Should I block packet at Edge Router or Firewall? (Pre-filter?)

[stownsend]

I'm filtering traffic on my edge router to relieve the load on my PIX. Should I bother? I started filtering out traffic to port 137-139 and to 445, since then people have complained of slower access to the internet.

My Edge Router is:

CPU utilization for five seconds: 20%/20%; one minute: 23%; five minutes: 29%

Cisco Internetwork Operating System Software

IOS (tm) C2600 Software (C2600-I-M), Version 12.1(2)T, RELEASE SOFTWARE (fc1)

Copyright (c) 1986-2000 by cisco Systems, Inc.

Compiled Tue 16-May-00 15:15 by ccai

Image text-base: 0x80008088, data-base: 0x80865F64

ROM: System Bootstrap, Version 12.1(3r)T2, RELEASE SOFTWARE (fc1)

uptime is 13 weeks, 6 days, 20 hours, 41 minutes

System returned to ROM by power-on

System image file is "flash:c2600-i-mz.121-2.T"

cisco 2621 (MPC860) processor (revision 0x600) with 44032K/5120K bytes of memory.

Processor board ID JAD05330C0L (3699876051)

M860 processor: part number 0, mask 49

Bridging software.

X.25 software, Version 3.0.0.

2 FastEthernet/IEEE 802.3 interface(s)

2 Serial network interface(s)

32K bytes of non-volatile configuration memory.

16384K bytes of processor board System flash (Read/Write)

My PIX is:

CPU utilization for 5 seconds = 1%; 1 minute: 0%; 5 minutes: 1%

Cisco PIX Firewall Version 6.2(2)

Cisco PIX Device Manager Version 2.0(1)

Compiled on Fri 07-Jun-02 17:49 by morlee

up 49 days 18 hours

Hardware: PIX-515, 32 MB RAM, CPU Pentium 200 MHz

Flash i28F640J5 @ 0x300, 16MB

BIOS Flash AT29C257 @ 0xfffd8000, 32KB

0: ethernet0: address is 0050.54fe.ef68, irq 10

1: ethernet1: address is 0050.54fe.ef69, irq 7

2: ethernet2: address is 0002.b3ad.7fda, irq 9

Licensed Features:

Failover: Disabled

VPN-DES: Enabled

VPN-3DES: Disabled

Maximum Interfaces: 3

Cut-through Proxy: Enabled

Guards: Enabled

URL-filtering: Enabled

Inside Hosts: Unlimited

Throughput: Unlimited

IKE peers: Unlimited

[thisisshanky]

Your inbound filter on the router, forces, the router to use process switching for all packets inbound on that interface. This increases the load on the router. Your pix utilisation is normal, so you might want to shift the filtering to the pix, rather than on the router. PIX is a hardware based filtering system, so it would perform the filtering, much faster than the router can do, and also relieve the load on the router. This might help.