy a NM or NME module to 3850 router more able than gigabit ethernet that brings the router (eg NM-1GE, 16 port switch, etc)

2.The switch is who is responsible for Layer 3


I've been watching the performance and I have some doubts, the datasheet says that NM have BW 600 Mbps and MNE 1.2 Gbps BW, I'm going on a 80 Mbps bandwidth on Gigabit Ethernet . What is this door ?.


Your suggestion is to remove the router and use the stack in L3 switch 3750 to route all traffic OR that the switches are responsible for routing traffic to the router B and router B send to router A and here to operator


Thank you for your effort



agrindley Tue, 03/03/2009 - 07:28
User Badges:

Thank you for you explanations. apologize if I understood well your answers

What I do is say that

1. I buy a NM or NME module to 3850 router more able than gigabit ethernet that brings the router (eg NM-1GE, 16 port switch, etc)

2.The switch is who is responsible for Layer 3


I've been watching the performance and I have some doubts, the datasheet says that NM have BW 600 Mbps and MNE 1.2 Gbps BW, I'm going on a 80 Mbps bandwidth on Gigabit Ethernet . What is this door ?.


Your suggestion is to remove the router and use the stack in L3 switch 3750 to route all traffic OR that the switches are responsible for routing traffic to the router B and router B send to router A and here to operator


Thank you for your effort



Joseph W. Doherty Tue, 03/03/2009 - 04:30
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Like Giuseppe, I suspect the root issue is the 3825s not being able to effectively deal with gig, especially during bursts. The 3825 can't truly handle FastEthernet either, in all situations.


If possible, slow the sending rate of the devices attached to the 3825s. For instance, on the connection between the 3825 and the 3750 stack, run it at 100 Mbps and use the srr-queue bandwidth limit command to slow the interface to about 50% of 100 Mbps. (Adjust up or down depending on the 3825's resulting interface performance.)


On the 3825s, insure there's minimum process switching and attempt to minimize usage of any other services to maximize forwarding performance.


Since you have a 3750 stack, if running it as L2, and performing LAN L3 on the 3825, instead run L3 on the 3750 stack for the LAN. (As also suggested by Giuseppe.) If you only have the base IOS, it still supports both static and RIP routing. Other dynamic routing protocols are supported in the next higher IOS feature set. (I.e. you'll then no longer need the VLAN/subinterface configuration on the one 3825.)

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