ISP has given two blocks of IPs. i.e WAN(/30) & LAN(/29). Right now i have only L3 switch. How do I configure WAN and LAN IP on layer 3 switch?

You really have to elaborate on the whole situation. We don't know what you're trying to achieve here. What do you need/want?
Didn't the ISP give you a router? Do you only need internet access, or is this some kind of VPN/subscribed lines situation?

An ISP doesn't give you LAN addresses...., (normaly)... and because of the lack of addresses in IPv4 might charge you handsomely if they do.
wrt. to IPv4 you will only get a Prefix.. ie. the first 48-64 bits of the address, the remainder is up to you.
So you have to better explain.

Might it be that the /30 is a private range (10/0, 172.16/12, 192.168/16) address meant as access network with the /29 range as 5 addresses for you to use?
Anyway you will need a Router not a Switch to configure this. (including all firewalling etc.).

I remember that one provider in the US tended to hand out addresses in the exact manner you're describing. It's very doable (however, I sadly don't totally remember exactly how I had done it). I used a Cisco SG-series layer 3 switch and *think* I ended having to have 3 VLANs: 1 for management, 1 for the /29 block, and 1 for the /30. Also had to have a static default route defined.

What model switch are you using?

A.B.C.206/28 = 16 addresses (-3 for infra)   ==> A.B.C.192 - A.B.C.207 / .192 = network, .207 = broadcast, .206 = default GW
13 addresses.

Default GW on switch should be A.B.C.206   (in one VLAN)
And another VLAN for internal...  
Default GW in FW's should be A.B.C.188

If you have THIS many addresses why not a unmanageble L2 Swich, and the Firewall on the .206 VLAN  and use .203/ .204 if addresses?


Be aware that your switch is connected to the internet this way and has NO firewall in front, L3 switch are by definition manageable.
And teh switch can be managed over BOTH interfaces. Inside & out from the internet because of the public addresses.

Typically when ISP gives you two ranges. a.b.c.x/30 and z.z.z.z/28
/30 IP address is configured on link between ISP and your router.
/28 IP address range is for you to deal with it however you want.

Let's say that ISP assign you IP address/ranges:
1.1.1.2/30
ISPs address is 1.1.1.1
And additional IP address range:
2.2.2.0/28

ISP's router configuration (interested for your case - simplified):

interface gi0/0
 ip address 1.1.1.1 255.255.255.252
!
ip route 2.2.2.0 255.255.255.240

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Your router (simplest configuration, example):

interface gi0/0
 ip address 1.1.1.2 255.255.255.252
!
! then if you want to configure your range directly connected to this router
!
interface gi0/1
 ip address 2.2.2.1 255.255.255.240
!
ip route 0.0.0.0 0.0.0.0 1.1.1.1

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So all traffic from ISP router to IP address range 2.2.2.0/28 will be sent to IP address 1.1.1.2. How you will deal with it that's your choice. :)
Even if it is not Cisco equipment code should be understandable.