I have really bizarre problem in clients network.
Clients have access to the internet via NAPT - I'm using several public ip addreses for this purpose. (I'll change ip addresses for obv reasons)
ip nat pool NAT 18.104.22.168 22.214.171.124 netmask 255.255.255.192 ip nat inside source list NAT pool NAT vrf NAT overload
Other NAT settings
ip nat settings pap ip nat log translations flow-export v9 udp destination 192.168.55.10 9995 ip nat log translations flow-export v9 vrf NAT on ip nat translation timeout 3600 ip nat translation tcp-timeout 1200 ip nat translation udp-timeout 120 ip route vrf NAT 0.0.0.0 0.0.0.0 126.96.36.199
interface GigabitEthernet0/0/0.220 description IP NAT OUTSIDE encapsulation dot1Q 220 ip vrf forwarding NAT ip address 188.8.131.52 255.255.255.192 ip nat outside ! interface GigabitEthernet0/0/2.202 description IP NAT INSIDE encapsulation dot1Q 202 ip vrf forwarding NAT ip flow monitor FLOW-MONITOR input ip flow monitor v3.12 input ip flow monitor FLOW-MONITOR output ip flow monitor v3.12 output ip address 10.128.1.2 255.255.255.248 ip nat inside
access-list NAT has about 477 entries
I am experiencing problems with accessing certain sites:
- google.com gives always gives me 500 error
- Can't access others several sites - just infinite load and white screen
Nevertheless, all this happens, when my global IPs from the pool above are .179 or .180
I tried to change my global ip with static nat to .189 (end of the pool) and all above described problems were gone: google's 500 problem is none and sites, that weren't loading load successfully.
I am really lost in trying to find the root of the problem. When I dealt with google problems I was thinking on botnet/viruses activity, or maybe bad TLS handshake due to lost/re-transmitted packets, but I would experience those problems on many resources then.
I don't even know if it's a NAT problem. I guess the only way to find out (now if I think of it) is reassemble NAT pool (make it smaller, exclude "bad IPs") and try to statically assign it to hosts and find out. It will tell (may be the problem is indeed in to many or bad requests from one IP).
Maybe to many request were handling from one global IP but to deal with it I tried ip nat settings pap
asr1.core#sh ip nat translations total Total number of translations: 60199
And the router is ASR1000X
asr1.core#sh ver Cisco IOS XE Software, Version 16.05.01b cisco ASR1001-X (1NG) processor (revision 1NG) with 3763831K/6147K bytes of memory. 6 Gigabit Ethernet interfaces 2 Ten Gigabit Ethernet interfaces 32768K bytes of non-volatile configuration memory. 8388608K bytes of physical memory. 6594559K bytes of eUSB flash at bootflash:.
I am asking advice in the approaches to troubleshoot such problems and maybe some real life experience with NAT/PAT problems?
asr1.core#sh ip route 184.108.40.206 Routing entry for 220.127.116.11/26 Known via "static", distance 1, metric 0 Routing Descriptor Blocks: * 18.104.22.168 Route metric is 0, traffic share count is 1 asr1.core#sh ip route 22.214.171.124 Routing entry for 126.96.36.199/26 Known via "static", distance 1, metric 0 Routing Descriptor Blocks: * 188.8.131.52 Route metric is 0, traffic share count is 1
So route to both just pointing to nat outside interface.
In NAT routing table there is nothing to global IPs, but it's understandable cause routing happens after de-nating to private IPs
asr1.core#sh ip route vrf NAT 184.108.40.206 Routing Table: NAT % Subnet not in table asr1.core#sh ip route vrf NAT 220.127.116.11 Routing Table: NAT % Subnet not in table
Global routing table (leads to nat inside interface)
Gateway of last resort is 10.128.1.2 to network 0.0.0.0 S* 0.0.0.0/0 [1/0] via 10.128.1.2 18.104.22.168/8 is variably subnetted, 2895 subnets, 14 masks B 22.214.171.124/24 [20/0] via BGP1, 2d10h B 126.96.36.199/22 [20/0] via BGP1, 2d10h B 188.8.131.52/24 [20/0] via BGP1, 2d10h B 184.108.40.206/24 [20/0] via BGP1, 2d10h B 220.127.116.11/24 [20/0] via BGP1, 2d10h B 18.104.22.168/24 [20/0] via BGP1, 2d10h B 22.214.171.124/24 [20/0] via BGP2, 2d10h B 126.96.36.199/18 [20/0] via BGP2, 2d10h .....etc
vrf NAT routing table
Routing Table: NAT Gateway of last resort is 188.8.131.52 to network 0.0.0.0 S* 0.0.0.0/0 [1/0] via 184.108.40.206 10.0.0.0/8 is variably subnetted, 889 subnets, 10 masks S 10.0.0.0/8 [1/0] via 10.128.1.3 .....etc